The aluminium/oxygen rocket is interesting. The idea of using powdered
aluminium fuels on the moon, has been explored in the past. Due to the problems
of pumping powdered Aluminium, molten aluminium may be used instead. Due to these problems, I'd sooner expect standard solid rockets much like the Shuttle SRBs. I saw an article where manufacturing such solids on the moon was looked at. The problem is that in addition to powdered aluminum, solid fuel also uses organics as a binder. They raised the possibility of silicon-based replacements, but couldn't be certain on this point. But to me, even if you had to ship all the organics up from Earth, to be able to make the aluminum powder, liquid oxygen, and rocket casings from lunar resources would be a tremendous savings. Then there's the hybrid rocket idea: solid fuel but liquid oxidizer. Turns out that approach combines the best of both worlds in a lot of ways. It's safer, and throttleable. I can't help but think about lunar setups when I think about them. There was a company looking into hybrids called Amroc, but they went bankrupt. The good news is that Jim Benson of SpaceDev acquired all their test data, and seems to be moving that research forward.

Regards,

Mike Combs

>>>Then there's the hybrid rocket idea: solid fuel but liquid oxidizer. Turns
out that approach combines the best of both worlds in a lot of ways. It's
safer, and throttleable. I can't help but think about lunar setups when I
think about them. There was a company looking into hybrids called Amroc,
but they went bankrupt. The good news is that Jim Benson of SpaceDev
acquired all their test data, and seems to be moving that research forward.>>>

I can remember someone on the Artemis list proposing something like this.
Their idea was to use an aluminium honey comb, with oxygen gas flowing through
it. In this situation, refueling wouldn't be too hard. If memory serves, LOX is
a soft cryogen. The Aluminium honeycomb could be loaded into the engine in
disposable tubes. This would prevent the inside of the rocket from becoming
clogged up with aluminium oxide. If ignition is a problem, then a charge
containing white phosphorus (which flames on contact with oxygen) could be
triggered. A large electric arc might also do the job.

Tony

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