On Thu, 2003-05-29 at 09:59, Pierce Nichols wrote: > A man-rated SSTO is quite a sizeable vehicle -- if the tanks are > designed to crush properly and the crew cabin is on top, you will have at > least 10m through which to decelerate. IIRC, ppl have take 16 G continuos > on their backs with their legs up -- it should be no problem whatsoever.
It seems to me that the generally accepted solution to this problem is parachutes - either some sort of ejection system for the crew or the whole crew cabin, or (probably preferably) for the whole vehicle.
The military's experience with ejections pods and seats has been lousy -- 50% survival rate is considered pretty good. If you can push the terminal velocity of the whole vehicle in landing configuration low enough, (which seems trivial for a TSTO or better flying fuel tank) then the brutal simplicity of designing the tank to crush correctly. However, I think a small parachute may be indicated, to solve the problem of what happens if your main propulsion failure mode starts you tumbling, i.e. your engine failures are unbalanced in such a way that your control system does not have the authority to fix it.
I wonder how much additional volume in the form of gasbags you'd have to add to the tanks to make the vehicle lighter than air?
Filling them with low pressure helium is probably not a viable solution -- even a good SSTO doesn't have that kind of mass ratio.
-p
Mars or Bust! www.marssociety.com
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