Question

According to A.J. Ward-Smith and D. Clements (1982; Aeronaut. J. 86: 384-391), a ski-jumper can, by control of posture, reach a lift-to-drag ratio of 0.3. Assume that after leaving the jump, a 70 kg jumper descends at 30 degrees below horizontal, at a speed (along the flight path) of 30 m/s, with a plan-form area (including skis) of 0.5 square meters. What fraction of the jumper’s body weight will the lift offset? Assume a drag equivalent to that of a sphere with a frontal area of 0.5 square meters.

Answer 1

Anse- I have seen some Phet simulations, for human They takes it as 0.5-0.6. so assume the value (0.5) and → assuming the density to be lKg/m? beacuse the cold temparature tends to increase they density whereas the highes altitude to decrease the density. find the fraction of the weight than the lift offsets & Feift » W = mx4 Feeft Farag 0.3 F lift = 0.34 Forag > cd= 0.5 → Pal v² = 302 Floag = 0.5X Cd X PX 22 = 0.5X0.5X1 X302 = 225N SO First = 0.3x225= 67,5N a the required, Feift - 67.5 700 cs Scanned ancha. W CamScanner