[AR] Re: mixed monoprops (was Re: DARPA responsive launch challenge)

  • From: Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx>
  • To: arocket@xxxxxxxxxxxxx
  • Date: Sun, 22 Apr 2018 15:32:50 -0700

On 4/22/2018 11:51 AM, Henry Spencer wrote:

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.

There is some hint of possible bipropellant bias in that title, mind.

Perhaps a more narrowly focused rule-of-thumb might be that, if a major component of a mixed monoprop already has its own history of handling explosions in pure form, optimism about the practical safety of the mix may be even less warranted than usual.

I'm thinking nitrous, but nitromethane would also qualify.

Multiple already-sensitive components (nitrous AND acetylene) even more so.

Has anyone ever tried a mixed monoprop with nitromethane, BTW? (I ask from morbid curiosity, NOT because I have any reason whatsoever to think it might be a good idea.)

Henry


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