The influence of air friction in speed skating.

With the use of a wind tunnel the air friction force Fw on six speed skaters of different body builds was measured. The dependence of the drag coefficient CD on air velocity v and the influence of different skating postures on drag were investigated. At an air velocity of v = 12 m/sec, an angle between upper and lower leg of 110 degrees and a horizontal trunk position, the measured air friction constant kn(=Fw/V2) of all subjects was calculated from their height l and weight m according to the formula 0.0205 l3 square root m (standard error 2%). CD and as a consequence k appeared to be strongly dependent on air velocity. Expressions to correct k for other velocities and postures were derived and substituted into a power balance by which the influence of posture, ice condition, wind and altitude on performance was predicted.