Up, up and away… Amazing to see motion blur on the airframe as I was shooting 1/2500-second frames with the long lens (f/7.1 100mm)
A stable flight… well, until the four fins detach (below)
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).
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
It went kinky at 0.7 seconds into the burn, as all 4 fins shear off 
The booster recovery was not quite a hole-in-one for this first launch, but we will work on it.
10,9,8,7,6,5… Fore!
Leave a Reply