Could you please elaborate?

@@3dspacemodelrocketry Indeed, I am preparing to design my own mini rocket, so I have trouble defining my cp push center, it pushes my mini rocket to be unstable, so I need stability, that's why I asked you this question, because I was hoping for the answer in you

We use openrocket to simulate the center of pressure and design the fin shape for our scratch built rockets.

@@3dspacemodelrocketry Ok thank you very much, indeed, I am more fluent in French than English, now there is a video in French or in English which explains the open rocket simulation perfectly well, (or the barrowman equations), and determine the number or the shape of the fins, please give me the video, it will make me happy

We used a generous amount of painter's tape, (as seen in the video) there were no retention issues. Thanks for commenting!

Yes but a simple screw on retainer would save so much time and hassle.

Pumpkin chunkin

We don't know the exact cause of the engine ignition failure, but it comes down to three things, 1. Minor differences in the three estes ignitors. 2. Minor differences in the propellant face of the three engines. 3. Differences in the insertion of the ignitors. Those are the three possibilities of what caused the ignition issue. Thanks for commenting!

Thanks for your feedback! The camera at the launch pad was a GoPro, it was specifically aimed at the engines so that it would capture ignition up really close. We originally meant to have a vertical Slo-Mo shot with a smartphone, but the smartphone that was specified for that job was required for a different job so we were unable to do that shot. (Fingers crossed) We should hopefully be able to get that shot next launch if we manage our camera resources better. Thanks for your feedback though, hopefully you can tune into our upcoming videos!

Thanks for commenting! But we are sorry to say that we cannot provide the file, due to it requiring very specific launch hardware, and it being experimental. Plus if your launch were to fail, we would not want to have to take legal responsibility for any damages and injuries that could occur. 3dspace model rocketry

@@3dspacemodelrocketry no worries, still enjoying your work keep it up