Nov. 29, 2007 — Around the sidelines of one of the basketball courts inside the Aquatics and Fitness Center, giant orange balloons rose from amid knots of huddled students, nearly all of whom were looking down with serious expressions on their faces.
Closer inspection revealed that the helium-filled balloons were tethered to intricately constructed balsa wood assemblies of various shapes and sizes, wrapped with insulated wires and punctuated by motor-driven propellers.
The students were enrolled in Kathryn Thornton's Introduction to Aerospace Engineering class. Their assignment: construct a lighter-than-air craft capable of hauling a payload around a figure-8 course. Each five-member group would be judged on a point system composed of three elements: speed through the course, with deductions for each "touch and go" and for off-course wanderings that required manual corrections; the weight of the payload carried; and a measure of cost, with a price assigned to each balloon and motor employed.
Tuesday was judgment day. At stake were not only a pile of nicely embroidered Engineering School T-shirts, but some serious bragging rights. In addition to the peer pressure involved, several faculty members – including Engineering School Dean James Aylor — were on hand as judges and observers.
Along one baseline, a group did some last-minute tinkering with its craft, which was unique among the 15 entrants; instead of the helium balloons hovering over the frame, the frame actually encapsulated the two balloons.
"It's the winning design," declared Bobby Dean, a fourth-year mechanical engineering major from Charlotte, N.C.
Moments later, though, the team's confidence dissipated. One balloon was riding higher within the frame than the other, pointing the whole craft nose-down. "Wow — that's a problem," said Mitchell Foral, a second-year aerospace engineering major. The team poked and prodded, seeking to restore the balance.
Foral, who had been holding the frame at waist level, then released it to test the weight, and the craft sank slowly to the ground, necessitating another adjustment to reduce the payload — coins in a plastic bag.
Nearby, the professor was getting itchy. Thornton had 15 runs to get through before the class ended at 10:45. It was already 9:38. "I'm getting a little worried," she said.
Finally, the first group was lined up along the gym's center court and ready to go. The rules of competition required the craft to enter through a 4-foot-wide portal (framed by two helium balloons tethered via a 10-foot-string to bags of rice on the floor), located at one corner of the floor. The craft then had to navigate a figure-eight course, rounding balloons strung over each free-throw line, before exiting through another portal opposite the starting line.
The first group's craft struggled from the start. It lurched and veered, rose and then plummeted. It hit the floor, the motor's buzz sounding like a housefly in its death throes. The impact broke the frame, and the team retired to the sideline to make emergency repairs, hopeful of a second chance.
The second trial, featuring the group that had boasted having the "winning design," went little better than the first. After a clean start, the craft proved virtually un-steerable, It eventually drifted to an adjacent court and petulantly refused to return to the course, despite the team's best efforts. Eventually, after reaching the five-minute time limit, the team reluctantly abandoned its efforts.
At this point, it should be pointed out that the students had not been working all semester on their crafts. One group estimated that it had spent "six to eight hours" in design and construction, and there had been only two days of testing for the entire class, meaning most of the craft had flown only two or three times before.
Still, it was beginning to look bleak for Thornton's students.
"The purpose of this project is to allow the students to actually practice engineering," Thornton said later. "They study about torques and moments and forces and center of mass, but this is a chance to put something together and make it work in six degrees of freedom, which is a lot more difficult than they had imagined it would be.
"The valuable part is the process of designing their craft — not so much whether they finished first or second, but how they went about designing it, the options they considered and how they came up with their final design."
That didn't mean the students would be content with moral victories, though. The third group, with second-year aerospace engineering and music major Chris Kennedy of Williams Bay, Wis., at the controls, proved that the assignment was doable. Its craft buzzed through the course in just 1 minute, 32.2 seconds, drawing cheers and applause as it cleared the finish line.
The secret? "Good balance, and a good method of controlling," Kennedy said, explaining that the craft might have been the only one in the competition with a reversing engine that allowed it to brake. "Being able to slow down really helps."
The remaining 12 flights were more of the same — some craft careening wildly about the gym, others dutifully staying on course. In all, nine of 15 teams finished; the most successful designs appeared to feature triangular platforms with the balloons mounted at the points, providing more stability than the dominant, cigar-shaped craft with balloons mounted in line.
Team 11 briefly looked like a winner, its triangular entry having completed the course in a mere 1:20. Its designers had originally envisioned a "stripped-down dragster," said Bryan Henning, a second-year aerospace engineering major from Vienna, Va., "but it couldn't fly at all, so we decided to make some adjustments."
Even as Henning spoke, Team 7's entry made a clean flight around the course. Though it was slightly slower, it carried a heavier payload. When the final calculations were done — most of the students had cleared out of the gym by then — a champion was crowned.
Take a bow, Nelson Bonilla, Anthony Colella, Danielle Crump, Danielle McWhorter and Michael Underhill. (They're the ones wearing the nifty Engineering School T-shirts around Grounds these days.)
As for the rest? "I'm sure all of the teams learned a lot, and had great ideas of how they would do it differently if they had another opportunity," Thornton said.