12

VentureStar was (IMHO) a pretty cool design; a reusable space plane designed for low running costs and rapid turn-around seems like just what the world needs. However, it was cancelled in 2001 due to (as I remember it) leaky tanks and excessive weight. Much of the technology was a bit too ambitious for the time. Given the technology of today and the progress made since then does the design still make sense and could it be built?

Alternatively, was the design a product of NASA being obsessed with space planes rather than simpler, less sexy rockets?

Community
  • 1
dave
  • 283
  • 1
  • 7

2 Answers2

13

Answers to this question are opinions. Assuming that the stackexchange police permit that, here is my opinion.

The real objective is lowering cost through reusability. In my opinion, the VentureStar approach made the unnecessary and suicidal leap that reusability required single-stage-to-orbit. It does not. It was single-stage-to-orbit that killed VentureStar, because of how thin the margins on everything had to be. The SSTO assumption, and the use of chemical propellants, leads inevitably to a very fragile architecture where any noticeable mass growth will push you off the cliff. It is simply an accident of nature that the size and mass of the Earth and the energy of chemical reactions conspire to make single-stage-to-orbit tantalizingly close to, but not quite practical.

If you want low cost and reliable, you want robust engineering solutions with lots of margin. The way to do that is with staging. If you can recover one stage, then there's no reason you can't recover two. A single or a second stage has the more difficult environment to deal with, which is entry from orbit. The first stage will have an easier time surviving to be recovered, coming in at lower speeds from lower altitudes. SpaceX is now developing the capability to recover their first stages.

If you went nuclear thermal, that's a different story. Then you could do SSTO, if they let you. But I don't think nuclear anything would be low cost, even if reusable. If you can do reusable chemical, that will be cheaper.

Mark Adler
  • 58,160
  • 3
  • 171
  • 251
  • Also, no tolerance for test failures. It has to be ok to have a failure, for an X-plane type model to work. The point of testing is to find the edge, then step back a smidge. Then rebuild and do again till the next edge. – geoffc Dec 04 '13 at 02:39
  • 7
    Had X-33 used that approach, it might have gone further. Instead they tried to go for the gold on the first test flight. They tried to shoot way past the edge to the point that they couldn't even build something to fly. It's one thing to tolerate flight test failures. It's another to tolerate a program that isn't even able to build something to fly. – Mark Adler Dec 04 '13 at 05:04
  • Exactly. Set goals appropriately. Is this a tech dev program? Be prepared for crashes. Is this a production vehicle? Don't push the envelope so far you cannot succeed. – geoffc Dec 04 '13 at 13:27
  • You can see the future! – uhoh Feb 22 '18 at 05:12
  • 1
    "SpaceX is now developing the capability to recover their first stages." SpaceX is now doing most of its launches with Falcon 9 boosters that have flown multiple times, has practically taken over the world commercial launch market, has put 700+ of their own satellites into orbit with that vehicle at costs competing constellations can't come anywhere close to, and is working on a fully-reusable two-stage launch vehicle. So, that worked out pretty well. – Christopher James Huff Sep 30 '20 at 01:34
2

Right up front, the government administrators listed a number of experimental technologies that they wanted incorporated in the VentureStar program. One of these technologies was a composite cryogenic fuel tank. The engineers stated immediately that this wasn't possible — the reason is obvious to anyone examining the facts: the composite material has a honeycomb-like layer inside and the cryogenic liquid would create condensation both on the outside of the tank and inside the cells of the honeycomb layer. Because of the extreme cold, that condensation would freeze, rupturing the honeycomb cells and weakening and/or destroying the strength of the tank. The administrators insisted, but the test tanks failed on numerous occasions. Meanwhile, the engineers decided to manufacture a tank from aluminum/lithium metal — though the main structure was heavier, the connections between the three lobes of the tank were much lighter in the Al/Li tanks vs the composite tank … problem solved! But a NASA scientist went before Congress and stated, basically, "Stick with the 'more advanced' composite design — we must use all the advanced technology or nothing!" And Congress canceled the program.

Nathan Tuggy
  • 4,566
  • 5
  • 34
  • 44
Eric Asmussen
  • 21
  • 2
  • 3
    This kind of seems to be focusing on a single technical glitch; can you add some references to show that this really was the most significant/only problem leading to its cancellation? – Nathan Tuggy Aug 11 '15 at 22:01