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RGClark
2009-Apr-02, 01:21 PM
I saw that this weeks Space Access '09 conference, http://www.space-access.org/, will have several presentations by companies working on suborbital flights for tourism.
According to this article, Virgin Atlantic is planning on marketing just suborbital flights at $200,000 and it reports a survey said orbital flights might be commercially viable at $500,000:

Space tourism survey targets cost factor.
Online results hint at future price points for suborbital and orbital flights.
By Leonard David
Senior space writer
updated 4:53 p.m. ET, Tues., Oct. 3, 2006
"Pricey seats.
"So far, orbital space tourism has been the propelled
province of well-heeled millionaires. Even for projected
suborbital jaunts — up to the edge of space and return to
Earth — the price tag for a Virgin Galactic spaceliner
seat slaps your purse or wallet for roughly $200,000.
Several key results of the space tourism survey point out:
The prices of current space treks into suborbital and
orbital are generally too high at present, with only 7
percent registering for a suborbital flight and 4 percent
for an orbital adventure at current price levels.
Suborbital flights would really take off at $25,000, and
orbital flights at $500,000, if such price levels were
compatible with an operator’s business plan. If price were
not an issue, nearly two-thirds of the respondents would
want to go on a round-the-moon adventure."
http://www.msnbc.msn.com/id/15120091/

I want to argue here that it would be feasible to provide service also for a much larger market: suborbital, hypersonic passenger flights for transcontinental and intercontinental transportation.
A round trip cross-Atlantic ticket on the Mach 2 Concorde cost around $10,000. I don't think it's out of the question that a substantial number of business executives and wealthy vacationers would be willing to pay $100,000 to make a cross-Atlantic or cross-U.S. trip that took less than an hour, especially when it included making a short stint to space in the process.
Likewise I think there would be a substantial market at $100,000 per ticket for a trip to Asia that only took 2 or 3 hours, compared to a full day as it does now.

You can make a calculation for how much fuel you would need for a rocket flying horizontally to reach a certain distance by using the rocket equation for velocity:

Vf -Vi = Ve*ln(Mi/Mf), where Vf, Mf are the final velocity and final mass, and Vi, Mi are the initial velocity and initial mass, and Ve is the exhaust velocity. The formula still works for intermediate points in the trip where you burned only a portion of the fuel, where Vf and Mf are the values at these intermediate times.
Let's say you're burning propellant at a rate r kgs/sec. Then the mass of the vehicle at time t will be Mf = Mi-rt. I'll say the initial velocity Vi is zero, and let the velocity at time t be V(t). Then the formula becomes:

V(t) = Ve*ln[Mi/(Mi-rt)]. Then we can integrate this formula for velocity to get the distance traveled, S(t):

S(t) = Ve*t - (Ve/r)*(Mi-rt)*ln[Mi/(Mi-rt)]

This formula is for the case of constant thrust, where the acceleration will gradually increase since the mass is decreasing as the fuel is used up. It might be more comfortable for the passengers if instead we used a constant acceleration flight. This would be accomplished by making the fuel flow rate, and therefore thrust, decrease as the weight decreases. The formulas for this case can be constructed in an analogous fashion to those of the classic rocket equation. I haven't calculated it but my guess is the total fuel usage would be the same as for using the fuel at a constant rate.
In any case, I will assume that just as for SpaceShipOne it will have aerodynamic shape to allow lift so that most of this propulsion can go towards providing horizontal thrust. I didn't include the drag in this first order calculation of the constant fuel rate case, but it can be added in a more detail examination. You can reduce the drag by having the craft undergo the hypersonic flight at high altitude. You can save fuel to reach this altitude by using a carrier craft such as the White Knight for SpaceShipOne. Note that you don't have to use the fuel on the carrier craft or suborbital vehicle to get to a height of say 100 km, but only to get to high enough altitude to reduce the drag and heating on the vehicle at the hypersonic velocities.
XCOR is planning on using kerosene and LOX for their engines so I'll use this type of engine for getting the Ve number. Kerosene/LOX engines can have Isp of 360 s at high altitude, which I am assuming will be the only time the rocket will be used. So Ve will be in the range of 3600 m/s at high altitude.
Let's say you want to go across the continental U.S., 4500 km. For a first generation transport vehicle let's say it's comparable in size to SpaceShipOne about 1,000 kg empty and 3,000 kg fully loaded with fuel to carry one pilot and two passengers.
Let's put in some numbers in order to calculate the distance, S(t): say t = 2500 s, about 42 minutes, r = 1 kg/s, and Mi consists of a 1000 kg vehicle with passengers and 2500 kg fuel, for a total of 3500 kg. Then we calculate: S(t) = 3600*2500 - (3600/1)*(1000)*ln(3500/1000) = 4,490,000 meters, or 4,490 km. The time of 42 minutes compares to about 6 hours for a normal passenger jet to travel this distance.
The maximum speed would be Vf = 3600*ln(3500/1000) = 4500 m/s, or Mach 15, quite a high speed. The X-15 was able to reach Mach 6.7 and was planned on being able to reach Mach 8. It had an Inconel skin with a titanium frame to resist the heat loads at these high Mach numbers.
Still for Mach 15 you might need materials even more heat resistant. In this article Burt Rutan says SpaceShipOne's carbon composite structure would not be sufficient for even the Mach 6.7 speeds of the X-15:

X-15 and today’s spaceplanes.
by Sam Dinkin
Monday, August 9, 2004
http://www.thespacereview.com/article/204/2

Still carbon-carbon composites are used for the leading edges of the wings for the Space Shuttle which have to withstand the highest temperatures of re-entry even at Mach 25, so presumably would also work at Mach 15. These carbon-carbon composites became infamous though for how they fractured under impact by foam in the Columbia accident. It turned out they are even more brittle than fiberglass.
This is a bit puzzling because the type of carbon composites used extensively for example in modern race cars is actually more fracture resistant than steel. This makes them an ideal material for race cars since they have greater strength than steel while being more fracture resistant and at a fraction of the weight. I can only assume that at the time the shuttle was being designed, these highly fracture resistant carbon composites were not available. Then the recommendation for the thermal protection is the carbon-composites of this highly fracture resistant type.
For the vehicle to be useful as a transport craft it will have to be able to take-off and land at least at international airports. Airport safety managers might not be too enthusiastic about rocket takeoff at their airports, and certainly not enthusiastic towards deadstick landings. At least for the takeoffs this uncertainly be could ameliorated by the jet engine carrier craft.
For the landings I suggest these rocket craft also have their own small jet engines so that they can do powered landings. There are some lightweight jet engines that could work for our 1000 kg first generation craft. For instance there is the TRS-18-1 engine that can produce 326 pounds of thrust and only weighs 85 pounds:

Microturbo TRS-18-1
Engine Specifications.
http://www.bd-micro.com/FLS5J.HTM#ENGINE

Two of these would probably be sufficient for landing our 1000 kg rocket plane assuming at subsonic speeds the craft had a lift/drag ratio typical for jets, which can be at 10 and above.
A more high performance and more extensively tested jet engine to use might be the PW610F. This weighs 260 pounds and can produce 900 pounds of thrust:

Pratt & Whitney Canada PW600.
http://en.wikipedia.org/wiki/Pratt_%26_Whitney_Canada_PW600

One of these would probably sufficient for our purposes. For this more high performance engine we might even be able to use it for takeoff to reach high altitude for the rocket plane, dispensing with the need for the carrier craft.
At this early stage, we would have separate jet engines and rocket engines. The jet intakes would be closed off when the rocket is operating and opened to be used only during low speed, subsonic flight. However, we can imagine with further development we would get a type of hybrid engine, as for example envisioned for the Skylon craft, where the jet and rocket engine are combined into one.


Bob Clark

NEOWatcher
2009-Apr-02, 03:25 PM
I'm only glossing over all your calculations because I'm not sure if that is a major component of the feasability of the plan.

I'm looking at it from a completely different angle relating to spaceship1, and am commenting not as a "I don't think so", but more of a "I don't know how it adds up".

SS1 goes 2200mph for 15 minutes. I'm not sure how much of that is actually acceleration, but it is only to get to that speed and not to maintain the speed for any amount of time.

You are proposing a faster speed for a sustained flight. That sounds to me like a considerably larger fuel load than your calculations indicate.

The only other option is ballistic, which would take an even higher speed.

And; you are proposing doing it for half the current cost. Somethings got to be missing.

djellison
2009-Apr-03, 06:43 AM
Somethings got to be missing.

It's called realistic engineering.

joema
2009-Apr-03, 11:52 AM
...I want to argue here that it would be feasible to provide service also for a much larger market: suborbital, hypersonic passenger flights for transcontinental and intercontinental transportation...You can make a calculation for how much fuel you would need for a rocket flying horizontally to reach a certain distance by using the rocket equation for velocity...for Mach 15 you might need materials even more heat resistant. In this article Burt Rutan says SpaceShipOne's carbon composite structure would not be sufficient for even the Mach 6.7 speeds of the X-15...

Describing SS1, SS2 or even X-15 as "suborbital" can be misleading. Technically that is true -- they didn't achieve orbit. However there's a vast difference between those and a suborbital transoceanic trajectory.

The best current example we have is the space shuttle doing a Transoceanic Abort Landing (TAL). That would actually cross the Atlantic under rocket power, just like the proposed suborbital hypersonic transport.

TAL altitude trajectory peaks at about 360,000 ft (68 miles). Required velocity varies with destination landing site, but is very high. E.g, the shuttle doesn't even attain single-engine TAL (ability to cross the Atlantic with two failed engines) until about 17,000 feet per second (11,500 mph, 5181 m/s).

Your actual required velocity for a trans-atlantic hypersonic transport would be similar to the shuttle's TAL abort MECO (Main Engine Cut Off) velocity. I don't remember that off hand, but it's close to orbital velocity.

Reentry heating and required thermal control for a TAL trajectory is similar to orbital entry, actually worse in some ways.

The required vehicle would be nothing like SS1, SS2, or even the X-15 in terms of energy required, thermal protection, etc. It would be more like the current space shuttle on a TAL abort.

However this same exercise shows a hypersonic suborbital transport is potentially feasible both technically and (surprisingly) economically.

Technically it's feasible since it has already been achieved -- the shuttle TAL abort.

Economically the shuttle's marginal launch cost (incremental cost of adding a single flight) is around $200 million -- and it's not a cheap vehicle. From a mass standpoint, the shuttle could carry 200 people in the cargo bay. They wouldn't all fit, so it's space-constrained.

If you could cram 50 people in there, for $4 million per ticket, the shuttle could be a suborbital transport right now.

If a vehicle not even designed for that role could approach that goal, it's logical a safer, cheaper, purpose-built vehicle is possible.

Something like a properly-designed, scaled-up, passenger-carrying X33 might work.

RGClark
2009-Apr-03, 02:05 PM
I'm only glossing over all your calculations because I'm not sure if that is a major component of the feasability of the plan.
I'm looking at it from a completely different angle relating to spaceship1, and am commenting not as a "I don't think so", but more of a "I don't know how it adds up".
SS1 goes 2200mph for 15 minutes. I'm not sure how much of that is actually acceleration, but it is only to get to that speed and not to maintain the speed for any amount of time.
You are proposing a faster speed for a sustained flight. That sounds to me like a considerably larger fuel load than your calculations indicate.
The only other option is ballistic, which would take an even higher speed.
And; you are proposing doing it for half the current cost. Somethings got to be missing.

You need to take into consideration the Isp of the engine for the fuel requirements. This is a measure of how much fuel you need to reach a specified thrust. The SpaceShipOne engine specifications are given here:

Scaled Composites SpaceShipOne.
Specifications.
http://en.wikipedia.org/wiki/SpaceShipOne#Specifications

SpaceShipOne uses an engine with an Isp of 250 sec, significantly lower than the Isp possible with kerosene/LOX engines when used in vacuum (actually near vacuum) of about 360 sec.


Bob Clark

NEOWatcher
2009-Apr-03, 02:36 PM
...SpaceShipOne uses an engine with an Isp of 250 sec, significantly lower than the Isp possible with kerosene/LOX engines when used in vacuum (actually near vacuum) of about 360 sec.
Ok, so that's about 1.4x the efficiency.
But; we are talking 5x just the speed alone. More for extra fuel, and more for distance.

RGClark
2009-Apr-03, 04:08 PM
Ok, so that's about 1.4x the efficiency.
But; we are talking 5x just the speed alone. More for extra fuel, and more for distance.

That is an important question you ask. The overwhelmingly key fact that makes space travel to orbit difficult is that the defining equation for rocket travel called the "rocket equation" specifies that the amount of fuel you need to reach a certain speed increases exponentially with the speed. Since the speed to attain orbit is so high, this means at least for a rocket you may need 10 times as much weight in fuel as what you wish to get in orbit.
There is also an exponential dependence on the velocity of the exhaust, i.e., small changes in the exhaust velocity causes exponentially large changes in the fuel required. This is true for all speeds not just the speed to reach orbit. So the difference in Isp from 250 s to 360 s which corresponds to a difference in exhaust velocity from 2500 m/s to 3600 m/s results in a large difference in the amount of fuel required.
See the explanation here:

Tsiolkovsky rocket equation.
http://en.wikipedia.org/wiki/Rocket_equation


Bob Clark

NEOWatcher
2009-Apr-03, 05:31 PM
The overwhelmingly key fact that makes space travel to orbit difficult is that the defining equation for rocket travel called the "rocket equation" specifies that the amount of fuel you need to reach a certain speed increases exponentially with the speed...
Right. I'm not sure the calculations which is why I'm giving vague references. But; you have me confused as to what your OP is about.

All I'm saying is that the SS1 comparisons of weights in the OP don't add up considering these issues.
I read the following that you can add 500kg of fuel to SS1(or equivalent craft) and reach 5x the speed.


Let's say you want to go across the continental U.S., 4500 km. For a first generation transport vehicle let's say it's comparable in size to SpaceShipOne about 1,000 kg empty and 3,000 kg fully loaded with fuel to carry one pilot and two passengers.
Let's put in some numbers in order to calculate the distance, S(t): say t = 2500 s, about 42 minutes, r = 1 kg/s, and Mi consists of a 1000 kg vehicle with passengers and 2500 kg fuel, for a total of 3500 kg. Then we calculate: S(t) = 3600*2500 - (3600/1)*(1000)*ln(3500/1000) = 4,490,000 meters, or 4,490 km. The time of 42 minutes compares to about 6 hours for a normal passenger jet to travel this distance.
The maximum speed would be Vf = 3600*ln(3500/1000) = 4500 m/s, or Mach 15, quite a high speed.

marsbug
2009-Apr-03, 05:47 PM
The required vehicle would be nothing like SS1, SS2, or even the X-15 in terms of energy required, thermal protection, etc. It would be more like the current space shuttle on a TAL abort.

However this same exercise shows a hypersonic suborbital transport is potentially feasible both technically and (surprisingly) economically.

Technically it's feasible since it has already been achieved -- the shuttle TAL abort.

Economically the shuttle's marginal launch cost (incremental cost of adding a single flight) is around $200 million -- and it's not a cheap vehicle. From a mass standpoint, the shuttle could carry 200 people in the cargo bay. They wouldn't all fit, so it's space-constrained.

If you could cram 50 people in there, for $4 million per ticket, the shuttle could be a suborbital transport right now.

If a vehicle not even designed for that role could approach that goal, it's logical a safer, cheaper, purpose-built vehicle is possible.

Something like a properly-designed, scaled-up, passenger-carrying X33 might work.

I've never thought of it like that! So we have a vehicle capable of point to point suborbital travel already, it's just not it's main function.
Would there be enough people needing and able to pay 4 million or so a flight to get to their destination in a couple of hours? I'm sure among businessmen and politicians there'd be some who value in person negotiations enough to pay, but would that be enough market? I'm sure there'd be military interest.

RGClark
2009-Apr-03, 06:13 PM
Describing SS1, SS2 or even X-15 as "suborbital" can be misleading. Technically that is true -- they didn't achieve orbit. However there's a vast difference between those and a suborbital transoceanic trajectory.

The best current example we have is the space shuttle doing a Transoceanic Abort Landing (TAL). That would actually cross the Atlantic under rocket power, just like the proposed suborbital hypersonic transport.

TAL altitude trajectory peaks at about 360,000 ft (68 miles). Required velocity varies with destination landing site, but is very high. E.g, the shuttle doesn't even attain single-engine TAL (ability to cross the Atlantic with two failed engines) until about 17,000 feet per second (11,500 mph, 5181 m/s).

Your actual required velocity for a trans-atlantic hypersonic transport would be similar to the shuttle's TAL abort MECO (Main Engine Cut Off) velocity. I don't remember that off hand, but it's close to orbital velocity.

Reentry heating and required thermal control for a TAL trajectory is similar to orbital entry, actually worse in some ways.

The required vehicle would be nothing like SS1, SS2, or even the X-15 in terms of energy required, thermal protection, etc. It would be more like the current space shuttle on a TAL abort.

However this same exercise shows a hypersonic suborbital transport is potentially feasible both technically and (surprisingly) economically.

Technically it's feasible since it has already been achieved -- the shuttle TAL abort.

Economically the shuttle's marginal launch cost (incremental cost of adding a single flight) is around $200 million -- and it's not a cheap vehicle. From a mass standpoint, the shuttle could carry 200 people in the cargo bay. They wouldn't all fit, so it's space-constrained.

If you could cram 50 people in there, for $4 million per ticket, the shuttle could be a suborbital transport right now.

If a vehicle not even designed for that role could approach that goal, it's logical a safer, cheaper, purpose-built vehicle is possible.

Something like a properly-designed, scaled-up, passenger-carrying X33 might work.

Thanks. Some good points.
The focus of the suborbital flight companies is just on tourism: you go up, take a look at the black night of space and come back to where you started from. But it's obvious that there would be a much bigger market if the passengers could actually travel somewhere they needed to get to quickly.
BTW, in your estimation of the speeds needed to make the hypersonic flight transatlantic, remember we are only going high speed to make the travel time short. We could of course even go subsonic and get across the Atlantic, as is done now. We don't necessarily even have to go to the altitude to be considered space, just high enough to reduce the drag at the highest speeds of the trip.
In the example of the shuttle TAL that's for when you cut-off the engine and the vehicle glides the rest of the way. However, you can in the case of the hypersonic transport trips have powered flight the entire trip.


Bob Clark

raptorthang
2009-Apr-03, 06:32 PM
The year is 2009 and not 1969. The population no longer worships at the feet of technology whether it be the Concord or the 'tallest building'. Bigger and faster had better have much better 'raison d'tre' than being the latest thrill for the rich and famous. Getting a businessman to Tokyo in half the time just won't cut it.

There are so many regulatory issues that this is dead in the water. The safetyhoops to take on paying customers as the focus would be insurmountable. These aircraft would just not have the numbers or infrastructure to even begin to meet safety standards. Large airlines with fleets of hundreds of planes can barely do it now.

No, a few tens of thousands of passenger seats in not enough....one needs repeat business and yes, the Concord 'only' cost ten thousand...but no, it was rarely full. Wealthy people are wealthy because they DON'T spend a hundred thousand on a seat when they can pay 900 for a first class ticket on a passenger airline. AND...as of this latest economic crisis no executive of any major corporation would fly at a hundred thousand since out of PR necessity many of them are now flying economy class instead of first class.

If someone wants to invest billons in airflight today. It should be, as in the automotive industry, in methods to improve energy efficiency. The Concord would not be approved today...too inefficient, too noisy and so on. For the rest of this century any large technology developments are going to have to jump environmental hurdles...PR hurdles and so on. Grandma won't be taxed for turning her thermostat up while the wealthy jaunt around in hundred thousand dollar seats.

djellison
2009-Apr-03, 06:57 PM
I
Would there be enough people needing and able to pay 4 million or so a flight to get to their destination in a couple of hours?

No, there wouldn't be. Seriously - the training, checkout etc for a sub-orbital flight like that will totally eliminate any possible savings.

LHR - LAX on a Jumbo is 11 hrs on a bad day. Add on 3 hrs checkin and baggage claim - 14 hrs. basically, a full day.

Now imagine a vehicle that's only slightly less performance orientated than a full space shuttle orbital launch - the training, the fitting out of suits, the safety briefings...that, in itself, is a day, maybe a week.

What possible benefit is there for long distance travel (the answer is none)

Sub-orbital joyrides in the SS2 / Lynx style will be it for a very VERY long time to come.

When I was a kid, you could fly to New York in 2 hrs 59 minutes.

Now, check in for that route opens 3 hours before take off.

Think about it.

joema
2009-Apr-04, 12:25 AM
...There are so many regulatory issues that this is dead in the water. The safetyhoops to take on paying customers as the focus would be insurmountable. These aircraft would just not have the numbers or infrastructure to even begin to meet safety standards...
The regulatory, safety and financial issues are being resolved for Virgin's SpaceShip 2: http://en.wikipedia.org/wiki/SpaceShipTwo

Virgin plans on a fleet of 3-5 vehicles and beginning passenger service by 2011.

Why would the regulatory and safety issues differ for a transatlantic flight vs SpaceShip 2's up/down trajectory? In both cases you're carrying paying passengers, the only difference is the velocity and destination.

raptorthang
2009-Apr-04, 01:56 AM
The regulatory, safety and financial issues are being resolved for Virgin's SpaceShip 2: http://en.wikipedia.org/wiki/SpaceShipTwo

Virgin plans on a fleet of 3-5 vehicles and beginning passenger service by 2011.

Why would the regulatory and safety issues differ for a transatlantic flight vs SpaceShip 2's up/down trajectory? In both cases you're carrying paying passengers, the only difference is the velocity and destination.

Ridiculous. Of course the two are different. If an airline had a crash every 50 or so flights it would be bankrupt in 2 seconds and have FAA launching massive investigtions as to how the aircraft was ever approved in the first place. Even if an an airline had a crash every 5,000 flights the same....immediate grounding forever.

Yup, save a couple of hours but go through a weeks training and full medical before and after every flight. You have to be kidding. 'Bye, dear I'm off to a meeting in Tokyo...it's three weeks from toady so I better get off to training school now....also, don't want to miss the special rates....only $100,000 if one stays only an extra month while the aircraft is refurbished'.

JonClarke
2009-Apr-04, 01:57 AM
The most technically developed ideas for ballistic transport AFAIK were Pegasus, Ithacus and Hyperion...

http://www.astronautix.com/craft/pegvtovl.htm

http://www.astronautix.com/lvs/ithacus.htm

http://www.astronautix.com/craft/hypnssto.htm

RGClark
2009-Apr-04, 02:25 AM
The most technically developed ideas for ballistic transport AFAIK were Pegasus, Ithacus and Hyperion...

http://www.astronautix.com/craft/pegvtovl.htm

http://www.astronautix.com/lvs/ithacus.htm

http://www.astronautix.com/craft/hypnssto.htm


Thanks for that. Hadn't heard of those before.


Bob Clark

joema
2009-Apr-04, 03:06 AM
Ridiculous. Of course the two are different. If an airline had a crash every 50 or so flights it would be bankrupt in 2 seconds and have FAA launching massive investigtions ...
None of two I mentioned were a conventional airliner.

You said regarding a hypersonic transport: "There are so many regulatory issues that this is dead in the water. The safetyhoops to take on paying customers as the focus would be insurmountable."

My point was SpaceShip 2 is a hypersonic transport, albeit not transoceanic. It's not dead in in the water due to regulatory issues. It plans on taking paying customers.

Since this is already in progress, how can it be "dead in the water"?

If you mean a transoceanic hypersonic transport, how are the regulatory and safety issue different between that and SpaceShip 2? They both carry passengers, are both hypersonic and both suborbital. They differ only the max velocity and destination.

What exact regulatory issues would render a transoceanic hypersonic passenger transport "dead in the water", and not likewise affect SpaceShip 2?

RGClark
2009-Apr-04, 03:59 AM
Right. I'm not sure the calculations which is why I'm giving vague references. But; you have me confused as to what your OP is about.

All I'm saying is that the SS1 comparisons of weights in the OP don't add up considering these issues.
I read the following that you can add 500kg of fuel to SS1(or equivalent craft) and reach 5x the speed.

You're right. The increase in the engine exhaust velocity is not enough to explain the difference. For SpaceShipOne the entire purpose is getting to that high altitude of 100 km. So alot of the thrust is working against gravity. And since its engine is lit at about 41,000 feet, about 14 km, there is still a alot of air drag in the initial part of the trip.
For the transport flight in contrast you don't need to get to the altitude of 100km. You can use your carrier craft to get you to the high altitude you need and the entire rocket thrust would be used just for increasing your horizontal velocity.


Bob Clark

RGClark
2009-Apr-04, 04:21 AM
Just saw this article on Rocketplane XP, which plans to offer suborbital, tourism rocket flights, while using jet engines for take-offs and landings:

Rocketplane reset
by Jeff Foust
Monday, November 5, 2007
http://www.thespacereview.com/archive/994a.jpg
The revised Rocketplane XP design (above) is intended ultimately to be more competitive in the emerging suborbital space tourism conference.
http://www.thespacereview.com/article/994/1

The Second Space Age.
March 6, 2008
Patrick Mahoney
"Ready for a space cruise? The technology is taxiing to the runway."
http://machinedesign.com/article/the-second-space-age-0306

Rocketplane XP's current design was modified from the original Lear Jet base airframe but still has the look of a passenger business jet, with a rocket in the tail.
It has some titanium and steel portions to withstand the heat of reentry in addition to an aluminum frame. This makes it heavier than a Lear Jet and it has to use a long military base runway for take-offs and landings. However, quite likely if it used all composite materials, as does SpaceShipOne, to replace the heavy steel, titanium, and aluminum it could take off and land from a standard sized airport runway.


Bob Clark

RGClark
2009-Apr-04, 05:17 AM
The Europeans have also proposed a business jet model for a suborbital tourism rocket:

DATE:14/06/07
SOURCE:Flightglobal.com
PICTURES: Astrium aims for 2012 suborbital tourism flights.
By Rob Coppinger
http://www.flightglobal.com/assets/getAsset.aspx?ItemID=18124
The space jet will take off from a conventional runway, powered by two jet engines, and fly to 39,300ft (12,000m), where it will ignite its liquid oxygen, methane rocket engine providing an ascent acceleration of 3g. After 80s the jet will reach 196,000ft and coast to its apogee.
http://www.flightglobal.com/articles/2007/06/14/214632/pictures-astrium-aims-for-2012-suborbital-tourism-flights.html

Interestingly, they consider this as a precursor to a point-to-point transport.


Bob Clark

marsbug
2009-Apr-04, 12:37 PM
No, there wouldn't be. Seriously - the training, checkout etc for a sub-orbital flight like that will totally eliminate any possible savings.

LHR - LAX on a Jumbo is 11 hrs on a bad day. Add on 3 hrs checkin and baggage claim - 14 hrs. basically, a full day.

Now imagine a vehicle that's only slightly less performance orientated than a full space shuttle orbital launch - the training, the fitting out of suits, the safety briefings...that, in itself, is a day, maybe a week.

What possible benefit is there for long distance travel (the answer is none)

Sub-orbital joyrides in the SS2 / Lynx style will be it for a very VERY long time to come.

When I was a kid, you could fly to New York in 2 hrs 59 minutes.

Now, check in for that route opens 3 hours before take off.

Think about it.

I agree, but a very long time isn't never, and at least this wild idea has a functioning, if totally impractical, example.
If one day you could walk onto a craft like we do 747's, and developments in related areas (like orbital and suborbital tourism) brought the cost of the technology down, and it's reliability and performance up, I expect someone would be there to make money from it.

RGClark
2009-Apr-04, 02:15 PM
The Europeans have also proposed a business jet model for a suborbital tourism rocket:

DATE:14/06/07
SOURCE:Flightglobal.com
PICTURES: Astrium aims for 2012 suborbital tourism flights.
By Rob Coppinger
http://www.flightglobal.com/articles/2007/06/14/214632/pictures-astrium-aims-for-2012-suborbital-tourism-flights.html

Interestingly, they consider this as a precursor to a point-to-point transport.



Another article on the proposed Astrium suborbital, tourism rocketplane:

Space planes 'to meet big demand'.
By Jonathan Amos, Science reporter, BBC News
Monday, 17 March 2008, 13:38 GMT
"Aerospace giant EADS says it will need a production line of rocket planes to satisfy the space tourism market."
http://news.bbc.co.uk/2/hi/science/nature/7298511.stm

There is a link to a nice video of a simulated flight on this page. In the video the passengers are wearing helmets with closed visors. But it doesn't look like they are wearing actual spacesuits with independent air supplies because the helmets are not connected to the rest of the suits. The helmets have more the look of motorcycle helmets. I don't know if this is really supposed to be accurate.


Bob Clark

RGClark
2009-Apr-04, 04:20 PM
Another suborbital, tourism rocket plane based on a business jet model:

Bristol Spaceplanes - Ascender.
http://www.bristolspaceplanes.com/projects/images/ascender_580.gif
http://www.bristolspaceplanes.com/projects/ascender.shtml

There have been several studies showing just for tourism there would be a sufficient market for such suborbital flights to be profitable. I have to think there would be a bigger market for cases where the traveler would actually want to go somewhere and this method could get him there in 1/10th the time.
As a point of comparison I did a search on the Japan Airlines site for round trip business class tickets from my town of Philadelphia to Tokyo.
It ranged from $6,600 to $21,000:



Select Your Flights

Philadelphia to Tokyo Thursday, April 9, 2009
Tokyo to Philadelphia Tuesday, April 14, 2009
Travelers: 1
Travel class: Business and First

Select your fare: Price differences within a fare type may be due to flight connections or availability. Prices are per adult passenger and include Taxes and Surcharges.

Fare type Fare description Lowest price
Business Saver Special Restricted. Bed-style seating on most long-haul routes -
Executive Class. more details $6,672.48
Business Saver Restricted. Bed-style seating on most long-haul routes -
Executive Class. more details $7,611.48
Business Normal Flexible. Bed-style seating on most long-haul routes -
Executive Class. more details $12,330.48
First Normal Flexible. World-renowned service and comfort - First Class.
more details $21,589.48

Note also, that the $200,000 ticket price mentioned for suborbital flights on SpaceShipOne is only for the first few flights. After, a few years the price is expected to come down to $20,000.


Bob Clark

RGClark
2009-Apr-05, 02:09 PM
Another suborbital tourism project was posted on the SpaceFellowship.com forum:

Project Enterprise.
http://www.european-spacetourism.eu/index2.html

I noted in their simulated video of the trip, it has the passengers wearing oxygen masks.


Bob Clark

RGClark
2009-Apr-05, 02:11 PM
In this animation of the SpaceShipTwo trip, the passengers also do not appear to be wearing actual spacesuits, though they do have helmets:

Virgin Galactic SpaceShipTwo Animation.
http://www.youtube.com/watch?v=Cw1WaW8JsFs


Bob Clark

Ara Pacis
2009-Apr-05, 07:39 PM
I have always liked this idea since I read about it in Heinlein's book, Friday. He didn't explain the technical details, just the basics of how it was part of the infrastructure.

That is, perhaps, where this argument should begin. We know it's techically possible. What we need to know is if it is financially plausible. Start by estimating the market and the potential demand. Include other issues not related to the technology, such as time and space and infrastructure restraints as well as possible regulatory necessities.

A purpose-built point-to-point hypersonic transport will not look like the Space Shuttle or those other ballistic rockets shown above. If it spends a lot of time in the hypersonic flight regime, it will probably best resemble a wave-rider (an inverted half-cone that creates compression lift) or something that resembles the simpler Sears-Haack body with wings, like the Skylon.

I also wouldn't consider the costs of the SST as much of that is government waste and labor retention. You need to estimate realistic fuel and labor costs for operations, while amortizing R&D (unless subsidized by a government) in order to arrive at an estimated ticket cost that is within an order of magnitude of reality. Additional real costs would be infrastructure acces and regulatory fees, security, etc.

Boarding and loading times will vary depending upon the capacity of the vehicle. The mention of 3 hours for pax is due to issues of security, curb-to-gate pedestrian transit time, general queing time, vehicle turn-around-time and built in delays, and actual boarding and loading time. If you plan to shuttle hundreds of people in one of these proposed vehicles, then it may take a while to load. So, if you load fewer people, the time is reduced. Howeover, if you require larger runways or other facilities more distant from the airport, then intra-terminal transit time can increase, or costs may increase if you desire to install a rail-line in between.

Life and health concerns are valid, but may not need to be prohibitive. Roller coasters already exclude people based on height and post disclaimers regarding ailments that may be problematic. Current air travel can be problematic for certain people. Deep Vein Thrombosis is also a risk of air travel, but that does not prevent airlines from operating or people from taking the risk. A viable business model will need to use a technology that does not require weeks of training, and/or include the cost of lobbying for regulatory changes to remove a training requirement. Pressure suits may or may not be required, depending on regulations and risk assessments and backup systems and probabilities or breach-and-repair or breach-followed-by-catastrophic-failure (in which case a p-suit is useless). A helmet-alone may indeed be more helpful on a mass/usefulness risk assessment.

NEOWatcher
2009-Apr-06, 02:32 PM
You're right. The increase in the engine exhaust velocity is not enough to explain the difference. For SpaceShipOne the entire purpose is getting to that high altitude of 100 km. So alot of the thrust is working against gravity.


... And since its engine is lit at about 41,000 feet, about 14 km, there is still a alot of air drag in the initial part of the trip.
But enough to count for 80% of the thrust?

