[AR] Re: [UK OFFICIAL] Moon Express - HTP/kero
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Fri, 14 Jul 2017 14:44:18 -0400 (EDT)
On Fri, 14 Jul 2017, Robert Steinke wrote:
In vacuum, you don't need high chamber pressure to get high Isp, so you
could run an HTP blowdown system at 100 psi or less. I suppose you could
have self-pressurized chilled nitrous at those pressures. That would help
the density too.
Unfortunately, chilled nitrous is only borderline storable -- now you need
to keep it cold. Not impossible, but a real complication, especially on
the lunar surface (as noted earlier, a rather hot environment).
Still, in biprop mode 100% HTP has a density and Isp advantage over
nitrous, and you can use HTP in monoprop RCS thrusters.
In principle you can do N2O monoprop thrusters, but the technology is
poorly developed. In particular, the known(*) catalysts need a lot of
preheating, and running liquid nitrous into them (without vaporizing it
first) reportedly has really serious flashback problems.
(* There are occasional rumors of proprietary cold-starting catalysts, but
last I heard nobody had shown anything in public. )
Henry
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