[AR] Re: Hypergolics with N2O?
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Sat, 25 Feb 2023 03:08:35 -0500 (EST)
On Fri, 24 Feb 2023, eric.pillai01@xxxxxxxxx wrote:
If the goal is hypergolic ignition of a nitrous + conventional fuel
engine, maybe the better approach is a hypergol with the fuel?
Unfortunately, that tends to get you the worst of both worlds -- rather
more aggressive oxidizers, plus a need for obnoxious fuels or obnoxious
major fuel additives.
Nitric acid isn’t exactly fun stuff but it’s been used successfully in
amateur rockets (Tom Mueller’s Micro Rocket) and would be a hypergol
with many conventional fuels.
All too few conventional fuels, alas. In particular, the US military
spent a great deal of money, time, and effort in the 1950s to find some
way of making WFNA or RFNA hypergolic with ordinary-ish hydrocarbon fuels
rather than horrible things like aniline, completely without success.
They found some more fuels that were hypergolic with the acid oxidizers,
but those were mostly unappealing in their own right, and you always
needed a lot of them, not just a little dash added to your kerosene.
Furfuryl alcohol is about the only one you'd really want to handle without
major protective gear. It's not bad... but then you need a seriously
aggressive oxidizer like WFNA (not just ordinary concentrated NA), and
oops, now you need the protective gear for handling that. Doesn't seem
like a big win.
Micro rocket seems like a decent template for what
a hypergolic ignition system on a bigger liquid biprop might look like.
Except then you're going to need *two* extra fluids for the igniter, one
of them seriously hazardous, and it starts to be hard to believe that this
is really an improvement on a spark-ignited torch igniter.
Hypergolics are a big win only if they're your primary propellants, not
extras.
Henry
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