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The Saint
2005-Aug-08, 12:00 PM
The Shuttle was conceived and designed in the 70s. If it was to be built today, assuming a huge budget, are there any significant improvements in its shape, structure, materials, engine, computers, safety etc that could be incorporated?

Or can it basically not be impoved on apart from some tweaks?

Is the very theory of the Shuttle still viewed as being the best practical way of getting an 80 ton vehicle with 7 crew into orbit?

Is there a better theoretical way?

madamwitty
2005-Aug-08, 02:20 PM
The Shuttle was conceived and designed in the 70s. If it was to be built today, assuming a huge budget, are there any significant improvements in its shape, structure, materials, engine, computers, safety etc that could be incorporated?

Or can it basically not be impoved on apart from some tweaks?

Is the very theory of the Shuttle still viewed as being the best practical way of getting an 80 ton vehicle with 7 crew into orbit?

Is there a better theoretical way?

I can't say whether or not the shuttle is the best implementation based on the design requirements that were given. However, I can say that (as always) many of the design requirements were based on political considerations.

I think the military had some pretty heavy requirements. IIRC, one of the requirements was that it should be able to take off, retrieve a (spy) satellite in orbit, and land again on a runway within one or two orbits. Can anybody back me up on this? Such a requirement would add a lot of vehicle capability which wouldn't be necessary in my book.

What I'm saying is that it's all a matter of what additional capabilities you want the vehicle to have.

DoktorGreg
2005-Aug-08, 03:07 PM
The shuttle was designed to retreive things from orbit, not launch them. As far as I know, the retrevial option has never been exercised. Get rid of the retreival option, and you have a 80 ton launch payload. So rather than launching school buses, you are launching 8 school busses.

On technology, we have been spoiled the last few decades, particularly in consumer electronics. I dont think material sciences has advanced as much computer technology. But even then, computers do nothing more than they did in the 60's. They only do it faster.

I dont see how you improve on chemical rocket technology beyond what we have now. The combustion chamber of a rocket is already at the limits of temperature and pressure. The entire rocket is cooled with liquid hydrogen heat tracing, to keep it within those tolerances. Unless someone invents a material that is radically stronger and heat tolerant (and light) than the metal it is currently made out of (I cant find a reference an alloy of some type no doubt) I dont see how the rocket is improved upon.

The re-entry shielding is the same thing. It was engineered to be reusable. So you dont get the same properties of an ablative coating, which is it cools as it errodes away. Also, the heat shielding is cerramic. Again, the problem is, I dont see how you get more heat tolerance than heat fused rock.

The material needed to radically improve upon the shuttle design has been invented. It is refered to it in the movie "The Core", Unobtainium. Until a ready supply of Unobtainium is found, the shuttle is the best thing going for a space plane.

Ilya
2005-Aug-08, 06:26 PM
I think the military had some pretty heavy requirements. IIRC, one of the requirements was that it should be able to take off, retrieve a (spy) satellite in orbit, and land again on a runway within one or two orbits. Can anybody back me up on this? Such a requirement would add a lot of vehicle capability which wouldn't be necessary in my book.

Correct. More specifically, the requirement was to retrieve or launch a satellite in POLAR orbit, which meant launching from Vandenberg AFB in California. Polar launches are never done from Florida because that means dropping spent stages either on continental US or on South America. Even more specifically, it was to launch a satellite without warning and to land the shuttle after one orbit (sorry, DoktorGreg, but both NASA and USAF intended Shuttle to be THE American launch vehicle, even as they touted its unique retrieval capabilities).The problem with that scenario is that during 90 minutes it takes to do one orbit, the Earth rotates 22.5 degrees, and Shuttle finds itself over Pacific Ocean 1000 miles west of Vandenberg. Hence 1000 miles cross-range capability was added to the requirements, which REALLY drove the costs up.

Needless to say, Shuttle was never launched from California nor into polar orbit, nor was this cross-range capability ever put to use. Satellite retrieval was done a few times -- the only one I can think of right away was LDEF satellite (Long Duration Exposure Facility), which was brought back to Earth after 5 years in orbit.

Madamwitty, why did you emphasize "landing on a runway"? Shuttle always lands on a runway.

Ara Pacis
2005-Aug-09, 01:49 AM
On technology, we have been spoiled the last few decades, particularly in consumer electronics. I dont think material sciences has advanced as much computer technology. But even then, computers do nothing more than they did in the 60's. They only do it faster.

Well, computers still compute in binary, but hardware and software do perform functions that are not just faster, but differently than in the 60's.


