Problem solved
 

Hi again,
I just wanted to let you folks and any future readers know--it WAS a chemistry problem. Perhaps burning Calcium Stearate was the problem, or perhaps there was something else odd going on. In any case, the problem was the stump remover.

After various experiments, we finally gave up and bought some lab grade 99.999% pure KNO3. We were not disappointed, as it worked quite well.

Thanks for your time and input! We are especially glad that you mentioned the risks of PVC casings.

You might try http://www.rocketryforum.com/ for additional information. They are always extremely helpful and courteous, especially when it comes to formulas. Just tell them "Uncle Ted sent me." :D

Ted, that's a great idea.
I'm sure they will be extremely helpful in advising this endeavor.

Somehow I just knew you'd be pleased. ;)

Thanks for the suggestion! I'll take a look. :)

I'd advise against it. Those guys were pulling your leg but asking for help at TRF. If you ask the question you asked here at TRF they're going to jump all over you in 2 milliseconds flat (and not in a good way).

FYI, I don't allow talk about experimental motors here either, but since you basically answered your own question I let it be.

http://www.rocketryforum.com/showth...s&p=1778191#top

Apparently, our newbie forgot to mention Uncle Ted. LOL!

I'm REALLY surprised they were as gracious to him on TRF as they were.
I expected them to go off like a short-fused grenade.

Thanks for the advice, but they've actually been pretty friendly. My apologies for breaking the rules here, too! I was ignorant of this apparently common policy.


This does not seem to be a username there, but I assume it's an inside joke. I'll mention it if you were serious and it's safe, but I'm suspicious that there is something important that I'm missing.


I was slightly surprised as well, especially after the first response. However, they have been helping. It seems that the joke is on tmacklin!

Updates
 

For those of you not following my progress on TRF, and are yet actually interested enough, here are some updates:
1. We've switched to poly casings. They don't insulate as well as we'd like, but they have not breached. The heat leakage is doing a little damage to the rocket body, but we can handle it.
2. We're having nozzle problems: they keep blowing out, and causing unpredictable flight.
3. Using a band-aid "solution" to these clay failures, we used some poly glue to help support the clay, and had some surprising success. We got about a 350-400 foot flight before the front plug blew, and the whole rig crashed. On recovery, all that was left was an empty tube, though we're not sure when the nozzle failed.
4. We set up and successful used a recovery charge, although the main nozzle blew out and the rocket crashed early, so it was in this case useless. Still, it's good to know that our delay system works.

We have been using diatomaceous clay rather than the usual bentonite for our plugs. Diatomaceous is quite rough, so we had hoped it would work as well or better. We couldn't find pure bentonite, but we have gotten some slightly contaminated stuff to try. Also, following some advice from TRF. we will probably begin forming our nozzles better, rather than just using cylinders.