This is very dependent on the size, distribution and quantity of other solids
in the formulation such as aluminum powder as well as ballistic modifiers such
as SSFO, ALO2, Guignet green etc. If you are using a surfactant, that also
comes into play. Most APCP is more than bi-modal or trimodal in terms of
solids. Only oxidizers seem to be referred to in this regard.
Most workhorse commercial propellants are bi-modal as far as oxidizers are
concerned BTW. This is primarily for mechanical properties, ballistics and
economics. 200 mu is the baseline feedstock with everything else being site
milled from that. 90 and 400 have expensive surcharges. Those sizes are
sometimes used in specialty formulations such as 90/10/1 for example or in the
case of 400, gas generators, slower burn rate propellants, delays etc. Until a
few years ago, 600 mu and 50 mu varieties were also produced. AP was also FDA
approved for use in cattle feed. It causes thyrosis so the bovine fattens up
quicker for market but I digress.
A good but expensive reference is “ The Handbook of Fillers for Plastics” by
Harry S. Katz. One method I experimented with many years ago to formulate
multi-modal start points was CAD believe it or not. It worked surprisingly
well.
Best.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
<http://www.cesaronitech.com/> http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
From: arocket-bounce@xxxxxxxxxxxxx <arocket-bounce@xxxxxxxxxxxxx> On Behalf Of
William Claybaugh
Sent: Friday, August 3, 2018 11:51 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Trimodal AP
Any one know the optimum mix of 400 micron, 200 micron, and 90 micron AP?
Bill