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Old September 3 2013, 10:00 PM   #30
gturner
Admiral
 
Location: Kentucky
Re: China to land rover on Moon by end of this year

A more NACA style mission would be for them to devote a lot of resources to figuring out how to make reliable, cheap rocket engines. One of the cheapest in the stable is the RS-68, which is about $19 million dollars. The RL-10, which we're still flying all the time even though it was the first LH2/LOX engine ever developed, weighs 610 pounds and costs $38 million, which is five times its weight in gold. We're talking about a glorified burner, plumbing, and some transistor circuits, designed to be used once and thrown away. You'd think a society with as much advanced technology and industrial capacity like our could build something like that for about $6,000 ($10 a pound), or given some of the freaky metals, maybe $50,000 tops. Yet to my knowledge, nobody except SpaceX has ever made a modern turbopump for much less than about $800,000 - for a fuel pump.

It's said that more than half the cost of the rocket is the engine, and most of the cost of the engine is the turbopump. It's also said that regarding costs, a rocket is some stuff you attach to a turbopump to get into space.

Xcor has developed a piston pump just to sidestep the problem, noting that nobody who makes a turbopump makes more than a handful of them a year on extremely expensive and specialized machines, so they'll of course cost a fortune, whereas if you use pistons you can go down to the local motorcycle performance expert and get some help.

For about a year I've been looking at an idea to make a turbopump without any moving parts, whose efficiency wouldn't be much less than existing methods, and it all hinges on whether I can recover pressure from a high speed stream of droplets, a feat that really has no other useful application.
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