Out of idle curiosity, I did a few ProPEP runs to see how rapidly Isp drops
when a stoichiometric mix of nitrous oxide and acetylene is mixed with carbon
dioxide. It isn't as bad as I expected. This might actually be a feasible
monopropellant.
Pc = 500 psi, Pexh = 14.7 psi.
441.380 N2O + 52.040 C2H2 gives
253.4 s frozen, 273.3 s shifting.
441.380 N2O + 52.040 C2H2 + 50 CO2 gives
243.6 s frozen, 261.8 s shifting, around 5% performance drop with 10% CO2.
441.380 N2O + 52.040 C2H2 + 100 CO2 gives
235.4 s frozen, 251.9 s shifting, a little over 8% performance drop with 20%
CO2.
There may be problems where CO2 freezes or evaporates out of solution prior to
the nitrous, but presumably there are worse problems with acetylene coming out
of solution with pressure/temperature.
How would one quantize sensitivity of a cryogenic liquid? Some sort of
insulated piston and cylinder with a calibrated drop weight, similar to a card
test?
--------------------------------------------
On Tue, 4/24/18, Ray Rocket <dmarc-noreply@xxxxxxxxxxxxx> wrote:
Subject: [AR] Re: mixed monoprops (was Re: DARPA responsive launch challenge)
To: arocket@xxxxxxxxxxxxx
Date: Tuesday, April 24, 2018, 2:45 PM
Could a small amount of carbon dioxide be
blended into a nitrous monopropellant to provide a degree of
stabilization? Sure, Isp will rapidly drop off, but
maybe there is a sweet spot that lowers detonation velocity
sufficient to allow a reasonable injector design while
preserving most of the performance.
--------------------------------------------
On Sun, 4/22/18, Henry Spencer <hspencer@xxxxxxxxxxxxx>
wrote:
Subject: [AR] mixed monoprops (was Re:
DARPA responsive launch challenge)
To: "Arocket List" <arocket@xxxxxxxxxxxxx>
Date: Sunday, April 22, 2018, 12:51
PM
On Sun, 22 Apr 2018, Henry
Vanderbilt wrote:
> Never say never, but
the history of such things seems to be
full of
> liquid monprops that could be
babied into
behaving right up until that
> essential
final step of firing it in an
engine. I am inclined to
> consider any hot new monoprop
candidate
coming along as a long shot
> (possibly
a worthwhile one, but nevertheless)
until proven
otherwise.
"Since
practical monopropellants of
relatively high specific
impulse are,
no doubt, much more hazardous
than [nitromethane, which despite poor
performance has had major explosions],
there is
serious doubt that the
term
'monopropellant' is really more than
an optimistic
rocketryman's
terminology for a
dangerous liquid high explosive."
-- M.A. Cook, "Explosion
Hazards in
Liquid Bipropellants", in
Vance&Duke, "Applied Cryogenic
Engineering",
1962.
Henry