So I thought this was interesting: not very applicable, but perhaps in
the future when we're air-starting motors...

-------- Original Message --------
Subject: [RocketsNW] Ignition materials
Date: Thu, 14 May 2009 18:21:53 -0700 (PDT)
References: <>

"Anyone ever mess around with Boron Potassium Nitrate (BPN) or Zirconium
Potassium Perchlorate (ZPP) for igniters?"


Forget Zirconium as it is pyrophoric in anyhting smaller than about 100
mesh.  Below 250 mesh it has to be stored in a liquid bath and handled
remotely in an atmosphere of inert gas.  Other than that it's the best
material available.  Creates almost no gas phase products as the boliing
points of the metal and the oxide are both around 5,000 C.

KNO3 + B is fairly good stuff.  It has a heat of approx 1.5 kcal/g and
packs to 3.3 kcal/cc when pellitized. Burns quick and the burn rate is
dependent on the pellet shape which is why it is extensively used.  By
putting KNO3 + B pellets in a basket you can control the loading
pressure of the igniter.  Larger rockets use pellets about the size and
shape of a bayer asprin.  To get it below that you would probably have
to corn it.

Loose as powder it's alright, much hotter than any of the thermites but
it goes really quickly and forms a good deal of gas.  N2 and K2O.  Loose
I had problems with it blowing everything out the nozzle.  Too much gas.
 If you are going to be at Brothers find me.  I have 3 KNO3 + B pellet
igniters built for this launch.  For the 38-720 and 38-1080 cases, I
used 1 cylindrical pellett (.1875 diameter) weighing .65 gram (about 1/2
inch long).  That is more than sufficient for those reloads.  Oh you can
currently get good boron material from Firefox.  It's combiner grade
surplus from Jhonston Mathey.

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Andrew Greenberg

Portland State Aerospace Society (  P: 503.788.1343  C: 503.708.7711

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