SAE confession time.....

The only teams I thought did well had a serious modeler on them or being advised by one. There was one school that brought nearly the same design every year until the rules changed.

We decided to throw together a prototype as soon as possible. It was one of the best things we did. My part of the project was the wing. I did a foam core sheeted with balsa that came out heavy. The wing needed a little washout and the fuselage just did not work. It was weak and hard to work on. The fuselage broke multiple times on hard landings. We lifted 15 pounds of steel with that plane. That was the max we could get off the ground in 200 feet at a DA of about 7000 feet with no wind. It wasn't too bad considering the plane weighed 24 pounds and was powered by a 61.

The problem with the fuselage was that they were getting on a 3D CAD program and making theses nice tear-drop swoopy shapes. They had never built anything like it before so it was never built right. The shapes also compounded the construction problem. The second fuselage was even harder to get in to access and it broke in the first flight. It only flew once. Again it was not built strong enough for what it was going to do.

I built the second wing. The new wing had a sheeted foam core D-tube and the rest was built up with glass on the D-tube at a 45 degree bias. It was bigger, but much lighter than the original. It had 3 degrees of washout, was tapered, had nearly a 10 foot span, and had a lot of camber. That was the most difficult wing I had ever built and don't think it would have been possible if I hadn't scratch built planes in the past.

I finally sat down with a piece of graph paper and designed a new fuselage. I made it strong, light, and accessible. I built it from light ply, carbon fiber, foam, and fiberglass. It was lighter and stronger that the two other fuses. After it flew very successfully we reverse engineered it for the report creating the 3D model and CAD drawings.

So, I built the wing, the fuselage, helped with the tail boom, tail feathers, and landing gear, did the final assembly, flew the plane, and helped with a good deal of the report. I didn't mind it too much because it was more of a labor of love.

I also did static thrust testing on a bunch of props and found our secret weapon. We were asked if our engine had been modified the way it was running. I also made 3" aluminum wheels with O-ring tires and double ball bearing on the axles. I couldn't believe some of the landing gear set-ups I saw. We had very little rolling resistance which made takeoff easier, but landing was interesting because it would roll out a good distance.

Our final plane was very difficult to fly. It was very unstable in the yaw axis, but was flyable if you stayed on top of it. There is no way that an unexperienced pilot could have flown it. We flew it multiple times and lifted 20 pounds well before the competition at a higher altitude than where the competition was to take place. After the first day of flying we were in first place. We ended up lifting over 25 pounds and taking third place overall. I was suprised to see how many teams made the journey without having ever flown their plane.

For us, we were all mechanical engineers and not aero engineers. The project was more about teamwork, crunching numbers, designing a product, and documenting everything. Now that I look back, I almost wish I would have chosen a different project.

It was fun and I would do it again if I had the chance, perhaps we should start the RCU Heavy Lift Competition.............that would be exciting. Anybody interested????