Rocket calc ?'s

[Ray]

The formula seems OK, but particle sizes aren't listed. Particle size is critical to the mix...

I would stay away from the Mg though. Its tougher to get, and it can be a bit nasty to work with in small particle sizes. You can use aluminum instead. Whether you use Mg or Al, remember to wet the metals with the PBAN completely prior to adding AP...you don't want things to combust unexpectedly...

Don't know about the boric acid, haven't used it, haven't researched it.

10% Mg seems pretty high too...I would adjust that down.

Can't comment on the cure ratio of the PBAN/Epoxy without knowing what kind of epoxy...DER331 is the most common type.

At 77% solids it should be pretty close to pourable.

You can guess a few characteristics from the formula. You can tell if its going to be fast or slow, flame color and temp etc...the devils in the details though, and there just isn't a way to predict burn rates at given pressures...I know it seems backwards, but there is a well defined process to arrive at the burn rate coefficient exponent and ISP*. Believe it or not, the pro's at Thiokol, Aerojet, etc do the same thing...

The pros can predict with a reasonable accuracy what a burn rate will be, but its based on a large database of other propellants they have done. They can't come up with the exact numbers until they do test burns...

I have a friend at Aerojet that says they build the motor with a given formula, then the characterize that build and build the nozzle at the end to make sure their operating pressures are a what they want...

[Zippiot]

Teacher said use the simple sugar recipe for the project, so composites go on hold for a while...

So now I need to make an endburner and calc burn rate at Kn...then plug that back into the formula for chamber pressure...
I need to measure thrust to get Isp also...
Wow lotta test motors just to get some numbers