Process
We iterated in a loop we called CAD, Code, Consider: change the model, change the simulation, check what broke, repeat.
Design changes
- Mass came down by moving the fins to carbon fiber and shelling the main body
- Air brakes, grid fins and chines added drag and steered the airflow
- The parachute deploys higher, where it has time to slow the rocket
- Thrust is capped, and reverse thrust fires only in the final phase
- Materials were chosen with a decision matrix: titanium airframe, carbon fiber fins, a graphite nozzle and a Kevlar and Nomex parachute
Results
The simulated touchdown came in at 4.43 m/s with a thrust-to-weight ratio of 1.01. We then re-ran the model with lunar gravity to show the approach carries over. The graders gave the report and technical work full marks and the video 98.
About the demo
The simulator is a simplified one-dimensional model I wrote for this site, not the team's original code.