Postural Changes and Aerodynamic Forces in Alpine Skiing

Abstract

A wind-tunnel experiment was performed to measure the aerodynamic forces acting on an alpine skier running down a slope at top speed and to clarify their relation to his postural changes. Throe wind velocities (10, 20, 30ms−1) were chosen. Two male Japanese top alpine skiers served as subjects. The following results wero obtained: (1) measured values of drag ranged from 11.76 N (10 ms−1) to 256.27 N (30 ms−1). (2) Measured values of lift ranged from 4.9 N (10 ms−1) to 113.68 N (30 ms−1. (3) The aerodynamic advantage of the so-called ‘ egg-shaped ’ posture in alpine skiing has been established. (4) Even at the lowest posture, however, lateral extension of the arm causes a substantial increase in drag (50 N for 30 ms−1 of wind velocity), which is comparable with the increase caused by raising the trunk. (5) For further application, drag area and lift area were calculated. (6) Using the above measured values, the influence of postural changes upon velocity, distance covered and consequent performance are discussed.