For the transport flight in contrast you don't need to get to the altitude of 100km. You can use your carrier craft to get you to the high altitude you need and the entire rocket thrust would be used just for increasing your horizontal velocity.
Just exactly how high would the carrier get you? And how much of that drag is reduced?
Sure you can reduce some, but the very reason you have drag is the very reason the mother ship can carry the craft in the first place.
I would imagine that SS1 is near that point of diminishing returns now.

RGClark
2009-Apr-07, 04:39 PM
But enough to count for 80% of the thrust?

Just exactly how high would the carrier get you? And how much of that drag is reduced?
Sure you can reduce some, but the very reason you have drag is the very reason the mother ship can carry the craft in the first place.
I would imagine that SS1 is near that point of diminishing returns now.

The velocity requirements to overcome gravity and drag just for getting to the altitude for space are quite high, nevermind that required for orbital velocity:

Delta-v budget.
"The delta-v requirements for sub-orbital spaceflight can be surprising. For the Ansari X Prize altitude of 100 km, Space Ship One required a delta-v of roughly 1.4 km/s. To reach low earth orbit of the space station of 300 km, the delta-v is over six times higher -- 9.2 km/s.
Launch/landing budget
* Launch to LEO — this not only requires an increase of velocity from 0 to 7.8 km/s, but also typically 1.5–2 km/s for atmospheric drag and gravity drag"
http://en.wikipedia.org/wiki/Delta-v_budget#General_principles

I'm estimating an altitude for low drag transport flight in the range of 100,000 to 150,000 feet, 30km to 50 km. Remember all the energy for getting to this altitude is made by the carrier craft. The U-2 and SR-71 aircraft were capable of reaching 85,000+ ft with payload. This was using 1960's technology, with steel, aluminum, and titanium materials.
Using all composites they could be made significantly lighter and very likely could reach 100,000 to 150,000 feet with payload. A variant of a 1960's era Russian aircraft, the MiG-25, was already able to reach 120,000 ft altitude in a test flight in 1977:

Mikoyan-Gurevich MiG-25.
# 1.2 Aircraft design phase
http://en.wikipedia.org/wiki/MiG-25#Aircraft_design_phase

The air drag is linearly dependent on air pressure. This page gives some air pressure values at altitude:

Atmospheric pressure.
http://en.wikipedia.org/wiki/Atmospheric_pressure

Judging from the information there, the pressure at 41,000 feet where SpaceShipOne is released is between 1/5th to 1/10th that at sea level. However, the pressure at 100,000 feet is 1/100th that at sea level, and at 150,000 feet it's 1/1000th that at sea level. Keep in mind though that in my estimate of the fuel requirements I didn't include the extra amount that would be required to overcome drag.


Bob Clark

Siguy
2009-Apr-07, 04:42 PM
None of the new space tourism rocket planes can really be compared to a hypersonic transport. Really, the only design I've seen that would ever be practical and cost effective is the Reaction Engines A2.
http://en.wikipedia.org/wiki/Reaction_Engines_A2

RGClark
2009-Apr-07, 04:49 PM
...
Life and health concerns are valid, but may not need to be prohibitive. Roller coasters already exclude people based on height and post disclaimers regarding ailments that may be problematic. Current air travel can be problematic for certain people. Deep Vein Thrombosis is also a risk of air travel, but that does not prevent airlines from operating or people from taking the risk. A viable business model will need to use a technology that does not require weeks of training, and/or include the cost of lobbying for regulatory changes to remove a training requirement. Pressure suits may or may not be required, depending on regulations and risk assessments and backup systems and probabilities or breach-and-repair or breach-followed-by-catastrophic-failure (in which case a p-suit is useless). A helmet-alone may indeed be more helpful on a mass/usefulness risk assessment.

In their usual good reporting, the BBC discusses directly the safety issues for these suborbital tourism flights:

Space ships: the next generation - Space Tourist- BBC Science & Nature.
http://www.youtube.com/watch?v=g_ROkapCj14&feature=related

Bob Clark

RGClark
2009-Apr-19, 08:28 AM
This site is an informative compendium of articles related to space flight, and particularly space tourism:

SPACE FUTURE.
http://www.spacefuture.com/home.shtml

Here's an article re-printed on the site on commercial orbital and suborbital flights:

New Commercial Opportunities in Space.
D M Ashford
The Aeronautical Journal, February 2007.
http://www.spacefuture.com/archive/images/new_opportunities_in_commercial_space.10.png
Of aeroplanes that have actually flown, and with the possible exception of SpaceShipOne, the one most suitable for providing the basis of a space tourism industry is perhaps the Saunders Roe SR.53 rocket fighter that first flew in 1957. This is probably the most practical rocket-powered aeroplane yet built.
If it had entered service, the RAF would soon have had a mature rocketplane with long life and rapid turnaround. With straight-forward development, the SR.53 could have had sub-orbital performance. Indeed, when it was cancelled as a fighter in 1958, Saunders Roe did propose a space research variant(17).
http://www.spacefuture.com/archive/new_opportunities_in_commercial_space.shtml

Note that the example of the Saunders Roe SR.53 shows that an aircraft can successfully operate with both rocket and jet engines.

Bob Clark

Siguy
2009-Apr-19, 12:13 PM
You keep up bringing out examples of suborbital space planes and space tourism vehicles. These are very bad examples of hypersonic transports! SpaceShipTwo, for example, doesn't even reach hypersonic speeds and has extremely limited downrange, essentially where it starts. It does not have the thermal protection to survive sustained hypersonic speed even if it could achieve it. Airbreathing LH2 powered craft are really the way to go, like the A2 I linked earlier.

Nicolas
2009-Apr-19, 05:04 PM
I've worked on hypersonic suborbital transport systems. You may want to research LAPCAT. LAPCAT M5 for starters, LAPCAT M8 for the real stuff (LAPCAT M8 can be considered the real Aurora, as shapewise it is very similar to the sketches of Aurora. Totally unrelated though, different continent and decade.). I worked on a.o. the propulsion system for the M8. There were some other variants for hypersonic suborbital transport systems researched, but then I get into the "I'd have to kill you" area.

Nicolas
2009-Apr-19, 05:06 PM
I'll add that if you want to transport a significant number of persons at hypersonic speeds from Europe to say Australia, you're talking about seriously different craft than these commercial edge-of-space-bump toys. Orders of magnitude different.

djellison
2009-Apr-19, 05:09 PM
Note that the example of the Saunders Roe SR.53 shows that an aircraft can successfully operate with both rocket and jet engines.

It never entered service. :rolleyes:

Thanks for the injection of reality-check Nicolas - some refuse to believe the reality of the challenge being presented here.

Nicolas
2009-Apr-19, 06:22 PM
To give you an idea:

When people asked us weight estimates of the craft designs, a give-or-take 100 tons precision was sufficient.
SpaceShipOne weighs 3.6 tons...

The range of our craft was Brussels - Sydney.
SpaceShipOne has a range of 65km...

Our designs had to fly at mach 8, sustained.
SpaceShipOne has a maximum velocity of mach 3.09...

True, we did intend to fly less high than SS1. But you can't simply scale a space tourism vertical jump craft to a large passenger plane hypersonic suborbital intercontinental craft. And if you want to scale it, use a LARGE factor.

(I use the past tense because I no longer work on the project; however it is quite possible that the project still continues today. Its goal is not to make a craft but to research the technology needed)

RGClark
2009-Apr-20, 03:39 AM
You keep up bringing out examples of suborbital space planes and space tourism vehicles. These are very bad examples of hypersonic transports! SpaceShipTwo, for example, doesn't even reach hypersonic speeds and has extremely limited downrange, essentially where it starts. It does not have the thermal protection to survive sustained hypersonic speed even if it could achieve it. Airbreathing LH2 powered craft are really the way to go, like the A2 I linked earlier.

I like the idea of Reaction Engines combining the turbojet and ramjet into a single engine:

Reaction Engines A2.
http://en.wikipedia.org/wiki/Reaction_Engines_A2

This Wikipedia article however says it might take 25 years to develop this hypersonic transport. I'm fairly certain that orbital space travel will be routine by then which would allow point-to-point travel at Mach 25, rather than the Mach 5 proposed for the A2.
Aircraft with separate jets and rockets have already been made. Given the knowledge on this going back 50 years, a modified SpaceShipOne prototype with both jets and rockets probably could be produced within a year to confirm the feasibility of its use for transport purposes.
We already have several methods that could solve the heating problems for the hypersonic transports. One would be the metallic thermal protection system developed for the X-33 which has been tested and proven to be viable:

New Thermal Protection For Reusable Rockets.
By Leonard David, Senior Space Writer.
posted: 07:00 am ET30 January 2002
http://www.space.com/businesstechnology/technology/armor_tps_020130-1.html


Bob Clark

RGClark
2009-Apr-20, 05:34 AM
To give you an idea:

When people asked us weight estimates of the craft designs, a give-or-take 100 tons precision was sufficient.
SpaceShipOne weighs 3.6 tons...

The range of our craft was Brussels - Sydney.
SpaceShipOne has a range of 65km...

Our designs had to fly at mach 8, sustained.
SpaceShipOne has a maximum velocity of mach 3.09...

True, we did intend to fly less high than SS1. But you can't simply scale a space tourism vertical jump craft to a large passenger plane hypersonic suborbital intercontinental craft. And if you want to scale it, use a LARGE factor.

(I use the past tense because I no longer work on the project; however it is quite possible that the project still continues today. Its goal is not to make a craft but to research the technology needed)

SpaceShipTwo will hold six passengers and two pilots. According to the news reports, the ticket prices initially will be $200,000 but will come down to $20,000 in just a few years. I'm envisioning a first generation suborbital transport will be analogous to this.
I calculated before in the simplified case that didn't include drag a cross continental U.S. suborbital transport the size of SpaceShipOne could have only moderately more fuel requirements than SpaceShipOne itself. Then IF the price estimates for SpaceShipTwo coming down to only $20,000 within a few years are accurate, we can imagine the same would be true for a comparably sized suborbital transport. Note that this price is comparable to round-trip trans Pacific first-class tickets now.
BTW, on another space discussion list someone did present the calculations including drag for the fuel requirements for a suborbital transport. The results showed, rather surprisingly, that in regards to drag, the fuel requirements depended only on the lift-drag ratio L/D. Then if you could get a fair L/D at hypersonic speeds such as 6 to 8 known to be possible with some lifting body shapes and you used now a liquid hydrogen engine, which has a higher Isp, then the fuel requirements again would be comparable to those of SpaceShipOne/Two. If you used easier to work with kerosene-fueled engines, the fuel requirements might be twice as great, but probably still doable.
However, another factor that I didn't take into account before was also mentioned on that space list, that at hypersonic speeds you can glide significantly farther than you would think just by the lift-drag ratio. For instance the space shuttle because of its large re-entry speed glides quite a large distance despite it's poor hypersonic lift-drag ratio. The idea behind this is that you trade your kinetic energy for altitude. Then the maximum distance for your glide would be (L/D)*(H + V^2/2g). You see this would be quite significant at hypersonic speeds. For more on this do a web search on "boost-glide" or "glide rockets".
When you take this into account, a kerosene-engine transcontinental U.S. suborbital transport would have comparable fuel requirements as SpaceShipOne/Two and a liquid hydrogen fueled engine would actually require less fuel.


Bob Clark

RGClark
2009-Apr-20, 05:46 AM
It never entered service. :rolleyes:

Thanks for the injection of reality-check Nicolas - some refuse to believe the reality of the challenge being presented here.

At the time it was proposed in the early 50's the idea was to get a Mach 2+ fighter, since jet engines weren't capable of that speed at the time. However, the development of Mach 2+ jet engines made it obsolete.
Now, there are no jet engines that can operate at say Mach 6 and above. Rockets do that routinely of course even up to and beyond Mach 25, orbital velocity. Then we can implement combined jet/rocket craft that can operate at these high hypersonic speeds now.
I would actively look forward to jets that can also operate at these speeds, but as for now rockets are the best we have.


Bob Clark

RGClark
2009-Apr-20, 06:26 AM
I've worked on hypersonic suborbital transport systems. You may want to research LAPCAT. LAPCAT M5 for starters, LAPCAT M8 for the real stuff (LAPCAT M8 can be considered the real Aurora, as shapewise it is very similar to the sketches of Aurora. Totally unrelated though, different continent and decade.). I worked on a.o. the propulsion system for the M8. There were some other variants for hypersonic suborbital transport systems researched, but then I get into the "I'd have to kill you" area.

On the Wikipedia page for the LAPCAT program I found this interesting reference:

Europe speeds up hypersonics research.
http://www.aiaa.org/aerospace/images/articleimages/pdf/Hypersonics_Aerospace_JUN2008.pdf

It contained this passage:



Both Scimitar and Sabre engines are designed
around existing gas turbine, rocket and
subsonic ramjet technology. One of the main
features of the Scimitar engine is the extensive
use of lightweight heat exchangers, required to
precool the air and transfer heat within the
thermodynamic cycle. This allows the use of a
relatively conventional turbocompressor.
“One of our major challenges has been the
design of the heat exchangers; we’ve had to design
them to transfer around 400 MW in the
precooling stage. In a conventional power station
that would take up 200 tonnes of equipment,
but we’ve had to compress that to 1.25
tonnes. By and large we’re there.”

I was reminded of heat exchanger methods using phase change which can transfer quite large amounts of heat rapidly.
I discussed this fact in this post to sci.astro:

================================================== =====
Newsgroups: sci.astro, sci.chem, sci.physics, sci.mech.fluids, sci.engr.mech
From: "Robert Clark" <rgregorycl...@yahoo.com>
Date: 9 Aug 2006 19:32:12 -0700
Local: Wed, Aug 9 2006 10:32 pm
Subject: Need a high heat of vaporization material.

This post discusses using heat exchangers to transfer the high
temperatures produced by slowing down the hypersonic air stream to
hydrogen fuel in airbreathing propulsion:

From: Robert Clark
Date: Fri, Jun 23 2006 12:52 pm
Email: "Robert Clark" <rgregorycl...@yahoo.com>
Groups: sci.astro, sci.space.policy, sci.physics, sci.mech.fluids,
sci.engr.mech
Subject: Proposals for air breathing hypersonic craft. III
http://groups.google.com/group/sci.astro/msg/efee9dd093664014

Because of the great amount of heat that would be produced and the
high speed of the air coming in, you would need a heat exchanger that
can transfer large amounts of heat quickly. One of the most efficient
forms of heat exchangers is the heat pipe:

Los Alamos-developed heat pipes ease space flight.
"Early Los Alamos heat pipes contained water or sodium. Now they also
use lithium, a soft silver-white chemical element that is the lightest
known metal. The lithium is inside a molybdenum pipe, which can operate
at white-hot temperatures approaching 2,200 degrees Fahrenheit.
"The lithium vaporizes and carries energy down the length of the heat
pipe,' says Reid. 'A lithium heat pipe developed at Los Alamos in the
mid-1980s transferred heat energy at a power density of 23 kilowatts
per square centimeter. To put this figure in perspective, heat is
emitted from the sun's surface at a mere six kilowatts per square
centimeter. We now routinely build heat pipes with similar capability."
http://www.lanl.gov/news/index.php?fuseaction=home.story&story_id=1021

Heat pipes work by using the heat provided at the hot end to vaporize
a working material. This hot vapor is transported to the cool end where
it condenses, thus giving up the heat that was used to vaporize it to
the cool end of the pipe. The condensed working material flows back to
the hot end by gravity or capillary action to continue the cycle.
For the application to an orbital craft, I want a working material
that would absorb the largest amount of heat in vaporizing at a
lightweight. Here's a table of the heat of vaporization for the
elements:

Standard enthalpy change of vaporization.
http://en.wikipedia.org/wiki/Standard_enthalpy_change_of_vaporization

This table is in kilojoules per mole. When you take into account the
molecular weight of the element, the highest in kilojoules per gram is
boron at about 44 kJ/g.
Are there highly refractory compounds that could do better than this?
Some possibilities that come to mind are boron nitride or boron carbide
or other refractory carbides:

ULTRA-REFRACTORY CARBIDES.
http://www.ultramet.com/carbide.htm

However, I haven't been able to find the heat of vaporization for any
of these.
================================================== ==

The lithium heat-pipe mentioned transferring heat at a rate of 23 kilowatts per square centimeter means it could transfer 230 megawatts per square meter. This though doesn't tell us how lightweight the system could be. Still it might be something the LAPCAT team might want to investigate as well as if replacing the lithium with boron could make the system even more lightweight.
Note also as discussed in the article such heat pipes might be used as part of a thermal protection system during hypersonic flight.


Bob Clark

RGClark
2009-Apr-20, 07:37 AM
On the Space Future site, another interesting article:

Flight Mechanics of Manned Sub-Orbital Reusable Launch Vehicles with Recommendations for Launch and Recovery.
Marti Sarigul-Klijn Ph.D. and Nesrin Sarigul-Klijn*, Ph.D
AIAA 2003-0909
January 2003 (Revised April 2003)
http://www.spacefuture.com/archive/images/flight_mechanics_of_manned_suborbital_reusable_lau nch_vehicles_with_recommendations_for_launch_and_r ecovery.7.png
Lockheed NF-104 (USAF image)
http://www.spacefuture.com/archive/flight_mechanics_of_manned_suborbital_reusable_lau nch_vehicles_with_recommendations_for_launch_and_r ecovery.shtml

It discusses four separate combined jet/rocket aircraft.


Bob Clark

Nicolas
2009-Apr-20, 07:56 AM
SpaceShipTwo will hold six passengers and two pilots. According to the news reports, the ticket prices initially will be $200,000 but will come down to $20,000 in just a few years. I'm envisioning a first generation suborbital transport will be analogous to this.
I calculated before in the simplified case that didn't include drag a cross continental U.S. suborbital transport the size of SpaceShipOne could have only moderately more fuel requirements than SpaceShipOne itself. Then IF the price estimates for SpaceShipTwo coming down to only $20,000 within a few years are accurate, we can imagine the same would be true for a comparably sized suborbital transport. Note that this price is comparable to round-trip trans Pacific first-class tickets now.
BTW, on another space discussion list someone did present the calculations including drag for the fuel requirements for a suborbital transport. The results showed, rather surprisingly, that in regards to drag, the fuel requirements depended only on the lift-drag ratio L/D. Then if you could get a fair L/D at hypersonic speeds such as 6 to 8 known to be possible with some lifting body shapes and you used now a liquid hydrogen engine, which has a higher Isp, then the fuel requirements again would be comparable to those of SpaceShipOne/Two. If you used easier to work with kerosene-fueled engines, the fuel requirements might be twice as great, but probably still doable.
However, another factor that I didn't take into account before was also mentioned on that space list, that at hypersonic speeds you can glide significantly farther than you would think just by the lift-drag ratio. For instance the space shuttle because of its large re-entry speed glides quite a large distance despite it's poor hypersonic lift-drag ratio. The idea behind this is that you trade your kinetic energy for altitude. Then the maximum distance for your glide would be (L/D)*(H + V^2/2g). You see this would be quite significant at hypersonic speeds. For more on this do a web search on "boost-glide" or "glide rockets".
When you take this into account, a kerosene-engine transcontinental U.S. suborbital transport would have comparable fuel requirements as SpaceShipOne/Two and a liquid hydrogen fueled engine would actually require less fuel.


Bob Clark

Bob,

I've actually worked on this thing. Believe me: about 100 passengers (IIRC), hypersonic, to another continent: a few hundred tons of hydrogen, it's more like a fuel tank with some passengers than the other way around. Note that hydrogen has a low density, so we're talking about a HUGE fuel tank.

It all seems possible and doable in the future. I just wouldn't take SS2 as the basis to scale things up, as it's a whole different thing. SS2 uses a rocket that burns for a short time, giving large acceleration and a short range. If you want to go to longer ranges, larger craft and better (re)usability and want to bring along more than just your own fuel tanks, you'd better look into air breathing engines. Rocket assisted to get them into their own mach range possibly. But rockets from start to finish would get nasty if you scale it up. If only for noise abatement reasons.

I don't know about smaller craft, I didn't look into that. Still, my gut feeling tells me that you'd need quite a rocket to shoot a business jet size thing hypersonically accross the ocean. The kind of rocket that would not be allowed at airports or above cities.

About the gliding: you can use that, but remember the goal is to get there fast. Brussels - Sydney in less than three hours in our case. That doesn't allow for a lot of gliding...

Nicolas
2009-Apr-20, 08:12 AM
Regarding "doing some calculations": you can use the rocket equation with some hypersonic drag and lift calculations to get an idea of a rocket propelled craft, but for air breathing engines it isn't that simple if you don't have the thrust and fuel figures already. It took me half a year to make a mathematical model of the engine, and it still wasn't complete at that stage. You get into all kinds of nastiness such as chemical decomposition of combustives because of the extreme temperatures.

RGClark
2009-Apr-21, 09:04 PM
Another method currently being investigated for cooling the hottest surfaces on spacecraft is cooling by heat pipes:

ACT Successfully Demonstrates High Temperature Heat Pipe Wing Leading Edge for Space Reentry Vehicles.
PRNewswire
(05/31/2005 12:00 PM EDT)
http://www.eetimes.com/press_releases/prnewswire/showPressRelease.jhtml?articleID=X333041&CompanyId=1


Bob Clark

RGClark
2009-Apr-23, 04:13 AM
Interesting early article discussing re-entry problems including thermal control. It gives a graphic showing a "corridor" where a rocket could cruise or glide at hypersonic speeds at manageable temperatures while maintaining aerodynamic lift:



Aerodynamics for Space flight.
E.P. Williams, Carl Gazley, Jr.
The Rand Corporation, 1958
The lower limit of the corridor of continuous flight is unfortunately quite sensitive to the allowable skin temperature. As you can see by extrapolating from 2500 deg and 2000 deg, a 1500 deg limit would cut off the corridor at less than satellite speeds. However 2000 deg is believed indicative of present design capability with high temperature alloys.
A cruise-type aircraft could be built to fly anywhere within this corridor. Glide rockets, including those re-entering from satellite orbits, will, of course, descend along this corridor.
p.15 (degrees given in Fahrenheit)
http://www.rand.org/pubs/papers/2007/P1256.pdf


Bob Clark

publiusr
2009-Apr-27, 06:52 PM
As you know, I'm always looking for the story behind the story.

As it stands now, Europe is having to rely upon the new R-7 pad and its launch vehicle to make up for the vacancy left behind by the phasing out of Ariane 4. Ariane 5 is still being "tweaked," what with the continued giganism of comsats: http://www.space.com/businesstechnology/090413-sn-busmon-ariane5-tweaked.html


The folks across the pond ultimately want an all European LV stable, and the DLR "Spaceliner" (which wisely leaves all the air-breathing nonsense out) seems to be just one 'payload' being promised so as to drum up support for the winged flyback booster whose true use will be as a strap-on for typical ELVs, or to replace EELV first stage altogether. That and German enthusiasts still want something named Silverbird to fly to space with wings.

If hypersonics are available, they might be open to that, but from what I gather reading from page 38 of the May 2009 Popular Science, the Spaceliner is just to be an all rocket NASP to be released from a multi-function fly-back booster that has other markets. I think this is the new name or replacement for "Oural," but that was a more Russian based system.

Related links:

http://www.portaltotheuniverse.org/blogs/posts/view/5262/ testbed work

Scroll down to see artwork of Spaceliner. The art seems similar to Pop Sci's
http://nextbigfuture.com/2009/04/europe-space-agency-hypersonic-plane.html
http://2.bp.blogspot.com/_VyTCyizqrHs/SeTD5lL1hUI/AAAAAAAADdQ/Vi4BkDyuogA/s1600-h/DLRrocketplane.JPG

Now according to this site, all of this is part of Aldebaran--and I don't mean Dandridge Cole's monster nuclear ship
--Actually it seems to be more a micro satellite line now that I look more closely

http://en.scientificcommons.org/martin_sippel
http://forum.nasaspaceflight.com/index.php?topic=9202.msg169837#msg169837

The spaceliner would serve as the fly-back boosters prestige payload, and be more useful than Rutan's toy as a latter day Silverbird:
http://www.flightglobal.com/articles/2009/01/28/321749/europe-aims-for-2015-spaceshiptwo-competitor.html
http://www.dlr.de/en/desktopdefault.aspx/tabid-4530/3681_read-8344/3681_page-2/

Cooling methods
http://www.springerlink.com/content/8m724k5545u08291/

Frankly, the Ariane M HLLV would be cheaper to develop, as its Vega based strap-ons are almost ready to fly now. Oh, wait such solid strap-ons are already flying with Ariane V. But what do I know.

"A simple scaled up tube, which an HLLV is? Nah--thats too hard. Let's put wings on everything--that's economical, right?"

I hope I am proved wrong. http://en.wikipedia.org/wiki/Ariane_M

But as you can see there is opposition to Ariane M
http://forum.nasaspaceflight.com/index.php?topic=5598.msg101286#msg101286
http://forum.nasaspaceflight.com/index.php?topic=5598.msg101197#msg101197

That is okay--the sad thing is that this fine website has now become "The Jim Show"
http://forum.nasaspaceflight.com/index.php?topic=8065.msg142163;topicseen#msg142163
Here are some of his greatest hits (or misses as is the case) plus nice blurbs from me for humor's sake :)

1.)Jim shows his ignorance on NRO, space-based radar, etc.
http://forum.nasaspaceflight.com/index.php?topic=5028.msg108396#msg108396
http://forum.nasaspaceflight.com/index.php?topic=5028.msg109881#msg109881
http://forum.nasaspaceflight.com/index.php?topic=5028.msg110892#msg110892

2.)His talk about the "Atk mafia"--and I call him on it.
http://forum.nasaspaceflight.com/index.php?topic=6388.msg106571#msg106571
http://forum.nasaspaceflight.com/index.php?topic=2665.msg40677#msg40677
http://forum.nasaspaceflight.com/index.php?topic=941.msg113784#msg113784

3.)--and low-rates the fine journalists at SPACE NEWS
http://forum.nasaspaceflight.com/index.php?topic=3797.msg113542#msg113542


4.)I also have questions on close-outs (I believe he is a something of a Delta II jockey-- and he knows all about that ELV--I'll give him that), and in the last link he debunks Kessler's objections to large structures in space

http://forum.nasaspaceflight.com/index.php?topic=11627.msg252125#msg252125
http://forum.nasaspaceflight.com/index.php?topic=16192.msg374858#msg374858
http://www.bautforum.com/forum-introductions-feedback/87318-over-moderation-4.html#post1478486

Back on topic

European manned spaceflight discussion:
http://forum.nasaspaceflight.com/index.php?topic=8659.0 http://up-ship.com/blog/?p=2427

DLR http://forum.nasaspaceflight.com/index.php?topic=14525.msg320972#msg320972http

More doable?
http://www.popsci.com/aeros/article/2006-02/flying-luxury-hotel

Nice pictures here...
http://www.sspi.gatech.edu/spacetransportation2007.pdf

PraedSt
2009-Apr-27, 06:59 PM
(LAPCAT M8 can be considered the real Aurora, as shapewise it is very similar to the sketches of Aurora. Totally unrelated though, different continent and decade.). I worked on a.o. the propulsion system for the M8.
You worked on the M8? Good looking plane. :)

Hotlink (but to ESA, so I think I'm ok)
LAPCAT M8 (http://www.esa.int/images/lapcat_2008-12-05_2_H.jpg)

RGClark
2009-Apr-28, 04:28 PM
As you know, I'm always looking for the story behind the story.

As it stands now, Europe is having to rely upon the new R-7 pad and its launch vehicle to make up for the vacancy left behind by the phasing out of Ariane 4. Ariane 5 is still being "tweaked," what with the continued giganism of comsats: http://www.space.com/businesstechnology/090413-sn-busmon-ariane5-tweaked.html


The folks across the pond ultimately want an all European LV stable, and the DLR "Spaceliner" (which wisely leaves all the air-breathing nonsense out) seems to be just one 'payload' being promised so as to drum up support for the winged flyback booster whose true use will be as a strap-on for typical ELVs, or to replace EELV first stage altogether. That and German enthusiasts still want something named Silverbird to fly to space with wings.

If hypersonics are available, they might be open to that, but from what I gather reading from page 38 of the May 2009 Popular Science, the Spaceliner is just to be an all rocket NASP to be released from a multi-function fly-back booster that has other markets. I think this is the new name or replacement for "Oural," but that was a more Russian based system.

Related links:

http://www.portaltotheuniverse.org/blogs/posts/view/5262/ testbed work

Scroll down to see artwork of Spaceliner. The art seems similar to Pop Sci's
http://nextbigfuture.com/2009/04/europe-space-agency-hypersonic-plane.html
http://2.bp.blogspot.com/_VyTCyizqrHs/SeTD5lL1hUI/AAAAAAAADdQ/Vi4BkDyuogA/s1600-h/DLRrocketplane.JPG

...

Thanks for all the informative links. I have to say though the ESA proposal for a Mach 8 airbreathing transport looks like a flying Dustvac.
I'm also surprised by the 2075 time frame they are giving for this. My feeling is most people knowledgeable with the development of space access will agree that routine space access will occur far before then, making in fact Mach 25 transport routine.


Bob Clark

Nicolas
2009-Apr-28, 04:47 PM
My feeling is most people knowledgeable with the development of space access will agree that routine space access will occur far before then, making in fact Mach 25 transport routine.

I'd think that the ESA hypersonic research team is quite compatible with "most people knowledgeable with the development of space access". ;)

btw, The LAPCAT M8 concept is a hypersonic, suborbital (not even ballistic but aerodynamic) passenger plane for many passengers, not a spacecraft.

RGClark
2009-Apr-28, 05:10 PM
...
That is okay--the sad thing is that this fine website has now become "The Jim Show"
http://forum.nasaspaceflight.com/index.php?topic=8065.msg142163;topicseen#msg142163
Here are some of his greatest hits (or misses as is the case) plus nice blurbs from me for humor's sake :)

1.)Jim shows his ignorance on NRO, space-based radar, etc.
http://forum.nasaspaceflight.com/index.php?topic=5028.msg108396#msg108396
http://forum.nasaspaceflight.com/index.php?topic=5028.msg109881#msg109881
http://forum.nasaspaceflight.com/index.php?topic=5028.msg110892#msg110892
...


I understand what you mean about "Jim". I had some run-ins with him as well when I was on that site. He claims to be a "rocket scientist". Anyone ever find out what his field of expertise actually is?


Bob Clark

RGClark
2009-Apr-28, 05:15 PM
I'd think that the ESA hypersonic research team is quite compatible with "most people knowledgeable with the development of space access". ;)
.

What's your personal opinion on this? Do you think by 2075 we still won't have routine passenger flights to orbit?

Bob Clark

PraedSt
2009-Apr-28, 05:23 PM
I have to say though the ESA proposal for a Mach 8 airbreathing transport looks like a flying Dustvac.

:lol:

Oh ye of little taste. A beautiful Dustvac.

RGClark
2009-Apr-28, 05:29 PM
Just saw this on the FlightGlobal site:

DATE:28/04/09
SOURCE:Flight International
Hot-flow test complete for Falcon ram/scramjet engine.
By Rob Coppinger
The US Air Force's Arnold Engineering Development Center (AEDC) has announced completion of a hot flow test on a dual ramjet and scramjet hypersonic engine for the Falcon combined cycle engine technology (Facet) programme.
http://www.flightglobal.com/articles/2009/04/28/325648/hot-flow-test-complete-for-falcon-ramscramjet-engine.html

Bob Clark

RGClark
2009-Apr-28, 05:31 PM
:lol:

Oh ye of little taste. A beautiful Dustvac.

If it works I will agree it will indeed be beautiful.

Bob Clark

RGClark
2009-Apr-28, 10:10 PM
On the Space Future site, another interesting article:

Flight Mechanics of Manned Sub-Orbital Reusable Launch Vehicles with Recommendations for Launch and Recovery.
Marti Sarigul-Klijn Ph.D. and Nesrin Sarigul-Klijn*, Ph.D
AIAA 2003-0909
January 2003 (Revised April 2003)
http://www.spacefuture.com/archive/images/flight_mechanics_of_manned_suborbital_reusable_lau nch_vehicles_with_recommendations_for_launch_and_r ecovery.7.png
Lockheed NF-104 (USAF image)
http://www.spacefuture.com/archive/flight_mechanics_of_manned_suborbital_reusable_lau nch_vehicles_with_recommendations_for_launch_and_r ecovery.shtml

It discusses four separate combined jet/rocket aircraft.





Interesting article here arguing for adapting the NF-104 for a suborbital tourism vehicle:

Rocket Starflyer™: Modified NF-104 for Space Tourism.
Eric J Wernimont* and Mark C Ventura†
General Kinetics Inc., Huntington Beach, CA, 92649
43rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit AIAA-2007-5839 Cincinnati, OH, July 8-11, 2007
http://www.gkllc.com/home/AIAA-2007-5839_Rocket_Starflyer-Modified_NF-104_for_Space_Tourism.pdf

They suggest improvements in power and weight in the rocket engines since the 1960's may allow it to reach the 300,000 ft. for a suborbital flight, rather than the 120,000 max altitude of the original NF-104.
Using carbon composites for the airframe might also decrease that part of the weight by a factor of 1/2 to 1/3 less than the original aluminum used, since SpaceShipOne proved carbon composites are sufficient for the heating of the Mach 3 flight and re-entry.


Bob Clark

Nicolas
2009-Apr-28, 10:45 PM
Dustvac...t-t-t. Back when I worked on it, one of the options was to have the inlet at the underside rather than the top side. Now THAT was a dustvac.

