The Mechanics of SpeedSkiing
Sayfa 1/6 123 ... SonSon
56 sonuçtan 1 ile 10 arası

Konu: The Mechanics of SpeedSkiing

  1. #1

    Standart The Mechanics of SpeedSkiing

    Speedskiing hakkında popular mechanics dergisinden faydalı bir makale

    Skiing's ultimate speed event is the next best thing to freefall.


    by Charles Plueddeman

    Speed skiing, the pursuit of peak terminal velocity, is the most intense and thrilling of all skiing disciplines. The wind tears at your body and the skis flop wildly as you fight to maintain a tuck position on the radically contoured mountain. You feel a strong surge of acceleration as you hurtle down the steepest portion of the course. Passing through the timing lights, your body punches a hole in the atmosphere that rips the air with a jet-engine roar. Slowing down in the braking area, you glance up at the digital scoreboard and see a speed posting in excess of 140 mph. Any faster and you'd need a parachute.

    The origin of speed skiing dates to 1898, when a Californian, Tommy Todd, allegedly zipped to 87 mph. However, the first official record was set in 1932 when Italian skier Leo Gasperi was clocked at 89 mph by the International Ski Federation (FIS) in St. Moritz, Switzerland. By the 1960s, speed skiing was a professional sport sanctioned by the FIS. In the last Winter Olympics, it was accorded the status of a demonstration sport, although it won't appear in this year's Winter Games in Norway.

    The basic goal of speed skiing is to harness gravity and defeat friction. To this end the equipment is highly specialized. The skis are about 240-cm long, compared to 225 cm for a downhill racing ski and 200 cm for a recreational ski. In addition, the skis are wide and made of wood and steel, which contributes to their hefty 25-lb. weight.

    The extra width helps the skis run flat on the snow and spread out the skier's weight over the largest possible area to reduce friction. To keep the tips on the snow at speeds over 100 mph, the skis are rigid, heavily damped and shaped to cut a low profile for minimal wind resistance.

    While speed skiers use widely available high-performance bindings and boots, they typically fit the bindings with a stiff racing spring and modify the boot cuffs to provide sharp forward lean in the lower leg, which allows the racer to bend low in the tuck position.

    To help air pass smoothly over their bodies, speed skiers squeeze into skintight suits. Last season, the U.S. team began using a new suit developed by Swany USA, of Gloversville, New York. The suit's material is a stretch fabric that's coated with polyurethane to give it density to resist the formation of slipstream bubbles in low-pressure zones along the racer's body. Each suit is custom-cut to fit the racer's tuck position.

    To smooth the airflow around the lower legs, a wedge-shaped fairing made of dense foam fits inside the suit behind each calf from the knee to the boot top. Interestingly, airflow concerns also play a part in glove design. Speed skiers use their hands as the leading edge to break the wind and to act as a controlling rudder. The gloves, also made of stretch material by Swany, have special cuffs that allow air to flow smoothly over the wrists.

    Speed skiers use poles to push off at the starting point and to act as a framework for bracing their arms next to their bodies. The poles are custom-bent to wrap around a skier's torso. Cones fitted to the end of each grip also help to streamline air. According to 26-year-old speed skier Jeff Hamilton, of Donner Lake, California, the speed skier's helmet is his most essential piece of equipment. Hamilton should know. He's currently the second-fastest skier in the world, with a mark of 144.23 mph set last season at Les Arc, France.

    "Each helmet is custom-made to fit the racer's body size and tuck position," explains Hamilton. "It directs wind from the top of the head in a straight line down to the back. A slight change in the shape of the helmet can cause a 1 mph or more difference in top speed."

    Hamilton's helmet is molded in Kevlar and fiberglass by Richard Landingham of Sanjuan Capistrano, California. Some helmets are designed with a fin along the top to increase stability and to allow the racer to steer by moving his head.

    Another essential element is the preparation of ski bases. Hamilton tunes his skis to fit conditions by using a stone grinder to create varied structural patterns and then applying one of several types of wax.

    There are only about 10 speed-skiing courses in the world capable of hosting a World Cup-level event. One of these is the RTS Course at Willamette Pass, near Eugene, Oregon, which will host the U.S. Nationals and a World Cup event this March. Each course must be able to safely produce speeds of at least 170 kph (about 106 mph). The current world record is 145.1 mph, set by Frenchman Phillipe Goitchel in 1993 at Les Arc, France.

    The racer's speed potential is dictated by the location of the starting point, which is typically 300m to 400m above the first timing light. The starting point is determined by race officials after calculating snow and weather conditions, the steepness of the hill and the ability of the athletes entered in the meet. In an effort to promote safety, the FIS has mandated that a start point must be chosen that will not produce a speed above 228 kph (about 142 mph). The rule is intended to encourage athletes to compete for the fastest speed at each event, rather than just gunning for a new record. When a record is set, it is a true accomplishment.

    The RTS Speed Course is 15 meters to 30 meters wide. Skiers study the course before each run and pick the smoothest path to the speed trap: two sets of timing lights set 100 meters apart. To start, the skier simply stands across the fall line of the hill, picks his line, and then jumps to face downhill. From there, gravity and technique take over.

    Since skiers reach top speed in less than 400 meters, initial acceleration is critical. Ski tuning plays an important role here, as does the technique of keeping your skis absolutely flat on the snow and maintaining an optimal tuck position: head low and butt high to create downward pressure. Initially, Hamilton has his hands positioned in front of his helmet, but as he builds speed he gradually extends his arms out about 8 in. in front of his body.

    In less than 15 seconds, acceleration goes from zero to more than 140 mph. The entire run takes just 20 seconds, but it is a very intense 20 seconds with little margin for error.

    A red line in the snow signals the end of the speed trap, and the skier begins the process of slowing down--the most dangerous part of the run. On slower courses, where speeds don't go much above 100 mph, skiers can just stand up and use the wind as a brake. But at 140 mph, you must slowly untuck to dirty the aerodynamics. Below 100 mph, you can carve very wide turns to burn off speed.

    For each round in a multi-day event, the starting point is moved farther up the hill and speeds increase by about 10 kph. There are four to six rounds in a typical meet, and the fastest skier in the final round is the winner.

    Despite its daredevil reputation, the sport is really quite safe. During the 1992 Olympics, only four skiers fell out of 450 attempted runs.

    Defying the best efforts of the FIS, speed skiers continue to bump the world speed record upward at sanctioned meets. Is there a limit to speed on the snow?

    "There's still more hill to climb at Les Arc," says Hamilton. "With perfect conditions, I think 150 mph or a little more is possible with today's gear and rules."



    kaynak: http://www.speedski.com/PopularMechanics.htm

  2. #2

    Standart Ynt: The Mechanics of SpeedSkiing

    bende geçen sene hız denemeleri yaptım. çok harika bir duygu. ama hızda olan bir kişinin düşmesini hayal edemiyorum. :o
    sadece snowboard...

  3. #3

    Standart Ynt: The Mechanics of SpeedSkiing

    Video gerçekten süper ,

    Normal pistte kayarken ne kadar hızla kaydığımızı ölçen bir alet ya da bu hizmeti olan kayak tesisleri varmı dır ?

    Şimdi çok erken ama ileride ölçmek isterim

  4. #4

    Standart Ynt: The Mechanics of SpeedSkiing

    Kola takılan GPS'ler var, maximum süratinizi ölçer, bende var, nereden aldığımı hatırlamıyorum, ama Avrupa'dan. Markasını bir ara bildiririm.

  5. #5

    Standart Ynt: The Mechanics of SpeedSkiing

    Kola takılabilen GPS'in internet adresi:
    www.navman.com
    Türkiye'ye shipment yaplılıyor gibi.
    Online shopping/GPS/sport tool'da görülebilir, üçgen olanlar...
    Max hızınız, kaç km kaydınız, irtifa kaybınız nedir vb. birçok bilgiyi veriyor.
    Ayla

  6. #6

    Standart Ynt: The Mechanics of SpeedSkiing

    Alıntı memet1987 Nickli Üyeden Alıntı
    bende geçen sene hız denemeleri yaptım. çok harika bir duygu. ama hızda olan bir kişinin düşmesini hayal edemiyorum. :o
    [ame="http://www.youtube.com/watch?v=qbj41CQhz78&feature=re lated"]YouTube - Speed Skiing & Crash[/ame]

  7. #7

    Standart Ynt: The Mechanics of SpeedSkiing

    ski olayı tamamdır da speed e gelemicem şimdilik )))))))))))
    prof. arkadaslara yararlı bir makale yinede paylaştığın için teşekkürler

  8. #8

    Standart Ynt: The Mechanics of SpeedSkiing

    İsveç speedski team antremanından görüntüler
    http://www.grimm.nu/swecup0802/

  9. #9

    Standart Ynt: The Mechanics of SpeedSkiing

    Güzel, bu arada tulum ve kasklar POC marka İsveç malı ya...

  10. #10

    Standart Ynt: The Mechanics of SpeedSkiing

    Arkadaşlar yakında çok deli bir rekor gelebilir
    eski rekortmen Harry Egger için RedBull'un yaptıklarına bir göz atın derim.
    Özellikle de "Emma" denilen sırt koruması-kask kırmasına, paraşütü bile var
    http://www.harryegger.com/#page=Arti...2-1444746933.1

Sayfa 1/6 123 ... SonSon

Yetkileriniz

  • Konu Acma Yetkiniz Yok
  • Cevap Yazma Yetkiniz Yok
  • Eklenti Yükleme Yetkiniz Yok
  • Mesajınızı Değiştirme Yetkiniz Yok
  •