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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 or, these days, more likely solid ice. At the elite level, jumps are likely to have a refrigerated track -- no more wet, slow tracks for the best jumpers in the world. 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. To confuse matters even further, an even newer hill size designation has been adopted, "HS" for "Hill Size" is the distance to a new point L which is past K. We describe L below.
The most recent design rules permit no straight section on the landing. Instead, the landing curves down to a
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 spectators 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 jumper's 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. The size of a hill is designated ambiguously, either by the distance in meters from the takeoff to the K point, or by the distance HS to the point L, which is past K. For example, the Large Hill for the 1972 Olympics in Sapporo, Japan, was called a P-90 at the time, and K was 110 meters from the takeoff. Modern changes to the landing (filling the bottom with soil to reduce the steepness) naturally increase the distance to K. In 2012, the same ski jump is called a K-120 or HS-134, and the distance record on that hill is 145 meters.
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. (No, it isn't there during the jumping -- it is removed after the distance marks are established along both sides of the landing.) The distance of a skier's jump is marked at a point directly under the ski boots when that portion of the ski contacts the snow. Today's jumping skis have very flexible front sections that curve up during impact and slap down on the snow after the boot area is down. The distance measurers must be careful not to be misled when the tails of the skis drag before the jumper lands. For top level competitions, FIS rules now require video measuring. Several small TV cameras set up along the landing feed video images to a computer where the operator uses instant replay to determine the precise moment of landing. The operator clicks on the point of impact and the computer, which was calibrated earlier, instantly calculates the jump distance and relays it to the scoring computer and the score board. Human measurers remain in place only as a backup.
Next, meet some great Ski Jumpers of the present and the recent past.