Olympic Ski Jumpers Use Wind Tunnels for Training Boost
for National Geographic News
|Updated February 21, 2006|
Twenty-first century sport is a mix of talent and technology. That's why some of the world's best ski jumpers are spending part of their summers strapped down in 60 mile-an-hour (100 kilometer-an-hour) wind tunnels.
"Ski jumping, from the scientific viewpoint, is a wonderful problem," said Michael Holden, an aerospace engineer for the Buffalo, New York-based Calspan Corporation.
"Once you're in the air, it's aerodynamics and nothing else. It's not too difficult to train people to get good lift over drag positions in a wind tunnel. That's what you use a wind tunnel for."
In his day job, Holden uses the tunnel to test vehicles and structures for clients like NASA and the U.S. military.
But he also uses it to help maximize the performance of speed-craving athletes, including alpine skiing champions Picabo Street and Bode Miller and gold-medal-winning speed skater Bonnie Blair.
The Original Extreme Sport?
Ski jumping is largely about the scientific tango between lift and drag that takes place in 100-meter (330-foot) flights through chilly winter air.
Reducing air resistance is one key in determining who flies farthest.
The quest for improved aerodynamics has yielded revolutions in clothing, helmets, and other gear designed for Olympic athletes to give them a performance edge.
But as that technology has proliferated, it has become harder for any single athlete to stand out.
"FIS [the global governing body Federation Internationale de Ski] has made a lot of rules, so we're not able to experiment as much as we used to," said Lasse Ottesen, a U.S. Ski Team coach and retired jumper who won a silver medal at the Lillehammer Games.
"Everyone has access to more or less everything, so it comes down to technique and physical ability."
Before going airborne, skiers take a wild ride down the steeply pitched jumpa 60-mile-an-hour (100-kilometer-an-hour) trip known as the "in-run." Olympic jumps can tower as much as 114 meters (374 feet) above the ground.
Medals can be won or lost during this in-run. Wind tunnels provide a controlled simulation of those crucial few seconds.
Small shifts in a skier's position can make a big difference, but the same stance isn't right for every competitor.
"It's like golf," Ottesen explained. "Nobody has exactly the same swing. You try to find the best position for each and every individual."
"The main thing for us is to test the in-run position and optimize a position for each [skier] that gives them the best speed but also a position that's correct [for takeoff]," he explained.
Takeoff lasts a split-second0.3 seconds to be exactas the skier transitions from ramp to air, requiring the proper position and coordinated, smooth movement.
Once it is completed, the real fun begins.
The Quest for Lift
Airborne jumpers benefit from the same aerodynamic principles that make airplanes fly. (For Kids: "Jumping Into Science")
As athletes fly through the air, their skis and body weight push down on the air below, which in turn pushes back up on them.
A jumper's speed reduces the air pressure above his body, so that the slower air below has slightly higher pressure. This acts as a lifting cushion to help keep them aloft.
The key to modern jumping is ski placement.
In 1985 Swede Jan Boklov introduced the V-shaped technique, in which the backs of the skis nearly touch and the fronts splay out to the sides. This results in greater surface area and thus greater liftand much longer jumpsthan the previously standard parallel style.
Tunnel research helps coaches and athletes adapt this V position to each skier's style and body type.
"When you're in the tunnel and the skis are out in the V style, we're able to see which angle gives us the best lift," Ottesen, the ski coach, said.
"We need to create as much lift as possible through the flight, so they can keep their speed and hopefully [achieve] longer jumps."
Calspan's Holden worked with jumpers before the V technique became the sport's new standard. The old parallel position, and much smaller thinner skis, made for an entirely different aerodynamic model, he says.
"They've doubled the lift and halved the drag," Holden said, "and for a time they ended up literally outflying just about every hill out there. In the old days you weren't much better [aerodynamically] than a bowling ball."
Today body position is less important than ski position, but a jumper's stance can still be critical in a sport where such a thin margin may separate medal-winners from also-rans.
"If you have your arms tucked all the way in, or 3 centimeters (1.8 inches) out, what's the difference? That's something that the jumpers feel [in the tunnel]," Ottesen explained. "They really feel a huge difference when they do this."
Ottesen reports that his U.S. jumpers have missed the last two seasons in the tunnel due to budget constraintssomething he hopes will change this year as his skiers chase the Europeans, who dominate the sport.
"Jumping is such a technical sport, for them to at least go in there and have that feeling, that's kind of the main thing," he said.
"We want to see and test the lift and find [the ideal] position. Hopefully the position that's comfortable is also the most effective one."
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