Darn I had the reply all typed out, then I spazzed and hit some wrong key combo and blew it away.. sigh.

Yes, you need to deavticate the ejction charge or not have one to begin with and there are several options; 1. 2. and 3. are dedicated to Estes D11/D12 or E9 motors. The internal construction fo the motors, from the nozzle forward, is: Propellant grain, delay grain, and ejection charge which is granular. The ejection charge is retained by a loosely pressed clay cap.

1. Buy D11-P motors if you can find them. They are intended for RC rocket gliders, and have no delay or ejection charge. The top is is sealed off with a hard clay cap.

2. Buy D12-0 booster motors. Pour a cap of 30 minute epoxy in the top of the motor, directly onto the exposed propellant face (black) and let it cure. 3/16" is plenty. You can pad out the epoxy with some filler or microballoons if you have it. The motor will shut off at propellant burnout and nothing else will happen.

3. With any motor with a delay and ejection charge, i.e. D12-3, D12-5, D12-7, E9-4, E9-6, E9-8.. carefully scrape away the top soft clay cap and the loose black powder (ejection charge) until you get to the hard top surface of the delay grain which is a gray color. Then pour in a thin cap of epoxy. You don't need as much as for option 1., because in option 1 you are containing the motor chamber pressure with the epoxy. Here you are not. BTW you can flush the scraped out debris down the toilet, it won't hurt septic or sewage systems at all.

Option 3 is better in my opinion, especially if you buy the longest delay you can find (D12-7 or E9-8) because the delay will give you a smoke trail for that many (7 or 8 respectively) seconds after motor burnout, which adds to the smoke and fire effect you're looking for.

If you use composite single use motors, for example Aerotech E15's you can do 3. above more easily - simply peel out the paper cap that retains the black powder ejection charge, and tap it all out. Done. Don't worry about the small exposed surface of delay charge you see on these, it will not cause any problem like leaving in the ejection charge on Estes motors will.

If any of this doesn't make sense I can conjure up a graphic of the three options.

MJD