In 2020 I was the simulation lead on a 50k ft altitude world record attempt for a two stage complex M class rocket. I also helped design the fin geometries and performed aeroelasticity calculations to ensure the futter velocity was never reached. 

The rocket was a minimum diameter 75mm booster to a 54 mm sustainer the booster used a M1350 and the sustainer used a K380. The sustaner was sucessfully recovered and had a maximum altitude of 4986 ft. This would have broken the previous world record by over 20k ft but due to the booster never being recovered the record could not be verified.