As for when we will have routine passenger access to space/suborbital travel/hypersonic travel: I don't know. We know more or less how to do it in "practical theory", but the technology for either of these concepts (I don't count SS2 as more than a very sleek toy, not a means of travel to anywhere) will still need quite some refinement before it is routine as in affordable. And just how long this refinement process will take, remains to be seen. Considering it costs more than a decade to develop something that is compared to these things very mundane, the A380, I think that 2025 is too early. And 2075 is too far away for me to make any predictions. :)

IMO, craft based on rocket technology solely will be possible a lot sooner than air breathing hypersonic vehicles though, as the latter still have quite some hurdles to be taken in an elegant way, whereas for rockets it's mostly a case of better reusability, lower cost, better heat shield when going orbital. But you simply can't do the kind of flights you'd want to do with a LAPCAT M8 type of thing with rocket exclusive craft. Noise abatement is "slightly" too strict for that kind of tricks, to name just one problem...

RGClark
2009-May-01, 05:47 PM
A startling proposal for suborbital tourism:

Rocket racers target space.
Posted: Friday, October 24, 2008 11:00 AM by Alan Boyle.
...Armadillo is to develop a reusable, vertical-takeoff rocket ship capable of rising beyond an altitude of 62 miles (100 kilometers) - the internationally accepted boundary of outer space. The two-person-capacity vehicle would be powered by Armadillo's modular rocket engines. Carmack said an eight-engine configuration should provide ample redundancy for safe manned flight.
Whitelaw said the ship would have a see-through passenger capsule, allowing for a "360-degree view of space." At the peak of the ascent, passengers would see the black sky of space above a curving Earth, and experience a thrilling taste of weightlessness.
Carmack said that the first unmanned flight tests would be flown next year from the Oklahoma Spaceport, with the prototype craft descending beneath parachutes. By the time passenger flights begin, sometime in 2010, he expected Armadillo to switch to a controlled, rocket-powered descent with a parachute backup system. By that time, the locale would switch as well, to New Mexico's Spaceport America, about 40 miles (64 kilometers) north of Las Cruces.
http://cosmiclog.msnbc.msn.com/archive/2008/10/24/1588168.aspx


Bob Clark

NEOWatcher
2009-May-01, 06:19 PM
A startling proposal for suborbital tourism
Good for water landings (http://img.timeinc.net/time/today_in_pictures/0903/tip_ny_0324_02.jpg). :lol:

RGClark
2009-May-01, 06:39 PM
Just saw this on the FlightGlobal site:

DATE:28/04/09
SOURCE:Flight International
Hot-flow test complete for Falcon ram/scramjet engine.
By Rob Coppinger
The US Air Force's Arnold Engineering Development Center (AEDC) has announced completion of a hot flow test on a dual ramjet and scramjet hypersonic engine for the Falcon combined cycle engine technology (Facet) programme.
http://www.flightglobal.com/articles/2009/04/28/325648/hot-flow-test-complete-for-falcon-ramscramjet-engine.html


Hypersonic ‘WaveRider’ poised for test flight.
U.S. military hopes to bridge the gap between airplanes and rocketships.
By Irene Klotz
updated 12:11 p.m. ET, Wed., April 29, 2009
"Officially, it's known as the X-51, but folks like to call it the WaveRider because it stays airborne, in part, with lift generated by the shock waves of its own flight. The design stems from the goal of the program — to demonstrate an air-breathing, hypersonic, combustion ramjet engine, known as a scramjet."
...
"The holy grail of scramjet is if you can capture air while you're flying very fast and not have to carry along an oxidizer," Brink said. "If you could do that you've made a lot more space for payload or cargo."
"The WaveRider's first flight is scheduled for October over the Pacific Ocean. It will be carried into the air by a B-52 bomber, then released at an altitude of about 50,000 feet. A solid-rocket booster will ignite and speed it up to about Mach 4.8 and if all goes well, the aircraft's engine will take over from there, boosting the speed to more than Mach 6."
http://www.msnbc.msn.com/id/30477653/

Tests Are Crunch Time for Scramjet Concept.
Mar 31, 2009
"Boeing will complete assembly of the first X-51A WaveRider static test vehicle over the next two weeks, paving the way for hypersonic flight tests designed to show that the supersonic combustion ramjet is ready for practical application in missiles and space launch vehicles.
"The flight tests, provisionally targeted to begin at the end of October, mark a couple of milestones: the first attempt to fly a fuel-cooled scramjet, and the initial try at flying an aerodynamically unstable, control augmented hypersonic vehicle. The Pratt & Whitney Rocketdyne SYJ61 engine at the heart of the X-51A will also be the first liquid-hydrocarbon-fueled scramjet to fly, and is designed to demonstrate sustained flight at up to Mach 6.5."
http://www.aviationweek.com/aw/generic/story.jsp?id=news/SCRAM033109.xml&headline=Tests%20Are%20Crunch%20Time%20for%20Scram jet%20Concept&channel=defense

If it works not only will it show that scramjets can produce net thrust but also the waverider concept can generate a high lift-to-drag ratio at hypersonic speeds.
This test will use a solid rocket motor to boost to Mach 4.8 before the scramjet takes over. However it is known that ramjets can operate to Mach 4.5+:

Lockheed Q-5/AQM-60 Kingfisher.
Data for X-7A-1, X-7A-3 and XQ-5 (AQM-60A):
Length X-7A-1: 9.98 m (32 ft 9 in)
X-7A-3: 11.3 m (37 ft)
XQ-5: 11.6 m (38 ft)
Wingspan X-7A-1: 3.7 m (12 ft)
X-7A-3, XQ-5: 3.0 m (10 ft)
Height 2.1 m (7 ft)
Diameter 61 cm (20 in)
Weight 3600 kg (8000 lb)
Speed Mach 4.3; 4500 km/h (2800 mph)
Ceiling 30000 m (100000 ft)
http://www.designation-systems.net/dusrm/m-60.html

Martin Marietta ASALM.
"In one of the PTV tests, the missile accidentally accelerated beyond the planned speed, and eventually reached Mach 5.5 at 12200 m (40000 ft)! The planned cruise speed for operational ASALM missions was to be around Mach 4.5 for a range of about 480 km (300 miles)."
http://www.designation-systems.net/dusrm/app4/asalm.html

Then we could have a combined cycle ramjet/scramjet where the ramjet is used instead of a rocket to get the vehicle to the speed where the scramjet takes over.
The SR-71 already proved that combined cycle turbojet/ramjet propulsion is possible. A successful X-51 test will suggest a fully jet powered vehicle is possible to Mach 6.5.
Then production of a Mach 6.5+ airbreathing transport very likely would be practical well within a 25 year time frame.


Bob Clark

PraedSt
2009-May-01, 06:47 PM
Then we could have a combined cycle ramjet/scramjet where the ramjet is used instead of a rocket to get the vehicle to the speed where the scramjet takes over.
The SR-71 already proved that combined cycle turbojet/ramjet propulsion is possible. A successful X-51 test will suggest a fully jet powered vehicle is possible to Mach 6.5.
Turbojet/Ramjet/Scramjet? That's a lot to do for one engine, no?

RGClark
2009-May-01, 07:13 PM
Turbojet/Ramjet/Scramjet? That's a lot to do for one engine, no?

I don't think so. The Falcon Facet engine already shows ramjet/scramjet is possible. To get a turbojet too you would only have to put a turbine in front of it. This might cut down on some of the air reaching the ramjet/scramjet but this could be solved as with the SR-71 by having some air completely bypass the compressors.


Bob Clark

RGClark
2009-May-01, 07:35 PM
A startling proposal for suborbital tourism:

Rocket racers target space.
Posted: Friday, October 24, 2008 11:00 AM by Alan Boyle.
...Armadillo is to develop a reusable, vertical-takeoff rocket ship capable of rising beyond an altitude of 62 miles (100 kilometers) - the internationally accepted boundary of outer space. The two-person-capacity vehicle would be powered by Armadillo's modular rocket engines. Carmack said an eight-engine configuration should provide ample redundancy for safe manned flight.
Whitelaw said the ship would have a see-through passenger capsule, allowing for a "360-degree view of space." At the peak of the ascent, passengers would see the black sky of space above a curving Earth, and experience a thrilling taste of weightlessness.
Carmack said that the first unmanned flight tests would be flown next year from the Oklahoma Spaceport, with the prototype craft descending beneath parachutes. By the time passenger flights begin, sometime in 2010, he expected Armadillo to switch to a controlled, rocket-powered descent with a parachute backup system. By that time, the locale would switch as well, to New Mexico's Spaceport America, about 40 miles (64 kilometers) north of Las Cruces.
http://cosmiclog.msnbc.msn.com/archive/2008/10/24/1588168.aspx



Video on early development of Armadillo Aerospace's vertical take off and landing (VTVL) suborbital system:

http://media.armadilloaerospace.com/misc/2009_Space_Access_Society.wmv


Bob Clark

Nicolas
2009-May-01, 07:54 PM
@Praedst: these combined engines are something that is actively researched. Basically, if you've got an adaptable geometry scramjet, you also have a ramjet already. And as "start air" you could add a rocket in a separate duct (whose high velocity exhaust is sent through the scramjet), or a turbojet that again sends its exhaust through the scramjet (operating as ramjet) until the thing goes fast enough to have the ramjet eat air directly. there are many variants on this, I'm just naming two common principles here. You could also make the rocket or turbine section completely separate from the main (sc)ramjet. It sounds more complex than it is, structure wise. To make it actually work though, remains massively complex.

publiusr
2009-May-01, 08:10 PM
To answer your question--I do think Jim is a Delta II handler.

O/T

No way I would ride on Armadillo's craft. Carmack has had too much trouble with his type craft getting away from him. I remember some of the 'small is good' types complain that Bezos Blue Origin craft was too big. Not so.

The larger these Phil Bono craft are the easier it is to throttle them. Smaller craft can get out from under you very quickly. Just because a computer has an ideal throttle range doesn't mean your plumbing can match.

I remember seing a device/drone that hovered directly over some netting. The device used tiny thrusters to keep the object in a certain spot above the ground.

Over the years the tech has just gotten better and better
http://www.youtube.com/watch?v=W1HCFM9yoKo
http://diydrones.com/forum/topics/lockheeds-thrust-based-uav?page=1&commentId=705844%3AComment%3A52750&x=1#705844Comment52750

For something that small to hold so steady is amazing. A large N-1 1st stage based RLV could move rather slowly due to its own mass giving time to throttle. The more engines you have, the better throttle range, or so I would think.

Remember, these small devices weren't meant to hover above the ground at 1 g, but to hold a rather steady course and track a missile. (The SS-18 was itself to be an armored ICBM and to have an agile bus, so an intercept would be interesting to watch.)

Carmack has yet to match the amount of control seen in that video.

The safest suborbital ride in theory is Stabilo.
http://www.astronautix.com/craft/stabilo.htm

There you float up gently, and the main rocket IS the escape tower. If something goes wrong you have time to bail out. It is a tractor rocket (as the Almaz/VA capsule was on return) and it is pulling up and away from you.

Launch from the surface and bad things can happen real fast. Rutans SS2 craft will be passing at high speed just above the runway. Not good if it bottoms out.

P.S.
I hate to say this but Lapcat doesn't resemble a dust-buster. It looks more like what I shave my back-hair with. One last dig. A few issues back in AV Week IIRC, there was an op-ed wondering why we were wasting money on hypersonic missiles that would cost more (and perform less) than the good old Skybolt missile http://www.astronautix.com/lvs/skybolt.htm

1150 mile range at 9,500 mph and toting a W-59 warhead that massed out to 550 pounds--and on a simple solid? That's going to be tough for an airbreather to match, just for it to be called an airbreather.

For now, lose the wings, lose the air-breathers. Burn your copies of "The Right Stuff" and the pilot culture with it.

Embrace the capsule.

Nicolas
2009-May-01, 08:35 PM
Publiusr, it depends on what you want to do with it. LAPCAT M8 aims at transporting more than 100 people from one continent to the other in one go. A capsule design for that amount of people doesn't seem very handy.

I agree though that you don't want airbreathing things just "because". As you say, for a simple missile, why not just use a good old rocket if it suits your demands and is cheap.

publiusr
2009-May-01, 08:45 PM
Now I would like to see space planes, esp like the Star Raker
http://www.astronautix.com/lvs/staraker.htm

I just think we need to wait for another materials revolution to come along for flight. Gas-dep' borazon diamond coatings, infra-red invisible materials like the optical invisible materials that might come along first...

Then too Bono wanted VTOVL troop ships with no wings
http://www.astronautix.com/lvs/ithacus.htm http://www.up-ship.com/apr/volume2.htm

Similar to Lapcats 200 person goal was this concept

"The smaller "Ithacus Jr." version would have had an intercontinental cargo capability of 33.5t or 260 soldiers. Douglas proposed to launch two Ithacus Jr. vehicles from an Enterprise-class nuclear aircraft carrier, which also would have produced liquid oxygen and hydrogen propellant from seawater. Power for the electrolysis process would have been taken from the carrier’s nuclear reactor: 112MW would have been required to produce 1150t of oxygen and 164t of hydrogen from 1470t of water. The rocketships would be stored inside hangars. One Ithacus Jr. would serve as a troop carrier while the other would deploy unmanned cargo to the same military site. The Ithacus Jr. vehicles would land 600 meters apart to deploy a fully armed group of 260 soldiers." A junior Sea Dragon, but pump fed.

With today's computers, landings of such craft are eased.

Now one concept I have only seen in the movies (You Only Live Twice) was its rocket, the Intruder. The first stage was expendable (or parachutable) and only the upper stage had to land. Now the vehicle would have to be much larger than shown on screen to do what it did, and the empty compartment to "eat" the capsules would have had to first disgorge some empty tankage to make room. (not shown in the movie)

It would probably have worked but would have had to parachute down and use engines to soften its landing to make sure.

So a simple rocket for a first stage and a fancy DC-X upper-stage/payload might be more useful and an intercontinental transport that would need no runway at all. And these Phil Bono designs? They are just big capsules.

The Big Onion SSTO (aka Fat Albert) looked like a giant Apollo capsule.

But this is what people want I guess
http://up-ship.com/blog/?p=2585

PraedSt
2009-May-01, 10:44 PM
I don't think so. The Falcon Facet engine already shows ramjet/scramjet is possible. To get a turbojet too you would only have to put a turbine in front of it.

And as "start air" you could add a rocket in a separate duct (whose high velocity exhaust is sent through the scramjet), or a turbojet that again sends its exhaust through the scramjet (operating as ramjet) until the thing goes fast enough to have the ramjet eat air directly. there are many variants on this, I'm just naming two common principles here. You could also make the rocket or turbine section completely separate from the main (sc)ramjet.
So naturally going to hijack this towards SSTO :D

If we can get this multiple geometry/function engine right...how far are we along the path towards SSTO? I think what I mean is- how much commonality does/could a hypersonic transport have with an orbital spaceplane?

RGClark
2009-May-02, 02:32 AM
Video on early development of Armadillo Aerospace's vertical take off and landing (VTVL) suborbital system:

http://media.armadilloaerospace.com/misc/2009_Space_Access_Society.wmv


Bob Clark

Near the end of that video at about the 6:45 mark is a perhaps more realistic looking version. It shows the usual cylindrical rocket, though with rather large windows.
You could of course just put cylindrical metal tubing around the bare framework in the original design to get this, which would probably be more reassuring visually to potential passengers.
I also don't know what transparent material could withstand Mach 3+ flight and reentry. You could achieve a similar result by having a retractable metal cover around the full 360 degree window.


Bob Clark

RGClark
2009-May-02, 03:14 AM
So naturally going to hijack this towards SSTO :D

If we can get this multiple geometry/function engine right...how far are we along the path towards SSTO? I think what I mean is- how much commonality does/could a hypersonic transport have with an orbital spaceplane?

Good question. Let's assume the X-51 engine will succeed to produce a Mach 6.5 ramjet/scramjet. Very likely you could make a combined cycle turbojet/ramjet/scramjet but for the purposes of this exercise you can assume you use one of the turbojets already capable of producing Mach 3+ thrust to get the vehicle to the speed where the ramjet takes over.
I attached an image showing the Isp's of turbojets, ramjets, scramjets according to Mach number taken from:

F-106 to X-106 Conversion Plan.
http://www.lorrey.biz/x-106/conversion.html

Assuming hydrogen fuel, use this for the Isp of the turbojet to get the mass ratio to get to Mach 3, then the mass ratio for the ramjet to go from Mach 3 to Mach 4.5, then finally the mass ratio for the scramjet to go from Mach 4.5 to Mach 6.5. Finally you can use the Isp of for example the shuttle main engines of 455 s for the mass ratio to get to the orbital velocity of Mach 25, or 7800 m/s. Keep in mind that since the rocket only has to take over at high altitude you can indeed use the full vacuum Isp of the rocket engines for the rocket propelled portion of the trip.
Note as well though there is an additional delta-v due to gravity/air drag loss of about 1500 m/s to get to 100 km altitude for space. This can be reduced though by the fact that you can use the ramjet/scramjet to get to quite high altitude, say 50 km, so you would have to add on actually a smaller delta-v, that required to get an additional 50 km altitude using the rockets. Now also subtract from this delta-v, the 462 m/s you get for free if you launch from the equator due to the Earth's rotation.
Multiply these mass-ratios to get the full mass ratio to orbit. I think you'll find for a shuttle orbiter size vehicle the fuel required would be significantly less than the shuttle's external tank and without requiring the solid rocket boosters.


Bob Clark

PraedSt
2009-May-02, 03:48 PM
I think you'll find for a shuttle orbiter size vehicle the fuel required would be significantly less than the shuttle's external tank and without requiring the solid rocket boosters.
If this is true I'm all excited now. :) Great answer, and thanks for the link.

Now I'm waiting for some of our experts to come and pour scorn on SSTO ... :(

Nicolas
2009-May-02, 04:26 PM
in 3-2-1... ;)

SSTO using air breathing engines only will not work, as you'd need to reach more than orbital velocity already at altitudes where there is still a significant amount of air. You don't want that, especially not with people on board.

SSTO using air breathing engines would hence require rockets to do the final part of the job (unless you really want to inject your oxidizer at hypersonic speeds into your scramjet). Looking at the rocket equation, it would be far more efficient to let go the scramjet by the time you reach that part, hence two stages. Maybe in the really far future we'll have plenty of performance and can keep the scramjets attached for only a small performance penalty, but in the near future that doesn't seem likely. So this means that you'd most likely end up with the following configuration in a launcher:

scramjet boosters aiding a rocket stage or two rocket stages. The (first stage) rocket accelerates the stack until speeds where the scramjet starts working as a ramjet or scramjet. From that point, they work simultaneously. When the altitude gets too high, the scramjet boosters are dropped and the (second stage) rocket carries the vehicly all the way up to orbit.

Again, there are many variants possible.

Antice
2009-May-02, 06:15 PM
It seems to me that a lot of people are too hung up in the launcher to cargo rate.
Tech like a space plane can not ever compete with a simple dumb rocket in that category. they aren't meant to either. it's all about the re usability.

Here is a quick comparison of the points about both concepts.

Good sides.
rockets.
1. they are already here, and there is extensive experience in launching them
2. they can attain what is probably the best take-off to cargo weight of any launcher this side of a space elevator/anti grav thingy.
3. rockets scale up nicely, and only $ limit how big a cargo you can get up there in one go.

SSTO/space planes.
1. will be fully reusable systems capable of quick turnarounds.
2. cost per launch will be significantly lower compared to building a brand new launcher for each trip.
3. can dispense with most of the specialized infrastructure needed to launch big rockets. (space planes will preferentially be able to use a runway)
4. in built ability to return cargoes to earth
5. built in low G abort. with engine jetison glide to runway abort scenarios as a possibility.

bad sides:
rockets.
1. you have to build a new one for each launch. pushing your cost up up and launch rate down.
2. needs a specialized pad and assembly structure in order to be assembled and made ready. (cost and manpower issue)
3. Needs a specilized return craft in order to take cargo back down to earth
4. most optimal launch trajectories forces high g abort profiles. Depressed trajectories as mitigation reduces overall payload ratio significantly)

SSTO/space plane
1. needs several near term technologies to work as advertised.
2. each vehicle will be very complex. (cost of dev. and production issue)
3. take-off weight to payload rate is fairly low compared to rockets. (waste of fuel issue)
4. Planes dont realy scale up to super size all that well. the bigger you make it the worse the issues of both tps and lifting power becomes.

summary: while space planes need technologies like active TPS and air breathing rockets to achieve their goals they are not too far off into the future any more. research is being done and progress made. the issues with the wasted fuel is not so large compared to the issues inherent with wasting the entire vehicle. this is assuming that full re usability is achieved. the orbiter failed in this category due to it's rather unwieldy TPS system. Otoh it was a big success at some of the other tasks that it was designed for.
Rockets will be the big throwers of mass when push comes to shove. when made big and simple so as to keep the wasted costs down (sea dragon et al.) they can lift big stuff that is just not really feasible to lift with a space plane type launcher. such cargoes are however fairly rare and the low launch rates inherent in rocket launches is not an issue for those cargoes.
For crewed launches a space plane offers a launch profile that is a lot gentler than sitting atop a big rocket. also, since the orbiter part of the craft is also the launcher/lander you end up with a craft with a lower overall complexity compared to a rocket with a capsule on top. esp since a capsule has to be almost as complex a vehicle as a space plane to do it's functions of keeping the crew safe. thereby balancing out the complexity issues between the concepts for manned launches.

Nicolas
2009-May-02, 06:22 PM
That post doesn't cover all there is to the subject. One could for example argue that it is wasteful to carry your own oxygen while your craft is traveling through an oxygen rich atmosphere. That's why they are considering scramjet (or other concept airbreathing engines) boosters in a rocket stack. Not for reasons of "it's a plane" or "it's reusable", but to try to gain performance by not having to carry your own oxydizer.

PraedSt
2009-May-02, 06:41 PM
in 3-2-1...:lol:
The evil experts are here.

Yes, I'm hoping for an air/rocket combination. So I agree with you that it will take a lot more time, but if we get to the stage where we have a viable hypersonic transport, we will have done most of the work for an SSTO, right? From that point in the future, looking forward, SSTO won't seem so unrealistic? Especially if I was drunk, say...

Antice
2009-May-02, 07:26 PM
once you have tps systems and hybrid jet/rocket engines you are close to halfway there engineering wise. the rest is doable in a fairly gradual evolutionary fashion.
in order to get orbital it might be good to say. make it a dual stage system with automated flyback boosters that detach at high altitude. that way you wont have to take your air breathers all the way up.
the upper stage would benefit from being a lifting body on the return to earth for an unpowered glide landing like the shuttle uses.

As i see it. if you cant make your launcher 100% reusable without needing extensive refurb you might as well stay with rockets. rockets do get cheaper if you just build a lot of them after all.

ofc. unless there is a market for lots and lots of flights. neither developing new rockets nor space planes makes sense. space planes even less so due to per vehicle cost and technological immaturity.

PraedSt
2009-May-02, 07:56 PM
Hmm. Not really interested in a dual stage system to be honest.

I have thought a bit about size and SSTO before:

Planes dont realy scale up to super size all that well. the bigger you make it the worse the issues of both tps and lifting power becomes.

can dispense with most of the specialized infrastructure needed to launch big rockets. (space planes will preferentially be able to use a runway)
Mass/weight- I was worried about landing gear and runways not being able to support the plane, especially pre-launch.

Size/TPS- I know there is more plane to cover, but I think a large size might be better regarding TPS.

During accent, I want to accelerate rapidly. I can't do it as fast as with pure rockets of course, but I want it to be fast enough so that heating is not a major issue. If that's possible.

During descent, a large size very high drag, especially with the right shape and orientation. So I'll get a high peak temperature, but as the plane will slowed down quickly total thermal/heat load (whatever its called!), will be much less.

Nicolas
2009-May-02, 09:07 PM
The question is why you are not interested in a two stage (or one stage plus boosters) system, or to turn the question around: why do you want to take your scramjets with you all the way to orbit?

Antice
2009-May-02, 09:11 PM
runways are a major limiting factor. even a modest craft like the proposed skylon would need especially reinforced runways to take off and land on. but so do some of the worlds largest passenger craft today. so it's not a realy big issue for the currently proposed crafts. Problem is that when scaling it up the structural load on the undercarriage increases fast. there are some engineering headaches there. esp since this is a type of craft that is by mass more than 90% fuel at take off.
scaling a rocket is much more straightforward. it's tower like structure is well suited for scaling up with heavier and heavier loads. dispersing the loads in pads you have to specially build for that type of launcher anyway is no harder than building a really tall building.

PraedSt
2009-May-02, 09:35 PM
The question is why you are not interested in a two stage (or one stage plus boosters) system, or to turn the question around: why do you want to take your scramjets with you all the way to orbit?
Well...good question. I can't see the point of all that hard work if I'm going to stage anyway. Might as well use a rocket. Also I hate the idea of bits falling off my vehicle, however reusable. Plus, it's way cooler of course- which means girls :D

Antice
2009-May-02, 10:13 PM
If only coolness factor got payloads to space /end wishfullthinking
:rolleyes:

Ara Pacis
2009-May-03, 07:53 AM
With regards to the SSTO extension of the Hypersonic Transport idea, has anyone yet explained the proposed mission profile for which such a vehicle would be used? In other words, instead of talking about how big it could be, it might help to know how big it needs to be. How much mass, in terms of either pax or cargo or a combination of them is the standard mission profile expected to be?

Nicolas
2009-May-03, 09:40 AM
I have not yet heard of any concrete hypersonic transport based SSTO project (likely for reasons listed above), so I can't answer your question.

Ara Pacis
2009-May-03, 10:32 AM
Even guesses might be illuminating.

Antice
2009-May-03, 02:03 PM
well. you might get an idea of how big a craft you need from the british skylon design.
you can find it here (http://www.reactionengines.co.uk/pdf_documents.html)
the topmost document has the most recent numbers from it's designers.

And for the lazy: Skylon max take off weight Is estimated at 275 tonne. out of that only 12 tonne is payload at 300km equatorial orbit.
for iss the payload is calculated at aprox 9 tonnes.

just to compare with something different.
Arianne V weighs in at 777 tonnes at takeoff with the ATV on top.
the ATV is aprox 20 tonnes at launch and deliveres 7,6 tonnes of cargo to the iss
warning numbers from wikipedia used, so i wont vouch for 100% accuracy.

the payload fraction for skylon works out at about 3,2% for ISS
And for Ariane V to about 0,9% to ISS not counting the ATV itself as part of the cargo.

joema
2009-May-03, 04:21 PM
The question is why you are not interested in a two stage (or one stage plus boosters) system, or to turn the question around: why do you want to take your scramjets with you all the way to orbit?
The problem is just intrinsically difficult.

If you go single-stage, there are immense problems with the mass and complexity of multiple propulsion systems carried all the way to orbit. Also it likely requires active thermal management -- something like the cooling tubes of a rocket engine, but over the entire vehicle.

You can eliminate some of that by going two-stage. But that introduces it's own problems.

Various trade studies show the optimum staging velocity is very high -- maybe around 12,000 ft/sec. That means the 1st stage will be very big and expensive, and headed downrange very fast and far at separation. To recover that expensive 1st stage will be difficult, yet to discard it would be expensive.

There's just no easy way. Every potential solution introduces its own drawbacks.

A trans-atlantic suborbital vehicle requires nearly the same velocity, energy and thermal management as an orbital vehicle. It's way beyond SpaceShipTwo.

Today the only manned, suborbital transatlantic vehicle is the Space Shuttle on a TAL abort. Any future suborbital vehicle whether pure rocket, air-breathing or a mix would require roughly the same velocity, energy and thermal managment.

Nicolas
2009-May-03, 06:53 PM
A trans-atlantic suborbital vehicle requires nearly the same velocity, energy and thermal management as an orbital vehicle. It's way beyond SpaceShipTwo.

Except for obviously the combustion chamber, I don't agree about the thermal demands. They were a bit lower than what a shuttle encounters when it returns from orbit. We could keep things solid just by applying a reasonably normal material and using the remaining fuel as a coolant. No thermal tiles needed. Edit: maybe at the leading edges, but as far as I recall, not on the body. We didn't look too much into thermal protection yet, but unless I'm mistaken it seemed doable without covering ourselves with tiles.

It is way beyond SS2 though.

cjameshuff
2009-May-03, 07:33 PM
SSTO/space planes.
1. will be fully reusable systems capable of quick turnarounds.

Unless, of course, they aren't.



2. cost per launch will be significantly lower compared to building a brand new launcher for each trip.

Again...unless it isn't.



3. can dispense with most of the specialized infrastructure needed to launch big rockets. (space planes will preferentially be able to use a runway)

Once again...

These claimed advantages are not particularly certain to materialize. To do what a spaceplane needs to do is hard. Such vehicles will almost certainly have very significant downtime and very expensive maintenance requirements, much of the same specialized facilities as rockets, and would only be able to launch from specialized airports equipped with that infrastructure. Their size would eliminate the possibility of carrying them like we do the Shuttle, meaning they would also have to land at those specialized airports.



1. you have to build a new one for each launch. pushing your cost up up and launch rate down.

Unless you build a partially or fully-reusable rocket. The relative simplicity would make it easier to achieve a short turn-around time with such a rocket.



2. needs a specialized pad and assembly structure in order to be assembled and made ready. (cost and manpower issue)

A shared difficulty. The relative simplicity should make the manpower issue less severe for rockets.



3. Needs a specilized return craft in order to take cargo back down to earth

Specialized craft for a specialized task...going to great expense to maintain a capability that is generally not used is wasteful.



4. most optimal launch trajectories forces high g abort profiles. Depressed trajectories as mitigation reduces overall payload ratio significantly)

The optimal trajectories are available for cargo launches, though. Spaceplanes are restricted to the suboptimal trajectory. This is an advantage of rockets, not a disadvantage.



3. take-off weight to payload rate is fairly low compared to rockets. (waste of fuel issue)

Fuel's cheap. The issue is that you can't lift sizable payloads at all and can only get miniscule payloads to higher orbits, and need many launches to do any orbital assembly.



summary: while space planes need technologies like active TPS and air breathing rockets to achieve their goals they are not too far off into the future any more. research is being done and progress made. the issues with the wasted fuel is not so large compared to the issues inherent with wasting the entire vehicle. this is assuming that full re usability is achieved. the orbiter failed in this category due to it's rather unwieldy TPS system. Otoh it was a big success at some of the other tasks that it was designed for.

Summary: space planes may be "cool", but are a waste of time and money. The preference for them is more a result of confusing "familiar" with "easy" than anything based on sound engineering.

Spaceplanes will be expensive to design and build because of the complexity, complexity that is not shared with manned rockets...controlled prolonged aerodynamic flight at hypersonic velocities is not simple. A capsule does not have to be "almost as complex a vehicle as a space plane", they aren't even close...supporting human passengers through a rocket launch and brief reentry is a far simpler task than dealing with the prolonged heating of sustained hypersonic flight. Spaceplanes will be far more complex than the alternative, will likely require as much specialized infrastructure and even more manpower, and will be limited in capability.



That post doesn't cover all there is to the subject. One could for example argue that it is wasteful to carry your own oxygen while your craft is traveling through an oxygen rich atmosphere. That's why they are considering scramjet (or other concept airbreathing engines) boosters in a rocket stack. Not for reasons of "it's a plane" or "it's reusable", but to try to gain performance by not having to carry your own oxydizer.

The problem is, that oxidizer is moving with the planet, not the vehicle, and is in low-pressure gaseous form and highly diluted with nitrogen. The only thing it has in common with LOX is that it is an oxidizer. Collecting it greatly increases drag losses and requires extended exposure to the heating and other stresses of hypersonic aerodynamic flight, and compensating for its dilution requires complex and massive machinery. Spending excessive amounts of time plowing through atmosphere and hauling the thermal protection and intakes, compressors, heat exchangers, etc into orbit is also wasteful, and also complex and expensive to design, build, and maintain. And you'll need a LOX tank anyway, you only make it moderately smaller and replace LOX and a bit of tank with a pile of complex and expensive machinery.

Antice
2009-May-03, 10:20 PM
These claimed advantages are not particularly certain to materialize. To do what a spaceplane needs to do is hard. Such vehicles will almost certainly have very significant downtime and very expensive maintenance requirements, much of the same specialized facilities as rockets, and would only be able to launch from specialized airports equipped with that infrastructure. Their size would eliminate the possibility of carrying them like we do the Shuttle, meaning they would also have to land at those specialized airports.


Moving such a craft is not hard. it can be built to be able to go there by itself if needed. the dry mass of the skylon is about 40 tonnes. it's small enough to be moved the same way the shuttle is. If you want even larger then you would need a larger airport and probably a larger transport craft for moving it.
a 40 tonn load is not much compared to the amount of cargo you can put into one of today's modern cargo aircraft.



Unless you build a partially or fully-reusable rocket. The relative simplicity would make it easier to achieve a short turn-around time with such a rocket.


Reusing a multi stage vehicle has issues that aren't present in reusing a ssto that can land in one piece. lifting bodies makes for easier recovery since you can decide exactly where you want to land barring any accidents ofc.
Reusing a simple booster is a marginal cost saving at best. you cant just crash land something in the ocean and refuel it for another go. unless it's made out of unobtanium that is.
the thermal loads on air breathers is manageable for launch and re-entry both. there is a lot of lessons from the shuttle that can be applied to the problem.



Specialized craft for a specialized task...going to great expense to maintain a capability that is generally not used is wasteful.


I totaly agree. I'd never propose to lift big cargoes in spaceplanes. their best use would be to bring up crew and suplies. as well as returning experiments and crew back to earth.



The optimal trajectories are available for cargo launches, though. Spaceplanes are restricted to the suboptimal trajectory. This is an advantage of rockets, not a disadvantage.


Again. for the big heavy stuff. I'd say HLLV all the way. Big is better there.



