申論題

3. The drag on the airplane shown in the following figure cruising at 240 mph in standard air is to be determined from tests on a 1:20 scale model placed in a pressurized wind tunnel. To minimize compressibility effects, the airspeed in the wind tunnel is also to be 240 mph. Determine

(1) The required air pressure in the tunnel (assuming the same air temperature for model and prototype) (use Reynolds number similarity)