ID Rocketeer: Flying Colors - Ejection System Ground Test

Today I finally got the recovery system ejection charge tested. I'd been concerned about the system deploying correctly due to how tightly it seemed to fit inside the airframe.

The first challenge to performing this test was the fact that while I'd managed to obtain a spent rear closure for my CTI Pro-38 motor case, I didn't have a forward closure to properly simulate the burn-out condition of the motor. The forward closure in these motors is part of the reload kit. Looking around my garage for something to fabricate a closure from I saw the can I'd been using to mix epoxy in for fiberglassing the airframe and fins. Fiberglassing the fins had in particular resulted in quite a bit of unused epoxy. I cut the can off the epoxy and then used a hole saw to cut a blank from the cleaner portion of the material. I mounted the blank on my hand drill and used this arrangement as a lathe to turn the blank down to the final diameter I needed. I also turned a shoulder on the part to insert into the front of the motor case. The hole saw left too large a hole through the blank, so I epoxied a washer with a small hole on the forward end of my pseudo-closure. I placed tape on the back of the washer before mounting it so that I was able to fill the central hole with epoxy on a second pass. Once the epoxy cured I drilled a 1/16" hole through the epoxy to simulate the hole between the delay charge and the ejection charge in the real motor. I applied double-sided outdoor carpet tape to the shoulder to secure it to the motor case once I had the ejection charge prepared.

I prepared a 1g charge of FFFF black powder by containing it in the tip of the thumb from a nitrile glove. I chose the thumb because I was able to obtain a large opening to pour the pre-measured powder into. Once the powder was in the tip the excess material was cut off. An Estes igniter was placed into the powder. One leg of the igniter was insulated with masking tape in advance of the insertion. Masking tape was used to gather the end of the glove tip together and tightly compact the powder. A drop of CA glue was applied to the opening to help insure it remained closed. The leads of the igniter were threaded through the 1/16" hole in the front of the simulated closure. The leads were restrained on the back of the closure by attaching them with double-sided tape after twisting them with the wires I'd be using to trigger the charge. More tape was placed over these weak unions to help insure they didn't separate. The wires had previously been threaded through the retainer ring, aft motor closure, and the motor case itself. At this stage the protective film was removed from the carpet tape and the simulated closure was stuck to the front of the motor case. Excess wire was drawn back through the motor and the rear closure attached. The assembly was then inserted into the rocket and the retainer ring installed. All that remained was to start the video camera recording, back off to a safe distance, and remotely trigger the charge with a 9-volt battery.

The photos and video show the results.