Fuel's cheap. The issue is that you can't lift sizable payloads at all and can only get miniscule payloads to higher orbits, and need many launches to do any orbital assembly.


9 tonne dont seem miniscule to iss orbit to me. it's more than ariane V can do with the atv today. ofc. having to strap a vehicle like the atv on top of the rocket is a serious crimp on performance. but some cargoes like food and crew require a pressurized carrier to get there inntact.



Summary: space planes may be "cool", but are a waste of time and money. The preference for them is more a result of confusing "familiar" with "easy" than anything based on sound engineering.



Spaceplanes will be expensive to design and build because of the complexity, complexity that is not shared with manned rockets...controlled prolonged aerodynamic flight at hypersonic velocities is not simple. A capsule does not have to be "almost as complex a vehicle as a space plane", they aren't even close...supporting human passengers through a rocket launch and brief reentry is a far simpler task than dealing with the prolonged heating of sustained hypersonic flight. Spaceplanes will be far more complex than the alternative, will likely require as much specialized infrastructure and even more manpower, and will be limited in capability.


I disagree on both accounts. Serious reputable engineers sit on both sides of the fence. I believe time will tell who is right. Space planes have a fair way to go on the drawing board before being realizable. Their feasability depends on developing new technologies like air breathing rocket engines. and a fully reusable TPS system that will hold together for 100+ launches. the cost of these technologies are not all that higher than what is being spendt on developing the ARES I/V launchers. or the next generation of fighter jet's for that matter.
the US tried to make a rocket only spaceplane. there is some flaws in the concept as well as a distinct lack of capability to make it fully reusable. A project that is going for the wrong market at the wrong time will fail always.
No disrespect to the shuttle. it's an amazing feat. but it was too early an attempt at such a craft, And i do hope the spaceplane developers will learn from the mistakes with the shuttle. Space planes are just not competitive with rockets in that particular niche without adding to the on orbit assembly cost of mission craft.
once your mission objectives and interplanetary craft starts to grow bigger and more reusable you will need to assemble them anyhow. that is when fast turnaround reusable crafts become a big factor.



The problem is, that oxidizer is moving with the planet, not the vehicle, and is in low-pressure gaseous form and highly diluted with nitrogen. The only thing it has in common with LOX is that it is an oxidizer. Collecting it greatly increases drag losses and requires extended exposure to the heating and other stresses of hypersonic aerodynamic flight, and compensating for its dilution requires complex and massive machinery. Spending excessive amounts of time plowing through atmosphere and hauling the thermal protection and intakes, compressors, heat exchangers, etc into orbit is also wasteful, and also complex and expensive to design, build, and maintain. And you'll need a LOX tank anyway, you only make it moderately smaller and replace LOX and a bit of tank with a pile of complex and expensive machinery.


all the extra stuff in the air is not a handicap. Rockets move by expelling reaction mass. burning fuel is just a nice easy simple way to put energy into the mass so that you can expell it as thrust out the back end.
it does not matter that only a fraction of the air is oxidiser since all the air you scoop up is expelled as reaction mass again. resulting in a lot less loss than what one would expect with "common" sense.

just take a second look at the calculated mass for skylon compared with the real mass of ariane V.
and before you say apples to oranges, yes I know. it's a paper craft vs a real one.

SSTO vehicles are very sensitive to the mass budget tho. And in order to achieve something that works out it has to be made out of parts that will in some cases needs be invented anew in order to make them light enough for the job. Its a real challenge and I am certain some pretty valuable patents will come out of it in the end.
I'n not trying to downplay the challenge in achieving ssto.
But neither do i believe that dropping the concept in order to toss more money on yet another rocket is viable. :hand:

Nicolas
2009-May-03, 10:34 PM
The problem is, that oxidizer is moving with the planet, not the vehicle, and is in low-pressure gaseous form and highly diluted with nitrogen. The only thing it has in common with LOX is that it is an oxidizer. Collecting it greatly increases drag losses and requires extended exposure to the heating and other stresses of hypersonic aerodynamic flight, and compensating for its dilution requires complex and massive machinery. Spending excessive amounts of time plowing through atmosphere and hauling the thermal protection and intakes, compressors, heat exchangers, etc into orbit is also wasteful, and also complex and expensive to design, build, and maintain. And you'll need a LOX tank anyway, you only make it moderately smaller and replace LOX and a bit of tank with a pile of complex and expensive machinery.

When we're talking about intercontinental flight, the proposed flight paths are not any longer than what you'd normally do. As for scramjet boosters, again it's not any longer than what a normal rocket would do (this area of application isn't well researched yet though). Only when you'd make an extended air breathing flight before launching you get to stay longer in the atmosphere, but as said before I haven't got any experience with that kind of project.

So in case of scramjet boosters:

Spending excessive amounts of time plowing through atmosphere
Not the case

and hauling the thermal protection
Not any more than a rocket needs during launch

intakes, compressors, heat exchangers, etc into orbit is also wasteful
In (sc)ramjets, the intake is the compressor. What heat exchanger are you talking about? And in case of boosters, you don't haul them into orbit.

and also complex and expensive to design, build, and maintain.
The complexity of a (sc)ramjet engine is remarkably limited, hardly any moving parts (getting this simple structure to actually work is very difficult though). Nothing is known about their maintenance costs. Designing and building them doesn't seem that more expensive than any new space launcher design to me.

And you'll need a LOX tank anyway, you only make it moderately smaller and replace LOX and a bit of tank with a pile of complex and expensive machinery.
Or, a pair of rocket boosters by a pair of scramjet boosters.

Of course, the technology isn't being used yet so it remains a bit uncertain, but I think that this does show that, in the launcher business, it makes more sense to apply air breathing engines as first stage boosters rather than use them in some kind of airborne high speed launch facility/spaceplane.

joema
2009-May-04, 12:17 AM
...Spaceplanes will be expensive to design and build because of the complexity, complexity that is not shared with manned rockets...controlled prolonged aerodynamic flight at hypersonic velocities is not simple....Spaceplanes will be far more complex than the alternative, will likely require as much specialized infrastructure and even more manpower, and will be limited in capability...Spending excessive amounts of time plowing through atmosphere and hauling the thermal protection and intakes, compressors, heat exchangers, etc into orbit is also wasteful, and also complex and expensive to design, build, and maintain. And you'll need a LOX tank anyway, you only make it moderately smaller and replace LOX and a bit of tank with a pile of complex and expensive machinery.
You have well summarized why hypersonic air-breathing launch vehicles have not been built.

There's no comittee giving out awards for getting to orbit the coolest, sexiest way. The only thing that counts is getting there the cheapest, most reliable way.

Airbreathing orbital or suborbital flight requires multiple propulsion systems, each with their own systems, fuel, development and support costs. It requires flying a depressed trajectory, staying within the atmosphere at very high mach speeds. It's like a reentering space shuttle in reverse, only for longer time periods.

This in turn typically means passive thermal control systems like tiles won't work. You have to use active cooling -- the vehicle skin must be lined with a network of cooling tubes. That means pumps, plumbing and possible leak issues. Any failure and you have a Columbia-like disaster, burning up in the atmosphere.

It does save carrying oxidizer, but that's of limited advantage. All the LOX used by the space shuttle costs about $12,000 per flight. The ET to hold it only costs about $5 million, and part of that is fuel.

Antice
2009-May-04, 05:02 AM
the oxidiser saved isnt about the cost of it. but the weight. for a SSTO to work the vehicle to payload rate has to go up. Pure rockets has a delta V shortfall for ssto uses. the savings of air breathing engines outweigh the extra engine weight giving a net saving in total vehicle launch weight. work is being done to make enough weight savings to achieve SSTO. new air breathing engines is just one of the things being looked at.
There is no extended atmospheric flight during launch either. the flightpath is one of a moderate speed climb then a quick accel to mach 5+ and a flip over to rocket only mode and a fairly standard trajectory up the last part of the well.
Compared to the heat at re-entry the climb itself is not going to be hot enough to even start worrying about. if you design it to come back down it will survive the trip up temperature way at least. we already have materials that can sustain high temperatures for extended time and multiple cycles without cracking. Hi temperature stable alloys is not rocket science, and is already being used in other applications on Earth.
The goal isnt to have a rocket with wings for coolness factor. it's to have a fully reusable SSTO vehicle that do not have to be resurfaced every flight.
Besides. as far as wings go. most of the SSTO concepts are lifting bodies. and not true winged vehicles.
you say 5 million extra recurring launch costs is nothing. but it's quite a lot. once you can start dividing your build costs over multiple launches price goes WAY down per launch.
There is a Huge difference in paying 600 mill for a craft that does 200 flights and paying 100 mill for one that does only 1
That being said. there is stil at least 10 years worth of slow and steady development work before it's time to actually make a SSTO vehicle like that. Materials needs to be tested and stuff is stil mostly in the early stages of developement yet. there isnt a huge amount of money being spendt on it either.
Before actually starting to build a full vehicle one needs to prove the key technologies needed. and that takes time more than anything to to do. and isn't a process that is rush able either.

PraedSt
2009-May-04, 08:59 AM
I came across this article. It's a couple of months old, so sorry if it's been covered before.

Pentagon seeks military role for space tourism technology (http://www.flightglobal.com/articles/2009/02/23/322951/pentagon-seeks-military-role-for-space-tourism-technology.html)


As commercial spaceflight draws closer to reality, the US Department of Defense is officially interested.

The National Security Space Office (NSSO) has invited companies such as Armadillo Aerospace, Blue Origin, Virgin Galactic and Xcor to a conference...to discuss how suborbital technology could be applied to military needs

Defence was an early and important market for both the aircraft and satellite industries, wasn't it?

Now the article is mainly about the Marines, who want rapid point-to-point transport, so SSTO doesn't fit the bill- but I was thinking maybe satellite repair? Rapid reconnaissance? Dropping bombs from orbit? Intercepting ICBMs from orbit?

Could be a lot of money in it...

RGClark
2009-May-04, 03:31 PM
...
I disagree on both accounts. Serious reputable engineers sit on both sides of the fence. I believe time will tell who is right. Space planes have a fair way to go on the drawing board before being realizable. Their feasability depends on developing new technologies like air breathing rocket engines. and a fully reusable TPS system that will hold together for 100+ launches. the cost of these technologies are not all that higher than what is being spendt on developing the ARES I/V launchers. or the next generation of fighter jet's for that matter.
the US tried to make a rocket only spaceplane. there is some flaws in the concept as well as a distinct lack of capability to make it fully reusable. A project that is going for the wrong market at the wrong time will fail always.
...

Good points. The first reusable suborbital vehicle was the X-15, a spaceplane. The second reusable suborbital vehicle was SpaceShipOne, a spaceplane. It's not a coincidence they were developed by people who's expertise was in the realm of aircraft.
If the X-51 test in October is successful at Mach 6.5, there will be a lot more discussion on the feasibility of a commercial hypersonic transport, and on the question of whether use of scramjets and rockets can make a reusable SSTO vehicle possible.

Bob Clark

Antice
2009-May-04, 04:04 PM
do you know how long it's suposed to stay in that speed range?

joema
2009-May-04, 07:06 PM
...the savings of air breathing engines outweigh the extra engine weight giving a net saving in total vehicle launch weight...There is no extended atmospheric flight during launch either. the flightpath is one of a moderate speed climb then a quick accel to mach 5+ and a flip over to rocket only mode and a fairly standard trajectory up the last part of the well...Compared to the heat at re-entry the climb itself is not going to be hot enough to even start worrying about. if you design it to come back down it will survive the trip up temperature way at least....
It's by no means clear the oxidizer weight savings compensate for the added weight, complexity, development cost and risk of airbreathing hypersonic propulsion. This is why no such passenger-carrying vehicle has yet been built.

A depressed trajectory is required for hypersonic airbreathers vs a pure rocket. A RAND Corp study of the NASP projected commented:

"The NASP ascent trajectory had to be depressed within the atmosphere to ensure its engines injected enough oxygen. This in turn led to high aeroshell temperatures during supersonic flight, which in turn necessitated the use of advanced TPS materials and active cooling"

The heat loads are extreme and far beyond reentering from lunar velocity, much less orbit. See attached chart.

If instead you envision using a slow-speed (below Mach 5) airbreathing 1st stage, this adds great development cost and contributes relatively little to size and propellant required of the orbiter stage. The kinetic energy equation KE = 1/2 * m * v^2 illustrates why. Most of the energy required for orbital or suborbital flight is from the higher speed regime. Getting a head start to Mach 5 when you ultimately need to reach Mach 20 doesn't help much, yet adds development cost and risk of a huge, complicated airbreathing booster.

This has been studied at great detail by many groups. Optimal staging velocity is about Mach 12, else either 1st or 2nd stage is even bigger and heavier. Yet an airbreathing Mach 12 booster stage is horrendously expensive and complex.

Here's a thought experiment to illustrate the problem. Assume the shuttle orbiter is modified so the entire payload bay is full of OMS propellant. That would give a total delta V of roughly 1,223 meter/sec (4,012 ft/sec). Yet required transatlantic suborbital velocity is about 15,500 ft/sec (4,724 m/s).

This would require an airbreathing booster capable of lifting a fully-loaded orbiter (about 265,000 lbs) to about 11,500 ft/sec (3,502 m/s), or about Mach 10. Picture a hypersonic 747, but bigger. That's why it hasn't been done.

RGClark
2009-May-04, 07:16 PM
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Then we could have a combined cycle ramjet/scramjet where the ramjet is used instead of a rocket to get the vehicle to the speed where the scramjet takes over.
The SR-71 already proved that combined cycle turbojet/ramjet propulsion is possible. A successful X-51 test will suggest a fully jet powered vehicle is possible to Mach 6.5.
Then production of a Mach 6.5+ airbreathing transport very likely would be practical well within a 25 year time frame.
...


We might make a guess on the time frame on the development of a hypersonic commercial transport if the X-51 test is successful based on the case of the jet engine.

Interesting articles on the developers of the jet engine:

Frank Whittle
http://en.wikipedia.org/wiki/Frank_Whittle

Hans von Ohain.
http://en.wikipedia.org/wiki/Hans_von_Ohain

Frank Whittle in England first came up with the idea for a jet engine in 1929. There was a lot of skepticism for the idea and he did not come up with a working prototype then. He was able though to get a patent on it in 1930. He was first able to come up with a working prototype in ground tests in 1937.
Hans von Ohain in Germany independently came up with the idea in 1933. He was also able to produce a working ground prototype in 1937. After some more refinements, it was first tested in aircraft in 1939, only 2 years after the first successful ground tests.
After finally getting funding and support from the British government Frank Whittle, was able to get the first tests in aircraft in 1941.
Actual deployed jet fighters for both countries came only a couple of years after these first flying prototypes.
The first jet airliner was first tested in 1949 and came into service in 1952:

Jet airliner.
http://en.wikipedia.org/wiki/Jet_airliner

So a prototype commercial jet transport was produced only 10 years after a prototype jet fighter, which came only two years after the first jet engine ground tests. Following this model, we might expect a prototype hypersonic jet fighter within 2 years, and a prototype hypersonic transport within 10 years after that.
The X-15 which flew up to Mach 6.7 in the 1960's was already able to withstand the thermal heating at those speeds and likely could be an already existing airframe to test the scramjet engine on. More advanced airframes to optimize range and lift-to-drag ratios would be waverider lifting body shapes.


Bob Clark

PraedSt
2009-May-04, 08:09 PM
The heat loads are extreme and far beyond reentering from lunar velocity, much less orbit. See attached chart.
That chart shows 90 mins exposure time for the X-30. Is that correct? For 'my' vehicle, I was thinking 10-15 mins supersonic+ exposure tops.


Picture a hypersonic 747, but bigger.If you had to design a 747 sized craft that could accelerate to M5-8 within 15 mins ('boost' phase, after level flight), do you think you could do it? Serious question... :)

Antice
2009-May-04, 08:23 PM
there is a lot of claims that the extra weight in airbreathing designs is heavier than the oxidiser saved. I find this absolutist tendency quite absurd considdering that as of yet there is no functioning air breathing rockets. there simply is no real world data on weither this is true or not. all we have so far is a lot of paper with estimates that goes both ways. and more often than not it's a case of who has done the calculus weither it favours air breathing or not.
There are several possible solutions for using air as oxidiser out there. ramjet/scramjet types. pre cooled turbo compressors and so forth.
until a working system is actually made and performance tested, can we know whither there is a saving there or not. It all comes down to what group of engineers you prefer to believe in until some real world performance numbers can be obtained.
Quite frankly It's WAY to early to say it cant be done.
I'm not advocating spending billions on making it hapen. my stance is that spending a few mill to keep the development of the engines that might enable ssto in the future is worthwhile. It's cutting edge aeronautics. And pushing boundaries is important. It's how new stuff get's discovered after all. We would still be lion snacks on the savannah if it wasn't for some bright guy back in the days daring to try to control fire. he probably did it despite all his tribe calling him crazy for playing with such a dangerous force.
The engineering behind some of the concepts floating around is pretty sound. it's not something we can pull off yet. but in time we will. new materials are alowing ever lighter engine components to be built. ever lighter structural materials for making the fuselage and so forth. SSTO with rocket engines only isn't currently doable on earth. the well is just about a bit too deep. so we need to loose take-off weight to get up there. the shortfall isn't really all that large. so saving a couple of tonnes on the take-off makes a very large difference in your payload ratio.And why is the orbiter even suggested as an example of a space plane. it clearly is not even close. Compared to the designs proposed it's a flying brick. it cant even launch itself from the pad.
a better comparison is the X-33 venturestar. and that one failed when they found out that the payload rate just got too small. especially without the promised composite cryogenic tanks.... now those tanks could really benefit any craft that do not use the tanks as part of the structure.
Scaled composites have already shown that lightweight materials can deal with the temperatures at launch easily enough. there really is no need for heavy tiles. add some ultralight insulation behind the outer temperature stable skin and you no longer need active cooling systems. We currently have materials that are lightweight yet completely stable at over 2000C. This is not a technology issue any more but a practical cost and engineering one. it's solvable today.
Getting rid of excess weight is the name of the game.

Nicolas
2009-May-04, 08:26 PM
It's by no means clear the oxidizer weight savings compensate for the added weight, complexity, development cost and risk of airbreathing hypersonic propulsion. This is why no such passenger-carrying vehicle has yet been built.

Erm, no. The main reason why it has not yet been built is that we haven't got a properly working large scale scramjet up and running yet. It's difficult you know. The useability of the thing isn't an issue yet, as we haven't got the thing yet. Give it some time, let's see how good we can make these scramjets, and then lets see for which uses they are suitable and for which they aren't.

joema
2009-May-04, 10:39 PM
The main reason why it has not yet been built is that we haven't got a properly working large scale scramjet up and running yet....
I don't agree. That's like saying the main impediment to building the Space Shuttle was SSME development.

No question -- whether scramjets or rockets -- main propulsion development is a key item. But it's one of many key items, any one of which could render the project infeasible.

As the NASP project showed, there's a host of extreme technical problems associated with airbreathing hypersonic flight to near-suborbital velocity. These include thermal management, aerodynamics, structures, control, etc.

Those problems are already solved for rocket-powered vehicles. The shuttle could do a suborbital trans-atlantic flight right now, carrying passengers. It wouldn't be cost efffective, but it's doable. Likewise a cheaper, newer, more reliable rocket powered vehicle could do it with essentially current technology. E.g, the hypothetical SpaceShipThree: http://www.flightglobal.com/blogs/hyperbola/2008/02/spaceshipthree-revealed.html. The airbreathing mothership's energy contribution to suborbital flight is tiny -- it's essentially a pure rocket from a kinetic energy standpoint.

By contrast an airbreathing suborbital passenger craft must be conquer formidable, entirely new areas -- just to achieve the same result as a rocket-powered vehicle can achieve right now.

It's true an airbreathing suborbital passenger craft is like the Gerry Anderson Thunderbirds or U.F.O. TV Shows. Unfortunately you don't get extra credit for using the most romantic, science-fictional technology. The only thing that counts is results.

Any future hypothetical airbreathing suborbital passenger vehicle must compete head-to-head with a similar new pure rocket vehicle. The development cost, technical risk, operational costs and reliability of each approach must be pragmatically evaluated.

The airbreather faces an uphill battle to prove its viability: http://en.wikipedia.org/wiki/Scramjet

publiusr
2009-May-04, 11:31 PM
I think you'll find for a shuttle orbiter size vehicle the fuel required would be significantly less than the shuttle's external tank and without requiring the solid rocket boosters.


Bob Clark

That is the German Spaceliner project I linked to above from DLR--althought it is suborbital

Finally pop sci released pics to the web
http://www.popsci.com/scitech/article/2009-04/planes-trains-and-sueprsonic-spaceships?page=1

The Marines wanted something called SUSTAIN.
Ithacus Jr. might live...no runway.

Nicolas
2009-May-05, 09:23 AM
I don't agree. That's like saying the main impediment to building the Space Shuttle was SSME development.

That is not a correct comparison. The SSME is a rocket engine, a new model of a known, working and routinely commercially applied principle.

How many working, routinely applied commercial scramjet types are their around? Zero. The technology still needs to be developed. SCramjets are absolutely not at the state rocket engines were when the SSME was designed.


Those problems are already solved for rocket-powered vehicles. The shuttle could do a suborbital trans-atlantic flight right now, carrying passengers. It wouldn't be cost efffective, but it's doable.

Which is exactly why they are also looking into other technologies to perform transcontinental hypersonic flights.


By contrast an airbreathing suborbital passenger craft must be conquer formidable, entirely new areas -- just to achieve the same result as a rocket-powered vehicle can achieve right now.

How can you at this stage make an assessment of how the costs would compare? What about noise regulations? Turn around time?


As the NASP project showed, there's a host of extreme technical problems associated with airbreathing hypersonic flight to near-suborbital velocity. These include thermal management, aerodynamics, structures, control, etc.
Apart from the inlet, the aerodynamic problems are unrelated to the propulsion system used. The structures, control and thermal management are unrelated to the propulsion system used. And what is "near-suborbital velocity"?


It's true an airbreathing suborbital passenger craft is like the Gerry Anderson Thunderbirds or U.F.O. TV Shows. Unfortunately you don't get extra credit for using the most romantic, science-fictional technology. The only thing that counts is results.

When we are researching scramjet vehicles at ESA, it has NOTHING to do with being romantic, sexy or whatever. It is purely about performance of the thing. Please stop with arguing against a technology by labeling it in a subjective way.


The development cost, technical risk, operational costs and reliability of each approach must be pragmatically evaluated.

Indeed it does, so let's wait until some results are in before jumping to conclusions.

Ara Pacis
2009-May-05, 11:10 AM
Just in case anyone hasn't already read it, here is some information on hypersonic Waverider craft designs.

Basic designs: http://www.aerospaceweb.org/design/waverider/design.shtml
Calculated designs: http://www.aerospaceweb.org/design/waverider/waverider.shtml

I am interested in the concept of variable geometry wings in the form of extendable cloth rogallo wings that might be used to improve lift and drag over various mach numbers.

Well, since we're talking about both hypersonic transport and SSTO and I have an interest in developing an idea that includes both, I'll put it in here.

I asked earlier what someone thought was a good mission profile to be used as a design goal. The number I use is 3000kg (3 metric tons). I would divide that evenly between cargo and passengers/crew, such that each passenger's total mass allowance was 150kg (assuming an average of 75kg per passenger and per passenger cargo), resulting in a "normal" (no frills) load of 18 passengers and 2 crew. (There are other pax/cargo combinations, but all must be 3000kg.) I calculated that I could fit all this mass into a cabin of minimal dimensions ~6'x35' plus a cockpit of about 4 to 5 ft length for a total pressure vessel length of around 40 ft. I'd use 18' for seating (no aisle), then 2' for a toilet module, then 15' for cargo. The single hatch into this pressure vessel is in the roof near the front of the passenger cabin, behind the cockpit partition (seat location 1B).

I'd use lightweight materials effectively, such as using strong and light fibers for mesh fabric seating that is more like a string hammock than a chaise lounger, such that the cabin configuration can change from a can-on-its-side layout to a can-on-its-end layout once in freefall.

I think of this as the bare minimum mission goal. 3000kg to orbital rendezvous with some sort of future space station, interorbital cycler, or tether link to a different orbital position. With life support from at least a few hours (until rendezvous) to a few days emergency supply. Assuming this pax+cargo load in the pressure vessel described, what do we need to wrap around it in terms of structure and propellant to get it to where it needs to go?

PraedSt
2009-May-05, 12:15 PM
I asked earlier what someone thought was a good mission profile to be used as a design goal. The number I use is 3000kg (3 metric tons).
Thanks for the links. I hadn't read the first one before.

Can I modify your design goal? :) The first models will be engineering tests I think. Proof of concept, try and walk before you run, blah, blah, blah.

So....how about 200kg payload max (not including payload structure)? Let's see if we can get that into space. If we can, then we move up to 500kg, then 1T, then 2T, etc.

Just a thought...

EDIT: I know 200kg is boring, but I think it's more practical :)

Antice
2009-May-05, 12:34 PM
I think just getting a test vehicle with extra instruments up there should be the first goal. there is a need for performance data on lighweight hull materials and how well they perform outside the lab.

RGClark
2009-May-05, 04:08 PM
do you know how long it's suposed to stay in that speed range?

I believe the articles said in this test X-51 was supposed to operate on the scramjet for 5 to 6 minutes. I don't know how long it will be for the highest Mach speeds.


Bob Clark

RGClark
2009-May-05, 04:42 PM
...

Here's a thought experiment to illustrate the problem. Assume the shuttle orbiter is modified so the entire payload bay is full of OMS propellant. That would give a total delta V of roughly 1,223 meter/sec (4,012 ft/sec). Yet required transatlantic suborbital velocity is about 15,500 ft/sec (4,724 m/s).
This would require an airbreathing booster capable of lifting a fully-loaded orbiter (about 265,000 lbs) to about 11,500 ft/sec (3,502 m/s), or about Mach 10. Picture a hypersonic 747, but bigger. That's why it hasn't been done.

Let me take a more optimistic approach to this. Instead of using the OMS engines, use the shuttle main engines and fill the payload bay with liquid hydrogen and LOX. This Wikipedia page gives the dimensions of the shuttle payload bay as 4.6 m by 18 m.:

Space Shuttle.
1.6 Technical data.
http://en.wikipedia.org/wiki/Space_Shuttle#Technical_data

I'll calculate the volume as 4.6*4.6*18 = 380.9 m^3. This about 1/5th the volume of the propellant in the external tank. So would amount to 1/5th the mass of the propellant in the ET or 140,000 kg. The empty shuttle masses about 100,000 kg so the total liftoff mass would be 240,000 kg.
The usual rocket equation gives the mass ratio of the fully fueled vehicle to the bare vehicle as M0/Mf = e^(delta-v/Ve) or equivalently delta-v/Ve = ln (M0/Mf). Using the vacuum exhaust velocity of the shuttle main engines as 4,550 m/s, this results in delta-v = 4550*ln(240,000/100,000) = 3,983 m/s. This leaves a delta-v to be supplied by the carrier craft of only 740 m/s, about Mach 2.5, not an unachievable speed as the SR-71 was able to reach Mach 3+ as was the XB-70 bomber.


Bob Clark

Antice
2009-May-05, 10:28 PM
Let me take a more optimistic approach to this. Instead of using the OMS engines, use the shuttle main engines and fill the payload bay with liquid hydrogen and LOX. This Wikipedia page gives the dimensions of the shuttle payload bay as 4.6 m by 18 m.:

Space Shuttle.
1.6 Technical data.
http://en.wikipedia.org/wiki/Space_Shuttle#Technical_data

I'll calculate the volume as 4.6*4.6*18 = 380.9 m^3. This about 1/5th the volume of the propellant in the external tank. So would amount to 1/5th the mass of the propellant in the ET or 140,000 kg. The empty shuttle masses about 100,000 kg so the total liftoff mass would be 240,000 kg.
The usual rocket equation gives the mass ratio of the fully fueled vehicle to the bare vehicle as M0/Mf = e^(delta-v/Ve) or equivalently delta-v/Ve = ln (M0/Mf). Using the vacuum exhaust velocity of the shuttle main engines as 4,550 m/s, this results in delta-v = 4550*ln(240,000/100,000) = 3,983 m/s. This leaves a delta-v to be supplied by the carrier craft of only 740 m/s, about Mach 2.5, not an unachievable speed as the SR-71 was able to reach Mach 3+ as was the XB-70 bomber.


Bob Clark

That Delta V shortfall is for a vehicle with no cargo, that is also a lot heavier than what it could be with more modern materials.
I keep going back to the skylon for references fro a comparison. because it's a oncept with most of it's referenses online for all to read.
the claim there is that the air breathing stage supplies 1500ms of orbital velocity and accounts for 1200ms of trajectory losses. leaving 6500ms for the rocket part of the ascent. that is enough to more than cover the shortfall for a non cargo vehicle. Add to that the fact that the skylon design will actually be a lot lighter structure wise than the shuttle is trough the use of composite materials throughout the craft.
The shuttle design is showing it's age. newer materials allow us to build a comparatively strong vehicle at only half the weight. and future advances will allow even lighter dry mass vehicles to be made.

Ara Pacis
2009-May-06, 01:26 AM
Thanks for the links. I hadn't read the first one before.

Can I modify your design goal? :) The first models will be engineering tests I think. Proof of concept, try and walk before you run, blah, blah, blah.

So....how about 200kg payload max (not including payload structure)? Let's see if we can get that into space. If we can, then we move up to 500kg, then 1T, then 2T, etc.

Just a thought...

EDIT: I know 200kg is boring, but I think it's more practical :)

Well, I would call those other steps "intermediate goals" but the particular vessel I described is what I think is a conservative minimum for a future work-a-day aero-space-taxi. Call it a distant commercial goal. I know it's a tight fit. I intentionally minimized the cross section to reduce drag and seek the absolute minimum, but feel free to increase the fuselage diameter by a few inches or a few feet. (The 6' dia. is actually about a foot larger than SS1 and a foot-and-a-half smaller than SS2 and about the same as many common private jets.) The vehicle is designed to have flexibility in it's interior layout. In fact, a more common loading might be 8 passengers & crew and more cargo. The maximum passenger+crew load would be 35 with no cargo (due to volume constraints, yet ~17.5% under nominal mass limit).

Note that my goal of 3T is only the basic passenger and cargo load, not the mass of the life support, or structure or anything else, although I would strive to keep all those systems as low-mass as possible. I would like the craft to be minimally shielded as the time in orbit should be minimized since it is merely taking passengers and cargo to or from a well shielded station. I know it may sound ridiculous, but I think a cloth-based rogallo wing (http://en.wikipedia.org/wiki/Rogallo_wing) similar to hang-gliders but made of high-strength and high-temperature resistant material may be worth investigating. The leading edge would see heating during hypersonic flight, but that might be cryogenically cooled if necessary and remove the need for heat-resistant tiles. Of course, I should mention that in a more fully evolved space infrastructure, there might be multiple ways of reducing velociting for de-orbit other than aerobraking (such as orbitally refuled retro-rockets or an electromagnetic captapult or a tether).

joema
2009-May-06, 03:15 AM
Let me take a more optimistic approach to this. Instead of using the OMS engines, use the shuttle main engines and fill the payload bay with liquid hydrogen and LOX. This Wikipedia page gives the dimensions of the shuttle payload bay as 4.6 m by 18 m.:

Space Shuttle.
1.6 Technical data.
http://en.wikipedia.org/wiki/Space_Shuttle#Technical_data

I'll calculate the volume as 4.6*4.6*18 = 380.9 m^3. This about 1/5th the volume of the propellant in the external tank. So would amount to 1/5th the mass of the propellant in the ET or 140,000 kg. The empty shuttle masses about 100,000 kg so the total liftoff mass would be 240,000 kg.
The usual rocket equation gives the mass ratio of the fully fueled vehicle to the bare vehicle as M0/Mf = e^(delta-v/Ve) or equivalently delta-v/Ve = ln (M0/Mf). Using the vacuum exhaust velocity of the shuttle main engines as 4,550 m/s, this results in delta-v = 4550*ln(240,000/100,000) = 3,983 m/s. This leaves a delta-v to be supplied by the carrier craft of only 740 m/s, about Mach 2.5, not an unachievable speed as the SR-71 was able to reach Mach 3+ as was the XB-70 bomber...

While a piggyback airbreathing launch has long been dreamed of, unfortunately more accurate numbers show it won't work -- if your goal is achieve transatlantic suborbital flight with something like the space shuttle.

The shuttle payload bay volume is about 10,000 cubic feet (283 cubic meters). Not all of that is usable, e.g, the Centaur-G upper stage had a diameter of about 14 feet. A reasonable guess to include insulation, plumbing, etc. would be about 8,500 cubic feet (240 cubic meters).

By contrast the shuttle external tank propellant volume is about 72,000 cubic feet (2,038 cubic meters). Hence the shuttle payload bay usable propellant volume would be about 11% of the external tank.

The ET propellant mass is about 1.62 million lbs (735,000 kg). Thus the shuttle payload bay full of tanked cryogenic LH2/LOX would mass about 11% of that or 178,200 lbs (80,830 kg). That's way over the shuttle weight limit, so the actual limit would be about 1/3 of that, or 60,000 lbs.

