INFLUENCE OF A SKI-JUMPER MODEL, SKIS AND SUITS ON AERODYNAMICAL CHARACTERISTICS IN SKI JUMPING

  • Pekka Luhtanen
  • Juha Kivekäs
  • Matti Pulli
Keywords: ski jumping, aerodynamics, wind tunnel, drag, lift, pitching moment

Abstract

Naked 2/3 scale model without and with reference skis, four different pairs of skis and two different suits were evaluated in the 2 * 2 m2 low speed wind tunnel. The tests were car-ried out using 30–35 ms–1 flow speed equaling Reynolds number 2.4 * 106. The positions of angle of attack ranged from -8 degree to +12 degree. Reference position 0-degree equals incidence of 30 degree of plane defined by skis with zero flow speed. The aero-dynamic characteristics were drag, lift and pitching moment, which were transformed into dimensionless coefficients. In general, it can be stated that 60 % of the aerodynamic forces were acting on the body of the model and 40 % on the skis. If the ski area in-creased by 1 % the aerodynamic forces increased 0.4 %. The relative increments in the length of the jump in a K 120 jumping hill with the skis A, B and C were 5.5 %, 6.2 % and 5.1 %, respectively. The effects of variation on air permeability of the suits were on the drag 7–12 % and lift 12–25 %.