NACA Rocket Fin - High Powered Rocketry

A rocket fin design based on the NACA m2-il profile. Attached are the design files for the fin, a mold for casting the fins, and a jig to mount the fins to a 3 inch rocket body tube.

This is the basic finset for a high powered amateur rocket using an M2020 motor that simulates to 35,000 feet altitude with a maximum velocity of mach 2.5. The model of the fin was derived directly from the NACA database and this particular profile was chosen for it's very good lift characteristics at high angles of attack in the subsonic region and low drag through transonic and supersonic regions. The fin model was used to create a two part mold which is used for an 18 layer Carbon Fiber and Fiberglass fin layup using an epoxy resin. (the mold must be carefully waxed and prepared with PVA to avoid bonding). Pictures of the fin coming out of the mold and trimmed are attached. In addition, a jig to hold the forward and aft portions of the fin for exact alignment is included. The jig fits the final molded fin perfectly and holds it orthogonal to the body tube and in perfect forward/aft alignment. The jig can also be used with 5/16" dowel to align mounting holes for an electronics bay, based on 3 #8 screws around the rocket body.

Subsequent development includes printed assemblies for electronics (altimeters, timers, and GPS transmitters). Jigs and alignment fixtures are build with 3 shells for stability and strength. The mold was printed with a 0 and 90 degree orthogonal fill for maximum clamping strength without warping under pressure. Electronic bay components are aligned with the direction of thrust and use a 30% fill to withstand 27G upon takeoff.