Performance factors in ski jumping

Abstract

Predominant performance factors in ski jumping are: High in-run velocity, high linear momentum perpendicular to the ramp at take-off due to the jumping movement and the utilisation of aerodynamic lift, accurate timing of the take-off jump with respect to the edge of the ramp, appropriate angular momentum at take-off in order to obtain an aerodynamically advantageous and stable flight position as soon as possible, choice of advantageous body and equipment configurations and angles of attack during the entire flight in order to obtain optimum lift and drag values and the ability to control the flight stability. After the transition from take-off to the flight phase the pitching moment has to be balanced close to zero (1) in order to avoid tumbling accidents; this can become extraordinary difficult when gust or other disturbing effects occur. During the flight, the gravitational force F g , the lift force F l, and the drag force F d act upon the athlete and his equipment and determine the flight path of the centre of gravity of a ski jumper with a given set of initial conditions and parameters. During the flight phase the athlete’s position changes. The athlete can strongly influence the aerodynamic forces by changing his posture. He can affect the drag force, the lift force and the torque; the latter enables him to change his flight position and angle of attack with respect to the air stream.