Yesterday’s build day was cancelled due to concerns about whether or not the Clark Y aerofoil would produce enough lift for our plane to meet the FAA’s part 103 specifications. After some careful consideration by our design and physics teams, we decided to continue with the Clark Y aerofoil, but made some other changes in our wing design that we will be posting soon. Today was extra exciting as it was the first day where everything we built will hopefully go on our final plane. We still anticipate lots of other design changes, but today felt like a big step forward.
The plane’s wings, specifically the ribs, have been the focus of the past few weekends. We’ve cut out many ribs, load tested them to failure, and made improvements. If you’ve been reading our blog posts, you’ll know that using a bandsaw to cut out ribs was an upgrade from our homemade hot wire cutter, but it was still time-consuming and required an extremely steady hand. We figured out a better solution where we make a rough cut of the rib with a jigsaw, then use a hand router to follow the edge of a wooden rib profile we cut out last week.
In addition to cutting out rib profiles, we also continued cutting aluminum disks to support the high stress points where the spars go through the ribs. Since we are working with large sheets of aerospace grade aluminum, we had to get a bit crafty. It turns out scissors are the perfect tool to cut out the disks. We divided up work by having some people cut disks while other people used the drill press with a 2” hole saw bit to put holes in the disks for the spars to go through.
We also made some improvements to the wooden clamps for the washers. Last time we used our wooden clamp design, we had a problem where the excess epoxy fused the clamps to the aluminum. We solved this by reducing the wood in contact with the spar. We CNC’d a few, then cut some more out using the band and drill press. We routed the three funky shapes out and were done! We got to enjoy some delicious homemade cookies made by Rudy mom. Finally working on parts for the plane was surreal, and we are looking forward to many more build days to come!