Posted on 02/05/2003 4:43:37 AM PST by from occupied ga
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Yup. Shouldn't we have that next generation low-orbit vehicle by now, after the disaster with Challenger? Columbia was older than 21, also. It was built in 1979.
It would be nice if the private sector were to take a leading role. I haven't stayed current with space exploration -- my horizons are set by electronic warfare and airborne early warning -- but if NASA is attempting to thwart private space exploration and development of orbital access alternatives, it's a monstrous crime and should be held up to the harshest possible light. No one knows enough to say with any justice that "we know exactly how this ought to be done, so the rest of you can just toddle off and leave it to us."
Come to think of it, does anyone ever have enough justification to say that? About anything?
Freedom, Wealth, and Peace,
Francis W. Porretto
Visit The Palace Of Reason:
http://palaceofreason.com
Scamjet? That is hilarious. I know that was probably a typo - but it's synchronistically very funny. A little about the workings of a Scramjet, or Supersonic Combustion Ramjet:
A turbojet has 5 basic stages - an inlet stage, a compressor stage, a combustor stage, a turbine stage - and an expansion nozzle. The inlet stage is self-explanatory - it actually is more complex at supersonic speeds but we won't worry about that for the purposes of this short explanation. The compressor stage is the fan blades you see when you look in the front of any engine. It's job in life is to compress the air coming in to raise the temperature and pressure before combustion. For reasons of thermodynamics, this is necessary to get more bang for the fuel buck. After the air flow is ignited by the combustor stage, it goes to the turbine stage - which is a parasitic stage in that its job in life is to get the energy out of the airflow so it can drive the combustor stage up front. After that, the air is free to go and expands in the expansion nozzle to basically push against the walls to drive the craft forward.
A scramjet is a marvelously simple device that does all the above. At Mach 4 or higher - the underside of the aircraft nose acts like a compressor in that it is sloped as a "compressor ramp" - such that the air volume is constricted as it moves down the ramp into the smaller inlet. Cramming 10 pounds of air into a 5-pound bag compresses the air. Voila! Get rid of the compressor stage. Well...if you don't have a compressor stage, why the hell do you need a turbine stage? So th turbine stage is pink-slipped too. What do you have left? A hollow tube with some "butane" torches sticking out of the walls.
Regarding the tiles. I do not hold it against the Shuttle that it uses aerobraking - using air friction to decelerate. It is really the only way to slow down. Carrying the fuel necessary to decelerate using retrorockets would basically double the fuel requirements of any orbital vehicle. That said, however, the tile concept as heat dissipator/absorber needs to be much improved - and that will take some serious materials science technology advancements. So be it. I'd be the last one to say that the next improvement to the Shuttle is technologically here already. It isn't. That's why the replacement will be VERY expensive - lots of new technology will have to be developed. However, in terms of what it will mean to future access to space - it will be well worth it.
One poster has backed you up, and I've found nothing to state otherwise, so for now, peace.
I did reread the article and, while I thought Vin was dissing space travel, it seems he is only dissing "government sponsored" space travel.
That makes more sense, anything Fedgov touches turns into a boondoggle of bureaucracy and job protection. Perhaps we should be looking at a private/public joint venture while we're moving towards changing vehicles?
The proposals I have seen use carbon-carbon for the really hot spots and titanium elsewhere.
I have heard of a California company that is working to be able to place vehicles in low orbit within 10 years. If I come across their name again, I will post it.
NASA has pretty effectively poisoned the well for private enterprise. New companies have routinely been starting with the idea of developing a cost-effective launcher, but a huge problem has been NASA flying monkeys telling every investor they get to that whatever the company is trying is stupid and will never work. What else would they say? Anytime someone has a better idea, the question is begged, "Why isn't NASA doing this?"
NASA can't admit that anything might be cheaper or more reliable than the shuttle and no one will believe that anybody can do it better than NASA.
The solution: Don't use rockets..
I believe they are farther along than anyone else has gotten.
It's the external boosters that's bringing down shuttles, I think -- not the tiles.
If we'd gone ahead and developed the X-20 Dyna-Soar back in the '60s, we wouldn't have this tragedy to deal with. The heatshield of the Dyna-Soar was composed of Inconel (a high-temperature nickel alloy) instead of fragile ceramic tiles, and the X-20 would have limited its re-entry heat profile by re-entering the atmosphere gradually, using the skip-glide method developed in the '30s by Ernst Sänger, instead of by the all-at-once method our Shuttles use.
The X-20 Dyna-Soar project was cancelled on 10 December 1963 -- only eight months before drop tests were scheduled. The first manned flight was scheduled for 1964.
(Graphic ©Dan Roam / DeepCold)
Do you work for the government? You are full of opinions, but the fact remains the shuttle is a big fat unconstitutional waste of resources that would better be put to use by the taxpayers who earned them in the first place.
So what's the alternative, jets? Can a jet be modifed for low-orbit space travel?
The shuttle is the most expensive way ever devised to reach low earth orbit. Your thinking is exactly the problem with the space program, and as long as it remains the established doctrine, will keep space as an expensive irrelevancy.
The reason the shuttle is so expensive is because NASA failed. The main reason for that failure is congress. For twenty years everyone has been staring this failure in the face but no one in a position to change the situation has ever brought themselves to fully admit this failure.
Why should they? The only solution is to go to congress and ask for money for a replacement which congress isn't going to give. They figured out a long time ago that entitlement programs are a far more effective way to buy votes.
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