AboutJames Bell Expertise I am a member of Tripoli Rocketry Association, and am certified to fly hi power rockets. I can answer questions anyone may have about design, materials selection, stability calculations, motor selection, altitude and performance predictions, and parachute and recovery options.
Experience I make my rockets from existing kits or parts readily made through commercial channels. I do NOT make my own motor propellants (they are challenging enough even for the companies that do this for a living), and I do not advocate making rockets using "typical household item" such as paper towel rolls.
Question What do you think would happen if you moved the fins on a rocket to the top, middle, and bottom?
Answer Devon -
Rocket stability of one of the basics of rocketry design you need to have a good grasp of. Think of the rocket as a weathervane, where the pivot point is the center of gravity. Having the CG far forward, and the fins in the rear, the rocket will weathervane into the wind and be stable. If you move the fins to the nose of the rocket, you can swing the rocket the other way. I have seen rockets come off the launch pad and turn into unstable missiles.
Many air-to-air missiles have fins mid-section and in the rear. The rear fins provide stability, while internal guidance computers control the forward fins to guide it to the target. In a hobby rocket, there is no guidance to these fins. It looks nice to have, but you need to calculate the CG (center of gravity) and CP (center of pressure). The CG always needs to be IN FRONT OF (toward the nose) the CP.
I hope this answers your question. If not, or you have more, don't hesitate to write back.
