My experiences with the University of Washington's Society for Advanced Rocket Propulsion
The UW Society for Advanced Rocket Propulsion (SARP) is a competitive student run rocketry organization at the University of Washington. Each year SARP designs, constructs, tests, and launches a hybrid rocket to compete in the Intercollegiate Rocket Engineering Competition (IREC). Being a member of SARP has given me the opportunity to improve many of my practical engineering skills, expand my interests in aerospace engineering, and served as a platform to express my love for problem solving, designing and building.
Below I have included the projects I found most interesting.
2018 Recovery Electronics System
On the 2018 rocket, I led the recovery electronics sub-team in developing a redundant recovery electronics system that would record flight data and deploy parachutes appropriately.
This task required three main design criteria. The component had to be light weight, exceptionally reliable, and practical to manufacture. Ultimately it was decided that using two off-the-shelf Featherweight Raven3 altimeters would give more reliability than anything we could manufacture in house. The Raven3 altimeters were accompanied by a custom Arduino based system that would collect additional data and send tracking information to the recovery team.
At apogee these altimeters were programmed to set off a charge within the on-board CO2 system, deploying the drogue. Once the rocket had reached a designated altitude, a second signal would be sent to deploy the main parachute. These systems demonstrated their full capability, but unfortunately the rocket had a structural failure mid flight. This failure ripped parachute resulting in a hard landing.
More information about problems during the 2018 launch can be found here.
To house the electronics, I designed and printed a housing made from ABS plastic using a variable infill technique. Within sections were stress is concentrated, infill is set at 100% and transitions to low stress areas with 50% infill.
2019 Recovery Coupler
For the 2019 rocket, I joined the structures team to get a better idea on how to analyze a dynamic structure. My focus has been on optimizing the recovery coupler for a better strength to weight ratio, and to improve the manufacturability of the coupler.
Buckling is the primary failure mode for the recovery coupler. As such, our team used many methods of analysis to optimize how mass is distributed in the cage section of the coupler. My analysis involved using MATLAB and Euler buckling theory to test several hundred column configurations. With the best coupler designs, I partnered with the simulations and analysis team to verify my findings using ANSYS. After a few iterations and a critical design review, my team found a compromise between manufacturability, acceptable wight, and safety factor.
Later on in the project our team was advised that our safety factor of 7 was not sufficient enough, so rather than building a new coupler, I designed 3 doors to relieve compressive stresses on the columns of the cage. Using my expertise in additive manufacturing, I printed the doors using a light weight composite thermoplastic. These new doors were about 30% lighter than last years design while increasing the overall safety factor of the coupler to 9.
In my spare time, I assisted the nosecone team with concept designs for integrating a pitot tube to measure the velocity of the rocket and contributed to building the nosecone. Although manufacturing this component involved quite a lot of sanding and late nights in the machine shop, the overall result was well worth it.
Our 2019 design also includes a plasma payload that will alow our team to control flow separation during flight resulting in less drag and a higher flying rocket. This type of technology has never been tested on a rocket at IREC, so our team hopes to leave our competitors in the dust.