[AR] Re: Hydrogen Peroxide (oxidiser)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Fri, 5 Mar 2021 13:26:44 -0500 (EST)
On Fri, 5 Mar 2021, Charlie Jackson wrote:
...appears to be somewhat of a dangerous ordeal from managing the
propellant, to getting stable combustion and oxidation.
The British built, first sounding rockets, and then an orbital launcher
with it, and their experience was that -- provided you were careful about
materials and cleanliness -- it was actually quite well-behaved. They
thought the unfavorable early US experience was largely the result of
working with impure or contaminated peroxide.
The classic problem for amateurs is finding a supplier of high-purity
high-concentration peroxide (who'll sell it to you). It's a specialty
product that doesn't really have much other use. You don't want to have
to concentrate it yourself.
However I don’t recall the mention of decomposing the peroxide in a
separate catalyst chamber, and using the oxygen released to be mixed
within the chamber. Would this work?
As Ben said, it's actually the usual way to build peroxide engines. Bear
in mind, though, that we're not talking about a little separate chamber
with a little pipe connecting it to the main chamber: a lot of gas has to
flow from one to the other. Such designs usually end up looking more like
a long two-part chamber, with the fuel injected halfway down.
The good news is that injecting fuel into a fast stream of hot oxygen-rich
gas is very good for atomization and mixing, and with high-concentration
peroxide it will generally give hypergolic ignition too. The bad news is
the care and feeding of catalyst packs, which are more complicated and
more troublesome than they might look.
You'd want to start with monopropellant peroxide: just flow the peroxide
through the catalyst, don't try to inject fuel. That makes a decent
rocket all by itself, and lets you sort out catalyst packs and the details
of working with peroxide in a simpler system. Once that's working well,
*then* start injecting fuel for higher performance.
I don’t really want to mess with cryogenic propellant due to lack of
experience, so would 50/60% peroxide suffice?
It's going to be a learning experience either way, I'm afraid. :-)
50-60% isn't really enough for catalytic decomposition. 80% and up is
desirable (although orthodox silver-based catalysts can't handle more than
about 90%).
Henry
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