Behind the Scenes of Design-Build-Fly

by Nick Terhall

Building a radio-controlled aircraft…couldn’t be that hard, right? Slap a wing on top of a fuselage, add a radio receiver and a propeller, what else could there be to it? As it turns out, there’s quite a bit more to it than that, especially if you’d like to build an entirely new aircraft. I’ve spent the last two years as part of a group called Design – Build – Fly (DBF), who designs and builds large scale radio-controlled aircraft for a national competition held every April. I won’t bore with you with all of the math-ey details, but as the aerodynamics and design team leader, I will give you a little insight into how the design and construction process for an aircraft works and the challenges that riddle that process.

Terhall plane 1Model of this year’s plane

The national competition has different requirements and missions each academic year, usually centered on modeling a specific type of aircraft. For example, last year the competition was a fighter aircraft, while this year it’s a backwoods, all-terrain (bush) plane. The first step in the design process is to evaluate what the rules say the aircraft should be able to accomplish in the competition’s three missions. Such rules are typically to carry a certain weight and type of cargo, complete the competition course in the fastest time possible, or take off in a certain maximum distance. Where the tricky part comes in is when mission requirements start to come into conflict with each other. At that point, my design team uses their expertise to maximize the aircraft’s design.

Terhall plane 2Foam plane construction

After the plane was designed on paper, the group built a model out of blue foam and carbon fiber to test the design. The first big success was actually putting a plane into the air, which was a first time Iowa State’s DBF had done so in its year and a half of existence (Last year’s model had, let’s just say, some severe issues. Like, not-being-able-to-fly issues). After three days and about twelve flight attempts, we have learned a lot about our design. For instance, when the plane had trouble turning in the air, we knew that the flaps on the wings that usually turn the aircraft were not big enough and needed to be increased. The aircraft also had stability issues caused by where the weight was located in the aircraft, which we were thankfully able to solve quickly. We additionally recently determined that our battery and propeller system as a whole was not powerful enough, so we are working on making the entire system more powerful.

Terhall plane 3Last year’s plane

Those flight tests were not without their share of close calls, held breaths, and bent landing gear. By some miracle, the plane is still operational today, despite its share of stalls on takeoff, rough landings in a corn field, and even a rather wet water landing. I’ve put so much time into this project that each time it starts to roll down the runway, I still get a little tense as it feels almost like a small part of my self is about to hurtle into the air, towards an uncertain future upon attempted landing.

Terhall plane 4Test flight this semester

Moving forward, the group is poised to start construction of our redesigned and optimized competition plane in the next week or two, which should bring its own set of challenges and hair-pulling. All in all, I have a lot of fun leading one of the group’s teams and am very excited for the upcoming national competition in Wichita, Kansas!


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