Assuming you could air-start the SSMEs after a piggyback launch, and use cryogenic LH2/LOX from the payload bay, here's how I calculate the achievable delta-V:

delta v = Isp g ln(Mr) , where:

delta v = veloc change in m/s
Isp = specific impulse in seconds (SSME vacuum Isp=453 sec)
g = grav. accel constant (9.8 m/sec/sec)
Mr = mass ratio, i.e., M fueled/M empty (dimensionless)

First get mass fraction:
Orbiter flight-ready mass minus payload (propellant): about 176,000 lbs (80,000 kg)
Orbiter gross mass inc'l payload: 238,200 lbs (108,000 kg)
Orbiter mass ratio is 238,200/176000 = 1.35

delta v = 453 sec * 9.8 m/sec/sec * ln (1.35)
delta v = 1332 meters/sec (4370 ft/sec).

It appears there's nowhere near the delta-V capability needed to for suborbital transatlantic flight, even if launched at Mach 3 or Mach 5.

RGClark
2009-May-06, 04:04 PM
While a piggyback airbreathing launch has long been dreamed of, unfortunately more accurate numbers show it won't work -- if your goal is achieve transatlantic suborbital flight with something like the space shuttle.
The shuttle payload bay volume is about 10,000 cubic feet (283 cubic meters). Not all of that is usable, e.g, the Centaur-G upper stage had a diameter of about 14 feet. A reasonable guess to include insulation, plumbing, etc. would be about 8,500 cubic feet (240 cubic meters).
By contrast the shuttle external tank propellant volume is about 72,000 cubic feet (2,038 cubic meters). Hence the shuttle payload bay usable propellant volume would be about 11% of the external tank.
The ET propellant mass is about 1.62 million lbs (735,000 kg). Thus the shuttle payload bay full of tanked cryogenic LH2/LOX would mass about 11% of that or 178,200 lbs (80,830 kg). That's way over the shuttle weight limit, so the actual limit would be about 1/3 of that, or 60,000 lbs.
Assuming you could air-start the SSMEs after a piggyback launch, and use cryogenic LH2/LOX from the payload bay, here's how I calculate the achievable delta-V:
delta v = Isp g ln(Mr) , where:
delta v = veloc change in m/s
Isp = specific impulse in seconds (SSME vacuum Isp=453 sec)
g = grav. accel constant (9.8 m/sec/sec)
Mr = mass ratio, i.e., M fueled/M empty (dimensionless)
First get mass fraction:
Orbiter flight-ready mass minus payload (propellant): about 176,000 lbs (80,000 kg)
Orbiter gross mass inc'l payload: 238,200 lbs (108,000 kg)
Orbiter mass ratio is 238,200/176000 = 1.35
delta v = 453 sec * 9.8 m/sec/sec * ln (1.35)
delta v = 1332 meters/sec (4370 ft/sec).
It appears there's nowhere near the delta-V capability needed to for suborbital transatlantic flight, even if launched at Mach 3 or Mach 5.

The mass limit for payload is based on how much mass can be transported to orbit based on the fixed amount of fuel in the solid rocket boosters and the fixed amount in the external tank. This is only around 25,000 kg because of the exponential dependence of fuel requirements on the final speed of vehicle, which is quite large for orbital flight. The payload limit due to structural limits is not known. But consider the space shuttle after SRB separation is supporting the weight of the external tank and the large amount of fuel still in the tanks after the SRB's are gone.
A more accurate number would be to suppose it could support this weight carried internally. Said another way, it certainly could support this weight carried externally since it already does carry a much larger amount now after SRB separation. And actually the structural loads are even worse there because of aerodynamic forces on the external tank.
The number I found for the shuttle payload bay volume was 300 cubic meters. If you look at diagrams for the shuttle external tank I would say the space not occupied by fuel is 10% or less. But using your number for available space for fuel in the payload bay of 240 cubic meters, this would result in 80,830 kg of fuel.
Since we already used up all the space in the payload bay we only now have the bare orbiter with no payload. Still it could carry up to seven passengers and crew. So it would mass 80,000 kg. Then the total mass with fuel is 160,830 kg and the delta-v would be:
delta-v = 453*9.8*ln(160,830/80,000) = 3,100 m/s.
This would require only Mach 5 to be supplied by the carrier craft, beyond what has been reached in operational craft now but within the range of the hypersonic scramjets now being tested.


Bob Clark

djellison
2009-May-06, 08:26 PM
TThis would require only Mach 5 to be supplied by the carrier craft, beyond what has been reached in operational craft now but within the range of the hypersonic scramjets now being tested.

By all means point us to a Mach 5 vehicle behing developed with lifting capacity for a space shuttle with a payload bay full of fuel.

Oh - and with a full payload bay - this thing has room for, basically, 5 passengers.

This is not a viable passenger sub orbital transport system.

Nicolas
2009-May-06, 09:24 PM
The LAPCAT range of vehicles do not intend to drag a space shuttle along with them (you're allowed to let gravity do its job on your jaw now ;)), but they are intended as sub orbital passenger transport vehicles. Note that it are research projects/technology demonstrators, but not meant as to lead to the complete craft being actually built.

RGClark
2009-May-06, 10:23 PM
By all means point us to a Mach 5 vehicle behing developed with lifting capacity for a space shuttle with a payload bay full of fuel.

Oh - and with a full payload bay - this thing has room for, basically, 5 passengers.

This is not a viable passenger sub orbital transport system.

We are agreed on that. This was purely a mental exercise. The shuttle wouldn't be used for that purpose.
But if the Mach 6.5 tests in October are successful there will be a lot more discussion on the possibility of a commercial hypersonic transport.


Bob Clark

joema
2009-May-07, 03:30 AM
The payload limit due to structural limits is not known...
On the contrary, this number is well known. It's roughly the same as liftoff payload, give or take a bit. This is known to a high accuracy because of the structural and aerodynamic limits involved in an abort landing.

Just like aircraft, the shuttle has a maximum takeoff gross weight and a maximum normal landing weight, and a maximum abort landing weight. Exceeding this means the vehicle integrity is at risk in an abort landing scenario.

The vehicle absolutely cannot fly and land safely with much over 60,000 lbs in the payload bay, whether composed of cargo or propellant.

Ara Pacis
2009-May-07, 10:55 AM
Maybe I missed this, but are the proposed hypersonic transports supposed to spend their time in the powered hypersonic flight regime at the apex of their flight or will the proposed HT coast through vacuum for a portion of its flight?

Nicolas
2009-May-07, 01:07 PM
Lapcat M5 and M8 would not go to vacuum, they'd be like regular planes but faster. Flying a bit higher as well, but nothing space related.

RGClark
2009-May-07, 02:35 PM
On the contrary, this number is well known. It's roughly the same as liftoff payload, give or take a bit. This is known to a high accuracy because of the structural and aerodynamic limits involved in an abort landing.

Just like aircraft, the shuttle has a maximum takeoff gross weight and a maximum normal landing weight, and a maximum abort landing weight. Exceeding this means the vehicle integrity is at risk in an abort landing scenario.

The vehicle absolutely cannot fly and land safely with much over 60,000 lbs in the payload bay, whether composed of cargo or propellant.

You are talking about landing with a certain amount of weight, not the amount carried during flight, which would be fully exhausted before landing.
As I said the shuttle after SRB separation carries far more than this amount externally when this weight is subjected to great aerodynamic loads than it would be if this weight were carried internally.


Bob Clark

RGClark
2009-May-07, 02:40 PM
Lapcat M5 and M8 would not go to vacuum, they'd be like regular planes but faster. Flying a bit higher as well, but nothing space related.

It wouldn't be at the altitude considered "space" at 100 km. You wouldn't get enough air for ramjet/scramjet propulsion then. But the altitude would be quite high and significantly above the altitude for normal commercial jets which fly around 30,000 ft, about 10 km.
Likely, the altitude for the hypersonic cruise would be in the range of 25 km to 50 km.


Bob Clark

joema
2009-May-07, 05:27 PM
You are talking about landing with a certain amount of weight, not the amount carried during flight, which would be fully exhausted before landing.
As I said the shuttle after SRB separation carries far more than this amount externally when this weight is subjected to great aerodynamic loads than it would be if this weight were carried internally...
You cannot guarantee propellant carried within the orbiter itself will be fully exhausted in flight.

It is exactly the same scenario as carrying a heavy payload, and (a) being unable to deploy it due to stuck payload doors, or (b) encountering an in-flight abort requiring an immediate landing.

It's not just structural. The weight affects wing loading, flight control, thermal margins, landing gear margins, etc, etc.

There are numerous failure modes that would necessitate an immediate landing with a full payload. Whether the vehicle can ascend with an overweight payload is immaterial. You can't write off the vehicle and crew because a mild in-flight abort happens and the overweight condition makes the the vehicle break up, burn up, or disintegrate upon landing.

Today, many orbiter parameters are right at the limit for landing with a 55-60,000-lb payload. It's impossible to reenter, fly or land with 3x that payload.

Nicolas
2009-May-07, 05:58 PM
It wouldn't be at the altitude considered "space" at 100 km. You wouldn't get enough air for ramjet/scramjet propulsion then. But the altitude would be quite high and significantly above the altitude for normal commercial jets which fly around 30,000 ft, about 10 km.
Likely, the altitude for the hypersonic cruise would be in the range of 25 km to 50 km.


Bob Clark

I may have entered the flight altitude (or the corresponding ISA pressure) of this beast a thousand times in my life, but I've forgotten it... But I thought it was something like that, 30km if you'd point a gun at me. I vaguely remember that it was higher than Concorde, which flew at 20km altitude.

Maybe it's somewhere in a paper I've written on the subject, but I don't have time to go through that now. Maybe it's also in the report of the Valencia space meeting of, erm, 2006?

joema
2009-May-07, 10:59 PM
...Today, many orbiter parameters are right at the limit for landing with a 55-60,000-lb payload. It's impossible to reenter, fly or land with 3x that payload.
To further elaborate on this, increasing payload to around 80,000 kg (about 178,000 lbs) would require redesign of the entire vehicle. You'd need larger wings, more robust landing gear, upgraded TPS, etc, etc. That in turn would increase total mass, so you'd need more propellant to achieve the desired delta-V, a bigger launch vehicle, etc.

However -- assume that magically, miraculously, the current orbiter could fly and (if needed) land safely with 80,000 kg of cryogenic propellant in the payload bay. Also assume the SSMEs can be air-started, and everything else just works.

The achievable delta-V would be:

delta v = Isp g ln(Mr) , where:

delta v = veloc change in m/s
Isp = specific impulse in seconds (SSME vacuum Isp=453 sec)
g = grav. accel constant (9.8 m/sec/sec)
Mr = mass ratio, i.e., M fueled/M empty (dimensionless)

First get mass fraction:
Orbiter flight-ready mass minus payload (propellant): about 176,000 lbs (80,000 kg)
On-board main engine propellant: 80,000 kg
Orbiter gross liftoff mass: 160,000 kg (352,700 lbs)
Orbiter mass ratio: 160,000 kg / 80,000 kg = 2.0

delta v = 453 sec * 9.8 m/sec/sec * ln (2.0)
delta v = 3,077 meters/sec (10,095 ft/sec).

Now, 10,095 ft/sec is a lot faster, but about 18,500 ft/sec is required for a 3-engine out TAL abort. If you don't reach that speed, you land in the ocean.

That means the launch vehicle must boost the orbiter to 18,500-10,095=8,405 ft/sec (2,561 m/s), which is about Mach 8.

The current 747 can barely lift a stripped, empty orbiter to 400 knots.

To lift a 352,000 lb orbiter to Mach 8 would require a mind-boggling launch vehicle. The only plane on earth today which could lift that (off the ground) would be the Antonov-225 -- gross weight (minus payload) about 800,000 lb.

You'd need something like a Mach 8 X-30 NASP (which was about 300,000 lbs), but probably 3x the mass.

In aerospace projects, development cost is closely related to gross weight. The required launch vehicle would be fantastically expensive, and entail great technical risk.

RGClark
2009-May-10, 01:53 PM
An article on the FaCET combined-cycle engine:

Hypersonic Jets Prepare to Soar.
By Chris Kjelgaard
posted: 28 September 2007
01:16 pm ET
"Using JP-7 jet fuel, PWR ran the combustor successfully at a variety
of Mach numbers from Mach 2.5 to Mach 6.0, demonstrating "desired
operability and performance" at each speed, the company said.
"No engine, to our knowledge, has (previously) demonstrated a range
from as low as 2.5 to a high of 6.0," said Michel McKeon, PWR's
hypersonics and advanced programs manager. "The FaCET (Falcon Combined-
Cycle Engine Technology) engine demonstrated a very wide Mach range,
with high performance. This really shows the technology lends itself
to application for a variety of different things."
...
"FaCET aims to develop a hypersonic test vehicle -- which could fly in
2012 -- that would take off and land by itself, use an advanced
turbojet to get up to a speed of at least Mach 4 and then use a liquid
hydrogen-powered scramjet to get to Mach 10 and beyond."
http://www.space.com/businesstechnology/070928-hypersonic-jet-fueled-aircraft.html

And here are some articles giving a more detailed discussion of the X-51A:

X-51A to demonstrate first practical scramjet.
DATE:20/07/07
SOURCE:Flight International
By Graham Warwick
http://www.flightglobal.com/articles/2007/07/20/215592/x-51a-to-demonstrate-first-practical-scramjet.html

X-51A Scramjet Engine Completes Ground Tests.
Nov 2, 2008.
By Graham Warwick
http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/aw110308p1.xml


Bob Clark

RGClark
2009-May-17, 02:52 PM
Saw these articles linked on the Wikipedia X-33 page:

Lockheed Test Flies Space Plane Prototype.
By Leonard David
Special Correspondent, SPACE.com
posted: 24 April 2008
11:41 am ET
"Lockheed Martin has tested a prototype reusable launch system by flying a sub-scale flight demonstrator from the site of New Mexico's proposed Spaceport America.
"The successful test flight of the proprietary vehicle took place in December and was only recently disclosed. A company official said Lockheed Martin is planning more tests using ever-larger vehicles.
"Lockheed Martin Space Systems teamed with launch provider UP Aerospace of Highlands Ranch, Colo., Dec. 19 to conduct a small demonstration launch at Spaceport America in southern New Mexico to evaluate proprietary technology the company currently has under development."
http://www.space.com/businesstechnology/080424-lockheed-spaceplane-test.html

Lockheed loses prototype of Space reusable launch vehicle.
18 August 2008
"Golden, Colorado: Lockheed Martin's second test flight of a prototype reusable launch system failed with the craft going out of control and becoming seriously damaged, rendering it unusable. The test, conducted 12 August, saw the winged craft take off from a launch rail under its own power and fly for some 12.5 seconds of a planned flight of less than a minute before it crashed."
...
"The 200-pound (91 kg) vehicle reached its planned altitude of roughly 1,500 feet (457 meters). It is 8 feet (2.4 meters) long with a wingspan of about 6 feet (1.8 meters) and is roughly one-fifth in scale. It is being flown to develop techniques and procedures for quick launch, ease of operations and low cost access to space."
http://www.domain-b.com/aero/space/launch_veh/20080818_lockheed_martin.html

Anyone know what the scoop on this is? Since the Lockheed X-33 was canceled because of the relatively trivial problem (compared to the complexity of the rest of the system) of the composite hydrogen tank debonding, I'm inclined to think Lockheed solved that problem and it's a version of the X-33. The dimensions given though are small for it actually being a one-fifth scale of the X-33:

X-33 Advanced Technology Demonstrator.
X-33 Specifications.
Length: 69 ft
Width: 77 ft
Takeoff weight: 285,000 lbs
Fuel: LH2/LO2
Fuel weight: 210,000 lbs
Main Propulsion: 2 J-2S Linear Aerospikes
Take-off thrust: 410,000 lbs
Maximum speed: Mach 13+
Payload to Low Earth Orbit: N/A
http://en.wikisource.org/wiki/X-33_Advanced_Technology_Demonstrator

If it is a version of the X-33, I wonder why it would now be classified. Perhaps Lockheed found it would be able to provide the suborbital troop delivery system wanted by the defense department. If so, it could also work as a suborbital commercial transport.

This article suggests the composite hydrogen tank debonding has been solved:

New Composite Hydrogen Fuel Tank For RLVs Successfully Tested.
Huntsville - Dec 22, 2003
"A team of engineers from Northrop Grumman and NASA's Marshall Space Flight Center, Huntsville, Ala. Have demonstrated that a new, specially designed fuel tank made from composite materials can safely hold and contain liquid hydrogen under simulated launch conditions."
...
"Fuel tank problems on the X-33 Venture Star project were critical to ending what was the last major new space transportation R&D program at NASA."
http://www.spacedaily.com/news/rlv-03p.html

Several companies are also working on developing lightweight composite cryogenic tanks:

An update on composite tanks for cryogens.
More automation, improved materials bring composite fuel tanks for space applications closer to reality.
Contributed by: Sara Black, Technical Editor
Article Date: 11/1/2005
http://www.compositesworld.com/articles/an-update-on-composite-tanks-for-cryogens.aspx



Bob Clark

Antice
2009-May-17, 04:08 PM
The state of the art on lightweight cryogenic fuel tanks is great news for all SSTO concepts. it's a step on the way to removing the Delta V shortfall we currently see in these kinds of vehicles.
Sooo Close.. can almost see the end soon. that last bit of LOX saved with air breathing engines might be the tip of the scale to make it work ya know.

Nicolas
2009-May-17, 04:45 PM
I still don't get the urge to make an SSTO that barely reaches orbit and hence cannot bring much payload along, versus a two-stage craft that easily reaches orbit. This comment has nothing to do with airbreathing hypersonic engines, just the focus on SSTO.

btw using scramjets, you'd most likely NOT have an SSTO, because the scramjet engines work only so far, and become dead weight on the last part of the ascent. That's why they're being investigated as boosters, not as an SSTO.

Antice
2009-May-17, 07:14 PM
it's not that it's a single stage that fascinates. it's reusability without having to rebuild the vehicle.
without that re usability you still havent got anything worthwhile.
Secondly. Scramjet's are only one method of air breathing. there ARE others.
Some reusable SSTO concepts don't use air breathers at all as well.
It's al about having one vehicle capable of doing multiple launches without significant maintenance. something the old rockets will never be able to do. They will always be cheaper as throwaway launchers than reusable.

Nicolas
2009-May-17, 07:32 PM
It's al about having one vehicle capable of doing multiple launches without significant maintenance. something the old rockets will never be able to do. They will always be cheaper as throwaway launchers than reusable.

This can also be done with multi stage vehicles. Putting the stack together isn't that expensive. There are concepts of flyback boosters and stages that land like planes, or that land on the land (less extensive refurbishing needed compared to ocean landings). I'm not sure that cheap reusability requires an SSTO craft. I can imagine a rocket stack with flyback boosters and stages and a capsule-like thing on top, which would result in only a small heat shield having to be refurbished between flights, where an SSTO craft is "completely" covered in heat shield. Of course it can be done better than the shuttle in the future, but the shuttle does show that this may be a major issue in keeping reusability costs down.

What other airbreathing engine concepts other than scramjets did you have in mind for launchers?

Antice
2009-May-17, 07:53 PM
the Sabre engines looks promising. they have the added benefit of having less dead weight since the air breathing part is only the 2/3rds of the engine. the last part is a rocket engine and works all the way up.
As for scramjet boosters as first stages. i find those concepts quite promising. esp since the first stage can fly back home by themselves and be reused maybe even inside of 24 hours with experience and refinement.
Both of these engine types have potential uses in hypersonic transport as well, so developing them isn't really taking money away from space exploration as some claim.

here is my list of priorities when it comes to what new launchers have to deliver:
1. fast launch rates with a minimum of pre processing.
2. re usability with short turnaround times.
3. Cargo range in the 10 to 20 tonne range at least, and ability to deliver passengers to LEO

Here is what i dont think they should care to aim for.
1. Big oversized cargoes. BDB's are cheaper for that kind of stuff.
2. Above LEO reentry profiles. It's just not practical with anything but a capsule for that.
3. Shuttle like construction. bringing a big robot arm is a waste of cargo space. Launch the darn robots separately and let em stay up there. Robots don't mind after all. and once up there can be reused without further investment cost.

Nicolas
2009-May-17, 08:48 PM
Thanks for detailing your thoughts. Sounds reasonable to me. everything is debatable, but I can find myself in your points. The Sabre engine does look interesting indeed.

regarding your comment on robot arms: if it's an optional item in your cargo bay, I don't see too many issues with it. When you need it, you bring it along; if not, nothing to worry about.

Antice
2009-May-17, 10:03 PM
Thanks for detailing your thoughts. Sounds reasonable to me. everything is debatable, but I can find myself in your points. The Sabre engine does look interesting indeed.

regarding your comment on robot arms: if it's an optional item in your cargo bay, I don't see too many issues with it. When you need it, you bring it along; if not, nothing to worry about.

true enough. but often times cargo space is at a premium while you still need stuff like the robot arm. for say the Hubble repair mission the shuttle arm is fine. but if you plan to build something then leaving it there at the first launch is much more economical. you dont realy have to have much for that.
basically a truss with arms and a pair of solar panels on it.
Once the shuttle is out of the picture that is kinda the only option left unless you do everything at the ISS anyhow. it's a concept very close to ideas of using tug's to move satellites and stuff around to refurbish them. and that is actually a potential use if satellites were designed to accept that kind of robotic service.

I have to admit that the limited cargo on most SSTO concepts ordain the use of such assembly constructs. with the Big rockets you can more or less just hard dock big parts. but even then you reach a limit very fast, and have to start to do it in multiple pieces instead.
However. having a launcher that only ever has a few cargoes is very uneconomical. the development investment is spread out over very few launches and this causes a very high average launch cost.
the rocket a day concept has some merit. but for rockets it's like this. at some point you no longer save as much by having many launches compared to having to pay the cost of excessive on orbit assembly. where the cargo capacity/ launch rate balance lies can be debated endlessly. but whatever rocket a day can do fully reusable launchers can do even better.

mugaliens
2009-May-18, 08:36 AM
If a vehicle not even designed for that role could approach that goal, it's logical a safer, cheaper, purpose-built vehicle is possible.

Bingo!

publiusr
2009-May-18, 08:18 PM
"So in case of scramjet boosters:"

Spending excessive amounts of time plowing through atmosphere
"Not the case"

not sure I agree

and hauling the thermal protection
"Not any more than a rocket needs during launch"

Rockets don't get quite as hot coming up as the payload does coming back--lesser need for total thermal protection across the airframe. A rocket, even on a sloped trajectory, still pops up through the atmo. It doesn't have to fly through it. It spends as little time in atmo as it can--so the whole 'tube' of the rocket doesn't need tiles...

intakes, compressors, heat exchangers, etc into orbit is also wasteful
"In (sc)ramjets, the intake is the compressor. What heat exchanger are you talking about? And in case of boosters, you don't haul them into orbit."

There are icing problems with intakes IIRC. That was to have been the case with the more modest HOTOL engine...You want a LOX tank to stay icy, on the other hand

and also complex and expensive to design, build, and maintain.
"The complexity of a (sc)ramjet engine is remarkably limited, hardly any moving parts (getting this simple structure to actually work is very difficult though). Nothing is known about their maintenance costs. Designing and building them doesn't seem that more expensive than any new space launcher design to me."

Once again, a Lox tank is just simple tankage with an extra bulkhead or three

And you'll need a LOX tank anyway, you only make it moderately smaller and replace LOX and a bit of tank with a pile of complex and expensive machinery.
"Or, a pair of rocket boosters by a pair of scramjet boosters."

Now, in defense, I do remember someone suggesting podded, parachutable F-15 engines to replace SMALL Delta II solids for thrust augmentation, but because the time spent in atmo is less for a pop up rocket, the pods would be shed before the scramjet regime were entered for any real time----- were I to hazard a guess.

"Of course, the technology isn't being used yet so it remains a bit uncertain, but I think that this does show that, in the launcher business, it makes more sense to apply air breathing engines as first stage boosters rather than use them in some kind of airborne high speed launch facility/spaceplane."

The future will tell.


A simple lox tank is better than complex LACE type systems that mass out just as much in orbit as they weigh on the ground. A LOX tank stages its weight off as thrust, losing LOX. An air breather has to stay in atmo longer to gain lox weight.

Air breathers are trying to gain weight. Rockets are getting lighter by the second, leaving a simple tube.

A few more things to consider. If you have a rocket plane like DLR, your airframe is simpler and more streamlined, with simpler tankage. With some airbreather designs, the whole of the airframe is one big inlet. This might lead you to have the ame problems with odd shaped tankage that hurt X-33 VentureStar designs.

Yes, the USAF would like to have something that flies without huge LH2 tanks, using hydrocarbon fuel. A similar volume of LOX weighs 16 times as much as a similar volume of LH2. So the Lox tank really isn't the problem. The problem is that we need to get off hydrocarbon, and that if you have a big LH2 tank (the bigger it is the more of the high volume low density hydrogen you can store) you are looking at a fat airframe the USAF would just not have.

My point is that--why not go even bigger, have thunder rods in orbit, and have a space strike capability from big rockets. You have the ordinance. You just don't need as many airplanes any more.

Nicolas
2009-May-19, 07:45 AM
There are icing problems with intakes IIRC.

Never heard of them on the scramjet I worked on. Can't really imagine it: the intake is large, and as it slows down air, it becomes very hot. Maybe the icing problems were related to the location of the fuel, or maybe it was a design cooling the inlet air. Our design didn't do that.


Air breathers are trying to gain weight. Rockets are getting lighter by the second, leaving a simple tube.

I don't really get this comparison. An air breather starts as machinery + fuel. It burns fuel, and becomes lighter. A rocket starts as machinery + oxidizer + fuel. It burns oxidizer and fuel and becomes lighter. Where is the part where an air breather tries to gain weight? A design challenge for air breathers is that they'd need to perform in a short amount of time (as the atmospheric passage is short), but any type of boosters also performs in a short amount of time.


Rockets are getting lighter by the second, leaving a simple tube.
A booster is dropped once it's done its course, leaving zero weight no matter what technology is used in it. The point is to start out lighter, as you don't bring LOX along. Of course it's a challenge to design an air breather that benefits over bring-your-own-LOX, but that's the design challenge we're taking at the moment.

Military systems in space are a whole different subject IMHO.

Antice
2009-May-19, 09:31 AM
the icing issue is from the sabre engine concept.
It already apears to be a solved as well. once they scale up the prototype we will see.

Ara Pacis
2009-May-19, 02:15 PM
This can also be done with multi stage vehicles. Putting the stack together isn't that expensive. There are concepts of flyback boosters and stages that land like planes, or that land on the land (less extensive refurbishing needed compared to ocean landings). I'm not sure that cheap reusability requires an SSTO craft. I can imagine a rocket stack with flyback boosters and stages and a capsule-like thing on top, which would result in only a small heat shield having to be refurbished between flights, where an SSTO craft is "completely" covered in heat shield. Of course it can be done better than the shuttle in the future, but the shuttle does show that this may be a major issue in keeping reusability costs down.

Why completely covered?

joema
2009-May-19, 02:55 PM
...I'm not sure that cheap reusability requires an SSTO craft. I can imagine a rocket stack with flyback boosters and stages and a capsule-like thing on top, which would result in only a small heat shield having to be refurbished between flights...
It's just an intrinsically difficult problem. SSTO gives full reusability and a single vehicle to develop. OTOH it means extreme light weight and critical mass fraction, which in turn drives up development cost.

Reusable TSTO solves the hardest part of the SSTO "rocket equation" penalty. Unfortunately a realistic booster (whether rocket, air-breathing, or a mix) is a very large, very expensive vehicle.

For a given TSTO configuration, there's an optimal mass relationship between the booster and orbiter stage. A smaller booster requires a bigger orbiter, and vice-versa. The lowest total mass typically requires a MUCH bigger booster than you'd first think. Staging velocity of around 10,000 or 12,000 ft/sec is not unusual. At staging the booster is a long way downrange, very high and fast. Recovering that typically requires heat shielding, and often supplementary propulsion.

If you make the booster smaller and simpler -- picture flyback liquid-fueled shuttle SRBs with fold-out wings -- they aren't big enough to majorly reduce orbiter size.

A flyback booster that can lift a realistic orbiter to 12,000 ft/sec is a gigantic, stupendous vehicle. You also must develop the orbiter, so there are TWO complex vehicles to develop (and maintain), not one.

Nicolas
2009-May-19, 04:11 PM
Why completely covered?

Notice the "" around "completely". What I mean is that an SSTO craft will be larger than a return capsule, and hence will have a much larger heat shield.

Nicolas
2009-May-19, 04:13 PM
It's just an intrinsically difficult problem. SSTO gives full reusability and a single vehicle to develop. OTOH it means extreme light weight and critical mass fraction, which in turn drives up development cost.

Reusable TSTO solves the hardest part of the SSTO "rocket equation" penalty. Unfortunately a realistic booster (whether rocket, air-breathing, or a mix) is a very large, very expensive vehicle.

For a given TSTO configuration, there's an optimal mass relationship between the booster and orbiter stage. A smaller booster requires a bigger orbiter, and vice-versa. The lowest total mass typically requires a MUCH bigger booster than you'd first think. Staging velocity of around 10,000 or 12,000 ft/sec is not unusual. At staging the booster is a long way downrange, very high and fast. Recovering that typically requires heat shielding, and often supplementary propulsion.

If you make the booster smaller and simpler -- picture flyback liquid-fueled shuttle SRBs with fold-out wings -- they aren't big enough to majorly reduce orbiter size.

A flyback booster that can lift a realistic orbiter to 12,000 ft/sec is a gigantic, stupendous vehicle. You also must develop the orbiter, so there are TWO complex vehicles to develop (and maintain), not one.

Thank you for this interesting description of (some of) the tradeoffs to be made when choosing a launcher concept.

Antice
2009-May-19, 07:47 PM
RE Re-entry heat. the shuttle TPS system is only one of several options.
one of the things that makes the shuttle TPS so heavy is that is have to insulate the entire orbiter against the heat... modern composite materials can withstand higher sustained temperatures than the stuff the shuttles hull is made out of. leaving only having to insulate the hull from the heat sensitive parts like avionics and cargo.
you can also use that big fuel tank you brought all the way up as a heat sink on the way down as well. allowing it to boil of it's remaining fuel and vent it overboard to take some of the heat out of the system.
Then there is the possibility to use a double hull structure that acts like a vacuum bottle. the only parts of the outer hull that is in contact with the inner one is the connection points between the outer hull and the cargo bay/fuel tank inside it.
it's quite possible to suspend these inside the outer hull by means of woven kevlar wires that are holding everything in place trough tension. this adds some vibration dampening for the cargo/crew as a nice bonus feature as well. The outer hull can be made out of hight temperature stable materials that can maintain it's integrity at temperatures way in excess of a normal re-entry profile. remember that radiative cooling is more effective the higher the temperature your black body object has. the fuel tank acts as a heat sink for the crew/cargo compartment until temperatures have dropped down again.
This do require more testing of such materials and mabe also making some new ones for the future. but these composites are already in use in high temperature processes in industry today. so it's an available technology that can be readily adapted.


30 second of googling found this reference (http://www.pyromeral.com/High_Temperature_Composites_and_Fire_Barriers_Pyro Sic_PyroKarb.htm) in suport of high temp resistant materials.

Nicolas
2009-May-19, 09:05 PM
It also needs to be lightweight. I've held a shuttle tile in my hand, and it was very light.

Antice
2009-May-19, 09:32 PM
those materials are lightweight.
also. the inner/outer hull system allows the use of lightweight structural suports as well. composites all the way in order to make the craft a lot lighter than the shuttle.
goal for the skylon craft is a measly 41 tonnes dry, with room for 12 tonnes of cargo and a whooping 220 tonnes of fuel.

Ara Pacis
2009-May-20, 05:21 AM
If we think far enough ahead, we might have the possibility of a space infrastructure providing fuel/propellant for retro-burns that reduce velocity enough to minimize re-entry heating issues.

RGClark
2009-May-20, 02:47 PM
The launch of a military satellite yesterday at the NASA's Wallops Island facility in Virginia reminded me that commercial launches are also being made from the site:

Mid-Atlantic commercial spaceport makes 1st launch.
Posted 12/16/2006 7:20 AM ET
http://www.usatoday.com/tech/science/space/2006-12-16-commercialrocket_x.htm?POE=TECISVA

There was a push by some to offer a prize for a suborbital commercial transatlantic transport to launch from the site but I don't know if that is still being considered:

Hypersonic Cruise for the V Prize.
Wednesday 2008.01.23 by gravityloss
http://gravityloss.wordpress.com/2008/01/23/hypersonic-cruise-for-the-v-prize/

This article did not optimize the cruise velocity to get the best fuel fraction and gets a too high cruise speed of 6,000 m/s. A later article on this site discusses how this could be optimized, giving a cruise velocity of only 3,000 m/s if you can get a high lift/drag ratio of 7 at hypersonic speeds:

Optimum Rocket Cruise.
Friday 2009.03.20 by gravityloss
http://gravityloss.wordpress.com/2009/03/20/optimum-rocket-cruise/

Some hypersonic waverider shapes can get a lift drag ratio in the range of 6 to 8 when optimized for a set hypersonic cruise speed:

Waverider Design.
http://www.aerospaceweb.org/design/waverider/waverider.shtml

If the delta-v required is only 3,000 m/s this could be obtained with a rather low mass ratio: Mi/Mf= exp(delta-V/Ve) = exp(3,000/3600) = 2.3, assuming an exhaust velocity Ve of 3,600 m/s, which can be reached by kerosene/LOX rockets. This is less than the mass ratio of SpaceShipOne.


