Ejection/Shock chord mounting – one way to NOT do it.

In our search for the best method to attach the rip chord to the rocket, we can say we have tried every idea possible. Below is a bit about what we found that works well; we have named it the XR1 method. It is NOT a good method for every type of rocket. This is excellent for larger rockets.

The objectives we wanted to reach where very simple; easy, lightweight, and not in the way like the conventional method suggested by many manufacturers which is, put the chord inside a folded and glued piece of paper and stick it to the inside of the rocket tube.

The biggest problem for us is waiting for the glue to dry. In the conventional method you’ll have to wait about 24 hours for this to happen. We are a bit impatient and don’t like to wait on the glue.

As we thought of various ideas, and even had a chance to put many of them to the test we found this method to works best.

This was a simple system designed to provide an out of the way, lightweight solution that is great for multiple stages of recovery, as well as a final stage.

Instead of using the typical system that often gets in the way of parachute of stage ejection we use an out of the way solution where we cut slits into the body of the rocket and weave the rubberband in it. We then put a thin piece of tape to add a layer on the rip chord to prevent heat damage. On the outside of the tube in this particular example we used black electrical tape to ensure that it would affect the flight as little as possible.

The reason for the bad flight on this rocket was mis-alignment of the fins, in conjunction with a crooked front end.

This is a common problem when building a homemade rocket. The booster stage did not deploy the streamer as intended so we could have clear vision of the system. Since we used a grocery bag as the material of the streamer, the heat from the booster engine unstuck the inner attachment to the booster, and cause it to stick to the main stage.

Deployment of the parachute occurred after crash. This made it impossible to calculate length of rubberband needed to ensure that there would be no ripping on the threads that connect to the chute.

Overall, we had a great time failing just about every benchmark that we set out to test. Hope this teaches our audience a bit about mounting the chord.