How to Plug a Hobby Rocket Motor

I am entering an outlaw class pinewood derby competition (no rules) with my local Cub Scout pack and I had the idea to use a rocket motor to propel my car. The only problem is most off the shelf rocket motors have an ejection charge which is designed to push a nose cone off the top of a rocket and deploy a parachute. This ejection charge is denoted by the 4 in B6-4 found on this particular rocket motor. Estes for instance does sell a A10-PT (which is plugged by the denotation PT) motor specifically used for gliders and small street racing cars but they are hard to get and cost a lot for a very small motor. So, I started thinking of a way to plug a motor meaning removing the ejection charge. If I didn't remove the explosive ejection charge once the thrust portion of the motor was spent the ejection charge would blow and push the hot motor out of the hole in the pinewood derby car and possibly injury someone. This Instructable will show you how to safely remove the ejection charge from a B sized motor which should translate to other size motors also.

PPE, work surface to catch motor guts, dental pick

I know all those reading this are very safe and it doesn't need to be said but I'm going to say it anyways. Please take the necessary safety steps to ensure you are safe while working with a rocket motor that could blow up in your face and cause damage to your body and your surroundings.

With a dental pick slowly dig out what I can only compare to as kitty litter at the back of the motor. Not the side with the hole as that is the nozzle and where the hot gas comes from. Dig the kitty litter out and you will find a small layer of black material and the some more kitty litter below.

Dig the kitty litter stuff out until you hit the propellant which is dark and solid.

Once you hit the propellant you back fill in with super glue. I'm not advertising this product but I used Q-Bond and the gray filler material. I'm sure baking soda and regular super glue would work similar.

I cut my motor cardboard tube in half since a B sized motor only takes up about half of the cardboard tube. This will allow the motor to sit in the pinewood derby car nearly flush and not stick out a lot off the top of the car. Then I drilled a hole in a piece of wood about the same angle of what it would be on the pinewood derby car.

Then like anything I tested to see if the plug would hold up to the pressure.

Success!!! As seen in the video the plug held and the motor didn't come flying out of the hole it was seated in.

Now to build the car and get everything ready for the race.