Bob Clark

NEOWatcher
2009-May-20, 05:01 PM
The launch of a military satellite yesterday at the NASA's Wallops Island facility in Virginia reminded me that commercial launches are also being made from the site:

Mid-Atlantic commercial spaceport makes 1st launch.
Posted 12/16/2006 7:20 AM ET
http://www.usatoday.com/tech/science/space/2006-12-16-commercialrocket_x.htm?POE=TECISVA

I'm having a hard time drawing the line for "commercial" vs "subcontractor" especially when it relates to this article.
To me, commercial is no government involvement (other than the normal taxes and regulations that most companies encounter).
As I walk through this article, I see:
1) A military satellite.
2) A governmental experiment satellite
3) Direct military hardware
4) A military mission director (ok; this could be part of 1 as the customer)
5) A launch facility built by a state agency...
6) ...built on government land through a lease.
I might be able to stretch 3 as being any commercial venture based on military surplus, but with all the other gov references, I don't think it really matters.

Ara Pacis
2009-May-20, 11:14 PM
I'm having a hard time drawing the line for "commercial" vs "subcontractor" especially when it relates to this article.
To me, commercial is no government involvement (other than the normal taxes and regulations that most companies encounter).
As I walk through this article, I see:
1) A military satellite.
2) A governmental experiment satellite
3) Direct military hardware
4) A military mission director (ok; this could be part of 1 as the customer)
5) A launch facility built by a state agency...
6) ...built on government land through a lease.
I might be able to stretch 3 as being any commercial venture based on military surplus, but with all the other gov references, I don't think it really matters.

I didn't look at the article, but 1-4 of the list looks like it could refer to a customer payload and involvement; 5 looks like nothing extraordinary when you think about how government subsidizes or outrights owns many infrastructure assets used for commercial purposes (like roads, airports, seaports...); and 6 reminds me of businesses that operate on other government owned assets, like restaurants built on an interstate oasis.

NEOWatcher
2009-May-21, 12:15 PM
I didn't look at the article, but 1-4 of the list looks like it could refer to a customer payload and involvement
Not 3. The rocket is built from existing military missiles.

5 looks like nothing extraordinary when you think about how government subsidizes or outrights owns many infrastructure assets used for commercial purposes (like roads, airports, seaports...); and 6 reminds me of businesses that operate on other government owned assets, like restaurants built on an interstate oasis.
I can accept those points, and individually taken, I'm sure I can find similar instances to explain away all my points. My issue here is the fact that they are all rolled together. How do you draw the line between a commercial venture and a contractor?
Sure; contractor is a subset of commercial venture, but until there is private industry expanding that subset, I don't really push it outside that definition.

What I'm looking for, is where is the additional business transactions that don't involve the government?

joema
2009-May-22, 02:43 PM
Anyone interested in this general area should read this excellent publication, available on-line:

Facing the Heat Barrier: A History of Hypersonics, by T. A. Heppenheimer

http://www.aoe.vt.edu/~mason/Mason_f/NASASP2007-4232Hypersonics.pdf

PraedSt
2009-May-22, 07:29 PM
Anyone interested in this general area should read this excellent publication, available on-line:

Facing the Heat Barrier: A History of Hypersonics, by T. A. Heppenheimer

http://www.aoe.vt.edu/~mason/Mason_f/NASASP2007-4232Hypersonics.pdf (http://www.aoe.vt.edu/%7Emason/Mason_f/NASASP2007-4232Hypersonics.pdf)
Very good!

RGClark
2009-May-27, 05:34 AM
Saw these articles linked on the Wikipedia X-33 page:

Lockheed Test Flies Space Plane Prototype.
By Leonard David
Special Correspondent, SPACE.com
posted: 24 April 2008
11:41 am ET
"Lockheed Martin has tested a prototype reusable launch system by flying a sub-scale flight demonstrator from the site of New Mexico's proposed Spaceport America.
"The successful test flight of the proprietary vehicle took place in December and was only recently disclosed. A company official said Lockheed Martin is planning more tests using ever-larger vehicles.
"Lockheed Martin Space Systems teamed with launch provider UP Aerospace of Highlands Ranch, Colo., Dec. 19 to conduct a small demonstration launch at Spaceport America in southern New Mexico to evaluate proprietary technology the company currently has under development."
http://www.space.com/businesstechnology/080424-lockheed-spaceplane-test.html

Lockheed loses prototype of Space reusable launch vehicle.
18 August 2008
"Golden, Colorado: Lockheed Martin's second test flight of a prototype reusable launch system failed with the craft going out of control and becoming seriously damaged, rendering it unusable. The test, conducted 12 August, saw the winged craft take off from a launch rail under its own power and fly for some 12.5 seconds of a planned flight of less than a minute before it crashed."
...
"The 200-pound (91 kg) vehicle reached its planned altitude of roughly 1,500 feet (457 meters). It is 8 feet (2.4 meters) long with a wingspan of about 6 feet (1.8 meters) and is roughly one-fifth in scale. It is being flown to develop techniques and procedures for quick launch, ease of operations and low cost access to space."
http://www.domain-b.com/aero/space/launch_veh/20080818_lockheed_martin.html

Anyone know what the scoop on this is? Since the Lockheed X-33 was canceled because of the relatively trivial problem (compared to the complexity of the rest of the system) of the composite hydrogen tank debonding, I'm inclined to think Lockheed solved that problem and it's a version of the X-33. The dimensions given though are small for it actually being a one-fifth scale of the X-33 ...



I was looking up other references on the X-33/VentureStar composite tanks when I found this:

Space Access Update #91 2/7/00.
The Last Five Years: NASA Gets Handed The Ball, And Drops It.
"The advantage of a lifting-body is that it doesn't (shouldn't) need
wings to maneuver during orbital reentry then land on a runway; it
thus saves the weight of wings - minimum vehicle weight of course
being critical to a successful Single Stage To Orbit vehicle. The
disadvantage is that the vehicle shape is such that propellant tanks
can't be the optimum circular cross-section shape that minimizes
tank weight for a given mass of propellant - any tank shape that
doesn't have a round cross-section will tend to try to balloon out
to being round anyway as soon as it's pressurized; preventing non-
round tanks from doing this requires heavy reinforcement. What
lifting bodies gain from omitting wings they more than lose again on
heavier tanks, at least with traditional tank construction methods.
"Lockheed claimed to have solved the tank-weight problem, via "multi-
lobed" tanks that combined partial circular sections with clever
internal bracing. Further, these tanks were to be made out of
graphite-epoxy composite rather than aluminum. The result was
supposed to be complex-shaped tanks that would conform to the
lifting-body shape while being just as light as conventional
circular-section tanks. We'll come back to this."
...
"And of course, part of L-M X-33's weight growth was the "multi-
lobed" propellant tanks growing considerably heavier than promised.
Neither Rockwell nor McDonnell-Douglas bid these; both used proven
circular-section tanks. X-33's graphite-epoxy "multi-lobed" liquid
hydrogen tanks have ended up over twice as heavy relative to the
weight of propellant carried as the Shuttle's 70's vintage aluminum
circular-section tanks - yet an X-33 tank still split open in test
last fall. Going over to aluminum will make the problem worse; X-
33's aluminum multi-lobed liquid oxygen tank is nearly four times as
heavy relative to the weight of propellant carried as Shuttle's
aluminum circular-section equivalent."
http://www.space-access.org/updates/sau91.html

This states that the X-33 tank mass to propellant mass carried is actually worse than for usual rockets, such as the space shuttle. This is surprising since I thought the composite tanks were to reduce the weight. However, as described here, the higher mass is because of the unusual shape of the tanks.
The author of that article does not like the VentureStar or the decision to fund it. But it is important to keep in mind that the primary subsystems for the X-33 were shown to be viable including the aerospike engines and the metallic thermal protection system, and it was only the comparatively trivial problem of getting the lightweight tanks to work that caused the program cancellation:

X-33/VentureStar - What really happened.
January 4th, 2006 by Chris Bergin
http://www.nasaspaceflight.com/2006/01/x-33venturestar-what-really-happened/

The greater tank mass to propellant mass ratio for the X-33 tanks can be confirmed by using the data for the X-33 tank sizes here:

X-33 Program in the Midst of Final Testing and Validation of Key Components.
Marshall Space Flight Center
Lockheed Martin Skunk Works
Sept. 28, 1999
http://www.xs4all.nl/~carlkop/x33.html

compared to the space shuttle external tank data given here:

EXTERNAL TANK.
http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/et.html

I had earlier proposed solving the problem of getting lightweight tanks by using high strength materials that, at their highest strengths, are only available in microscale fibers or particles, by using them in hollowed out form:

From: Robert Clark <rgregorycl...@yahoo.com>
Newsgroups: sci.astro, sci.space.policy, sci.physics, sci.energy
Date: Tue, 29 Jul 2008 09:59:14 -0700 (PDT)
Local: Tues, Jul 29 2008 12:59 pm
Subject: High strength fibers for hydrogen storage on the VentureStar.
http://groups.google.com/group/sci.astro/browse_frm/thread/c3ed912875d2d96c

A problem though is that these fibers or particles might be only 10 microns wide. The wall thickness of the aluminum alloy space shuttle external tank is in the range of 5 to 10 millimeters with the tank diameter on the order of 10 meters. This is a diameter to wall thickness ratio of around a 1000 to 1. If the microscale hollow fibers were to match or exceed this they would have a wall thickness of only 10 nanometers or less. This would cause extreme problems in manufacturing them and handling them so as not to damage them.
However, this was based on the idea that you had to get a material that was stronger for weight than aluminum alloy. But the real problem is that the X-33 tanks are not of the usual cylindrical or spherical shape.
Then we can get the minimal weight by using numerous small diameter cylindrical tubes to make up the shape of the conformal tanks without requiring the ultrahigh strength of the microscale fibers. Because of the large size of X-33 tanks we might even be able to have these cylindrical tubes be as large as say 10 centimeters across, and have them be of varying lengths so when bundled together they make up the conformal shape of the X-33 tanks. If they are 10 cm across and using the aluminum alloy, to be of the 1000 to 1 diameter to thickness ratio of the shuttle ET, they would have to have a 100 micron wall thickness. This is easy to achieve since for example common household aluminum foil may be only 16 microns thick:

Reynolds Wrap* Aluminum Foil.
http://vwrlabshop.com/reynolds-wrap-aluminum-foil/p/0014244/

Smaller diameter tubes if necessary would have a smaller wall thickness. Even tubes 1 cm wide requiring wall thickness of 10 microns is well within the range of commonly used aluminum sheeting. The effect of bundling the many tubes together would also give the complete tank strength as it would be be in the form of a honeycomb, a structure of inherently high strength to weight ratio.
The viability of this idea would be easy test by using tubes made from common aluminum foil and testing how well they hold up to the pressures and temperatures seen in the cryogenic tanks. The tubes could be formed by epoxying the edges together and then epoxying the tubes together to form the shape of the conformal tanks. To form stronger tubes and bonds between the tubes we could also use a light brazing technique.
The aluminum foil doesn't have the same strength to weight ratio of the aluminum alloys but it would serve to give a first level indication of how well the idea would work. At this first level you would probably also want to use liquid nitrogen rather than liquid hydrogen as well.
Assuming the multitube method works to provide similar tank mass to propellant mass ratio as the shuttle ET, the bare mass of the X-33 liquid hydrogen tanks could be reduced from 9,200 lbs. to 4,600 lbs, and the liquid oxygen tank from 6,000 lbs. to 1,500 lbs, quite a large mass saving for a vehicle of bare mass of 65,000 lbs.
For so many small cylindrical tanks, probably you would not want to have separate valves for each cylinder that all had to operate in unison. A couple of ways to release the fuel in a throttleable fashion might be to have each small cylinder be completely used up once it is opened, with a group of cylinders being opened sequentially, or to have one end of the cylinders be closed off and a single cap cover the other open end of all the cylinders which would be used to connect to a single valve for the tank.
NASA does not seem to have much interest in funding further X-33 development. However, the U.S. Air Force is interested in developing a suborbital troop transport (which of course could also work as a commercial suborbital passenger transport):

Pentagon seeks military role for space tourism technology.
By Stephen Trimble
DATE:23/02/09
SOURCE:Flight International
http://www.flightglobal.com/articles/2009/02/23/322951/pentagon-seeks-military-role-for-space-tourism-technology.html

Then considering the low cost nature of the idea, the Air Force might fund this since if viable it would lead to a suborbital transport in the X-33, and likely therefore also to a reusable single stage to orbit vehicle in the VentureStar.


Bob Clark

Antice
2009-May-27, 06:51 AM
One has to think. the weight penalty of wings might actually be a lot lower than the penalty of using oddly shaped tanks. besides. the wings need not be large at all. I tend to think of wings more as a thermal issue on reentry problem than a weight penalty problem. none of these issues seem unsurmountable tho.

However. i dont think many engineering issues are showstoppers in any case. if you have enough money to throw into developing a solution.

Ara Pacis
2009-May-27, 07:45 AM
One has to think. the weight penalty of wings might actually be a lot lower than the penalty of using oddly shaped tanks. besides. the wings need not be large at all. I tend to think of wings more as a thermal issue on reentry problem than a weight penalty problem. none of these issues seem unsurmountable tho.

However. i dont think many engineering issues are showstoppers in any case. if you have enough money to throw into developing a solution.

If you re-enter at high-speed with a nose-up attitude, the wings will need to endure higher loads than if it was used for gliding. This means they need to be stronger. You could design the wings to be as light as necessary for level flight, but when you re-enter in the manner of the shuttle they would be ripped off.

Now, if they used a different re-entry trajectory, they might get away with lighter wings.

Antice
2009-May-27, 08:36 AM
yeah. reentry profile is important. SSTO will always be a leo only service i think. I do wonder. how do nose first compare to belly first when it comes to thermal and aerodynamic loads on the craft?

joema
2009-May-27, 12:30 PM
The competing design to X-33/Venturestar was DC-X/DC-Y/DC-1, which avoided the complex multi-lobed tank problem.

Unlike the X-33, the DC program emphasized use of existing technology. It further emphasized simplified ground and flight operations, vehicle maintenance, rapid turnaround, and operational characteristics.

http://www.astronautix.com/lvs/dcy.htm

Background: http://newpapyrusmagazine.blogspot.com/1999/02/resurrecting-delta-clipper.html

Such a vehicle could also function as a suborbital transoceanic passenger transport. It could probably be developed for that role quicker and cheaper than airbreathing alternatives:

http://www.newscientist.com/blogs/shortsharpscience/2009/03/rockets-not-air-breathing-plan.html

Antice
2009-May-31, 07:41 PM
while i think DC-X might very well have done better than X-33. it would really have a much worse payload ratio than any other system ever proposed. hovering at landing is terribly fuel expensive. i haven't done any math's to prove it but my gut is saying that wings carry a lot less penalty than the fuel needed to land safely. I am certain some of the very number savy ones will likely post some numbers soonish to flame my gut into submission. :whistle:

joema
2009-May-31, 11:29 PM
DC-X...would really have a much worse payload ratio than any other system ever proposed. hovering at landing is terribly fuel expensive. i haven't done any math's to prove it but my gut is saying that wings carry a lot less penalty than the fuel needed to land safely...

I don't have the details at hand, but I believe VTVL systems are competitive with VTHL systems from a wings vs fuel standpoint.

VTHL has mass penalties that don't appear HL-specific at first glance. This includes increased primary structure (more varied loads from more points and more directions), thermal protection for the wings, more robust landing gear, etc.

Modern VTVL systems wouldn't hover around like a helicopter looking for a landing area. Rather they'd use precise differential GPS guidance, rely on atmospheric braking for most of the deceleration and rely on rockets for a brief terminal phase.

Antice
2009-Jun-01, 07:45 AM
And i guess you can use your main engines for de orbit burn as well as a heat shield during re-entry? they are already designed to take heavy thermal loads for launch....
The idea seems quite workable. altho i keep getting an image of what hapens if you have a last minute engine failure during descent....

Nicolas
2009-Jun-01, 08:21 AM
Why did that last sentence remind me of what happens to Wile E Coyote?

ffffffwheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee *pof*

Landing rockets are one system that simply has to work. But then again, so are wings.

joema
2009-Jun-01, 11:34 AM
...The idea seems quite workable. altho i keep getting an image of what hapens if you have a last minute engine failure during descent....
Generally there's less problem on descent than during ascent.

During ascent the vehicle is heavy and needs full thrust from all engines. Some vehicles cannot tolerate even a single engine failure. E.g, if a single engine failed on the Saturn V before about T+15 sec, it would fall back onto the pad.

By contrast an SSTO, VTVL ship during descent is very light, yet it carries sufficient engine power for a fully-loaded lift off. Typically it would be using a small subset of engines and/or deeply throttled. In most cases an engine failure could be accomodated by simply throttling up the remaining engines.

Staying with the topic title, such a vehicle could be a hypersonic, trans-oceanic transport.

RGClark
2009-Jun-02, 07:00 PM
...the real problem is that the X-33 tanks are not of the usual cylindrical or spherical shape.
Then we can get the minimal weight by using numerous small diameter cylindrical tubes to make up the shape of the conformal tanks without requiring the ultrahigh strength of the microscale fibers. Because of the large size of X-33 tanks we might even be able to have these cylindrical tubes be as large as say 10 centimeters across, and have them be of varying lengths so when bundled together they make up the conformal shape of the X-33 tanks. If they are 10 cm across and using the aluminum alloy, to be of the 1000 to 1 diameter to thickness ratio of the shuttle ET, they would have to have a 100 micron wall thickness. This is easy to achieve since for example common household aluminum foil may be only 16 microns thick:

Reynolds Wrap* Aluminum Foil.
http://vwrlabshop.com/reynolds-wrap-aluminum-foil/p/0014244/

Smaller diameter tubes if necessary would have a smaller wall thickness. Even tubes 1 cm wide requiring wall thickness of 10 microns is well within the range of commonly used aluminum sheeting. The effect of bundling the many tubes together would also give the complete tank strength as it would be be in the form of a honeycomb, a structure of inherently high strength to weight ratio.
The viability of this idea would be easy test by using tubes made from common aluminum foil and testing how well they hold up to the pressures and temperatures seen in the cryogenic tanks. The tubes could be formed by epoxying the edges together and then epoxying the tubes together to form the shape of the conformal tanks. To form stronger tubes and bonds between the tubes we could also use a light brazing technique.
The aluminum foil doesn't have the same strength to weight ratio of the aluminum alloys but it would serve to give a first level indication of how well the idea would work. At this first level you would probably also want to use liquid nitrogen rather than liquid hydrogen as well.
Assuming the multitube method works to provide similar tank mass to propellant mass ratio as the shuttle ET, the bare mass of the X-33 liquid hydrogen tanks could be reduced from 9,200 lbs. to 4,600 lbs, and the liquid oxygen tank from 6,000 lbs. to 1,500 lbs, quite a large mass saving for a vehicle of bare mass of 65,000 lbs.
For so many small cylindrical tanks, probably you would not want to have separate valves for each cylinder that all had to operate in unison. A couple of ways to release the fuel in a throttleable fashion might be to have each small cylinder be completely used up once it is opened, with a group of cylinders being opened sequentially, or to have one end of the cylinders be closed off and a single cap cover the other open end of all the cylinders which would be used to connect to a single valve for the tank.
NASA does not seem to have much interest in funding further X-33 development. However, the U.S. Air Force is interested in developing a suborbital troop transport (which of course could also work as a commercial suborbital passenger transport):

Pentagon seeks military role for space tourism technology.
By Stephen Trimble
DATE:23/02/09
SOURCE:Flight International
http://www.flightglobal.com/articles/2009/02/23/322951/pentagon-seeks-military-role-for-space-tourism-technology.html

Then considering the low cost nature of the idea, the Air Force might fund this since if viable it would lead to a suborbital transport in the X-33, and likely therefore also to a reusable single stage to orbit vehicle in the VentureStar.


AFRL Seeks Reusable Booster X-Plane Ideas.
Posted by Graham Warwick at 5/12/2009 2:36 PM CDT
"Guy Norris alerted us to it a couple of weeks ago in Aviation Week,
but the Air Force Research Laboratory has finally released its request
for information on concepts for a reusable launch vehicle. They are
calling it the Reusable Booster System (RBS), because the focus is on
a fly-back first stage carrying an extendable upper stage.
"The RFI's stated objective "is to identify potential operational RBS
concepts, including a family of expendable stage variants, and
feasible system development approaches." And it is a step towards a
potential subscale X-plane demonstrator that could fly in 2017-18."
http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogScript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3a3cea718e-0347-4d3d-bdfe-7a7a675f97de

Reusable Booster Integrated Demo – Concept Options Maturation Study.
(RBID-COMS)
Solicitation Number: RFI-PKV-09-01
Agency: Department of the Air Force
Office: Air Force Materiel Command
Location: AFRL - Wright Research Site
https://www.fbo.gov/index?s=opportunity&mode=form&id=d3e825368b36760bf2ece9d87750ff98&tab=core&_cview=1&cck=1&au=&ck=

This is for proposals for a reusable vertical launch, horizontal
landing unmanned booster to serve as the first stage of a two-stage-to-
orbit (TSTO) system.
The description seems to be tailored made for the X-33 suborbital
system. I'm inclined to think intentionally so.
Then this might open up funding for alternative methods for obtaining
lightweight tanks for the X-33 such as the multiple cylindrical tanks
method.
It also would make possible a suborbital troop carrier or commercial
transport system.


Bob Clark

RGClark
2009-Jun-03, 02:23 PM
More on the Air Force's "Reusable Booster System":

USAF Seeks Reusable Booster Ideas.
May 14, 2009
By Graham Warwick
"The plan is to conduct an integrated demonstration of technologies and processes culminating in a subscale X-plane vehicle that would fly by 2017-18 and take the concept to a technology readiness level of 6, ready to enter full-scale development.
"AFRL has several ground-based experiments already under way involving structures, controls and systems for an operationally responsive launch vehicle. The work is focused on a reference concept for an unmanned vertical takeoff and horizontal landing reusable booster capable of turnaround in 24-48 hours and launch within 4-8 hours of a request."
http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/Reuse051409.xml

Spacelift Development Plan.
http://www.acq.osd.mil/nsso/conference/briefs/HampstenSDP%20Public%20Release.ppt


Bob Clark

RGClark
2009-Jun-04, 02:47 PM
More on the Air Force's "Reusable Booster System":

USAF Seeks Reusable Booster Ideas.
May 14, 2009
By Graham Warwick
"The plan is to conduct an integrated demonstration of technologies and processes culminating in a subscale X-plane vehicle that would fly by 2017-18 and take the concept to a technology readiness level of 6, ready to enter full-scale development.
"AFRL has several ground-based experiments already under way involving structures, controls and systems for an operationally responsive launch vehicle. The work is focused on a reference concept for an unmanned vertical takeoff and horizontal landing reusable booster capable of turnaround in 24-48 hours and launch within 4-8 hours of a request."
http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/Reuse051409.xml

Spacelift Development Plan.
http://www.acq.osd.mil/nsso/conference/briefs/HampstenSDP%20Public%20Release.ppt



Also from the Aviation Week article:

"AFRL's reference concept includes an integral all-composite airframe and tank structure that carries both internal pressure and external flight loads. The concept vehicle is powered by pump-fed liquid-oxygen/hydrocarbon rocket engines."

The suggestion to limit the fuel to hydrocarbon rather than the higher energy liquid hydrogen probably stems from the fact that for this purpose the vehicle only needs to have a max speed in the range of Mach 3.5 to 7, as indicated by slide #5 in the "Spacelift Development Plan" powerpoint presentation.
However, all three competing proposals for the X-33 liquid-hydrogen fueled vehicles, which needed to get to Mach 13+, probably could be adapted to use hydrocarbon fuel, for this Mach 7 max. proposal.
This would be another method to effectively re-open the X-33 competition.


Bob Clark

publiusr
2009-Jun-04, 10:12 PM
Everything old is new again.

Look for the USAF to try to rob Ares in order to fund this rat-hole. I hope Bolden is smart enough to recognice this bait and switch. Sadly, "Sustain" might convince him away from Ares/Orion.

I hope not.

PraedSt
2009-Jun-04, 10:50 PM
Different budgets, no? Defence Dept and NASA.

Antice
2009-Jun-05, 06:41 PM
this happens every time there is a change in the leadership.... all the old whipping horses are dug out again. it's a good thing that the cots program is funded by earmarks methinks... since that is where the next us astronaut launcher is going to come from if this drunken wobbling in direction continues. barring any big hiccups in the development of the spacex dragon capsule there is going to be some commercial capacity there in a few years.

mugaliens
2009-Jun-08, 09:03 PM
yeah. reentry profile is important. SSTO will always be a leo only service i think. I do wonder. how do nose first compare to belly first when it comes to thermal and aerodynamic loads on the craft?

Blunt is better - larger surface area over which to spread the heat. Pointed objects don't fair well during reentry.

Antice
2009-Jun-09, 03:55 PM
that means that any pointed craft would have to belly flop then. kinda explains the shape of the wings on the skylon concept design as well. i was wondering about the broad short wings with the engines on the outside edge. more flat surface with less thin leading edges.

Ara Pacis
2009-Jun-11, 05:42 AM
Blunt is better - larger surface area over which to spread the heat. Pointed objects don't fair well during reentry.

That depends on re-entry profile. A shallow profile with appropriate wings might need to enter at a different attitude to make use of waveriding techniques. Also, once a space infrastructure becomes robust enough, a retro-thrust method may be employed to reduce re-entry speed to the point that heating is negligible... although belly flopping may be employed for ergonomic and aerodynamic reasons, even if thermodynamic necessities are mooted.

FDLoser
2009-Jun-11, 08:05 PM
You guys need to do some real researchand look at the FDL-7 Shape. A Sharp leading edged high L/D lifting body with small wings. ALL of the technology to build this vehicle exists and current industry can make it all. An entire program including orbital flight testing can be done for the cost of ONE shuttle flight. Saying there is any single "Show Stopper" is a complete admission of pure ignorance.

The Shuttle is a fantastic lesson in what NOT to do. Make a monstrosity that has to satisfy Military AND Civilian needs. Give it the most fragile overly complex (I mean give me a break.... 27,000+ unique tiles?!?!?!) Thermal Protection System you can find. Give it underpowered overly complex engines that need a major overhaul between flights when NASA was GIVEN something far better by the Military (Read about the XLR-129 if you want to cry). The whole program bloated into an unrecognizable "Frankenshuttle" compared to the original concept.

SUSTAIN may be the only hope humanity has for a cheap, meaning high flight rate Orbital vehicle for LEO manned access. Once you go to orbit you can do point to point or Suborbital "Space Flight to Nowhere" Space Tourism.

And don't worry. NASA money will not be stripped to make SUSTAIN happen. It's a whole Different Animal NASA doesn't even know it needs yet. Once it exists NASA will be asking nicely if it can stop by the ISS to drop off a few guys and cargo on the way to one of Bigelow's Orbital Hotel complexes.

PraedSt
2009-Jun-12, 07:11 AM
You guys need to do some real researchand look at the FDL-7 Shape. A Sharp leading edged high L/D lifting body with small wings. ALL of the technology to build this vehicle exists and current industry can make it all. An entire program including orbital flight testing can be done for the cost of ONE shuttle flight. Saying there is any single "Show Stopper" is a complete admission of pure ignorance.

The Shuttle is a fantastic lesson in what NOT to do. Make a monstrosity that has to satisfy Military AND Civilian needs. Give it the most fragile overly complex (I mean give me a break.... 27,000+ unique tiles?!?!?!) Thermal Protection System you can find. Give it underpowered overly complex engines that need a major overhaul between flights when NASA was GIVEN something far better by the Military (Read about the XLR-129 if you want to cry). The whole program bloated into an unrecognizable "Frankenshuttle" compared to the original concept.

SUSTAIN may be the only hope humanity has for a cheap, meaning high flight rate Orbital vehicle for LEO manned access. Once you go to orbit you can do point to point or Suborbital "Space Flight to Nowhere" Space Tourism.

And don't worry. NASA money will not be stripped to make SUSTAIN happen. It's a whole Different Animal NASA doesn't even know it needs yet. Once it exists NASA will be asking nicely if it can stop by the ISS to drop off a few guys and cargo on the way to one of Bigelow's Orbital Hotel complexes.
The Shuttle TPS is actually an ingenious solution, especially given the materials and cost constraints at the time it was built. Your TPS will expand considerably during reetry, and you have to be able to accommodate that without breaking up the spacecraft. And an all-metal heat sink is heavy!

The Shuttle wings are there to give it cross range capability. Which it needs, for safety reasons, if nothing else.

The last I heard, PlanetSpace had rejected the FDL-7/Silver Dart shape. They didn't win the X-prize, and they haven't actually flown anything yet. Good luck!

And SUSTAIN is now sub-orbital.

Welcome to BAUT! :)

FDLoser
2009-Jun-12, 03:21 PM
The Shuttle TPS is actually an ingenious solution, especially given the materials and cost constraints at the time it was built. Your TPS will expand considerably during reetry, and you have to be able to accommodate that without breaking up the spacecraft. And an all-metal heat sink is heavy!

The Shuttle wings are there to give it cross range capability. Which it needs, for safety reasons, if nothing else.

The last I heard, PlanetSpace had rejected the FDL-7/Silver Dart shape. They didn't win the X-prize, and they haven't actually flown anything yet. Good luck!

And SUSTAIN is now sub-orbital.

Welcome to BAUT! :)

The All refractory metal alloy TPS was offered to the Shuttle guys in the late 1960's and rejected for political reasons. The Alloy TPS shingle has the same weight per square foot as the shuttle tiles without the same fragile properties as shuttle. The cost would have been LESS too. And since metal shingles overlap you do not have the expansion issues of tiles butted up against one another. X-33 TPS technology was a huge success we just never got to see it fly (yet).

The shuttle fails in cross range due to the required hight angle of attack. FDL-7 can glide one earth circumference from orbit allowing it to land anywhere from anywhere in orbit at any time. So there is no waiting for a reentry window to come home in an emergency. This is why the USAF chose it for the MOL supply vehicle and life boat.

If you look here http://planetspace.org/lo/uav.htm you will see work on the shape continues in the form of UAVs to understand the low speed handling of the shape. Dale Reed would be proud! :)

Remember: just because there is noting in the media about most of the NuSpace guys does not mean they are idle. ;)

PraedSt
2009-Jun-12, 06:45 PM
The All refractory metal alloy TPS was offered to the Shuttle guys in the late 1960's and rejected for political reasons. The Alloy TPS shingle has the same weight per square foot as the shuttle tiles without the same fragile properties as shuttle. The cost would have been LESS too. And since metal shingles overlap you do not have the expansion issues of tiles butted up against one another. X-33 TPS technology was a huge success we just never got to see it fly (yet).

The shuttle fails in cross range due to the required hight angle of attack. FDL-7 can glide one earth circumference from orbit allowing it to land anywhere from anywhere in orbit at any time. So there is no waiting for a reentry window to come home in an emergency. This is why the USAF chose it for the MOL supply vehicle and life boat.

If you look here http://planetspace.org/lo/uav.htm you will see work on the shape continues in the form of UAVs to understand the low speed handling of the shape. Dale Reed would be proud! :)

Remember: just because there is noting in the media about most of the NuSpace guys does not mean they are idle. ;)

1. joema posted a really good document about the history of hypersonics (http://www.bautforum.com/1493305-post148.html). It has a lot about shingles and their problems. And the problem with metal TPS in general. Have a look!

2. The X-33 was cancelled. It wasn't even designed for orbital speeds and hence temperatures. Therefore, the TPS system can in no way be described as "a success". At least that's not how I define it.

3. The FDL shapes have range, but little control. They're indeed perfect for emergencies- you just need to get down, and as long as you hit land, where you land is a secondary matter. Where they fail is under normal operating conditions- you need pin point accuracy. The Shuttle, for all of its "flying brick" reputation, can fly rings round the FDL, especially on final approach. Range is meaningless without low-speed control.

4. The MOL was a 1970's program that got cancelled. You keep bringing up cancelled programs...

5. Low speed handling of the shape. I think it's quite well understood- "not good". You mean it needs to be improved. The solution will probably involve wing-like contraptions.

6. There's nothing we'd like more than low cost access to space. But the Shuttle, for all it's faults, works beautifully. :)

NEOWatcher
2009-Jun-15, 12:36 PM
The All refractory metal alloy TPS was offered to the Shuttle guys in the late 1960's and rejected for political reasons...
I can understand that there were a lot of political trade-offs in the shuttle. But a statement on the politics on an engineering issue needs some backup to me.
I searched, and there doesn't seem anything political about it. It sounds more like a lack of understanding the production issues of the current system. Engineers can't always make the perfect decision.
Here's one example (http://www.absoluteastronomy.com/topics/Atmospheric_reentry) reference I found.

A radiatively cooled TPS for an entry vehicle is often called a "hot metal TPS". Early TPS designs for the Space Shuttle called for a hot metal TPS based upon titanium shingles. Unfortunately the earlier Shuttle TPS concept was rejected because it was incorrectly believed a silica tile based TPS offered less expensive development and manufacturing costs.

FDLoser
2009-Jun-18, 03:08 AM
That was a very informative book about Hypersonics and heating. There was some great stuff in there about the Metallurgy involved in make the metal TPS. It never fails to amaze me what human ingenuity can come up with to salve a seemingly impossible problem. I get from it that the biggest problem beyond heating is flutter. It also looks like NASP created the technology needed to do reentry with metal TPS. [“If I cruise in the atmosphere for two hours,” says Paul Czysz of McDonnell Douglas, “I have a thousand times the heat load into the vehicle that the shuttle gets on its quick transit of the atmosphere.”] So if they were solving that problem for the X-30 with a thousand times the heat load then transit from orbit is "easy" by comparison.

