Re: SpaceX Aims For 2009 Re-usability Demo



Derek Lyons wrote:
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.

I've often though the same thing.

That was one of the options examined for unmanned cargo derivatives of the Shuttle, and IIRC, the core stage of Energia also.
If you could make a domed ablative heatshield into the bottom bulkhead of the lower propellant tank, and used a circumferential shaped charge to separate the propellant tankage from it, you could at least save some weight.
But now you need a retrorocket on the upper stage, and a means to align it for retrofire after the satellite separates.
That adds both complexity and weight to it, cutting into its payload...especially when parachutes are figured into the equation.
I don't think that it all makes sense from a economic point of view, and Elon Musk's comments on upper stage recovery suggests he thinks it's pretty iffy from a economic point of view also.
Meanwhile, pad tests of Falcon 9 move forward: http://spaceflightnow.com/falcon/090112f9vertical/

Pat
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