字幕列表 影片播放 列印英文字幕 There's a lot of nerves and excitement you gain quite a bit of speed in a short period of time. So you start kind of getting like tunnel vision almost. And then when you get into the flying you see the whole mountainside just open up. My name is Anders Johnson and I am the Women's World Cup coach for USA Nordic. He's also a 3 time Olympian in the sport of ski jump a sport that's all about using technique in physics to fly as far as humanly possible. And doing that successfully all comes down to this shape. 100 years ago, Olympic ski jumpers looked like this. Skis were held tightly in parallel. Hands in front of their face, kind of like a less posed version of Superman. By the 1950s, jumpers moved their arms back and to the side. But they kept their skis in the same shape. Everyone did, because... The goal here is to fly farther and with style. Farther because the further you land from this line, the more points you get. And with style because judges award more points on top of your distance score, just for looking cool. And for a while, the best, coolest, most stylish way to ski jump was this. In a straight, elegant line, with skis tight underneath you. This parallel position helped athletes cut through the air — quickly. It was the standard for decades. That is, until the 1980s. This Swedish guy named Jon Boklov. He struggled with keeping his skis parallel but he noticed on some of the jumps that he, you know, opened up his skis a little bit wider into a bigger v he was achieving longer distances. That's because this position allows you to catch a lot more air with your body than this one. You have kind of two key parameters you're trying to optimize: how fast you're moving forward but also how fast you're moving down. Tess Saxton-Fox is an assistant aerodynamics professor at the University of Illinois Urbana-Champaign. My research is on the flow of air really close to the surface of planes. Air flow is key to ski jumping to because... You want to go down as slowly as possible once you're in the air because you want to stay aloft but you want to go forward as fast as you can. Surface area has a lot of power there. The parallel position has fairly low surface area. It makes the athlete as thin and small as possible. This is actually a pretty good aerodynamic shape if you're just trying to maximize your forward speed. You are lining up your body with the skis and so the air can go around the ski and the body at the same time in kind of the same little bubble that it forms around you. And so that's good actually for reducing drag. What its not good at is resisting gravity. It doesn't do much to prevent you from falling through the air to the ground. In contrast, when athletes open their skis up into a V they're maximizing their surface area by allowing air to directly push against their body. Instead of just trying to be like a bullet, you're trying to be a wing. This position helps create something called “lift.” Yeah, lift is a tricky concept. And it's an important concept, it's the basis for, you know, flight. It's what makes planes fly, what makes birds fly. The key is that as the air kind of moves over the body it kind of follows the shape of the body. So you'll see that they're at an angle. And that's actually really important. If you put your hand out the window of a car and you put it straight it just pushes straight backwards. But if you put it on an angle, you can kind of play with it, right? It'll actually push you up, push your hand up and back. That's really what they're doing is they're putting themselves at an angle so that they get a force that actually wants to push them up as well as backwards. This 1995 paper from the Journal of Applied Biomechanics does a great job of showing this graphically. The researchers used computer simulations to test out different ski styles. Most importantly the parallel style, which they refer to as classic style and the V-style. The V-style generated much more lift. This extra lift means that athletes got more air time which in turn allows further distances and, ultimately, more points. When Jan Boklov first implemented the V-style it was ridiculed it for its ugly appearance. The Chicago Tribune described the switch as going from an “elegantly parallel position” to “resembling puppies leaping into a swimming pool.” And Jan lost style points because of it. "Here's the man with a unique style." While he travelled 78 meters in this 1988 jump, he only got 85.4 points. Denis McGrane of the US travelled the same distance but he used the classic method. He got 90.4 points. Somewhere along the lines in the early 90s, people started to notice that it was effective. Other teams and other athletes kind of started to test it a little bit. By the 1992 winter Olympics, the gold medal was given to Finnish skier Toni Nieminen, a 16-year-old who used the V-style. He traveled 122 meters, beating every other athlete on distance. And as more gold medals went to athletes who used the V-style, the old style faded away. It sort of just became, you know, probably one of the biggest progressions in the sport. Today, you'd be hard pressed to find an athlete who doesn't use V-style or a variation on it. But that doesn't mean that there isn't still room to innovate on body shape. One thing that I would be curious about is doing a V the other way. So having the tips more closed and the back more open. There's a lot of kind of research on the stability of having that kind of a triangle shape. I would think it would be a very stable configuration.
B1 中級 美國腔 滑雪(Why ski jumpers hold their skis in a V) 13 1 joey joey 發佈於 2022 年 02 月 10 日 更多分享 分享 收藏 回報 影片單字