On Fri, 14 Dec 2018 10:48:01 -0800 (PST), Its Me
wrote:

On Friday, December 14, 2018 at 1:34:12 PM UTC-5, Its Me wrote:
On Friday, December 14, 2018 at 1:15:07 PM UTC-5, wrote:
On Fri, 14 Dec 2018 09:44:30 -0800 (PST), Its Me
wrote:

it had 4 times the power (specific impulse in newton-seconds) of a military Stinger

===

Are you able to calculate that in advance using knowledge of the
chemistry and rocket geometery, or do you do test firings on the
ground?

These are commercially produced motors. You can buy single use motors, or aluminum tubes and end caps, then buy the reload kits that have the propellant, O-rings, nozzles, etc for "building" the motor. They have been tested and are rated for their impulse, usually complete with graphs of how it is delivered (bell curve, big spike then slowly tapering off, etc..).

The motors are sized by the letters of the alphabet. The Low power black powder Estes motors are 1/4 and 1/2-A, A, B, C. The fat ones were D motors. E and F are considered mid power. High power starts at G and up. Each letter is a doubling of impulse range in N/s, like 2-4, 4-8, 8-16, etc... Supposedly the Stinger was in the K range. My cluster was 1 L, 2 J's and 2 I's, putting it into the M range.

Here's one source: https://www.apogeerockets.com/Rocket_Motors/Cesaroni_Propellant_Kits/54mm_Motors

Oh, and for a little while I got into building "experimental" motors. That basically consisted of mixing a prepared recipe of chemicals together and casting your own fuel grains. Then you cut them and drilled the center core out, and loaded them into the casing with a nozzle and O-rings. The science of making it work properly had already been worked out.

It's funny, the propellant really isn't dangerous. It's some pretty nasty, poisonous stuff, but once cast and set, you can bang on it with a hammer and it's just rubbery. It's hard to light. It's just that once lit, it's hard to put out and it has it's own source of oxygen. Put it in a tube with the proper sized nozzle, and you have a motor. If the nozzle is too big, you have a blow torch. If the nozzle is too small, you have shrapnel.

That was our process. We found a doweled cell in a destroyed building
that use 1.5" galvanized pipe for the dowel and we chipped out an 8x8
block section 2 blocks high for our test stand.
We had a couple zinc sulfur "bombs" that were totally contained.
When we started playing with potassium chlorate, we blew a hole in our
test stand. I doubt anyone would sell you that stuff now and if they
did an ATF agent would be delivering it.