ski jumping in the eastern u.s.a.

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Harris Hill in Brattleboro, VT during the 75th anniversary competition, Feb. 1997.

Facts about Ski Jumping hills Impress your friends with facts and jargon about ski jumps. When you look up at the landing of a ski jump, it looks almost vertical. You can win bets from your friends by asking them to guess the steepness, you will hear guesses like sixty degrees when in fact the steepest landing hill in the eastern U.S. is only about 38 degrees, and new large hills are being built at 35 to 36 degrees. A Little Terminology: Starting at the top of the jump, the skier puts on his skis and gets into the start. In the early days, there was just one start, a platform at the top. Later, several platforms were used at different heights as a way to regulate takeoff speed.

Current practice is to use bar starts with platforms on the side where the skiers put on their skis. The bar start has a wooden beam or metal pipe spanning the track and supported on both sides of the track. The skier sits down on the bar and slides sideways until he is at the center of the track. When the hill is clear, he shifts his weight forward, slips off the bar, and settles into the track. The best start bars are counterbalanced and pivot up out of the way. The jump at the right, in Reit im Winkl, Germany, has a good, up-to-date start arrangement. The side platforms are as long as jumping skis, with stairs running up the backs of the platforms. Two lower start bars are visible, pivoted up and leaning away from the track. The seven lowest platforms, not recently used, are buried in snow.

The skier gathers speed as he zips down the inrun to the takeoff. The track is one half to one inch deep in hard snow. The first part of the inrun is straight with an angle of 28 to 36 degrees. The next section is a transition curve leading to the takeoff. This curve is usually a circular arc and its radius is limited by the rules for ski jump design. The radius of this curve is denoted by R₁ and because there is also a transition below the landing, people simply refer to the inrun transition as R₁ (in the same spirit, the transition below the landing is frequently called R₂).

If you let cartoon illustrations be your guide, you might think that the takeoff shoots the ski jumper up into the air -- not so! Takeoffs actually angle downward at 7 to 12 degrees. And the track is not curved all the way to the end of the takeoff, the last section is straight. The rules for ski jump design prescribe that the length of the straight part of the takeoff (the table) be chosen so that the skier traverses it in one quarter of a second.

At the edge of the takeoff (the lip) the jumper leaps up and out in a subtle and difficult compromise between wanting maximum upward thrust and wanting never to have his body in a full vertical position. The air resistence encountered by a vertical head and chest erodes the skiers forward velocity and cuts precious meters off his jumping distance, so he tries keep the chest low and still exert great thrust with the legs.

In the old days, ski jump landings were flat just ahead of the takeoff, then rolled over abruptly at the knoll and ran straight down to the transition. This was bad design; today the landing will have no noticable knoll, instead it will have one smooth curve, almost to the top of the transition. The K point on the landing marks the place where the bottom of the landing meets the top of the transition (R₂). Until just a few years ago, hill size was designated by the distance to the norm point P which is approximately 80% of the distance to K. For example, the 70 meter Olympic jump in Lake Placid became the K-86 without physical modification. In writing or conversation, people often include the "K" to make sure that it is understood that they are using the new designation.

The most recent design rules permit no straight section on the landing. Instead, the the landing curves down to a

(Photo - Carol Keck)

steepest point at P, and then very slowly become less and less steep down to K and beyond. This permits safe landing considerably past the K point. The V- style (right) originated in the late 1980's by Swede Jan Bocloev gives jumpers increased aerodynamic lift. Skiers who use good aerodynamics can land gently on portions of the landing where the angle is less than 30 degrees.

The ski jumper flies over the landing in an aerodynamic position, trying to get some lift from his body and skis while keeping his forward drag as low as possible (another compromise).

The height of a jumper above the landing depends on the skill and style of the jumper and on the design of the hill. There are hills where a jumper can fly 400 feet but never be higher than six feet above the landing. On the other hand, a hill can be designed with a high takeoff and with the landing dropping away steeply below the takeoff, where jumpers might be more than twenty feet above the landing. First-time specators are often surprised at how low the jumpers fly. Ideal snow conditions on a landing hill consist of a perfectly smooth base of very hard snow covered by a half inch to one inch of fast granular snow.

According to the rules, jumps are now tolerated about ten percent past the K point. If jumpers fly too far, the takeoff speed is reduced by using a lower start. The jumpers goal, of course, is to fly as far down the hill as possible, then land gracefully and ski through the transition to come to a safe stop before the end of the outrun. Hill size is designated by the distance in meters from the takeoff to the K point. A measuring tape is stretched from the edge of the takeoff downward through the air until it meets the knoll on a tangent. Then the tape is laid along the landing surface down to K. This tape is also used to measure the distance of each jump. The distance of a skiers jump is marked at a point directly under the ski boots when the entire skis contact the snow. The distance measurers must be careful not to be misled when the tails of the skis drag before the jumper lands.

Next, meet some great Ski Jumpers of the present and the recent past.