Re: SpaceX Aims For 2009 Re-usability Demo

Pat Flannery <flanner@xxxxxxxxxx> writes:

Jochem Huhmann wrote:
This would be a good point to finally try active cooling. Let the fuel
tank heat up and design in pressure-controlled valves that vent residual
(vaporized) fuel over the skin of the stage, cooling it and protecting
it from the plasma. I have always thought that this is the best way to
get anything mainly consisting of large and nearly empty fuel tanks
intact through reentry.


But you are going to have to keep it stable as far as orientation goes
during reentry, and that's probably going to mean spinning it up so a
nose-mounted heatshield/active cooling system stays pointy-end first as
it comes in...given it's shape that may not be easy.

Pointy-end first seems like a bad idea (and should be almost impossible
since the heavy end is at the engine).

Since the only expensive things on it are the guidance electronics and
engine, it might be smarter to mount the electronics back at the tail
end of the stage near the engine, and just have that section come down
via parachute while the propellant tankage is allowed to burn up. That
would certainly save a lot of weight on the parachute system.

This would mean having a clean separation point between tail and tankage
and a real heat shield... You would need to build the thing totally
different then. While I agree that the tanks are actually quite
worthless, using them to brake high and early and to have a large area
to spread reentry heat over makes more sense.

Anyway, I think recovering the second stage with its single engine isn't
really worth the trouble. Recovering the first stage with its 9 engines
is both more useful and easier. And even then it would be wise to
have it fly back and land instead of dropping it into seawater and
recovering it there.


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery
.

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