[AR] Re: Hydroxylammoniumnitrate (HAN)
- From: John Schilling <John.Schilling@xxxxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Mon, 3 Apr 2017 19:45:37 -0700
On 4/3/2017 10:41 AM, Henry Spencer wrote:
On Mon, 3 Apr 2017, Galejs, Robert - 1007 - MITLL wrote:
I was under the impression that the "green" monopropellants were
based on
HAN...
Some are, some aren't. LMP-103S, the Swedish one, is based on ADN
instead.
At Space Access last year, John Schilling (who's worked on these
things) described the USAF's AF-M315E as "HAN plus HEHN plus
stabilizers plus water", if I remember correctly. (HEHN is
hydroxyethyl hydrazine nitrate.) He went on to add that the details
are still not public and you really need to get the stabilizers
*right* to make that mixture halfway safe to handle.
Now, now. Just the HAN, HEHN, and water would be three-quarters of the
way safe to handle :-)
For the last 25%, yes, you need the stabilizers, and while the USAF
won't tell you their recipe there is other published work in the field.
Probably simpler just to use LMP-103S, though.
And do remember that the guys who *developed* these mixtures had
plenty of explosions along the way. Experimental work with energetic
monoprops is unusually dangerous even by rocketry standards -- people
keep finding new ways to die. Any attempt at it should assume that
your propellant *is* a dangerous high explosive: think remote mixing,
very small quantities, detonation traps, carefully-written checklists
for returning to a safe state even if valves freeze or plumbing leaks
or software crashes or the power goes out. Don't forget blast
shields, firefighting gear, and independent safety reviews.
This, absolutely. The ionic-liquid mixed monopropellants do have the
advantages of A: negligible vapor pressure, hence less concern with
bubbles and mixed-phase flow, and B: very high water solubility, so you
can render them safe by dilution. But you do have to assume you'll have
things go wrong before you get everything right.
Which brings up another item for your safety planning: By dilution or
otherwise, make sure you have, and test, a reliable way of getting rid
of the stuff. I know of one team that used AF-M315E, insisted in spite
of the manufacturer's recommendation that "dilution is not the the
solution", and copied the chemical decontamination procedure for a
related but different propellant. Applied to AF-M315E, it broke the
stuff down into a bunch of compounds, most of which were harmless and
one of which was nitrogen tetroxide.
John Schilling
john.schilling@xxxxxxxxxxxxxx
(661) 718-0955
Other related posts:
