Possibility of Improving Air Permeability Patchwork Ski Jumping Suit Aerodynamics

Abstract

Ski jumping is a sport in which the competitor is judged based on the flight form and flight distance; therefore, ski jumpers attempt to fly as far as possible upon take-off. In general, the ski jumping suit fabric with lower air permeability is considered to be advantageous in lift generation. According to the rules and regulations for ski jumping competitions, the outstretched fabric should have a minimum air permeability of 40 L/m2/s at a water pressure of 98 Pa (10 mmAq). The purpose of this study is to investigate the effect of fabric air permeability on aerodynamic characteristics of ski jumping suits. In this study, wind tunnel experiments were carried out on an elliptic cylinder clothed with ski jumping suit fabrics of different air permeability and with two types of modified fabric made by combining different air permeability (patchwork fabric). The aerodynamic forces acting on the fabric-clothed elliptic cylinder were measured using a three component force balance. The significant lift enhancement occurs and the maximum lift coefficient shows a remarkable increase for the patchwork fabric with high air permeability placed at the front side on the upper surface of the elliptic cylinder.