Aerodynamics of ski jumping flight and its control: I. Experiments

In a ski jumping competition, it is essential to analyze the effect of various posture parameters of a ski jumper to achieve a longer flight distance. For this purpose, we construct a model of a ski jumper by using three-dimensional surface data obtained by scanning a ski jumper’s body (Mr. Chil-Ku Kang, member of the Korean national team). An experiment on this model is conducted in a wind tunnel. We consider four posture parameters (forward leaning angle, ski opening angle, ski rolling angle, and ski spacing) and measure the drag and lift forces for various flight postures at various angles of attack ($\alpha$ = 0$^{\circ}$ - 40$^{\circ}$) and Reynolds numbers (Re = 5.4 $\times$ 10$^{5}$ - 1.6 $\times$ 10$^{6}$) based on the length of the jump ski. Then, we derive optimum values of posture parameters for maximum lift-to-drag ratio using a response surface method. We also conduct a full-scale wind tunnel experiment with members of the Korean national team and confirm the results obtained from the experiment on the model.