ABSTRACT

　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 thebeauty 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 skijumping competition rules, suit fabric must show the air permeability of a minimumof 40 liters per m2/sec under 10 mm water pressure. However, the effect of airpermeability of suit fabric on aerodynamic characteristics has not been completelyclarified yet. The purpose of this study is to investigate the effect of air permeabilityof suit fabric on aerodynamic characteristics. Four types of fabric with different airpermeability are used and the wind tunnel experiments were carried out using thefabric clothed elliptic cylinder. The drag coefficient decreases with increasing the airpermeability. Also, the stall delay occurs for the fabric with high air permeability, andthe lift to drag ratio at the high angle of attack can be improved. Furthermore, it wasconfirmed that the velocity profiles near the surface show the different tendency for different air permeability fabric. It is presumed that the aerodynamic performance ofski jumpers during a flight can be improved by depending on the air permeability ofthe ski jumping suits fabric. The flight distance for each fabric was calculated with theaerodynamic force data assuming that the elliptic cylinder flies. Case-2 with increasedair permeability have longer flight distances than Case-1（ original air permeability）．

DECENTE SPORTS SCIENCE Vol.40/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE