Saturday, June 20, 2009

SAE Collegiate Design Challenges

I know what you're thinking. Why am I talking about collegiate challenges when school is out? Well, it's because many of the challenges happen at the end of the school year, and the results are not that old (2009 Aero Design East Results). Also, many design teams don't take the summer off. I speak from experience when I say that it is a LOT of work to design and manufacture everything necessary for the competition. More to the point, it is expensive. Years full of Ramen Noodles dinners does not prepare you for the added expense of being able to compete.

You see, most teams like the one I was on pay for everything that goes into the airplane, formula, mini-baja, or snow mobile out of pocket. Costs can exceed $5000 plus travel expenses. And the students participating in these challenges spend some time looking for sponsors, but most of the time are busy with school work and designing or fabricating the competition vehicle. They don't have time to market themselves. But the sacrifice is worth it.

I remember my senior year working on the Aero Design Challenge, open class. I won't tell you which one in the picture is me. But, that washed out piece of cardboard at the front of the plane is the award check for getting 1st place and a new world record!
I was on campus by 8:00am each morning. If I didn't have class, I was in the computer lab that early. It was the only time I could find a terminal open to compile my Fortran code. In between classes I was in the student commons area, working on all the homework I just got. After the last class, it was down to the lab building the airplane you see above. The team was there until 1:00, 2:00, and sometimes 3:00 in the morning. Just enough time to get back to the apartment, sleep for a couple hours, shower, and do it all over again. I stayed as long as I could until I started dropping screwdrivers and utility knives on my feet. That's when I knew it was time to go. Steel-toed boots are the best!

Because the aero competition is all about lifting weight, the design you see above is a lifting tail configuration. Anyone who is in the industry knows that lifting tail designs are inherently unstable. My kudos goes out to our pilot to be able to control such a monster, but even he couldn't correct for the first hard learned lesson.

You see, that carbon composite wound boom was designed to be strong and light weight. In our haste, we forgot to consider deflection. We're on the runway for our first test flight. The pilot starts the roll-out and we can see the wing tips starting to lift. Then the tail starts to lift. And then the boom deflects to compensate. And the tail lifts more. And the boom bends more. And the tail lifts until it flips the plane over, smashing the vertical fin and cracking other parts. Flight testing over, back to the lab.

I remember comments from other teams during the competition itself. To elaborate a bit, you keep your design pretty hush-hush as well as the potential weight you think you can lift. Yeah, that's all calculated out wayyy ahead of time. We go into the competition fully aware of where our plane will start falling apart. There were two classes for the Aero Design Competition. The regular class is smaller planes, and the design is limited to wetted area of the lifting surface and so on. Smaller planes means less weight aloft. The open class had design limitations on fuel. Build as big of plane as you can, but the rules of the competition require it to take off within a certain distance, run the rectangular pattern, and land in the same area you took off in. Too big, and you'll run out of fuel on the downwind. Too small, and you won't be able to carry enough weight to bother competing.

Back to my story. Talking to a competitor in the regular class, they were impressed by an open class competitor that stated they needed about 10 lbs of cargo just to get their weight and balance right for stable flight. The regular class lifts around 10-20 lbs during competition. I didn't have the heart to tell him our plane needed 30 lbs. Yeah, just to get the plane off the ground, we needed more weight than the world record holder in the regular class. Think about this for a minute, a baby is born at 6-10 lbs. We're lifting 3 times that. We're lifting a small child into the air just to get started.

These are just two of the many fond memories I have about the experience. I urge all of you to support your alma mater's or local university's participation in the SAE Collegiate Design Challenges. Sponsor your local team. Be an industry expert or consultant. Provide donations like: tools, storage, work space, even Bologna sandwiches. It all helps and creates a wonderful experience for future engineers.

One more picture, for the road.