First test flight today. The F9 model rocket kit from SpaceX is designed for Estes D12 or E9 engines. I noticed that the rear plastic hub was exactly 29mm in diameter, so I decided to make it a supersonic high-power rocket. It was surprisingly easy. Instead of using the Estes motor mount tube provided, I used a LOC Precision 38 to 29mm motor mount adapter. It fits perfectly upside down, leaving enough internal room for the clear plastic fin tabs too. I ran RockSim simulations for some H and I motors (end of video), and wow, it hits Mach 1.1 on an H motor. So that is what I flew today. For safety, I applied 3D-printed launch rails left over from my 38mm fin can print, and I filled the front of the nose cone with copper BBs set with expanding gorilla glue (need to add nose weight for a stable flight). I also added a beefier nylon parachute. The plastic base took the thrust just fine, and she flew straight as an arrow until all of the fins ripped off 0.7 seconds into flight; she then went into a corkscrew ending the climb well below the simulated 4K ft., and did a flat roll return to land softly, deploying the parachute after landing. Other than the fins, she is ready to fly again. I had reinforced the fins with glue fillets, but it was not enough to hold them. I will try with new fins (easy to replace) and much heftier epoxy fillets for the next flight. And if that doesn’t hold, I know I can use my 3D-printed 38mm fin can with integrated launch lugs (I’ll just need to snip the plastic rod guide from the bottom of the rocket). • SpaceX Kit: https://shop.spacex.com/accessories/f9-flying-model-rocket-kit.html • LOC 38/29 MMT Adapter: http://www.sierrafoxhobbies.com/en/motor-adapters/376-motor-adapter-mma-2-2938-locprecision.html • My 3D-Printed Fin Can Design: https://www.thingiverse.com/thing:630086 More build photos: https://www.flickr.com/photos/jurvetson/33188549888/#comment72157706729723404