The blimp started as Ben Narin's idea, and he approached me asking for some help with the frame and envelopes. Having a little experience with RC helicopters and having built a couple of balsa wood airplanes as a kid, I agreed to help, and began design on a balsa wood frame.
We decided to go with just a single envelope (the balloon that holds the blimp up), so the frame was designed around that. Using some basic hard-balsa wood, I designed a frame around the two circuit boards we used (one was an OSU designed board, called a Tek-pet, which had usb outputs and a motor controller, the other board was an Xbee, a serial communications board).
Surprisingly enough, for gluing balsa wood, Elmers glue seems to work the best. Watered down a bit so that it soaks into the wood, it kept the frame together really well. For the propellers, I mounted them on some small pager motors, zip tied to the ends of a long abs tube. To allow the propellers to rotate, I attached a LEGO gear in the middle of the rod, put the corresponding gear on a micro-servo, and mounted the whole apparatus to the frame. Though simple, this seemed to work well for our purposes.
So, with the frame done, and Ben and Marshal (the other person working on the project) having finished their programming, it was time to test. We ended up adding a second envelope to carry the weight of the frame and board. After some initial hiccups, such as removing weight from the frame and changing some minor programming errors, we were able to get the thing in the air and fly around the room.
So, after tweaking a few things, Ben informed me that the blimp was to be entered into a freshman design competition (which I had no knolege of in the beginning), and that we could win some cool prizes. I was all for it, so we entered it. We ended up taking home about $500 in prizes, including an xbox and a high-end robotics kit.
All in all, it was a rewarding build. I look forward to working with Ben in the future.