FDL low speed handling is actually very good. The landing speed for the FDL-7 C/D glider is on the order of 125 knots, longitudinally stable without augmentation. Bill Dana piloted the X-15, X-24A and X-24B. He observed that landing the X-24B (AKA FDL-8X) was easier compared to landing the X-15 Dale Reed’s built and flew a FDL-7MC radio controlled model at NASA Dryden. He almost lost his job as he stopped working on the round bottom NASA configurations that were all inherently unstable and difficult to control manually. One of these models is known as the Hyper-III. The AFFDL and Mcdonnel configurations were inherently stable at all operational angles of attack from at least Mach 22 to landing speed. The FDL shape can also do anywhere form about an 11 degree angle of attack (13 degrees being the optimum for max range) up to 45 degrees for high G turns to shorten glide range.

Anyways my point is there are no show stoppers for an orbital system you stick on a rocket to orbit. The USAF reusable booster RFI is interesting coupled with Sustain. The commercial applications are great for a system like this for point to point. You don't NEED some kind of fancy air breathing rocket based near term technology. It can be done with the current state of the art.

From here on I cannot really add much more to the conversation as I have been asked not to. :silenced:

This message thread is a great bit of discussion with some great links to excellent information. I'll keep watching it thats for sure.

RGClark
2009-Jun-18, 08:01 AM
...
The shuttle fails in cross range due to the required hight angle of attack. FDL-7 can glide one earth circumference from orbit allowing it to land anywhere from anywhere in orbit at any time. So there is no waiting for a reentry window to come home in an emergency.
...


That's quite a claim. Do you have a reference for that? A long glide range would mean a suborbital transport craft, which wouldn't have to get to such high velocities as an orbital craft, could achieve transcontinental distances with much reduced delta-v requirements.
BTW, this site with videos of the X-24B, a craft derived from the FDL-7, gives its hypersonic lift/drag ratio as 2.5:

X-24B.
http://www.dfrc.nasa.gov/Gallery/Movie/X-24B/index.html


Bob Clark

PraedSt
2009-Jun-18, 12:55 PM
Some hypersonic research coming up from the ESA and Thales.

From the BBC (http://news.bbc.co.uk/2/hi/science/nature/8104355.stm)
Thales Alenia Space in Italy has been given the authorisation to build the wedge-shaped Intermediate eXperimental Vehicle (IXV).

The European Space Agency (Esa) demonstrator will be launched in 2012.

It will be packed with sensors and should give engineers new insights into how objects fall back to Earth.

The lessons could prove extremely valuable if Europe decides to press ahead with its own astronaut transportation system. A controlled, safe re-entry capability is a pre-requisite for such a system, but it has relevance to all high-velocity atmospheric vehicles including rockets.

The IXV will be about the size of a big car and weigh almost two tonnes. It is booked to launch on Esa's forthcoming small rocket, Vega, from the Kourou spaceport in French Guiana.

And from the ESA site (http://www.esa.int/esaCP/SEM52E3XTVF_index_0.html)
The IXV project is part of the ESA Future Launchers Preparatory Programme (FLPP). The objective of IXV is to develop a European autonomous atmospheric reentry demonstrator system, characterised by high aerodynamic performance due to its lifting body shape, equipped with a high-performance control system based on propulsion and aerodynamic surfaces and having advanced thermal protection for atmospheric reentry.

The vehicle will weigh about 1800 kg and will be launched by Vega from the European Spaceport in Kourou. The launcher will place the IXV vehicle at an altitude around 450 km from which IXV will start its flight back to Earth, smoothly and safely splashing-down in the Pacific Ocean. With an entry velocity of approximately 7.5 km/s, the IXV system will perform a mission fully representative of a Low-Earth Orbit (LEO) reentry mission.

PraedSt
2009-Jun-18, 01:03 PM
That was a very informative book about Hypersonics and heating.That pdf link? Yeah, I liked it too.

From here on I cannot really add much more to the conversation as I have been asked not to.What? Who told you that? Add by all means. We like arguing over here, that's all. :)

Anyways my point is there are no show stoppers for an orbital system you stick on a rocket to orbit. The USAF reusable booster RFI is interesting coupled with Sustain. The commercial applications are great for a system like this for point to point. You don't NEED some kind of fancy air breathing rocket based near term technology. It can be done with the current state of the art.True. We're trying "fancy air breathing" because some of think it'll become cheaper than rockets. Others think it's nuts!

FDLoser
2009-Jun-18, 05:15 PM
That's quite a claim. Do you have a reference for that? A long glide range would mean a suborbital transport craft, which wouldn't have to get to such high velocities as an orbital craft, could achieve transcontinental distances with much reduced delta-v requirements.
BTW, this site with videos of the X-24B, a craft derived from the FDL-7, gives its hypersonic lift/drag ratio as 2.5:

X-24B.
http://www.dfrc.nasa.gov/Gallery/Movie/X-24B/index.html


Bob Clark
Yes that X-24B was pretty good at 2.5 since the shuttle is around 1.0.

My reference for the FDL-7 is:
http://books.google.ca/books?id=aI9QhDA4AVwC&dq=future+spacecraft+propulsion+czysz&printsec=frontcover&source=bl&ots=Nj6MgbRfgg&sig=1SyWVBBcnpkAb7iFt3aeK0yJ4Z4&hl=en&ei=GXU6SpS_DeKPmAe8nqXMBw&sa=X&oi=book_result&ct=result&resnum=1

Antice
2009-Jun-18, 06:13 PM
there is currently 2 schools of thinking when it comes to lower launch costs.
one is to throw away lots and lots of rockets. it's called economy of scale. This takes literally hundreds of launches per year to achieve.
the second school is the SSTO crowd. SSTO's also needs hundreds of launches to make the cost go down. however. with a fully reusable SSTO you no longer throw anything except fuel away. so even tho your vehicle is very expensive. you get the same net benefit on launch cost. if you scale the launches up to the level of 1k+ per year then you get a manufacture economy of scale on top. making it possible to get even lower launch prices than just disposables.

the formula for per launch cost is something along the line of:
(((R&D/LB)+ LBC)/LL)+ LC + (AFC/LPR)

where R&D/LB is development costs amortised over number of launchers built during the vehicles production lifetime, LBC is the fixed materiel costs of making 1 launcher. LL is the divisor for reusable launchers denominating how many launches is possible for each vehicle. LC is the fixed launching cost in fuel and other resources used up in the process. and AFC/LPR is the annual fixed launch pad costs divided between the number of launches per year.
using this formula it's possible to draw out a graph depicting how the number of launches affect the cost per launch of each type of vehicle.
what is quite readily seen is that when you start being able to fully reuse your vehicle and LL becomes greater than 2 you can afford a lot more expensive vehicle and still maintain the cost per launch at a reasonable level. the higher you get LL the better. when LL starts to go up to 100+ range it tends to outcompete the one shot vehicles by the fact that you can now divide the admittedly lot higher per vehicle R&D and manuf costs over a lot of launches. (R&D/LB) +LBC would have to be LL times larger for the reusable one than the non reusable one in order for the non reusable to be cheaper. this allows an approximate apples to apples comparison of such disparate systems. however. the other end of the formula.
AFC/LPR is often also wildly different for these vehicles as well. with some SSTO concepts using only a reinforced runway to take off instead of a dedicated launch tower.

some factors like LBC has their own economy of scale as well. when mass production kicks in build costs tend to drop quite a bit down towards the true material costs involved. this also has to be taken into account when comparing real costs.

PraedSt
2009-Jun-18, 10:27 PM
the formula for per launch cost is something along the line of:
(((R&D/LB)+ LBC)/LL)+ LC + (AFC/LPR)

where R&D/LB is development costs amortised over number of launchers built during the vehicles production lifetime, LBC is the fixed materiel costs of making 1 launcher. LL is the divisor for reusable launchers denominating how many launches is possible for each vehicle. LC is the fixed launching cost in fuel and other resources used up in the process. and AFC/LPR is the annual fixed launch pad costs divided between the number of launches per year.
Good post. My view is that costing is too difficult. A lot of this is new.

For example, rocketry is more advanced than SSTO. So you have to assume that the state of the art for SSTO will catch up somehow. This will be expensive.

But both a new company building a rocket for the first time, or an old company building a new model, have large learning costs- even though rocketry is old.

After the first rocket is made, the rest are expensive to build, but cheaper than the first one. With SSTO, for costing purposes one assumes that the first expensive machine is the only that is built.

So you could compare, say 100 "machine-launches". For the rocket: 100 machines*1 launch each. For SSTO, 1 machine*100 launches.

One assumes revenue per machine-launch will be the same.

For rockets, building 100 machines will add to costs per machine-launch. For SSTO, the expensive first machine will mean high interest expenses per machine-launch.

An SSTO craft wiil be more complex, so maintenance costs per machine-launch may be high. They are zero for throw away rockets.

Rockets need expensive facilities for launch. SSTO might not, one hopes; so that might be lower costs per machine-launch.

The rest might be the same. I'm sure I've missed a few. When everything's so complicated, I'm never happy with the costing. It's easy to get it way wrong. And SSTO is so behind rocketry that I'm not even sure it's a worthwhile exercise at the moment.

Ara Pacis
2009-Jun-19, 06:15 AM
There may be a hybrid solution. You might achive full reusability with more than one stage to orbit, and possibly get the best of both worlds. Of course, if you do it wrong, it could be the worst of both worlds. For example, an air-breathing hypersonic mothership that releases an ascent stage for orbital insertion might be fully reusable but overcome some of the physical issues of SSTO. We might also have disposable elements of an ascent stage (that do not return to the Earth's surface with the main aero-spacecraft), but if we recycle that material in orbit, it becomes part of the payload mass instead of a throwaway mass, even though it may never again be used for a surface-to-orbit maneuver.

mugaliens
2009-Jun-19, 07:27 AM
You might achive full reusability with more than one stage to orbit, and possibly get the best of both worlds. Of course, if you do it wrong, it could be the worst of both worlds. For example, an air-breathing hypersonic mothership that releases an ascent stage for orbital insertion might be fully reusable but overcome some of the physical issues of SSTO. We might also have disposable elements of an ascent stage (that do not return to the Earth's surface with the main aero-spacecraft), but if we recycle that material in orbit, it becomes part of the payload mass instead of a throwaway mass, even though it may never again be used for a surface-to-orbit maneuver.

I'm willing to bet one of these days we'll build SRBs where even most of the casings are consumed in the ascent, thereby pushing the thrust/weight ratios to the limit and leaving very little unused mass behind to worry about.

Sort of a "continual stage," perhaps in a tapered profile such that the acceleration remains steady throughout the ascent.

Possibly even a design whereby the lower section of this design has far less oxidizer, but ram-air scoops along the lower sections. As the rocket ascends, the propellant mix becomes more oxygenated and the scoops fewer until it's no longer profitable to use scoops at all.

Technically, a winged "mother" ship will use less fuel overall, but cost is a factor, as well, and while it uses more fuel to stand her on her tail, it's cheaper, as wings for 5 million pound, supersonic rockets are very expensive!

Antice
2009-Jun-19, 02:33 PM
it get's ugly fast when you try to add in even more factors to the equation. however. one of the main reasons we pay so much per launch today is that the amortization is done over way to few vehicles.
something like skylon is still at least 10 years off before the first one might fly barring any dificulties. they project 200 launches of 12 tonnes payload each per craft. the expect to build at least 10 craft of the first model before they take what is learned into the development of the SSTO mk2
this stil leaves an amortization burden that is very high on each craft. ending the cost per craft at somewhere between 500 mill and 1 bill... my guess it would end up a lot closer to 1 bill here. but with 200 launches you end up with a craft cost of only 5 mill per launch. the usual costs of a launch comes in addition to this. the question then remains. what does it really cost to build a single use rocket? how much more does a half reusable one cost? a half reusable might have a LL of 1,5 to signify that you reuse parts of the rocket. but then refurb costs have to be added as well.
All these factors fudge up the trade studies a lot and makes comparisons very hard to do.

Current status is that for now rockets is the only way to reach orbit. in 10 years time when we might be able to get the first truly reusable SSTO's tested out that may change. the shuttle proved that spaceplane shapes are well suited towards bringing cargo and crew back to earth from LEO, at the same time the shuttle had some major flaws. the TPS system is one of them. but we have come a long way on materials technology since it was designed, and i do think designers could make a lot better and efficient shuttle if they made a new design today with the lessons learned with the shuttles.

publiusr
2009-Jun-19, 03:30 PM
I think it is going to be farther down the road than 10 years. This love for wings has stagnated Shuttle-replacement efforts for too long. I for one find it very strange that the same folks who based Orion Ares as just an engineering development program now want to raid its budget just to basically reopen RLV demonstrator missions?

Talk about the pot calling the kettle black. Frankly, I want to see DARPA forced to only develop Ares V payloads, and all RLV research tabled for 20 years for more materials to develop. A modular system like Buran could have the orbiter swapped out with near full scale hypersonic boilerplates, not tiny ingots/warheads like X-43. With engines under the External tank (Energiya core block), you might have a Columbia style orbiter, Faget straight wing orbiter, large lifting body, etc.

But it's too late for that. The common wisdom for now is that we have learned one thing from STS, and putting wings on payloads--and that is not to do it again.

Antice
2009-Jun-19, 04:37 PM
As i've stated before and will again countless times. it's not about the wings at all. it's about making SSTO work. if it works better without wings then by all means. Drop the wings.
RLV's in general need a lot more dev work before any useful results will show.
Most of the failed projects so far has failed by NOT making certain that all the prerequisites were present and actually working, before trying to build the full launch system.
It's like trying to make a car when you've barely invented the steam engine. it can work once in a while but don't expect useful results more than once in a blue moon.

Your hate for winged craft comes across as an emotional response rather than a rational one.
Do you consider extended downrange capability worthless? or how about being able to just refuel and take off again. DC-X is an example of doing the SSTO without wings. do you think that is a better aproach? Or do you think that RLV's wont work ever?
there are many concepts and ideas worth looking into. but building large test vehicles for each one isn't worthwhile. however it IS worthwhile looking into their prerequisites. useful technologies that can be used other places as well can easily come about in that manner.
new types of air breathing engines may one day give rise to hypersonic transport planes as well as new first stages for rockets and so forth.

publiusr
2009-Jun-19, 05:00 PM
Your hate for winged craft comes across as an emotional response rather than a rational one.

That is a better description of the love for winged craft actually, as Bob truax has argued for years--about the price for elegance.

Even this scramjet advocate has admitted that HTHL systems are for the birds at this point.

http://www.thespacereview.com/article/1129/1

"He (Snead) is, on the other hand, quite right in noting an increase in TPS needs, probably even worse than he alludes to, because of the active cooling acreage needed. This may be scramjet’s Achilles’ heel..."

"Snead did not mention, nor did he have to, having made his point without it, but the wings and the takeoff gear, which would be dependent on the gross takeoff weight, also contribute mightily to making the HTHL SSTO option untenable."

Now this author wants vertical scramjets. Better, but If I rocket upward, I spend less time in atmo if I have to fly up through the murk.

A rocket, even one with a more depressed trjectory, still pops up through the atmosphere to the point where air breathing systems don't have much time to work.

Keep your propellants in a tube, forget intakes. Maybe 100 years from now we can revisit the concept with newer materials.

Antice
2009-Jun-19, 05:13 PM
Scramjets are not the only concept on the table. other options include using rockets with an added air compression system to allow air to be used as oxidiser for the trip up to mach 5.5.
several options just use a rocket engine all the way. but this tends to eat into the payload ratio a lot due to the weight of the oxidiser used to go from 0 to mach 5.5
if you want to compare fuel use you have to realize that the ISP for a rocket goes from around 500sec to around 2000sec when you replace the oxidiser with air for that part. that is a real mass saving on fuel that compensates for some of the other weight adders like the undercarriage.
Undercarriage weight is not only controlled by the takeoff and landing loads on the craft. but also on how much load the runway can take.
a stronger runway alows for lighter more compact landing gears. this is something that has to be traded for when studying concepts like these.
How much is the ability to land and and relaunch within 24 hours worth?
Being able to return to your launch site. load cargo and fuel then just take off again is the real goal for RLV's. Anything short of that is not a true RLV.

Ara Pacis
2009-Jun-19, 05:52 PM
I'm willing to bet one of these days we'll build SRBs where even most of the casings are consumed in the ascent, thereby pushing the thrust/weight ratios to the limit and leaving very little unused mass behind to worry about.

Sort of a "continual stage," perhaps in a tapered profile such that the acceleration remains steady throughout the ascent.

Possibly even a design whereby the lower section of this design has far less oxidizer, but ram-air scoops along the lower sections. As the rocket ascends, the propellant mix becomes more oxygenated and the scoops fewer until it's no longer profitable to use scoops at all.I always wondered if that could be done. The only real problem (assuming it worked) is that it would have to be low on the stack because a rising exhaust outlet might threaten the structural integrity of whatever it's strapped next to, kinda like what happened to Challenger.


Technically, a winged "mother" ship will use less fuel overall, but cost is a factor, as well, and while it uses more fuel to stand her on her tail, it's cheaper, as wings for 5 million pound, supersonic rockets are very expensive!That's why I would down-scale everything as much as possible to it's bare minimum. The aero-spacecraft would not do multiple duties like the shuttle Orbiter (personnel taxi, freight truck, assembly crane, space station, science laboratory, and strategic reconnaissance/bomber (the 1000mile crossrange requirement by the USAF seems suited to these roles, even if never stated). I'm thinking a basic payload capacity (not including the vehicle) would only be 3 metric tones and the structure of the orbital vehicle proper wouldn't be much more than that, using light wings (possibly cloth) and a hypersonic waveriding re-entry profile to reduce both aerodynamic and heating loads (possibly including high-powered retro-rockets equiped from a space station from lunar material to significantly reduce re-entry velocity). The internal rocket engine or a strap-on booster (at the rear) would increase the mass of the vehicle by whatever mass is needed for LOX/fuel (CH4 or RP1) to get 6tons+engine&tankage from ~mach 5 to orbital velocity. Whatever that total mass is, it's likely to be a lot less than the STS. Thus, a winged mothership need not be gargantuan.

Actully, this might also be launchable atop a stack as well as using an airbreathing hypersonic mothership. Flexibility's not a bad thing.

Ara Pacis
2009-Jun-19, 06:14 PM
it get's ugly fast when you try to add in even more factors to the equation. however. one of the main reasons we pay so much per launch today is that the amortization is done over way to few vehicles.This is why I am in favor of government subsidized research. It costs too much up front to make it seem economical. We shouldn't look at space access is just a commercial venture, but as a utility infrastructure. 100 years ago, cars may have seemed more expensive because fewer were sold because roads were so poor that people didn't feel as inclined to use them. With government built roads and bridges being built, the commercial auto industry took off. In this case, I see prototyping vehicle design as akin to the road not the car. After good designs are available and R&D is absorbed by the public, commercial ventures could use those base designs to build their own vehicles and operate their own launch services with lower amortization. If it's still too expensive, government loans and insurance might help, and private investment would cover the payloads.

But it's too late for that. The common wisdom for now is that we have learned one thing from STS, and putting wings on payloads--and that is not to do it again.

As i've stated before and will again countless times. it's not about the wings at all. it's about making SSTO work. if it works better without wings then by all means. Drop the wings.It's about the wings for me, but I'm less interested in using them for ascent as I am for descent. If we get rid of the tiles, we reduce a major point of failure. If we use something other than an ablative cooling TPS, we remove a major source of mass. If we reduce the angle of descent, we reduce both aerodynamic as well as thermal loads, further reducing mass. The lesson to learn from the STS is not to do it that way again.

publiusr
2009-Jun-19, 07:15 PM
This is why I am in favor of government subsidized research. It costs too much up front to make it seem economical. We shouldn't look at space access is just a commercial venture, but as a utility infrastructure.

Now that is where we are in agreement.

Spaceflight is more TVA than MSN.

I remember seeing this on my Charter On-Demand page

http://www.researchchannel.org/prog/displayevent.aspx?rID=28390&fID=572

Now, the folks there seemed a little too impressed with the tiny rocket racer not much different than the ME-163 KOMET that caused only minor problems to the B-17s that had much longer legs. IIRC, Peter admitted that he thought that NASA had an 'anti-gravity room."

This tells me that he has a woeful lack of understanding as to how this world works.

It is going to take big gov't to do big space.

Antice
2009-Jun-19, 07:15 PM
have to agree with you there on your last point Ara Pacis. they are not there for ascent primarily, but descent. However it does not hurt to make use of them during ascent to reduce gravity loss during the early part of the ascent either. it allows you to run engines at their optimal thrust for longer. at first you get to accelerate horisontaly at max thrust without having to pay any cost to gravity. then you nose up to remain at the same thrust level as the craft starts to loose weight due to fuel use. it increases aerodynamic losses somewhat but it balances out with reduced gravity loss due to standing upright on your thrust alone.
while it costs the same amount of energy to get up there, your budget is changed in a way that allows the use of a weaker engine in the first 2 minutes of launch.
One that still runs without having to throttle down significantly until the last bit to orbit when your launcher has lost 80% of it's total weight already.
Every bit of performance you can gain makes it just that much more viable as a launcher.

publiusr
2009-Jun-19, 07:22 PM
That's why I would down-scale everything as much as possible to it's bare minimum. The aero-spacecraft would not do multiple duties like the shuttle Orbiter.

The smaller you make a top mount spaceplane--the more you have to worry about weight creep, because at small scale docking hatches, wings landing gear--eat up more mass in relation to everything else. Pitch loads and bending moments also are problems.

A Buran style orbiter is rather like a full frame ford LTD of space. It is large, and all of your tankage is outside of the airframe so it is less like a hypersonic dirigible or an eggshell. With dead mass on orbit SSMEs off the orbiter, Buran could be exchanged with payload pods, and ringed with Zenit/EELV class strap-ons and you had an Ares V strength Vulkan.

So it was a little bit of everything. Perhaps China could have such a modular system with a better TPS.

Ara Pacis
2009-Jun-19, 08:19 PM
The smaller you make a top mount spaceplane--the more you have to worry about weight creep, because at small scale docking hatches, wings landing gear--eat up more mass in relation to everything else. Pitch loads and bending moments also are problems.

A Buran style orbiter is rather like a full frame ford LTD of space. It is large, and all of your tankage is outside of the airframe so it is less like a hypersonic dirigible or an eggshell. With dead mass on orbit SSMEs off the orbiter, Buran could be exchanged with payload pods, and ringed with Zenit/EELV class strap-ons and you had an Ares V strength Vulkan.

So it was a little bit of everything. Perhaps China could have such a modular system with a better TPS.

I know it may mass more than I guess, but I don't have the engineeering chops to quantify it, so it's all rather vague. I'm thinking of a craft with a minimum cabin+flightdeck size of ~38ft x 6ft (inside diameter). However, it might need to be wider to accomodate better tankage designs, depending on fuel volume requirements. I was also considering simply strapping the tankage and engine to the rear of the cabin fuselage, and leaving the tankage and engine in space for use there as spare parts or raw materials. On the other hand, it might be used for significant retro-burns for deorbit, if space-based fuel is in plentiful supply.

I was thinking the wings might have a variable geometry, with a solid leading edge with TPS and/or active/cryo cooling that pivots away from a fairing along the fuselage, unrolling a high-strength/high-temperature composite fabric that constitutes the rest of the re-entry/landing wing with an adjustable rogollo wing shape. Picture a hang-glider wing where the side members pivot at the vertex and flatten against the main keel like how an artist's easel folds up. It would not just fold from stored to extended position, but adjust position to maintain the best aerodynamic performance at whatever speed the craft is flying. There may also be solid (non retracting) canards or stabilators at the rear, if needed.

Docking hatch designs would vary depending on the level of space infrastructure. I am looking ahead to having a space station with an enclosed and radiation shielded hangar. The craft might still dock with a boarding bridge that maintains an airtight seal (similar to that used with jetliners, but through the roof of the aerospace craft instead of the side), but due to the immobility of the craft once it's secured in the hangar, the docking collar may not need to be so robust as that needed for a free-floating docking maneuver.

I know, I might be looking too far ahead and removing too much capability from that vehicle which ascent space vehicles will need for the near future. However, my goal is to design a minimum mass yet safe vehicle and move other issues to other aspects of the space infrastructure. In this way, I hope to expand the need for mass in orbit, but not in individual craft, while also lowering complexity and costs of each component and generate a reason for high launch volume to break through the "there ain't enough launch customers" argument and establish an industry with economies of scale.

I hope I'm not derailing the thread with my idea, maybe I should start a separate thread since it keeps coming up here.

Ara Pacis
2009-Jun-19, 08:26 PM
have to agree with you there on your last point Ara Pacis. they are not there for ascent primarily, but descent. However it does not hurt to make use of them during ascent to reduce gravity loss during the early part of the ascent either. it allows you to run engines at their optimal thrust for longer. at first you get to accelerate horisontaly at max thrust without having to pay any cost to gravity. then you nose up to remain at the same thrust level as the craft starts to loose weight due to fuel use. it increases aerodynamic losses somewhat but it balances out with reduced gravity loss due to standing upright on your thrust alone.
while it costs the same amount of energy to get up there, your budget is changed in a way that allows the use of a weaker engine in the first 2 minutes of launch.
One that still runs without having to throttle down significantly until the last bit to orbit when your launcher has lost 80% of it's total weight already.
Every bit of performance you can gain makes it just that much more viable as a launcher.Well, If we use a mothership that gets it to high altitude around 100,000 ft and around mach 5, the utility of wings on the aero-spacecraft for the reminder of the ascent may become negligible. If we use a rocket stack, then wings probably won't be needed for ascent either. This is one of the reason I suggest a retractable cloth wing. It can stay out of the way during ascent and extend to a large wing area for descent. However, it would need to use a different descent profile than current re-entry vehicles.

Antice
2009-Jun-19, 09:09 PM
wings are more useful for a SSTO in the case i outline. since everything goes into orbit. and everything comes down in one piece. instead of using cloth wings on your craft you can use a lifting body shape that is enhanced by using a steerable parachute instead. it's a lot simpler than having variable geometry wings. and potentially also lighter.

I've seen some small scale testing of rubber skinned foldable wings tho. your idea kinda resembles those.
the wings would be folded inside the craft during the hot phase of re-entry and is only exposed to any aerodynamic loads once the speed has dropped to a more reasonable speed. the advantage here is that the wing is mainly a frame that is able to change shape as speed drops from swept back to fully extended with the flexible rubbery skin material acting as wing surface so that it maintains it's shape for a soft glide to the runway. cloth would wither need a tightening mechanism to keep the surface tight, or would seriously affect the ability to alter the wing shape in flight.
these wings would be way lighter than a more traditionally wing as well as giving a very efficient glide profile trough multiple speed regimes.

cjameshuff
2009-Jun-19, 11:53 PM
It's about the wings for me, but I'm less interested in using them for ascent as I am for descent. If we get rid of the tiles, we reduce a major point of failure. If we use something other than an ablative cooling TPS, we remove a major source of mass. If we reduce the angle of descent, we reduce both aerodynamic as well as thermal loads, further reducing mass. The lesson to learn from the STS is not to do it that way again.

Wings are a liability on descent, difficult to make passively stable and easy to damage. The value of capsules has been well proven, Soyuz capsules have on several occasions entered on ballistic trajectories without loss of life...not something a winged craft is likely to survive.

A long and slow reentry increases heat loading...it only decreases maximum temperatures. Higher temperatures over a shorter period lead to more heat being radiated or left behind in the atmosphere rather than absorbed by the craft. You need big and massy cooling systems or a big and massy tank of expendable coolant. Ablatives do the same thing, but get expended at higher temperature and insulate the vehicle in the meantime...and there's no plumbing to fail.

Antice
2009-Jun-20, 07:21 AM
Non ablative radiatively cooled TPS is what i have my fingers on. one needs to insulate the inner stiffening structure and tankeage from the very hot TPS Aero shell. But that is quite possible to do with current tech. making a lightweight inner structural reinforcement structure is a bit tougher. but carbon fibres seems to have the strength to weight ratios needed to be able to do it. Needs some more R&D love before one can say either way methinks.

Ara Pacis
2009-Jun-20, 06:42 PM
wings are more useful for a SSTO in the case i outline. since everything goes into orbit. and everything comes down in one piece. instead of using cloth wings on your craft you can use a lifting body shape that is enhanced by using a steerable parachute instead. it's a lot simpler than having variable geometry wings. and potentially also lighter.I'm not against using wings for ascent, I would use them for the mothership, however, the wings on the ascent craft may not provide enough lift to be used for the remainder of the ascent. Or maybe they will, I'm not sure, but if it does help more than hinder, then they could be used. I like flexibility.

BTW, the hypersonic waverider shape I mention is, IIRC, a lifting body. It's not as obvious as other designs, but the double-caret or "M" cross-section makes use of the fuselage to generate compression lift.

I'd prefer not to use a parachute for reasons of control over long distances at altitude. Even though a rogollo wing (http://en.wikipedia.org/wiki/Rogallo_wing) was considered for use with the Gemini capsules, I'd rather incorporate the design into the vehicle directly, if possible.


I've seen some small scale testing of rubber skinned foldable wings tho. your idea kinda resembles those.
the wings would be folded inside the craft during the hot phase of re-entry and is only exposed to any aerodynamic loads once the speed has dropped to a more reasonable speed. the advantage here is that the wing is mainly a frame that is able to change shape as speed drops from swept back to fully extended with the flexible rubbery skin material acting as wing surface so that it maintains it's shape for a soft glide to the runway. cloth would wither need a tightening mechanism to keep the surface tight, or would seriously affect the ability to alter the wing shape in flight.
these wings would be way lighter than a more traditionally wing as well as giving a very efficient glide profile trough multiple speed regimes.That's a different flight profile from what I'm considering. The idea I'd like researched is using the wings at high altitude to slow the craft before it's gotten into the denser regions of the atmosphere where, IIRC, heating is more of a problem. Of course, in my concept of a space infrastructure, powerful retro-rockets would also negate a lot of the velocity so that heating isn't as much of a problem. Instead of entering the atmosphere at mach 25, it would enter closer to mach 10, or less if possible. Since the craft as a whole masses light, it should slow down much more quickly. Instead of a rubbery fabric, the cloth may perform better for that intended use, according to the wikipedia article (http://en.wikipedia.org/wiki/Waverider).


One candidate for a multi-speed waverider is a "caret wing", operated at different angles of attack. A caret wing is a delta wing with longitudinal conical or triangular slots or strakes. It strongly resembles a paper airplane or rogallo wing. The correct angle of attack would become increasingly precise at higher mach numbers, but this is a control problem that is theoretically solvable. The wing is said to perform even better if it can be constructed of tight mesh, because that reduces its drag, while maintaining lift. Such wings are said to have the unusual attribute of operating at a wide range of mach numbers in different fluids with a wide range of Reynolds numbers.

Also, changing the wind would mean either rolling the fabric into or out of the fairing to alter the depth of the caret cross section, or pivoting the wing to increase or decrease its sweep angle. I'm not sure if it would need one or the other or both, or neither.

Ara Pacis
2009-Jun-20, 07:15 PM
Wings are a liability on descent, difficult to make passively stable and easy to damage. The value of capsules has been well proven, Soyuz capsules have on several occasions entered on ballistic trajectories without loss of life...not something a winged craft is likely to survive.

A long and slow reentry increases heat loading...it only decreases maximum temperatures. Higher temperatures over a shorter period lead to more heat being radiated or left behind in the atmosphere rather than absorbed by the craft. You need big and massy cooling systems or a big and massy tank of expendable coolant. Ablatives do the same thing, but get expended at higher temperature and insulate the vehicle in the meantime...and there's no plumbing to fail.
I understand what you mean about spending more time in some sort of heating regime, but I understand the waverider overcomes this in two ways. First, and from what I've read (meaning I could be wrong), a properly designed waverider would not experience high heat loading because the glide is much longer than that of a capsule or the shuttle orbiter. So, while it might experience more potential heating overall, the heating could be overcome with less demanding thermal protection systems. Second, the shock wave isn't attached to most of the body, although it might be attached at the few points that produce the shockwaves depending on how its designed.

I am basing this idea on what I've read from others, and I am not an aerodynamicist, so I could be wrong, but I'd like the idea to be researched. Moreover, the design and mission of the specific vehicle I'm considering is very light-massing (~6-10 metric tons upon re-entry). If possible, I would use powerful retro-rockets (supplied while space-side) to reduce the velocity at atmospheric interface by half or more. In a more advanced idea, the infrastructure might include a catapult on a massive space station to also reduce the re-entering crafts forward velocity.

cjameshuff
2009-Jun-20, 10:48 PM
I understand what you mean about spending more time in some sort of heating regime, but I understand the waverider overcomes this in two ways. First, and from what I've read (meaning I could be wrong), a properly designed waverider would not experience high heat loading because the glide is much longer than that of a capsule or the shuttle orbiter. So, while it might experience more potential heating overall, the heating could be overcome with less demanding thermal protection systems.

Again, that just spreads it out over more time, leading to more heat total being absorbed. Sure, the rate of heating is low enough you can keep the temperature low with a mere heat exchanger and tank of water or LH2...but that's a lot of heat exchanger area, and a lot of plumbing, and pumps, valves, and the total amount of heat you have to handle is larger than it is for other methods and your rejection temperature is low, so really big coolant tanks...those "less demanding" systems are complicated and heavy! And if something goes wrong (and consider the points of failure in the above system, and compare to those in an ablative heat shield), maybe the craft won't melt outright, but it doesn't need to...if a tank of boiling coolant or fuel doesn't explode and destroy the craft, the crew will still die horribly.

Ablatives are a far more elegant solution. Simple, reliable, and very effective. More advanced ablatives that perform better and mass less seem like a much better approach.

