The Structural Composition of the Jump
To most spectators that have little knowledge of ski jumping
it appears as a pretty crazy thing to do for fun. Flying the
length of 1-2 football fields in the air with out pads does
not seem very sane. But the immense amount of planning and
engineering that goes into designing the jumps makes ski
jumping relatively safe. There are two parts to a jump, the
in-run and the landing. The way these two pieces of the jump
work together make it possible for the athletes to "defy
gravity".
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State of the art jump
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The In-Run
The In-Run is the upper portion of the jump where the jumpers gain speed. The in-run is a crucial part in the design of the jump.
At the top of the jump, the jumper will
slide out onto a metal or wooden bar which is about 1.5 feet
above the actual track. This is called the start. Once the
go ahead is given and the jump is clear, the jumper will
lean forward and start down the track. In modern day jumps
the initial slope of the jump is in between 28°and 36°, this
doesn't seem like much on paper but it is actually extremely
steep. The portion between the takeoff and the upper portion
of the in-run is called the transition. It is the shape of a
arc of a circle. This portion of the track will exert G's
that are up to twice the weight of the jumper. The takeoff,
contrary to popular belief, does not slope up. It actually
has a slope down between 8° and 12°, if the takeoff were
sloped up the the jumper would fly higher but not farther.
This it would make the jump much more dangerous.
The Landing portion of the jump can be different for every single jump. One jump could have a landing that does not drop off after takeoff and never lets the jumper fly higher than 6 feet off the ground. While another jump could have a landing that drops off very quickly and the jumper can be more than 20 feet above the ground. In the Olympics there are two sizes of jumps the K90 and the K120, there are smaller jumps that juniors and kids will use, starting at K10. The 'K' point of a jump is where the concavity of the landing changes, it is normally around 30°. This point is set as the par for jump. If you jump farther than the 'K' point you gain points for every meter past 'K' you are and you are deducted points for landing behind it. 'K' is measured from the lip of the takeoff to the critical point. The 'K' for every jump can be at a different length but will always be somewhere around 90m or 120m because there are different sized jumps.
The shape of the landing is designed specifically for safety and maximum flight length. Once a jumper is in the air they are a projectile and their path can be calculated using rather simple physics. Hills are designed to initially mimic the flight path of the jumper so they stay about the same height above ground at all time. If your were to watch a jumper from the side, the ground would appear to be falling away in the same path. After the 'K' point, the landing is designed so that the jumper can land safely and their kinetic energy will dissipate leaving the jumper with little impact. In the old jumps that were built jumpers would experience impact similar to a 12 ft free fall. Today, with the new advancements in jumps, the jumpers experience and impact close to that of jumping off a 3 ft table.
The Landing
The Landing portion of the jump can be different for every single jump. One jump could have a landing that does not drop off after takeoff and never lets the jumper fly higher than 6 feet off the ground. While another jump could have a landing that drops off very quickly and the jumper can be more than 20 feet above the ground. In the Olympics there are two sizes of jumps the K90 and the K120, there are smaller jumps that juniors and kids will use, starting at K10. The 'K' point of a jump is where the concavity of the landing changes, it is normally around 30°. This point is set as the par for jump. If you jump farther than the 'K' point you gain points for every meter past 'K' you are and you are deducted points for landing behind it. 'K' is measured from the lip of the takeoff to the critical point. The 'K' for every jump can be at a different length but will always be somewhere around 90m or 120m because there are different sized jumps.
The shape of the landing is designed specifically for safety and maximum flight length. Once a jumper is in the air they are a projectile and their path can be calculated using rather simple physics. Hills are designed to initially mimic the flight path of the jumper so they stay about the same height above ground at all time. If your were to watch a jumper from the side, the ground would appear to be falling away in the same path. After the 'K' point, the landing is designed so that the jumper can land safely and their kinetic energy will dissipate leaving the jumper with little impact. In the old jumps that were built jumpers would experience impact similar to a 12 ft free fall. Today, with the new advancements in jumps, the jumpers experience and impact close to that of jumping off a 3 ft table.
