Index Home About Blog
From: "Jeff Greason" <>
Subject: Re: H2O2 hypergolic hybrid?
Date: Mon, 30 Aug 1999 11:10:23 -0700

Aaron Smith <ttocs*nospam*> wrote in message
> Hi again,
>     I was wondering if I could imbed a small about ( < 2% ) MnO2 of
> KMnO4 in the hybrid grain to make a hypergolic ignition system for an
> HTP hybrid.

Worth a try, but KMnO4 is rather extremely hygroscopic, and I
suspect that if you have enough of it exposed to serve the purpose
of catalyzing the H2O2, it's going to do unpleasant things to your
fuel grain.

I've toyed with a number of ideas for hypergolic hybrids over the
years, many based on H2O2.  My enthusiasm rather waned when
I found out that you have to use fairly high concentrations of
H2O2 (70-85%, usually) to get a high enough decomposition
temperature to provide reliable and swift ignition (slow ignition,
of course, is a Bad Thing, since it can lead to hard starts).

Nothing wrong with high concentration H2O2, of course, but
for most applications where you're looking at hybrids, you're
looking for safety, ease of shipping, and ready availability of
propellant -- and H2O2 above 50% requires great care in
handling, can't be readily shipped, and is difficult to buy (almost
impossible in small quantities).

A system I've always wanted to try is calcium carbide with just
enough binder to make a grain burned with 50% hydrogen peroxide.
H2O + CaC2  goes to C2H2 (acetylene) and calcium oxides.
The H2O2 decomposes to H2O and O2, the O2 burns the
acetylene.  Gives a quite respectable theoretical performance,
but the question (which must be settled experimentally) is
whether the ignition delay between the O2 and the acetylene
is acceptable at this concentration.

"Limited funds are a blessing, not         Jeff Greason
a curse.  Nothing encourages creative      ex-Rotary Rocket
thinking in quite the same way." --L. Yau  Propulsion Manager
   (Hughes is my ISP, not my employer)     <>

Index Home About Blog