Airframe
Meet Our Airframe Team!
The airframe team was headed by Jacob Markham, who focused on composite materials and fins, from the leading edge to the layup. Josh Warren spent most of the year designing and testing fly-away rail guides that we never used (sadness), but he also conducted some strength tests for various 3D printing materials and helped out with the final rail guide design. Ella Mulholland worked on the nose cone before transitioning to the public-relations / communication-with-parents role for the team. Sarah Laurel spent most of the year managing the budget, which turned out great (we used much less than we allotted ourselves). Kade Sullivan was in charge of all things bolting, which turns out to be a lot between all the jigs we messed up and the drilling and tapping of some 34 holes.
Nosecone
This is our 5:1 6" fiberglass von karman nosecone from Madcow rocketry. It will house our payload and connect to our forebody tube.
Forebody Tube
This is our 6" fiberglass forebody tube. It connects to the nosecone with shear pins and the upper ox tank head coupler with bolts.
Ox Tank FEA
Stress concentrations, especially involving the complex geometry of the ox tank heads are difficult to simulate. FEA is simply an algorithm for breaking large shapes down into simple shapes that are much easier to perform calculations on. I took some more notes on my ox tank FEA process here.
Flyaway Rail Guides
Rail guides cause a large amount of protuberance drag, so fly-away rail guides gave us the opportunity to increase apogee significantly. They are designed to wrap around the body tube, held together by a spring which also flings them off of the rail guide once the rocket exits. To further ensure the rail guides wouldn't hit the rocket, we placed a spring pushing the two semi-circles away from each other. However, our design was not finished and we later transitioned to more conventional rail guides. Fly away rail guides are difficult to design and test but their potential benefits make them worthy of consideration.
Carbon Fiber Overwrap
We decided to use an overwrap to strengthen the aftbody of our rocket. Carbon fiber composites are very lightweight, so having the overwrap will not increase the overall weight of our rocket very much. Composites are also very strong and having the overwrap around the combustion chamber will help prevent the walls from failing. The overwrap also glues together the aluminum that couples to the ox tank, the phenolic tube, and the steel that holds in the nozzle.
Carbon Fiber Fin Can
We chose to use a fin can because it will be constructed directly onto the rocket body so we won't encounter problems with bolting. Instead, our four fins will be epoxied straight onto the overwrap. Then, extra layers of carbon fiber will be epoxied across the fin and body tube faces in tip-to-tip layup.
Leading Edge
A leading edge is necessary to prevent delamination of the foam core in the fins. Having an airfoiled leading edge reduces drag on the fin, with different shapes working best at different ranges of velocity. It also prevents delamination, since the air doesn't flow directly under the carbon fiber. Our leading edge was made using the same ablative mixture used in the pre and post combustion chambers of the rocket and we utilized a 3D printed mold to shape the ablative into the airfoiled shape seen in the picture which was then epoxied onto the fin edge.
Manufacturing Gallery
Laying Carbon Fiber
Cutting the Ox Tank
Rolling Ablative
X-Winding
XWINDER WRAP.mp4