Experimental determination of the aerodynamic characteristics of ski-jumpers

Summary The aerodynamic pitching moment, lift and drag forces acting on a ski-jumper during the free flight and landing phases were measured using scaled models in a wind tunnel. Comparisons are made between those meaurements and observations of actual ski-jumps. It is shown that the high angles of incidence (typically α varies from 35° to 55°) adopted by ski-jumpers during free flight is determined by the need to prevent tumbling. Over this range of incidence angles, the opposing moments due to weight distribution and aerodynamic pressure distribution are approximately in equilibrium, and small out-of-balance moments can be accommodated by arm movements. The maximum lift/drag ratio on a ski-jumper in free flight occurs at α ≃ 25°. If it were possible to avoid tumbling at low incidence angles, maximum jump lengths would be achieved at α ≃ 8°.