[AR] Re: alcohols (was Re: Re: ADN Q?)
- From: John Schilling <john.schilling@xxxxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Fri, 12 Jul 2019 12:48:18 -0700
On 7/10/2019 4:20 PM, Henry Spencer wrote:
The best of the ionic-liquid monoprops so far, AF-M315E, actually
competes moderately well, *except* that it burns hot enough to chew up
the usual sorts of catalysts, so ignition is a problem. And it has a
few issues of its own. By the way, it's not something you can breathe
or drink safely even though it almost certainly contains no methanol
Nit: I *think* you can "breath AF-M315E" safely in that you can't breath
AF-M315E at all, it has essentially no vapor pressure, and the small
percentage of volatiles that will come out of the mix are not the
energetic parts and are reasonably harmless at STP equilibrium. I don't
want to swear to that, in part because as Henry notes the exact formula
is proprietary and so I am deliberately not looking it up and going
through the MSDS for everything.
That doesn't mean it's safe to have in your cabin. If you manage to
aerosolize it, which is probably not hard to do when it is stored in a
pressurized manifold, getting the droplets in your lungs would be bad.
And I think I've mentioned before that the one time someone managed to
spill a bunch of the stuff at the Cape, the improvised deconamination
procedure they came up with before consulting the experts managed to
chemically transform some of it to nitrogen tetroxide. Big oops, there,
and a reminder that whatever propellant you come up with you need to
have a validated spill-cleanup procedure *before* you start even serious
ground testing.
But if e.g. one of your astronauts manages to spritz AF-M315E all over
his spacesuit while doing an EVA to repair a balky thruster, you
probably don't have to lock him outside and leave him to die lest he
kill everyone else when you let him back in the spaceship.
LMP-103S is a bit worse because it has some methanol and ammonia, though
they really like to stay in solution and it's still leagues ahead of
hydrazine and especially NTO. You can still do ground testing and
propellant loading with just splash protection and the aforementioned
validated spill-cleanup procedure close at hand. But nothing that you
can move a spaceship with is going to be something whose hazards you can
wholly ignore on account of it being "green" or "safe".
John Schilling
john.schilling@xxxxxxxxxxxxxx
(661) 718-0955
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