PDA

View Full Version : Single Stage To Orbit



Stuart
2004-Oct-28, 04:38 PM
Hypothesizing that a single-stage-to-orbit spaceplane can be built (using integrated turbojets/scramjets/rockets) to reach a space station that's in orbit 200 miles up.

The problem arises, how do we land the spaceplane on the station and move it inside to an atmosphere environment without excessive atmosphere loss but also without also compromizing the ability of the spaceplane to operate off standard runways and be flown like a normal aircraft - yet also only using technology that exists now (ie 1990 - 2004 era)

Glom
2004-Oct-28, 04:45 PM
I wouldn't have thought that a spacestation would ever bother having a facility to for fixed wing spacecraft to land. I would expect that they would dock as usual. By the time space stations are that decadent, there would probably be some technobabble containment field for atmosphere.

Moose
2004-Oct-28, 04:50 PM
Why bring it inside at all?

Wouldn't an exterior docking hatch, even if it needs to be protected by some kind of retractable aerodynamic shielding while in flight, be easier to manage than an oversized recycling airlock?

Stuart
2004-Oct-28, 05:01 PM
Why bring it inside at all?

What concerns me is if the bird is kept in the airless environment, we'll get damage to seals, loss of plasticizer from composite materials etc, loss of lubricants etc. Also, the planes would be up there for some considerable time ata stretch and would require routine maintenance. The idea is that the station would have an embarked group of spaceplanes that would fly off it, returning to earth for major maintenance and duty cycling.

at the moment, my idea is basically an aircraft-carrier style deck and lift with the upepr end of the left well being sealed by hatches when the lift is in the "down" position - then fill the lift well and then open the hatchway so the spaceplane can be towed into a hangar.

Humphrey
2004-Oct-28, 05:40 PM
Safely bring it in? I suggest a underside or topside operation. Bringing it in to a opening in the side could pose a hazard if the forward momentum cannot be stopped. But to enter from the top or bottom you need to stop forward momentum and then move vertically into a open hangar area that cna be presurized.

When its depresurized you can have a pump store the extra atmosphere into a tank on the side of the station.

TinFoilHat
2004-Oct-28, 09:40 PM
This might actually be a good use for an inflatable structure. Dock the SSTO craft to the station normally, then have a flexible structure unfold from the station to enclose the ship. It could be something as simple as a cylinder with accordian pleats, just barely larger than the ship it's going to encluse, normally collapsed nearly flush to the side of the station. Once it's extended around the ship you'll need to seal off the open end - probably the most difficult part of the job, as that's a large seal on a flexible structure - then pump air in to hold it inflated.

This approach would work when you only want to protect a small number of ship, don't mind having a seperate enclosure for each one, and are worried about the size and weight of your space station.

Jpax2003
2004-Oct-29, 04:47 AM
If there is enough traffic with regular arrivals and departures then I suspect that there would be little need for extended aerospacecraft (ASC) parking. For stations that are less frequently visited I would recommend using spacecraft that are rated for space use only. But there are ways around all of these issues.

I would start by mandating that at least one large facility which is a hotel /casino /themepark /hospital /museum /science station also have an excess of terminals to be used for aerospace-to-space transfers. This means that ASCs would only dock temporarily, as measured in hours. I suspect that your issues related to ASCs might be abated by the short duration in vacuum. Space-Only-Craft (SOC) would then ferry people to other more distant or less complex stations (e.g. dedicated science stations or lunar stations).

I think a good design for ASCs would have the access hatch in a dorsal location, maybe to the rear of the cabin (due to latch and hatch mechanism weight and mass). A retractable spiral stairway might be extended from the floor for ingress/egress in gravity environments while a simple rope guide/ladder would be used in freefall. Passengers, crew, and small cargo would all enter through the same portal.

Alternately, I can see the need for occasional long term parking of ASCs for specific or emergency needs. The loss of atmosphere from the occasional use of a big airlock need not be drastic. However, if it is used more often, then perhaps a formfitting airlock could be designed. This might require that all ASCs be designed with identical cross-sectional profiles, if not all dimensions. Or replacement air for non-compliant ASCs using a generic airlock could simply be billed to the ASC operator and applied to the general operating fund or air replacement and life support systems line items. Another temporary method could be using flexible envelopes around an ASC, as suggested by TinFoilHat.

I think that the SOCs would probably be cylindrical in nature possibly tending toward elliptical in larger models (cf. puddle jumper from Stargate: Atlantis). Being cylindrical, without wings or other control surfaces, would allow for the craft to enter form-fitting airlocks for minimal loss of air. Perhaps the larger SOCs would only dock by insertion of a cylindrical appendage into a similar style airlock/terminal dock. As these craft are meant for vacuum, they could be built of heavier materials that do not suffer the same issues as more lightweight materials necessary for ASCs.

Perhaps landing/docking issues in space and on luna could be solved with magnetic technology. Several cables could be loosed from the ASC/SOC as it approaches the station to be magnetically grappled by the docking web. The cables are kept taut as the docking web gently slows the craft and then mechanically guides it into the correct alignment. Perhaps the craft could also carry laser ablation plates that are lased from the station's docking complex to counter most of the forward velocity not reduced by ship's main thrusters and RCS. Cargo vessels and larger passenger or specialty ships might need a more robust electromagnetic maglev type rail system for docking on an extended terminal. This might also be adapted for landing/docking use on the lunar surface.

phongn
2004-Oct-30, 06:45 AM
The anime Planetes (which has rather realistic depictions of near-future space travel, IMHO) has most craft hook up to a collapsable docking arm which grabs a ship and then pulls it into the docking bay. The arm includes the pressurized (and padded ;)) pathway to the station, communications, electrical power and sundry other goodies to take the burden off the ship while it is docked with a station.

Ships also seem to have a dedicated datalink to ground and space controllers and the amount of traffic is sufficiently low to ensure that they usually can have their own dedicated controller. I'd imagine that SAC will have at least the datalinks anyways, though.

For future-TBOverse once more stations are operational these things might be useful for follow-on stations both civilian and military.

Finally, one thing that the anime specifically addresses is all that junk floating around is a serious hazard (in fact, a SSTO passenger aeroplane lost a window to it with predictably bad results). Someone will probably have to clean up the area, if only so SAC's orbital spacecraft don't get plastered with stuff at high closing speeds.

Out Of Level
2004-Oct-30, 07:49 PM
Your question has validity in regards to the basic requirements of any structure in space that must be fed by reusable vehicles. The concept of space based maintenance capabilities" would serve to secure the safety' as well as economic viability of the structure. Therefore one could easily imagine an area that could be used to service as well as "Repair" critical systems. I would imagine this to be part of the hard-structure of any station. For now, it would most likely be decades before multiple internal facilities are needed. The "S.T.O." concept is down the road , but not too far.

To the Stars.
Or at least, around the block.

Lou. 8)

electromagneticpulse
2004-Oct-30, 09:22 PM
As im guessing its for regular use or you wouldn't have this problem it is going to be a relatively big station. One idea would be a ion field. Electron guns or some other method are used to knock electrons off the air molecules which are then forced back inside by a large superconductor(s) around the entrance which would force the ions back in where they can get their electron back and behave like normal atoms again.
A ship coming in wouldn't be effected by the magnetic field or the ionizing guns or it seriously shouldn't be in space in the first place. Just one recommendation dont dock a ship with an ion drive at the station :lol:

Ships would be able to come and go and you would have a pritty view of space from your docking bay :D

This is just an idea i have no idea if it would work well or not.

Another way is simply an air lock entrance. You fly the ship into the entrance which closes behind you and then the second doors open and atmosphere enters the airlock and then your ship goes into the station and the second door closes. Atmosphere gets pumped out after the second door closes either on the way in or out so no atmosphere is locked.
This isn't my idea BTW its the way you dock at a station on X:BTF or X2. They use this docking system in everything from stations to ships, but the larger ships can't dock with stations as they rival the size of them.

I personaly like the idea of big clear docking bay like in the death star but i would also be disconcerted by it and i would only walk where there is a hand rail and i'd keep taking deep breaths while saying to myself "its not going to fail, its not going to fail... damn it failed!" :D

Jpax2003
2004-Oct-31, 06:34 AM
I hope my last post was not too much information. It would help to know the timeframe and size of the space station. Stuart writes of using an aircraft carrier style of "landing" which would be rather large. However, I am not so sure a docking system modelled on an aircraft carrier would be the best solution for low gravity operations. The inbounds would not be moving significantly faster than the station as they are in near identical orbits. However, the inbounds will need to execute several accelerations/ decelerations in order to walk their orbital position toward the spacestation. Eitherway, aiming for a skidding stop on a large hard piece of flat real estate might not be wise, even with arrester cables. I'm unclear as to how a craft could be made to stay on the surface of the deck and how it is to move, or be moved, to the elevator/airlock without ejecting it off the surface. I think that arrester cables used solely on the bottom of the craft might torque it around and cause it to fling back off the opposite direction. That is why I suggest a active docking web system that makes contact with several hardpoints on the craft, both fore and aft.

I'm a little puzzled by this thread. I don't recall Stuart ever starting a thread, much less asking for help on a technical issue.

Stuart
2004-Nov-01, 02:47 PM
I hope my last post was not too much information. It would help to know the timeframe and size of the space station. Stuart writes of using an aircraft carrier style of "landing" which would be rather large. However, I am not so sure a docking system modelled on an aircraft carrier would be the best solution for low gravity operations. The inbounds would not be moving significantly faster than the station as they are in near identical orbits. However, the inbounds will need to execute several accelerations/ decelerations in order to walk their orbital position toward the spacestation. Eitherway, aiming for a skidding stop on a large hard piece of flat real estate might not be wise, even with arrester cables.

Holding down is the function of the arrester wires - it should be possible to bring the bird in with such low approach velocities and rate-of-descent that the actual landing is very soft - but the belly hook catches the wire and holds it, allowing the spaceplane to be fastened down. It would then be towed in using tractors that run along grooves in the deck to hold them down.

Timeframe is that this thing starts construcution in the middle of the 1980s - think the Freedom Space Station multiplied by four and with a lot more power generating capacity. Its set in a Universe where the Cold War and Vietnam never happened (for a series of reasons) and space technology is much better funded.


I'm a little puzzled by this thread. I don't recall Stuart ever starting a thread, much less asking for help on a technical issue.

I've started a couple in the past - normally I find that people here know so much more than I do about the issues raised that I keep quiet and read. My technical knowledge is in a somehat limited field; this is outside that so I need help and this was the best place I could think of to get it.

Jpax2003
2004-Nov-01, 09:11 PM
Holding down is the function of the arrester wires - it should be possible to bring the bird in with such low approach velocities and rate-of-descent that the actual landing is very soft - but the belly hook catches the wire and holds it, allowing the spaceplane to be fastened down. It would then be towed in using tractors that run along grooves in the deck to hold them down.Yeah, I think the velocities would be very low, but the masses and momentum would still be high. Even though many aircraft carriers can arrest larger planes like Hawkeyes, I suspect aerospacecraft would still be more massive. But even if they are smaller I think the tension and flexion of an arrester cable might do more harm than good. An Inbound would need to have a very specific vector. If the inbound's vector was off they would hit the deck and bounce off, missing the arrestor.

If they were moving parallel ot the deck, but too "high" the cable-grab would yank the craft against the deck. Without the benefit of gravity, the yanking would probably be unequal across the frame and the craft might pivot around this point and smack it's nose against the deck. I suspect that the best way to attenuate this possibility is by reeling out more cable in order to increase the decelleration time and reducing it's severity (incresing the radius of the arc around the pivot point). However, I think this might still just pull the craft to the deck but allow it to bounce off again.

I'm not saying that all of that bouncing need cause damage, but it might be disconcerting to passengers. You may want to look into the suspension systems used on carrier aircraft to determine their suitability for use in vacuum. Would inflated tires work, or explode? Would hydraulic suspension systems loose pressure or seize up in vacuum or low gravity? I think spring-based suspensions would only increase the bounce problem.

It might take up a fair amout of RCS to land a large bird softly on the deck. If this is what you meant, then I think a docking clamp would work better than cables. Cables can be fairly massive and might exhibit unanticipated flexion causing a stationary craft to move. Maybe cables could be used like lassos to grab onto a docking appendage once the craft has come to a relative stop above the deck. If you want to use a tractor running on embedded tracks, you may consider just using the tractor itself as the target dock. The craft could come to a relative stop, "hovering" above a painted target. The docking tractor, with a large flatbed extension on it's topside, runs underneath the craft and lassos several hardpoints. Then it reels in the cables as the craft settles into the flatbed. Maybe the flatbed is not a contiguous area but more akin to the adjustable X-shape of a hydraulic carlift. But you may want a more massive flatbed with mating latches or form-fitting intrusions so that the craft does not skid off of it. This would allow for increased acceleration of the tractor in order to clear the "flight" deck more quickly. However, the use of special hardpoints and landing "feet" instead of the wheels increases the mass and weight of the craft.



Timeframe is that this thing starts construcution in the middle of the 1980s - think the Freedom Space Station multiplied by four and with a lot more power generating capacity. Its set in a Universe where the Cold War and Vietnam never happened (for a series of reasons) and space technology is much better funded.They let you write fiction? I thought that was verboten for someone in your position... :o

But, I was thinking of a larger station. Imagine two Sear Towers end to end, run through a couple of super domes like donuts on a stick, all with a couple aircraft carriers stuck on one end.



I'm a little puzzled by this thread. I don't recall Stuart ever starting a thread, much less asking for help on a technical issue.

I've started a couple in the past - normally I find that people here know so much more than I do about the issues raised that I keep quiet and read. My technical knowledge is in a somehat limited field; this is outside that so I need help and this was the best place I could think of to get it.Oh ok. I thought maybe you had a doppelganger posting under your name. :D I'm not an expert in this field, but I think about it a lot. You probably already know a lot about orbital mechanics, but I have to recommend this book (http://www.amazon.com/exec/obidos/ASIN/0471146366/qid=1099343050/sr=2-3/ref=pd_ka_b_2_3/002-1511988-3804834), by Tom Logsdon.

electromagneticpulse
2004-Nov-02, 12:08 AM
Price: $110.00
:o

Out Of Level
2004-Nov-02, 02:26 AM
Perhaps the "Capture and exit would consist of a "Magnetic Deck that conveys the craft to the desired point.

Lou.

Jpax2003
2004-Nov-02, 09:59 AM
Perhaps the "Capture and exit would consist of a "Magnetic Deck that conveys the craft to the desired point.

Lou.That was what I was thinking for lunar use. Using an elevated maglev track system to catch and slow lunar inbounds also using magntic repulsion for breaking. Gravity would stabilize craft on the maglev track. However in a freefall orbit, I think having a single large magnetic source might cause more problems. That's why I think a magnetic docking web would work better.

electromagneticpulse
2004-Nov-02, 05:18 PM
That's why I think a magnetic docking web would work better.

I dont 100% get what you mean by a docking web. I dont want to conclude anything from it as i get my own idea's of what you might mean, so could you explain a bit?

Thanks :)

Jpax2003
2004-Nov-02, 09:35 PM
That's why I think a magnetic docking web would work better.

I dont 100% get what you mean by a docking web. I dont want to conclude anything from it as i get my own idea's of what you might mean, so could you explain a bit?

Thanks :)I know that the TV show Farscape has something called a docking web, but that is not what I mean. I am thinking of a series of rails or cables arrayed in a cone shaped web terminating at the door of the Airlock. It might actually look like a spider web when you factor in the cross beams/bracing cables. Or maybe a plastic bandminton shuttlecock is a better reference. The idea is that the inbound craft floats toward and into the center of the cone. When it is inside the craft reels out a cable with a magnet on the end. I propose 3-4 cables at the front and 3-4 cables at the rear. These extra cables on all sides would brace the craft from torquing in any direction. Then a Spider (for lack of a better word) running along each web-rail magnetically grabs the craft's docking cables and pulls it into the the airlock in the correct orientation. I think this idea would allow for rapid ingress of small passenger or courier craft with the least amount mass or energy expenditure. Of course, I could be wrong.

electromagneticpulse
2004-Nov-02, 10:15 PM
That's why I think a magnetic docking web would work better.

I dont 100% get what you mean by a docking web. I dont want to conclude anything from it as i get my own idea's of what you might mean, so could you explain a bit?

Thanks :)I know that the TV show Farscape has something called a docking web, but that is not what I mean. I am thinking of a series of rails or cables arrayed in a cone shaped web terminating at the door of the Airlock. It might actually look like a spider web when you factor in the cross beams/bracing cables. Or maybe a plastic bandminton shuttlecock is a better reference. The idea is that the inbound craft floats toward and into the center of the cone. When it is inside the craft reels out a cable with a magnet on the end. I propose 3-4 cables at the front and 3-4 cables at the rear. These extra cables on all sides would brace the craft from torquing in any direction. Then a Spider (for lack of a better word) running along each web-rail magnetically grabs the craft's docking cables and pulls it into the the airlock in the correct orientation. I think this idea would allow for rapid ingress of small passenger or courier craft with the least amount mass or energy expenditure. Of course, I could be wrong.

Okay thanks for explaining it, i know the show Farscape does but i was infact thinking along similar lines to you. It could also include backup systems like a reinforced steel net which could be used to stop a ship crashing into an airlock door or the side of the station. The last thing you want is a hull puncture especialy if its a space ship sized one :lol: