GLIDING HIGH Ilan Kroo, earth-bound and hang-gliding
courtesy Ilan Kroo

His finalist year: 1974

His finalist project: Designing a wind tunnel that uses magnets to hold test models in place

What led to the project: As a child growing up in rural Oregon in the 1960s, Ilan Kroo was obsessed with flying. Along with friends, he built a hang glider from bamboo poles, duct tape and plastic. They took the contraption to a nearby dairy farm, ran down a hill, and would actually get a few feet off the ground before crashing. "Any landing that we could walk away from was a good landing," Kroo says.

Fortunately, he survived that learning experience and, in high school, with the help of a research program at the Oregon Museum of Science and Industry in Portland, decided to build a better wind tunnel to help him understand the aerodynamics of other flying objects. One of the big problems of wind tunnels is that the object being tested requires a support structure to stay in place as air blasts around it. But these constraints affect airflow, thereby skewing the data.

To get around this problem, Kroo built a wind tunnel lined with magnets on its top and bottom. A photo sensor monitored the test object and sent signals to change the strength of the magnets' field so they, rather than a support structure, could hold the object in a stationary position. "I learned a lot about circuits as well as wind tunnels and magnets," Kroo says. The concept also won him one of his first actual plane flights—a trip to Washington, D.C., for the final round of the 1974 Westinghouse Science Talent Search.

The effect on his career: Doing so well in a prestigious science competition encouraged Kroo to raise his sights and "made it possible for me to go to a place like Stanford," where he enrolled as a physics major. He fell in love with California, and so stayed at the university to get a PhD in aeronautics. His thesis looked at how the forces acting on hang gliders—inertia, drag, lift, the object's own elasticity—interact. At the time, in the late 1970s, hang gliding was "not a very safe thing to do," he says. He looked at the interaction between structure and aerodynamics, did wind tunnel tests, and worked with a number of hang-glider companies on implementing the findings.

After earning his PhD, Kroo took a job at NASA Ames Research Center at Moffett Field, Calif. With fuel prices skyrocketing in the early 1980s, he worked on the then-urgent idea of a more efficient airplane, although, of course, some of that interest "disappeared as fuel prices fell," he says.

What he's doing now: Though public interest in efficient planes has waxed and waned with the price of oil, Kroo has stayed on the problem. Now, as a professor at Stanford, one of his major areas of research is "sustainable aviation"—that is, "the idea of making aircraft that have a sufficiently small environmental footprint [so] that we can accommodate the growth expected in air transportation while not increasing the impact on the environment," he says.