During the academic year of '22-'23 structures was focused on two main new development projects: carbon fiber body tubes & carbon fiber airfoil fins.
Carbon Fiber Body Tubes
As depicted in the image to the left, the structures sub team fabricated several 1in carbon fiber body tubes. We tested several methods for the tube fabrication to settle on the most precise method. The image to the left shows one of our first iterations on the right with our most recent iteration on the left. We then performed crush tests using an Instron to determine how much load these tubes can withstand. After determining the best fabrication method, and confirming these tubes were strong and safe, we proceeded to layup some 4in carbon fiber body tubes for our Spring '23 launch of Phoenix V in Amesbury, MA.
4in Carbon Fiber Body Tube
Above is an image of one of the carbon fiber body tubes for our Phoenix V rocket. This is the tube after being release from the mandrel but prior to being sanded.
Liquid Nitrogen Release Technique
Above is an image of our liquid nitrogen release technique being used on a 4in carbon fiber tube. This technique involves putting our tubes in a liquid nitrogen bath and pouring liquid nitrogen down the inside of the aluminum mandrel. This allows us to release the epoxy and slide the carbon fiber tube right off the aluminum mandrel.
Fiberglass Airfoil Fin Layup
Similar to the image to the right we layed up the fiberglass fin half on a 3d printed base. The two separate halves were then combined and another two layers of fiberglass were added.
Carbon Fiber Airfoil Fin Layup
This is a layup method which we tested where we made two halves of the fins which we later connected. The image above is of the 3d printed fins which then have a layer of carbon fiber and a layer of peel-ply. This photo was taken before the assembly was vacuum sealed. Making two halves allows us to either have a hollow fin (optimize the weight) or insert ribs to maintain a low weight with stronger cross-sections.
Rocket Stability Simulations
Using OpenRocket we perform extensive simulations on the rocket's apogee and stability. Given the fin's impact on the rocket stability, the fin team on structures spends a lot of time running various simulations to determine the best fin shape for an ideal apogee and stability. The image to the left is an example of a stability curve for our Phoenix V rocket where our stability off the rail was about 2.2 cal.
Phoenix IV Fiberglass Fins
The image to the left is the CAD of the fins (without the fin tab) that were flown on our Phoenix IV rocket. We did extensive research and testing to determine the ideal fin shape to fly on our rocket. We determined a clipped delta shape would best fit our requirements. We then ran more simulations to dial in the exact dimensions and then sent the fins out to be waterjetted.