I dont see how you improve on chemical rocket technology beyond what we have now. The combustion chamber of a rocket is already at the limits of temperature and pressure. The entire rocket is cooled with liquid hydrogen heat tracing, to keep it within those tolerances. Unless someone invents a material that is radically stronger and heat tolerant (and light) than the metal it is currently made out of (I cant find a reference an alloy of some type no doubt) I dont see how the rocket is improved upon.

Are we sure that we have discovered every form of high-energy exothermic reactions? Are there chemical reactions that might be possible if catalyzed by nuclear or antimatter tech? I don't know if we are at the limits of material science for combustion chamber and exhause nozzles, but if we are then perhaps there is room for improvement in structure and mechanics. Perhaps we'll discover a way to confine combustion with electromagnetics or fluid-dynamics or use ablative coatings for temporary engines and nozzles.


The re-entry shielding is the same thing. It was engineered to be reusable. So you dont get the same properties of an ablative coating, which is it cools as it errodes away. Also, the heat shielding is cerramic. Again, the problem is, I dont see how you get more heat tolerance than heat fused rock.

Wave-rider type designs might prolong descent but also reduce heating per unit time. This would reduce the need for expensive and delicate reentry tiles or heavy and cumbersome ablative shields. IIRC, the orbiter's heat tiles are made of foam, so the heat properties are not just related to it's mass and chemical composition, but to it's physical structure as well.


The material needed to radically improve upon the shuttle design has been invented. It is refered to it in the movie "The Core", Unobtainium. Until a ready supply of Unobtainium is found, the shuttle is the best thing going for a space plane.

Actually, I think that material is called "gray-matter". We can augment the physical properties of a material by varying it's macroscopic structure and interfaces with other materials, such as heat transport fluids.

I propose a dart-shaped passenger-only craft that would be less than 1/4 the size of the STS orbiter and a separate vehicle for cargo or satellites. This might launch on the same stack as the STS or use another system. It would re-enter using wave-rider principles instead of ablative or heat shields and would only need intense cooling at the few parts of the airframe that interact with the hypersonic compression wave (nose and wing-tips). Basically, think of the Orbiter without the exta-wide delta wings, cargo bay, engines, and heat tiles. It wouldn't need to be as complicated as an SSTO space-plane so it could be maximized for cool re-entry.

The Saint
2005-Aug-09, 03:52 PM
Apart from better rocket seals after 1986 and better foam after 2003, what other improvements or changes have been made to the Shuttle, its flight plan and method of operation since it first flew in 1980?

formulaterp
2005-Aug-09, 04:31 PM
what other improvements or changes have been made to the Shuttle, its flight plan and method of operation since it first flew in 1980?

See here, (http://spaceflight.nasa.gov/shuttle/upgrades/upgrades2.html) here, (http://spaceflight.nasa.gov/shuttle/upgrades/upgrades3.html) or here. (http://spaceflight.nasa.gov/shuttle/upgrades/upgrades4.html)

madamwitty
2005-Aug-09, 04:50 PM
Madamwitty, why did you emphasize "landing on a runway"? Shuttle always lands on a runway.

I suppose I was referring to the fact that the landing site was also specified in the requirements, but I didn't remember off the top of my head where that was. I guess I also made the assumption that they wouldn't specify an air force base and allow them to land somewhere else than a runway.

P.S. I watched the shuttle land on a runway this morning. Way cool!

Glom
2005-Aug-09, 05:06 PM
If we accept the DoD requirements which would require a delta winged behemoth, there are still some things that can be done. First, we have CAD, which can mean the design will have more efficient aerodyanmics perhaps meaning that the L/D ratio improved and as such the wings could maybe smaller.

More importantly, we must remember that metal is so last cenutry. Various composites would be used throughout the spaceframe making it much lighter and hence requiring, again smaller wings, and also more payload weight with reduced fuel requirements.

Of course, if the Space Shuttle concept was revived, we're be talking about a more modest structure with short stubby wings like X-15.

Hamlet
2005-Aug-09, 05:57 PM
Apart from better rocket seals after 1986 and better foam after 2003, what other improvements or changes have been made to the Shuttle, its flight plan and method of operation since it first flew in 1980?

Have a look here (http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts_asm.html#sts_mods).

This list is from shortly before return to flight in 1988. It has most of the mods that were done as a result of the Challenger accident. It doesn't include more recent mods but it gives you an idea of the history of changes.

hammo1j
2005-Aug-09, 06:02 PM
BTW

CONGRATULATIONS TO THE SHUTTLE ASTRONAUTS ON A SUCCESSFUL MISSION!

Here's a thread on the same topic in the ATM forum.

http://www.badastronomy.com/phpBB/viewtopic.php?t=21410.

Didn't twig the importance of retrieval in the design which is going to be a mainly military usage.

Eliminate the retrieval capacity and you have a much smaller reusable vehicle.

How about this idea:

Much smaller crew compartment mounted on rest of shuttle stack with a bdb + payload taking place of shuttle. The bdb goes into space and the valuable engines are disconnected when in orbit and stored in the smaller crew compartment for return to earth.

Ara Pacis
2005-Aug-09, 06:10 PM
If we accept the DoD requirements which would require a delta winged behemoth, there are still some things that can be done. First, we have CAD, which can mean the design will have more efficient aerodyanmics perhaps meaning that the L/D ratio improved and as such the wings could maybe smaller.

More importantly, we must remember that metal is so last cenutry. Various composites would be used throughout the spaceframe making it much lighter and hence requiring, again smaller wings, and also more payload weight with reduced fuel requirements.

Of course, if the Space Shuttle concept was revived, we're be talking about a more modest structure with short stubby wings like X-15.

Hey Glom, do you think an extendable heat resistant rogallo wing (http://en.wikipedia.org/wiki/Rogallo_wing) would be feasible for a shuttle replacement so that it can act as a waverider?

Glom
2005-Aug-09, 06:32 PM
I dunno. Looks intriguing.

publiusr
2005-Aug-10, 08:22 PM
This is yet another reason I love Energia/Buran.

With the ET having the engines--if the orbiter is grounded--you still have an HLLV.

The Zenit strap-ons are EELVs in their own right--and with engines on the ET--you are not limited to just one kind of orbiter as we are.

We could side-launch a Faget straight wing, an orbiter sized waverider, a near full scale X-43 test craft first released for low-speed tests, or a Buran type orbiter with F-111 type escape-cabins.

I remember some Shuttle-C drawings showing large circular aerobrake disks wider than the orbiter's wingspan being proposed

Foam-fall notwithstanding, side payload mount allows for outsized articles to be launched. Top mount spaceplane options will impart pitch-loads and bending moments, and can be a problem.

The rugged R-7 and the immensely strong SRB/stick might overcome this problem for Kliper and TAV.


The original STS was a TSTO design--but there you had twice the weight of the wings, landing gear, etc. Both stages were winged. So here comes the weight creep.

The TSTO concept also used side staging, so insulation/debris problems would also have to be addressed.

The TSTO Martin astrorocket would need no foam--but used a lot of hypergolics. Perhaps China could use this design--provided they stick with hypergolics. The RD-270/RD-253 would be good choices for the first and second stage.

www.starbooster.com suggests that flyback boosters sould be used.

Buran was a big orbiter, but had no SSMEs. A flyback booster would have big engines--but needed no heat shield per se, as it flew back at slower speeds.

Having big engines and a lot of heat shield problems all on the same craft as in our STS is questionable.

I am not one to always go the don't mix crew and cargo mantra--a metal heat shield Buran type craft/crafts would allow tons of space processed goods to return after being processed on 100 ton station modules launched in place of Buran--so in large scale crew and cargo were separated.


The best reason I can think to give you on why a Buran system is best-- is that it kept the rocket people and the airplane people away from each other. The rocket people worked on the engine-equipped ET, and the orbiter people don't get in their way and vice versa. Buran was one of many payloads, only had to hang ten on Energia. It didn't matter if Energiya and its engines were full of stress cracks--they were going to burn up anyway. It only had to work once.

The orbiter had a more benign flight envelope--and without wing-weight, the Energia itself made for a fine HLLV.

This STS system would have been perfect for the USA. If only the USSR had flown the Columbia system and we had invented theirs. The fuel cells could have kept turbojets warm in space, and venting water into turbojet exhaust adds to their thrust after flowing around them to transport heat away from them and into exhaust--a non-hypersonic cooling set up test to help with hypersonic versions later on.

Everything synchs up.

But we didn't go that route.

DRAT!

jfribrg
2005-Aug-10, 08:49 PM
I think we should dispense with the retrieval capabililty. A large portion of the cost and complexity is related to having the entire shuttle reenter. I say we should design something that will take you to orbit, and then when you are finished, you get into an apollo style capsule and we're done. The rest of the rocket is sent back into the atmosphere where it will burn up and whatever survives drops into the pacific.

publiusr
2005-Aug-10, 09:18 PM
That seems to be where we are heading. At the bottom of www.nasawatch.com (Aug 7) is a nice color drawing of a capsule.

Think Kliper after it had eaten Big Gemini. It is quite lovely.