2019 Volume 40 Pages 72-80
Ski jumping competition is a sport that competes in term of the total point of "Distance Point" that digitizes the flight distance and "Judges Point" that digitizes the beauty of flight attitude and landing, and ski jumpers attempt to fly as far as possible. In competition, there are many regulations to ensure fairness. In the international ski jumping competition rules, suit fabric must show the air permeability of a minimum of 40 liters per m2/sec under 10 mm water pressure. However, the effect of air permeability of suit fabric on aerodynamic characteristics has not been completely clarified yet. The purpose of this study is to investigate the effect of air permeability of suit fabric on aerodynamic characteristics. Four types of fabric with different air permeability are used and the wind tunnel experiments were carried out using the fabric clothed elliptic cylinder. The drag coefficient decreases with increasing the air permeability. Also, the stall delay occurs for the fabric with high air permeability, and the lift to drag ratio at the high angle of attack can be improved. Furthermore, it was confirmed that the velocity profiles near the surface show the different tendency for different air permeability fabric. It is presumed that the aerodynamic performance of ski jumpers during a flight can be improved by depending on the air permeability of the ski jumping suits fabric. The flight distance for each fabric was calculated with the aerodynamic force data assuming that the elliptic cylinder flies. Case-2 with increased air permeability have longer flight distances than Case-1 （original air permeability）．
