Subject: Re: What does the term "hypogolic" mean?
From: Henry Spencer <henry@zoo.toronto.edu> 
Date: Mar 22 1996
Newsgroups: sci.space.shuttle,sci.space.tech

In article <4is77s$phr@clark.net> prb@clark.net (Pat) writes:
>I thought, Lox and Kerosene were hypergolic,  in fact i thought pretty much
>any hydro-carbon in contact with LOX will spontaneously combust, a fact
>worked out in early rocket testing. I believe the X-2 was damaged
>in one such incident.

Yes and no.  "Hypergolic" is generally used only when ignition is reliable
and reasonably prompt.  Hydrocarbons in contact with LOX typically do not
ignite spontaneously at all, in fact:  they just sit there waiting for a
little nudge to set them off, at which point the mixture explodes.

Considerable effort was expended trying to find a way to *make* such
combinations hypergolic, with little success.  Oh, it can be done, but
usually only with sufficiently large amounts of additive that the additive
becomes a major propellant component in itself.  For example, you can make
LOX hypergolic with almost anything by adding about 15% fluorine, but that
hardly qualifies as an insignificant additive.

Four of the early rocket research aircraft (one of the X-2s and three of
the X-1 series) were lost to mysterious internal explosions, and the
puzzle was not solved until the fourth had the decency to explode
relatively mildly under conditions that permitted a thorough postmortem.
Some idiot had decided to use treated-leather gaskets in the LOX plumbing. 
When somebody finally asked oxygen experts about this, the reply was "that
material is suitable for oxygen gas, but when exposed to LOX it becomes a
powerful explosive". 
-- 
Americans proved to be more bureaucratic           |       Henry Spencer
than I ever thought.  --Valery Ryumin, RKK Energia |   henry@zoo.toronto.edu