At 03:21 PM 2/2/2003 -0800, Randall Clague wrote:
Oh - Pierce left out flight test. Henry Spencer beats up on staging because it's more difficult, dangerous, expensive, etc. to test. A TSTO is three vehicles - 1st stage, 2nd stage, and the stack - each of which must be flight tested. I'm designing for very gentle staging, but RTLS and mass fraction conservatism has forced me into a 3STO, and I haven't confronted the in-atmosphere staging demon yet. I don't even want to *think* about flight testing six vehicles - this is a paper study dammit. :-)
It's all a balancing act. You can make a very good TSTO with stage mass fractions in the range of 7-8. For SSTO, you need to hit 20 or higher. That's an enormous jump. I think that avoiding it probably gains you much more than you lose to the additional flight testing requirements, at least for the first couple of generations of cheap, reusable launch vehicles.
-p
PS -- I still don't understand how adding a third stage could possibly get you enough of a relaxation of mass fraction requirements to make it worth the trouble.
Mars or Bust!
www.marssociety.com
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