The SpaceX kit comes with the little Estes engine mount tube (center) and I modified the build to take High-Power motors from AeroTech, like the I200W on the left.
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. 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).
And here’s a little video of the first test launch…. it is short because both videographers freaked out a bit when the rocket leapt off the pad with a throaty roar, and that flinch reflex makes it hard to track the rocket 🙂
• SpaceX Kit
• LOC 38/29 MMT Adapter
• My 3D-Printed Fin Can Design
I happened to have one of these adapters laying around from 16 years ago! It is the perfect MMT as built, just inserted backward with the white part at the bottom 
Beefier ‘chute and attach point 
Rocksim of the modified build. The nose weight makes it plenty stable with these high-power motors.
For reference, Mach 1 is 1,125 ft./sec.
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