A twirling skater with arms outstretched spins slowly; as she brings her arms in, her rotations accelerate until she is no more than a blur on blades. This principle is the oldest truism known to sports science: angular momentum – the product of a spinning object’s mass, radius squared an spin rate – remains constant. This formula means that if a skater like Michelle Kwan (photo) reduces her radius by bringing in her arms and legs, her spin rate increases. To come out of the spin, the skater extends her arms again. Although conventional wisdom says that the higher you jump the more axels you can squeeze in before landing, biomechanics expert Sarah Smith of the U.S. Olympic Committee finds otherwise. According to a paper by Smith and colleagues at the USOC, for a triple axel a skater needs to jump only a few inches higher than for a single. But she must pull her arms in about 28 percent faster .05 second instead of .07. Scott Davis, who beat his idol Brian Boitano at last month’s Nationals, is the king of high-speed spins because “he gets his body into a tight position, and quickly,” says Smith.
For years, the Americans bought their bobsleds off the shelf, from European manufacturers. Not this time – thanks to stock-car racer Geoff Bodine, who got interested in bobsledding after the 1992 Olympics and promptly crashed Olympian Bruce Rosselli’s sled. He did penance by helping to raise $780,000 to build a true-blue American version. Connecticut’s Chassis Dynamics, maker of Formula I race cars, loaded mathematical specifications for the best of the European designs into IBM computers and “test-drove” various models on screen. Then the engineers got to work. They moved the handle six inches up; when athletes don’t have to crouch while launching, they get more power into the start. To keep the driver from frittering away the speed attained at launch, the engineers used a flexible material to attach the runners to the body; that cuts down on vibrations that can rob energy, and speed, from the sled. IBM even stuck sensors all over the sled to measure speed and G-forces and tell the driver when he’s turning too late into a curve.
Nine years after Swede Jan Boklov shocked the judges by launching with his skis in a V, rather than parallel, “there is no other way to jump,” says Michael Holden, aerospace engineer with Calspan Corp. in Buffalo, N.Y. He should know: Calspan lent its wind tunnel to the American jumpers, suspended them in Peter Panstyle harnesses and measured how the V works. By acting like an airplane wing, the V creates low pressure above the skis, increasing lift. The ratio of lift to drag shot from 0.8 to 1.4. Now Helge Norstrud of the Norwegian Institute of Technology has gone Boklov one better. To dampen turbulence, which makes the skis vibrate, Norstrud attached a blob of plastic to each tip. Then the skis are “almost like wings,” said world champion Espen Bredesen. The souped-up skis haven’t been approved for Lillehammer.
About 15 years ago, speed skaters started wearing what can only be called a body condom: the skintight Lycra came so close to aerodynamic perfection that air resistance was cut to a minimum. But Mizuno Corp., the world’s largest sporting-goods company, thought it could do better – by emulating the rough skin of a shark. It added raised stripes, made of silicone elastomer and about the thickness of a rubber band. On Dan Jansen’s suit (photo), the stripes run from the neckline across the shoulder to the elbow, and along the outer calf to just above the ankle. These patches of roughness trap a “boundary layer” of air next to the speeding skater, just as the shark’s sandpapery skin traps a boundary layer of water. As a result, there is less of an air pocket – a zone of low pressure – behind the skater to pull him back and slow him down, explains physicist Peter Brancazio of Brooklyn College. In wind-tunnel tests, the stripes cut drag 5 percent.
Skating had seen about as much technological innovation as the toaster: the last breakthrough came 32 years ago, when Canadian Paul Enoch raced in his wife’s nylons rather than the standard baggy, woolen pants and lopped an astonishing three seconds off the world record in the 3,000 meters. Now Finn Halvorsen, former coach of the Norwegian national team, has reinvented the speed skate. “if you’re running with heavy shoes, you run slower, don’t you? Well, it’s the same with skating,” he says. So he replaced the leather boot with one made of Kevlar, a carbon composite used in bulletproof vests, and the hardened steel of the blade with a composite of steel and carbon fiber. The new model weighs 12 to 16 ounces rather than the usual 24. Even more revolutionary, only a sliver of blade shows: air whistling through blade and boot creates drag. Halvorsen’s skate should trim a full second off every 1,000 meters of Olympic racing. (The difference between the gold and the silver medals in the 1,500 meter at Albertville was .04 second.) But don’t look for it this week: when Norway’s Johann Olav Koss (photo), the only skater with a pair of Halvorsens, hurt his heel last year, the skates no longer fit. A new pair could not be made in time for Lillehammer.
