Live Gimbal Test 5

A project log for Project Rockoon

Actively stabilized model rocket by means of a motor gimbal, originally designed for launching a rocket from a high-altitude weather balloon

Julian CostasJulian Costas 08/30/2016 at 17:320 Comments

Today I conducted the 5th gimbal test with a live motor. This time I used an E engine, which has 4 times the impulse of the C engine used previously. I used a similar test configuration with a tethers on either side. I made some improvements to the rocket, most notably a method of precisely adjusting the positions of the solenoids. This allowed me to find a "sweet spot", where the permanent magnet in the solenoid that locked the slug in the extended position actually assisted in nudging the motor to one side. This was important because the E engine had significantly more mass. After adjusting the calibration screws on each solenoid, the mechanism was reliably angling the engine in all 4 possible directions.

Here's a clip of the test:

As seen in the video, there was a rapid unscheduled disassembly. The forces exerted by the tethers caused the gimbal/engine assembly to shear from the electronics/payload bay. The gimbal/engine assembly, still being propelled, flew off in another direction. I was able to recover most of the parts, but I was not able to find 2 out of the 4 solenoids. Some of the 3D printed parts also broke. The cost of replacing the solenoids will set me back about $10, so it is not the end of the world.

Unfortunately, this test was also not very productive. Despite adding additional dead weight to the rocket, he engine imparted so much speed off of the launch rod that I'm not even sure if the gimbal factored into stabilizing it. This fact, combined with the CATO, leads me to think that the only way to accurately test the gimbal mechanism with an E engine will be to fly an untethered rocket. This means developing some sort of recovery method.

I will be going back to school in 5 days, and that being said, I do not have sufficient time to rebuild the broken parts, develop and test a recovery method, and wait on a shipment of 2 more solenoids. I believe that this was the last test of the summer.

That being said, I will rebuild the parts that did break and bring what I have so far to school with me. With classes and shared resources, progress will certainly be slower. I may also discover another rocketry project at the club. With these factors, I may not continue work on this project until I come back for winter break. I will move in prepared for either option, and I will make my decision after learning more.

Also, I have one last E engine left. I may throw a simple model rocket together to end the summer with a launch, just for fun.