efluids image gallery
previous BACK to Gallery of Flow Images Submit Image
Amy Wilbur
Science Digest, February, 1986

Streamlining for the slopes: downhill racers improve their speed by skiing at a standstill.

There's no snow to be seen, but an anxious Olympic-hopeful downhill racer is about to take a run through a rigorous training course complete with jumps, straightaways and tight tums. Instead of gliding to the starting gate through the crisp, crackling snow, the skier cautiously steps onto a gridded platform in a test cell. The wind begins to rush by, and he drops into a compact tuck.

The scene is the Calspan Corporation's wind tunnel in Buffaio, New York. NormalIy used to test the dispersion of pollutants and the airfiow around buildings, the tunnel is sometimes a training arena for members of the U.S. Olympic ski team. Mike Holden, a ski instructor and a principal engineer at Calspan, directs the program, helping both new and accomplished skiers to perfect their high-speed zigzags on treacherous downhill courses.

The training has already proved its worth. Bill Johnson -- who in 1984 became the first American man to take a gold medal in downhill racing -- mastered his incredible tuck in the wind tunnel. And the sleek, aerodynamic style of Doug Lewis, a hot new downhiller, is attributable to his wind-tunnel training. "There's no way a skier can effectively evaluate and improve his aerodynamics on a downhill course," Holden says. "But in the wind tunnel, we can help him learn how to diminish drag." As a 200-horsepower motor generates a 70-mile-per-hour wind, the racer either watches a video of a course, moving his body as if he were skiing, or experiments with different positions. Sensors in the platform measure the changes in drag caused by his movements; a digital readout on the floor displays drag figures and improved time. Another screen shows the skier himself so that he can correlate drag and position.

But just how much of a difference does the training make? "In a low-tuck position, with arms held tight in against the body, a skier generates a drag of about eighteen pounds," Holden explains. "But if he holds his arms along the outside of his legs, as some skiers do in approaching a jump, drag can increase to forty-three pounds."

Other countries have wind-tunnel training programs, but the American program's success at integrating the tunnel work into racing is unique. "You have to study what really works on.the slope and apply it in the tunnel -- not find something that works in the tunnel and try to apply it on the slope," Holden says. Stability is crucial: If a skier's position in the tunnel has low drag but he feels uncomfortable or can't hold it, it's no good.

Downhill racers aren't the only visitors to Calspan's tunnel. Skaters, ski jumpers and luge sleds have all come to improve their performance. "Jumping is an area with lots of potential, and it's never been studied in any great detail," says Holden. "Once a jumper leaves the ground, it's all aerodynamics."

He concedes that wind-tunnel ski jumping is far from perfect. "The technical equipment isn't fully developed. Also, it's difficult for the skier to get the feel of a real jump, because he must hold himself differently in the tunnel in order to simulate the correct angle between body and wind."

During the next year, Holden will take his testing to the slopes. He is just finishing a device that will fit into a ski binding and measure forces as a skier actuaily negotiates a course. A small backpack housing a portable computer records the readings, and after the skier completes the course, these are matched frame by frame with a video of the run. "We'll be able to tell in each instance how the forces are generated by the skier -- on which ski, on which edge, toward the front or toward the back," explains Holden. The measurements will be used to improve overail skiing technique. "A lot of people forget," he says, "that not only are top competitors mentally tough, they ski in a technically superior manner."

© Copyright on the images is held by the contributors. Apart from Fair Use, permission must be sought for any other purpose.