Ara Pacis
2009-Jun-21, 07:26 AM
Well, let's throw a few billion at it and see if you're right.

Okay, maybe only a few million. I'm gonna need a second job.

publiusr
2009-Sep-25, 07:09 PM
The Sept Air and Space magazine has an article on LAPCAT
http://www.airspacemag.com/issue/September-2009.html

But in terms of true spaceplanes...
http://www.thespacereview.com/article/1092/1
http://www.thespacereview.com/article/1129/1

He is, on the other hand, quite right in noting an increase in TPS needs, probably even worse than he alludes to, because of the active cooling acreage needed....Anything with high GF can quickly spiral out into a nowhere land (like HTHL SSTO)...the other hand, his take on the scramjet testing design and verification challenges is quite true, and is debilitating. However, concentrating on the scramjet side, rather than on the TBCC side, will help, perhaps substantially (especially in this era of highly-limited funding!)

A very nice article just out that explains why spacecraft look the way they do
http://www.airspacemag.com/space-exploration/How-the-Spaceship-Got-Its-Shape.html

Let's hope that changes
http://www.space.com/businesstechnology/technology/sharp_rocket_001007.html

Antice
2009-Sep-25, 09:28 PM
I just dont get the fixation for scramjet's. they cant be utilized all the way from the ground til orbit. If I was in charge I'd rather go for something like the sabre engine. it combines the efficiency and thrust of rockets with the benefit of free oxidiser and more importantly, reaction mass, through the most fuel hungry part of the ascent. Planet earth is kinda just barely too big for SSTO's to be an easy endeavour. but not so large as to make them impossible. Just frustratingly hard. The primary goal of any SSTO concept must be to shed as much non payload mass as possible from the design in order to get as much payload as possible into space.
Or in some cases. even getting into orbit at all.

FDLoser
2009-Sep-26, 03:16 AM
Is there some way to attach a PDF file here without hosting it somewhere online?

Nicolas
2009-Sep-26, 12:00 PM
I can't find the LAPCAT article In this month's A&S. Under which part is it? I'm interested in it... Does it only discuss those LAPCAT M5 Media coughcoughcoughs or also LAPCAT M8?

Antice
2009-Sep-26, 05:07 PM
Here (http://www.reactionengines.co.uk/lapcat.html) is the primary source for Lapcat 2.

Nicolas
2009-Sep-26, 08:43 PM
Thank you, but I don't need a different informative source on LAPCAT. I worked on LAPCAT. "I am LAPCAT". Sorry for that last one, this is not a Hollywood movie. ;)

I was interested in the article itself to see how and what is corresponded to the media about the LAPCAT projects. Especially if they tell anything about the M8 this time, because the M5 generally is all you see in the press.

loglo
2009-Sep-27, 01:32 AM
Is there some way to attach a PDF file here without hosting it somewhere online?

Newbies are restricted from attaching files until they have a certain amount of posts. Ask the moderators, they should be able to help.

publiusr
2009-Oct-02, 05:22 PM
I can't find the LAPCAT article In this month's A&S. Under which part is it? I'm interested in it... Does it only discuss those LAPCAT M5 Media coughcoughcoughs or also LAPCAT M8?

http://www.airspacemag.com/flight-today/The-Perfect-Airplane.html?c=y&page=1

A blurb

"But the prize for truly advanced design programs—as well as for best acronyms—belonged unequivocally to the Europeans. In addition to the FAST 20XX, they had LAPCAT I and LAPCAT II (Long-Term Advanced Propulsion Concepts and Technologies), along with ATLLAS (Aerodynamic and Thermal Load Interactions with Lightweight Advanced Materials for High Speed Flight). The three programs, coordinated by the European Space Agency, aimed to produce two vehicles: one to fly at Mach 5, the other at Mach 8. Of the two, the Mach 8 craft seemed far less likely to get much beyond the idea stage. For one thing, it resembled a flying dustpan: a wedge consisting of a long and broad air intake scoop followed by tail fins, and little else—no windows, for example (see middle image, opposite). For another, as the European Space Agency itself admitted, while the Mach 8 vehicle “seems feasible, the fuel consumption during acceleration requires a large fraction, severely affecting gross take-off weight.” Meaning that the Mach 8 hypersonic aircraft might be very speedy, but not able to actually go anywhere."

Ouch.

Ara Pacis
2009-Oct-02, 05:58 PM
Just to jump in here on the acronym issue, maybe we should have an SSTO aerospace plane called Aero-Space Transit Reliably to Orbit. (ASTRO) :D

bebe7
2009-Oct-03, 08:00 PM
That's alot of cosmetics for the cost of one flight initially. Certainly as we progress the cost will come down.

publiusr
2009-Oct-05, 09:33 PM
Actually, I think there was something called ASTRO or three.

http://www.astronautix.com/lvs/astro.htm
http://www.astronautix.com/craft/astro.htm
http://www.astronautix.com/craft/orbastro.htm
http://www.up-ship.com/drawndoc/sdoc54ani.jpg

And there is this--the Martin Astrorocket among other things
http://www.epizodsspace.narod.ru/bibl/shun/shun2.html
http://www.capcomespace.net/dossiers/espace_US/shuttle/1960-80/1960.htm
http://www.hitechweb.genezis.eu/spacefighters0.htm
http://www.up-ship.com/apr/volume3.htm
http://www.up-ship.com/drawndoc/sdoc17ani.gif
http://www.astronautix.com/lvs/marocket.htm
http://www.up-ship.com/drawndoc/drawndocspaceother.htm
http://history.nasa.gov/SP-4221/ch2.htm


Why Roton was a bad idea
http://www.optipoint.com/far/rotary.htm

What the USAF might look into for small payloads
http://www.responsivespace.com/Papers/RS3%5CSESSION%20PAPERS%5CSESSION%206%5C6006-RAYMER%5C6006P.pdf

http://www.cyrus-space-system.com/

Spaceplanes
http://www.darpa.mil/tto/solicit/BAA08-53/VULCAN_Industry_Day_Presentations.pdf
http://www.astronautix.com/data/saenger.pdf
http://www.bautforum.com/science-technology/93398-nuclear-electric-ssto-vehicle-best-propulsion-mechanism.html


New propulsion
http://www.amazon.com/Future-Spacecraft-Propulsion-Systems-Astronautical/dp/3540888136/ref=sr_1_1?ie=UTF8&s=books&qid=1251834599&sr=8-1
http://selenianboondocks.blogspot.com/2008/06/orbital-access-methodologies-part-v.html Boostback
http://forum.nasaspaceflight.com/index.php?topic=1139.180 Nuclear methods
http://forum.nasaspaceflight.com/index.php?topic=17984.0 Profac
http://forum.nasaspaceflight.com/index.php?topic=18104.0

Nuclear DC-X
http://forum.nasaspaceflight.com/index.php?topic=17522.0
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA426465&Location=U2&doc=GetTRDoc.pdf

Diborane for Mars
http://forum.nasaspaceflight.com/index.php?topic=18657.0


Stabilo
http://www.arcaspace.ro/
http://forum.nasaspaceflight.com/index.php?topic=18951.0


Sea Dragon
http://forum.nasaspaceflight.com/index.php?topic=9733.75
Smaller water rockets
http://home.people.net.au/~aircommand/howitworks_1.htm#DropAwayBoosters

http://forum.nasaspaceflight.com/index.php?topic=14392.0 China spacelab

History Channel Space Wars
http://www.history.com/shows.do?action=detail&episodeId=488264
http://www.history.com/content/universe

http://www.bautforum.com/science-technology/94557-flyback-booster-concept.html#post1593804

RLV develpment http://nasawatch.com/archives/2009/10/commercial-rlv.html

RGClark
2009-Oct-19, 04:58 PM
RLV develpment http://nasawatch.com/archives/2009/10/commercial-rlv.html

I would love to be able to go to the conference mentioned:

NASA Announces Commercial RLV Technology Roadmap Project.
PRESS RELEASE
Date Released: Tuesday, October 13, 2009
Source: NASA HQ
"NASA is committed to stimulating the emerging commercial reusable launch vehicle industry," said Lori Garver, deputy administrator at NASA Headquarters in Washington. "There is a natural evolutionary path from today's emerging commercial suborbital RLV industry to growing and developing the capability to provide low-cost, frequent and reliable access to low Earth orbit. One part of our plan is to partner with other federal agencies to develop a consensus roadmap of the commercial RLV industry's long-range technology needs."
...
"This NASA and Air Force study will begin at the Commercial and Government Responsive Access to Space Technology Exchange 2009, held in Dayton, Ohio, Oct. 26-29. NASA and the Air Force Research Lab, with participation from the Federal Aviation Administration's Office of Commercial Space Transportation, will meet with representatives from the commercial RLV industry to explore and understand their long-range growth plans and the technology they could use to implement those plans successfully."
http://www.spaceref.com/news/viewpr.html?pid=29390

2009 Commercial and Government Responsive Access to Space Technology Exchange (RASTE) Oct. 26-29, Dayton, OH.
http://www.usasymposium.com/craste/cfa_extend.htm

But attendance fees are in the range of $650. Why do such aerospace conferences such as the AIAA meetings always have such high attendance fees? Do they think the only people interested would have the fees picked up by their industry firms?

Bob Clark

publiusr
2009-Oct-19, 05:16 PM
Their way of keeping the 'riff-raff' out. Here are the things you would probably hear if you were a fly on the wall:

__________________________________________________ ____________________

One Blue-suit
"Well if we can get Constellation killed we can free up some money for responsive space."

Another Blue-suit
"Yeah, once we get NASA to toe our line, the funds can keep coming in. Too bad about F-22. And that tanker mess! The cost of in-flight refueling on force projection is higher than that spent on missile defense!"

"Shhh, a missile advocate might hear you... Ah! here comes one of those starry-eyed scramjet engineers. Look interested."

FDLoser
2009-Oct-19, 05:29 PM
Their way of keeping the 'riff-raff' out. Here are the things you would probably hear if you were a fly on the wall:

__________________________________________________ ____________________

One Blue-suit
"Well if we can get Constellation killed we can free up some money for responsive space."

Another Blue-suit
"Yeah, once we get NASA to toe our line, the funds can keep coming in. Too bad about F-22. And that tanker mess! The cost of in-flight refueling on force projection is higher than that spent on missile defense!"

"Shhh, a missile advocate might hear you... Ah! here comes one of those starry-eyed scramjet engineers. Look interested."

Thanks! I haven't laughed that hard in about a week. :)

publiusr
2009-Oct-19, 05:42 PM
Wat 'till I tell you about some of these X-prize events, where everyone is selling and no one is buying.

A few space advocates use what little money they've raised in making nice glossy hand-outs, and one lone Venture Capitalist walks in, eats the steak they offer, then still says no, rolls his eyes at another true believer, laughs at a few more.

He then goes home and watches CNBC, screams at the TV set over a new tax, then when a story about how NASA needs money comes on, he says to himself. "Aw, private initiative can do a better job than gov't"--forgetting that he himself refused to invest in anything of the kind earlier in the day, thus debunking himself unknowingly.

Then, as head of the Aerospace Corp or whatever, he hires the first two blue-suits I mentioned earlier--calls his two old room-mates "space experts"--and they all head for the links.

If you want to know about what really goes on in this world--ask a caddy. Or be one. A better education you will never have.

FDLoser
2009-Oct-19, 06:18 PM
Wat 'till I tell you about some of these X-prize events, where everyone is selling and no one is buying.



Your levels of pessimism never fail to amaze me.

If the government unleashes the Entrepreneurs of this great nation no other country in the world will be able keep up. But yes, it does have to start with the Government funding the private companies in order for them to get the legitimacy that NASA funding brings.

Times they are a changin' whether you like it or not.
http://www.hobbyspace.com/nucleus/index.php?itemid=16103

publiusr
2009-Oct-19, 07:39 PM
I hope you are right, I really do. But look at some of the problems Elon Musk has faced. The is a real firestorm leveled against ATK, just like that leveled at Northrup Grumman when Boeing lost THAT competition. My guess is that, should Ares fall, the COTS folks will also start to feel hostility from the usual suspects. Musk has surprised me. He has more staying power than Beal ever did. But his success came from avoiding wings. As far as hypersonic passenger markets, the all rocket design I link to below is probably the best way to go:


http://www.flightglobal.com/articles/2006/07/18/207854/dlr-studies-suborbital-space-travel.html

Here are some other links to this and similar concepts:
http://www.popsci.com/scitech/article/2009-04/planes-trains-and-sueprsonic-spaceships?page=1
http://nextbigfuture.com/2009/04/europe-space-agency-hypersonic-plane.html
http://www.airspacemag.com/flight-today/The-Perfect-Airplane.html?c=y&page=1
http://www.dlr.de/en/desktopdefault.aspx/tabid-4530/3681_read-8344/3681_page-2/
http://www.theregister.co.uk/2009/01/29/dlr_spaceliner_concept_gets_pennies/print.html

Also in the news
http://www.space-travel.com/reports/NASA_to_aid_commercial_RLV_industry_999.html
http://www.space.com/businesstechnology/091015-lockheed-spaceplane-testflight.html
http://www.space.com/businesstechnology/091021-tw-alice-rocket.html

djellison
2009-Oct-19, 07:50 PM
the usual suspects.

Which are?

Note, the single most publicised plan as an alternative to Ares 1+V is the Direct plan, which still uses SRB's from ATK.

publiusr
2009-Oct-19, 07:55 PM
I wish that were true. I mean of course the EELV only advocates, but that's for another thread. In terms of rocketplanes we all remember Von Brauns designs. The closest thing I have seen to his early winged LV plans is this craft from the sites listed below:

http://www.astronautix.com/stages/n1mok.htm
http://www.astronautix.com/graphics/n/n1var.gif
http://www.astronautix.com/lvs/n1.htm

The lifting body looks to be revived under the 305-1 http://www.buran.ru/htm/history.htm http://www.buran.ru/htm/family.htm

It really isn't that tall. Still too expensive--for now...

djellison
2009-Oct-19, 08:23 PM
I mean of course the EELV only advocates,.

Who are, exactly? Who's doing this campaigning, where and who is this ATK attacking going on. Bearing in mind, once again, at least one of the EELV's writes cheques to ATK each time it uses GEM's.

publiusr
2009-Oct-19, 08:29 PM
Who are, exactly? Who's doing this campaigning.

Well ULA wouldn't be campaigning at all now would they? No way they'd be pushing their product and scmoozing behind the scenes, or shouting down foes on message boards, for example.

Getting back on topic--if we can--what do you think of DLRs liner concept? No airbreathing, and a flyback that can just as easily be used to boost non-winged LVs I wonder if this might be the new definition of Oural...

The Jim
2009-Oct-19, 09:12 PM
Well ULA wouldn't be campaigning at all now would they? No way they'd be pushing their product and scmoozing behind the scenes, or shouting down foes on message boards, for example.

No more than you do with your clueless posts.

The Jim
2009-Oct-19, 09:20 PM
Their way of keeping the 'riff-raff' out. Here are the things you would probably hear if you were a fly on the wall:

__________________________________________________ ____________________

One Blue-suit
"Well if we can get Constellation killed we can free up some money for responsive space."

Another Blue-suit
"Yeah, once we get NASA to toe our line, the funds can keep coming in. Too bad about F-22. And that tanker mess! The cost of in-flight refueling on force projection is higher than that spent on missile defense!"

"Shhh, a missile advocate might hear you... Ah! here comes one of those starry-eyed scramjet engineers. Look interested."

That is so wrong.

You have no credible information to base these asinine points on. You have no insight into the DOD nor the experience to make comments like these. These only exist in the warped and twisted world that you live in and have no basis in a reality that everybody else shares.

You denigrate the very people that protect your freedom with these unsubstantiated lies that you create. You post this crap all over the internet. Unless you have real information that backs your points, I demand that you refrain from making them.

They are nothing more than lies since they misrepresent the truth.

publiusr
2009-Oct-19, 09:38 PM
Like the lie you said against me writing that certain letter to Av week? And that is just one of your falsehoods.



You denigrate the very people that protect your freedom...

That's an old one. Wrap yourself in a flag and question the patriotism of others.

"How dare you use the freedom of speech that was fought for." A self negating statement if there ever was one.

If the freedom of speech itself--so much as tell a harmless joke--- is under assault, then what were folks fighting for? The last folks who actually fought for my freedom of speech (in a war we actually needed to fight) were the WWII vets, only some of whom were part of the US ARMY Air Corp--back in the days before the Air Force was formed. The USAF gets the lions share of the Pentagon budget, and I am not the only person critical of that. The "purple" thing never fooled me. Purple is closer to 'blue' than any other color. But I wasn't speaking to you at all Jim, I was talking to the gentlemen on this board.

Swift
2009-Oct-19, 09:39 PM
No more than you do with your clueless posts.
If you can't discuss this topic like adults, it won't be discussed at all. Please review the rules of this forum (http://www.bautforum.com/forum-rules-faqs-information/32864-rules-posting-board.html#post564845), particularly as they regard politeness. Consider this an official warning.

And by the way, though that was first aimed at The Jim, that goes for everyone on all sides of this issue.

The Jim
2009-Oct-20, 01:46 AM
1. If the freedom of speech itself--so much as tell a harmless joke--- is under assault, then what were folks fighting for?

2. The last folks who actually fought for my freedom of speech (in a war we actually needed to fight) were the WWII vets, only some of whom were part of the US ARMY Air Corp--back in the days before the Air Force was formed.

3. The USAF gets the lions share of the Pentagon budget, and I am not the only person critical of that.

4. The "purple" thing never fooled me. Purple is closer to 'blue' than any other color.

5. But I wasn't speaking to you at all Jim, I was talking to the gentlemen on this board.

1. It is not harmless joke. You keep pushing the same agenda which is not based on anything in reality

2. You conveniently omit the Cold Warriors which kept us safe from the Soviets. It was the mostly USAF that kept the USSR in place. You seem to align yourself more with the Soviets that the US Armed Forces.

3. You don't know enough to make that judgment. Your posts back me up.

4. What the H does that have to do with anything? What does purple have to do with it?

5. They aren't listening to you

The Jim
2009-Oct-20, 01:50 AM
That's an old one. Wrap yourself in a flag and question the patriotism of others.



Yes, your patriotism is questionable. You make claims about our armed forces without any data to back it up.

You have no idea about the inner workings of the DOD and USAF space program, yet you make unsupported comments about them.

Swift
2009-Oct-20, 02:36 AM
Yes, your patriotism is questionable.
The Jim,

This is my final warning. I don't know quite what your beef is, or what exactly you two are arguing about (and I'm not reviewing 8 pages of this thread to figure it out), but it doesn't seem to have much to do with the suborbital market for passenger flights - more like re-living the Cold War.

But it doesn't matter. Politeness is the primary rule in this forum and you will keep this discussion civil. We are not rude to other members and we do not question their ideals, or their motivations. Debate the concepts, not the people.

If you can not discuss this matter civilly, maybe you shouldn't participate in this thread. If you continue to break the rules, you will be suspended.

RGClark
2010-May-28, 07:01 PM
We might make a guess on the time frame on the development of a hypersonic commercial transport if the X-51 test is successful based on the case of the jet engine.

Interesting articles on the developers of the jet engine:

Frank Whittle
http://en.wikipedia.org/wiki/Frank_Whittle

Hans von Ohain.
http://en.wikipedia.org/wiki/Hans_von_Ohain

Frank Whittle in England first came up with the idea for a jet engine in 1929. There was a lot of skepticism for the idea and he did not come up with a working prototype then. He was able though to get a patent on it in 1930. He was first able to come up with a working prototype in ground tests in 1937.
Hans von Ohain in Germany independently came up with the idea in 1933. He was also able to produce a working ground prototype in 1937. After some more refinements, it was first tested in aircraft in 1939, only 2 years after the first successful ground tests.
After finally getting funding and support from the British government Frank Whittle, was able to get the first tests in aircraft in 1941.
Actual deployed jet fighters for both countries came only a couple of years after these first flying prototypes.
The first jet airliner was first tested in 1949 and came into service in 1952:

Jet airliner.
http://en.wikipedia.org/wiki/Jet_airliner

So a prototype commercial jet transport was produced only 10 years after a prototype jet fighter, which came only two years after the first jet engine ground tests. Following this model, we might expect a prototype hypersonic jet fighter within 2 years, and a prototype hypersonic transport within 10 years after that.
The X-15 which flew up to Mach 6.7 in the 1960's was already able to withstand the thermal heating at those speeds and likely could be an already existing airframe to test the scramjet engine on. More advanced airframes to optimize range and lift-to-drag ratios would be waverider lifting body shapes.


A more detailed discussion of the Wednesday test flight of the X-51A hypersonic scramjet:

Scramjet Success.
Aviation Week and Space Technology, May 28, 2010
By Graham Warwick
Washington
http://www.aviationweek.com/aw/generic/story_generic.jsp?channel=awst&id=news/awst/2010/05/31/AW_05_31_2010_p27-230271.xml&headline=Scramjet%20Success

This mentions the key advance that this is over the X-43A flight that ran on hydrogen even though that earlier flight reached higher speeds. The X-43A flight only lasted 10 seconds before the engine melted from the heat. The X-51A engine could run indefinitely at hypersonic speeds, a key requirement for a engine used for transport.

I like the way Charlie Brink X-51A program manager described the Wednesday test flight:

May 26, 2010, 6:18 p.m. EDT
Pratt & Whitney Rocketdyne Scramjet Powers Historic First Flight of X-51A WaveRider.
"Charlie Brink, X-51A program manager with the Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio, said: 'We are ecstatic to have accomplished many of the test objectives on the X-51A's very first hypersonic mission. We equate this leap in engine technology as equivalent to the post-World War II jump from propellers to jet engines."
http://www.marketwatch.com/story/pratt-whitney-rocketdyne-scramjet-powers-historic-first-flight-of-x-51a-waverider-2010-05-26?reflink=MW_news_stmp

My opinion is that prototype scramjet flight vehicles will be fielded in similar time frames to how soon jet aircraft prototypes were flown after the first working jet engines were made.


Bob Clark

NEOWatcher
2010-Jun-02, 01:14 PM
My opinion is that prototype scramjet flight vehicles will be fielded in similar time frames to how soon jet aircraft prototypes were flown after the first working jet engines were made.
Although I do see a lot of parallels in the two, I think there's going to be a few differences that may make the time frame longer.
The biggest is the need for multiple engine types, or a carrier vehicle. It may take time for the passenger market to warm up to this, or make it efficient enough.
Also; the jet aircraft were not much different in material or design than thier propeller counterpart. I'm not sure how much expensive materials would need to go into one of these.

RGClark
2010-Jun-18, 12:20 PM
Air Force Sees Hypersonic Weapons and Spaceships in Future.
By Jeremy Hsu
SPACE.com Staff Writer
posted: 17 June 2010
05:30 am ET
"Rise of the space planes.
"If scramjet technology advances far enough, it could become part of a system that helps propel unmanned or manned vehicles into space. Space planes might even emerge that can fly into space at just about any time, without launch window constraints.
"A scramjet-powered vehicle would need to rely upon a regular rocket or jet engine to reach Mach 4, so that the scramjet could take over for hypersonic speeds during the first stage to Earth orbit.
"The X-51A scramjet engine would not be enough by itself to allow a vehicle to reach orbit, said Joseph Vogel, hypersonics director and X-51 program manager at Boeing Phantom Works/Defense, during the teleconference. Both Boeing and Pratt & Whitney Rocketdyne formed part of the private consortium that helped design and build the X-51A.
"Any future space-lift system would also need a more energetic hydrogen-based fuel, rather than the JP-7 jet fuel used in supersonic aircraft, Vogel explained.
"I would say that within the next 15 to 30 years — I'll give you the broad side — but probably 15 to 20 years, you could start to see this technology being expanded to the point where you could get aircraft into outer space," Vogel said."
http://www.space.com/businesstechnology/hypersonic-weapons-spaceships-future-100617.html

This time estimate is for space ships. Then we would estimate the time frame for transports just within the atmosphere to be shorter.

Bob Clark

NEOWatcher
2010-Jun-18, 12:31 PM
This time estimate is for space ships. Then we would estimate the time frame for transports just within the atmosphere to be shorter.
Space ships? The article also says "into outer space". I think we need to be careful with those words. I don't see how the scramjet (alone) is going to get it out of suborbital.

danscope
2010-Jun-18, 06:03 PM
The scram jet will never exceed 8000, never mind 18,000 MPH, minimum escape velocity. You run out of air .

NEOWatcher
2010-Jun-18, 06:14 PM
... You run out of air .
Or the engine will. :whistle:

Garrison
2010-Jun-18, 06:19 PM
The scram jet will never exceed 8000, never mind 18,000 MPH, minimum escape velocity. You run out of air .

And I don't know why Bob is pushing scramjets when there's a better solution to the same problem in the shape of SABRE (http://www.reactionengines.co.uk/sabre.html).

RGClark
2010-Jun-19, 05:21 PM
And I don't know why Bob is pushing scramjets when there's a better solution to the same problem in the shape of SABRE (http://www.reactionengines.co.uk/sabre.html).

Er, because it's been proven to work?
I fully expect the Skylon Sabre engine also to be successful when it is full-up tested. Nothing wrong at all with having more than one hypersonic airbreathing technology operating at the same time.


Bob Clark

danscope
2010-Jun-19, 05:34 PM
I think we will all enjoy seeing the test results from the Sabre engine. All things take time.
Miracles take a little longer. Money is the accelerant.

Dan

Antice
2010-Jun-19, 05:52 PM
Scramjet's work for cruise missiles, but they are not proven as a viable stand alone technology for space launch at all.
Unless you can use it as an upgrade to existing engine technology the entire concept ends up adding more complexity than airbreathing at beyond mach 5 speed will be able to make in gains.
It is the first part of flight that has the highest oxidizer mass demands. (an obvious consequence of the rocket equation) making an oxidizer saving in the mach 5 to 10 range has a far lesser impact on overall mass than saving it from 0 to mach 5.

Here is the synergistic technologies in SABRE: Rocket propulsion. Ramjet thrust augmentation and pre cooled turbo compresors.
Turbo compressors are a proven technology in high performance jet aircraft. only the precooling is a new addition. That is a 3 technologies in one design. can you do the same with a scramjet? maybe. Nobody has attempted to marry a scramjet to a jet engine yet. while ramjet's have been combined with jet engines several times already. LACE proved that a rocket engine could use air as oxidizer. so the last step is to marry the components into a working system. the biggest hurdle was to make a functional extreme performance precooler that could work troughout the flight regime of a viable SSTO launcher. This hurdle is almost over. they have a working prototype, and a facility for mass production has been comissioned and assembly techniques are being investigated for efficient reliable manufacture of said heat exchangers. As far as making the SABRE engine a reality. we can be very confident that it will indeed be built.

Jens
2010-Jun-22, 06:36 AM
While this is straying a tiny bit, I think that eventually we are going to see some kind of super-fast transportation technology. But I think that there are two potential models. One is the hypersonic transport discussed here. I think the other is a sort of maglev train in an evacuated tunnel. I think the advantages of hypersonic aircraft is that there is less need for infrastructure and more freedom of where you can go, so it should win initially. A maglev network would require tremendous infrastructure, and wouldn't have as much freedom, but I think there would be advantages in terms of being able to locate stations in city centers and perhaps in terms of safety.

Antice
2010-Jun-22, 07:22 AM
I see no reason why high speed maglev and hypersonic air flight may not coexist. hypersonic air transport is never going to be cheap. the energy requirement is just too high for that.

danscope
2010-Jun-22, 07:03 PM
In my opinion, it is simply cheaper, cleaner, safer,less work and less material intensive, with less environmental impact, reasonably fast and more accessable for the general public ... to build a good, solid monorail . It doesn't have to be some ridiculous maglev concept at super inflated costs. We know how to do it. We simply require the will to produce good, clean ground transportation that real people can afford and that doesn't poison you and offend your nostrils. It's day has arrived. And..... it makes good jobs for people. This is a good thing.No question.
Best regards,
Dan

Garrison
2010-Jun-22, 07:24 PM
In my opinion, it is simply cheaper, cleaner, safer,less work and less material intensive, with less environmental impact, reasonably fast and more accessable for the general public ... to build a good, solid monorail . It doesn't have to be some ridiculous maglev concept at super inflated costs. We know how to do it. We simply require the will to produce good, clean ground transportation that real people can afford and that doesn't poison you and offend your nostrils. It's day has arrived. And..... it makes good jobs for people. This is a good thing.No question.
Best regards,
Dan

But as an intercontinental transport system? I'm not sure about Hypersonic passenger planes either, I guess it comes down to how many people they can pack in per plane and what they could sell a ticket for. Concorde never went mass market mainly because it was simply to expensive to buy a ticket for anyone but the niche market of business execs for who time really was money, and celebrities.

Larry Jacks
2010-Jun-22, 08:29 PM
For most of the US, passenger train service has to be heavily subsidized to survive. The distances are too great and the passenger density is too low even for lowly Amtrak to be profitable. In the more densely populated northeastern corridor, that isn't the case but it is for the rest of the country. A monorail system is far more expensive to create than ordinary passenger rail service so it also wouldn't be economically viable outside of the high density areas.

Hypersonic airliners face both economic and technical barriers that will be difficult to overcome. The economic barriers include the high cost of R&D, the exotic materials required to withstand the temperatures, and the amount of energy required to achieve and sustain those velocities. Look at how much Airbus spend to develop its A-380 or Boeing the 787. Those planes are dirt simple compared to a hypersonic transport. The technical barriers include dealing with the heat issue, developing the propulsion system that can function from zero airspeed at the start of the takeoff roll though Mach 5+ (the definition of hypersonic) cruise. The heat issue alone is substancial. A former coworker of mine served for 5 years as a backseater on the SR-71. He said that they frequently had to do touch-and-goes at the end of a flight to give the plane a chance to cool down. If they had to land immediately, the plane was so hot that it was difficult to get out of it even when wearing a spacesuit. A hypersonic plane will be much hotter than the Blackbird and the passengers will be wearing ordinary clothes. It does little good to fly across a continent or an ocean super fast only to have to wait an hour or more for the plane to cool down.

As for suborbital airliners, there's the barf factor. A significant percentage of trained astronauts get sick when first encountering weightlessness. What percentange of untrained, off the street passengers would be able to get through a flight without blowing chunks? Once one person loses it and it starts spreading through a weightless cabin, well, I'd hate to be on the cleanup crew.

Jens
2010-Jun-23, 06:39 AM
For most of the US, passenger train service has to be heavily subsidized to survive.

This is true, but it's true with other forms of transportation as well. In most countries, roads are maintained with tax money, so car transportation is actually subsidized. In the air, probably less so though airports and air traffic control are also subsidized. So I would assume that the rail system would have to be a government project.

Antice
2010-Jun-23, 11:00 AM
All transport is subsidized to one degree or another. It is in a nations self interest to do so in order to facilitate the movement of people and goods.
The ironic thing about transport subsidies is that those governments that do this usually get all the money back, and then some, trough increased trade taxation revenue. (not to mention the taxes from all the jobs all this trading generates.

Larry Jacks
2010-Jun-24, 02:27 PM
This is true, but it's true with other forms of transportation as well. In most countries, roads are maintained with tax money, so car transportation is actually subsidized. In the air, probably less so though airports and air traffic control are also subsidized. So I would assume that the rail system would have to be a government project.

In the US, gasoline is taxed and that money is supposed to go for things like highways. That isn't a subsidizy in the direct sense but a user tax. In Colorado, the tax rate is about 43 cents per gallon with somewhere around 16 cents of that going to the state. The gasoline tax varies widely by state. Likewise for air travel, aviation fuel is taxed and so are tickets. For example, 40 cents per gallon of aviation gasoline is tax that goes to the General Aviation Trust Fund which is used for things like airport improvements. In that sense, the users of the system are paying for its operation so it isn't a subsidizy.

A subsidizy is where everyone's taxes are used to benefit a narrow set of people such as for nuclear power plants, windmills, solar electric projects, ethanol, etc. From what I've read, no mass transit program built in America for decades has been self-sufficient. They were built with heavy taxpayer subsidizies and need continuous subsidizies every year to cover the operations costs. Amtrak is subsidized by an average of $32 a passenger (http://reason.com/blog/2009/10/27/riding-the-subsidized-rails-of). In some small town markets - especially those with strong political connections - airline service is subsidized as well.

Swift
2010-Oct-11, 03:28 PM
From CNN.com (http://www.cnn.com/2010/TRAVEL/10/11/california.space.flight/)


A pair of pilots flew the world's first manned commercial spacecraft over California's Mojave Desert on Sunday, though they were the only ones aboard.

The mission was a test flight for Richard Branson's dream of affordable space travel and put his vision a step closer to reality, he said after watching the spaceship land.

"Now, the sky is no longer the limit, and we will begin the process of pushing beyond to the final frontier of space itself over the next year," Branson said, according to a statement released by his company, Virgin Galactic, which is behind the project.

The spaceship, called the VSS Enterprise, completed a successful free flight from a mothership at 45,000 feet (13,700 meters) to a landing in Mojave, California, Virgin Galactic said.

NEOWatcher
2010-Oct-11, 05:00 PM
Another milestone reached. Good for them.

And good for CNN to fully qualify "manned" when saying first commercial spacecraft (although I'm sure that's going to get skewed eventually).

Here's another story (http://cosmiclog.msnbc.msn.com/_news/2010/10/10/5266767-spaceshiptwo-flies-free-for-first-time). It mentions an upcoming documentary.

The National Geographic Channel is scheduled to air a documentary about the making of SpaceShipTwo on Oct. 18. Here's a press preview:
Links to a 7:49 video preview.