L1 Certification Rocket

My L1 HPR Certification rocket was my first true exercise in engineering as well as my first design risk taken as an engineer. Part of my thought process was that I wanted to do something unusual, challenging, and that required more from me than the typical model rocketry design process.

Out of all the possible options, I landed on attempting reverse swept fins, an unusual fin geometry that I was explicitly advised against. This choice was not made at random though, as fins chipping or breaking is one of the most common sources of failure in the L1 certification exam. By sweeping the fins forward I could exploit extra fin surface area without posing a major structural threat. I believed I could make it work and on the path of ensuring my rocket was safe to fly, I essentially had to teach myself CFD and FEA principles.

I simulated my fin in Ansys workbench which allowed me to conduct a freestream CFD analysis that fed into a pressure-based FEA analysis where I determined that the total stress was far below what my materials could handle.

Manufacturing this also came with a set of challenges, such as designing a jig to chamfer the fins to reduce drag and subsequent stresses on the fins.

My effort thankfully led to a successful certification flight, and I now hold my NAR L1 Certification Card. After the flight, an inspection of the fins showed no deformation or tearing in the fin filets or interfaces which was expected.