X-33 Venturestar
- Thread starter Lestoicire
- Start date
I didn't know what it was either...
so I looked it up. Here's the wiki article http://en.wikipedia.org/wiki/Lockheed_Martin_X-33
so I looked it up. Here's the wiki article http://en.wikipedia.org/wiki/Lockheed_Martin_X-33
I understand the people who were against using whatever break-through material they were trying to use for the hydrogen tanks claim regular materials would have done the job.
Of course, that's talking while during the design board stage - I'm pretty sure the people working in the actual tried (and failed) hydrogen tanks claimed the same about their design.
It's an engineering question, which I'm not qualified to answer. I think the fact that none tried again by using the supposed regular materials for the hydrogen tanks means the hydrogen tank problem isn't solvable with currently known materials.
I understand there were another problems as well, but the hydrogen tank was the most difficult of them. So I'm inclined to think it couldn't have worked.
Of course, that's talking while during the design board stage - I'm pretty sure the people working in the actual tried (and failed) hydrogen tanks claimed the same about their design.
It's an engineering question, which I'm not qualified to answer. I think the fact that none tried again by using the supposed regular materials for the hydrogen tanks means the hydrogen tank problem isn't solvable with currently known materials.
I understand there were another problems as well, but the hydrogen tank was the most difficult of them. So I'm inclined to think it couldn't have worked.
It'd have been quite difficult, even if the X-33 itself had not been cancelled. There's a very good, in-depth summary here by Chris bergin of NASAspaceflight. However, even had the X-33 worked, it was a highly suborbital demonstrator. The success of a scaled-up vehicle aimed at orbit would still be unlikely.
The annoying thing is that reusable SSTO is about three steps to the wrong side of plausible given almost any fuel you choose. Use hydrogen, and your tanks mean you end up with a minimum structural fraction of about 13-15%, but you need less than 9% to make orbit. Use methane/LOX or kerosene/LOX and you can get away with a smaller structural fraction (since they're not as freaking fluffy as hydrogen, you need less tank wall to contain them) but even so 9-10% is the minimum. However, because kerosene or methane is less efficient as a propellant, the rocket equation spits out that you can only have about 5-6%. Once again, you can't quite make it.
Staging or fancy air-breathing techniques are really the only way to answer that.
The annoying thing is that reusable SSTO is about three steps to the wrong side of plausible given almost any fuel you choose. Use hydrogen, and your tanks mean you end up with a minimum structural fraction of about 13-15%, but you need less than 9% to make orbit. Use methane/LOX or kerosene/LOX and you can get away with a smaller structural fraction (since they're not as freaking fluffy as hydrogen, you need less tank wall to contain them) but even so 9-10% is the minimum. However, because kerosene or methane is less efficient as a propellant, the rocket equation spits out that you can only have about 5-6%. Once again, you can't quite make it.
Staging or fancy air-breathing techniques are really the only way to answer that.
Yes it is. A large number of rockets, including the Japanese H-II, the European Ariane 5, the (at the time) United States Space Shuttle, and (later) the Delta IV utilize hydrogen fuel. None of them have any particular problems with their hydrogen tanks, above and beyond the problems inherent to hydrogen (hydrogen brittling, having to manage deep cryogens, and so on). This experience, dating back forty years or so (at the time) was the basis of people saying that tanks made out of conventional materials, which had been proven on a large number of past rockets, would not have been any heavier than the experimental composite tanks that were built. Additionally, as the article posted by e of pi mentions, they began fabricating a conventional hydrogen tank for the X-33, which was lighter than the composite tank, but were prevented from testing it due to the program being cancelled.
The thing about the hydrogen tanks being used in the X-33 design was that they were a new, experimental design made out of a new, experimental composite material, which was made out to be necessary to reach the performance targets e of pi mentions. People pointed out that the technical details of the X-33 design (mainly its lifting body shape) meant that the composite tanks weren't actually any lighter, but that wasn't actually why it was cancelled; it was cancelled due to being tied up in presidential politics. Basically, the whole program was Gore's baby, so when Bush came in instead, it was cancelled. Many of the technical problems with the design were either solvable or avoidable, and the X-33 probably could have flown in some fashion eventually, though as e of pi points out it wouldn't have been nearly as interesting as it was made out to be early on. The whole program was overambitious from the beginning, really.