Answer Happy

In a pressurized wind tunnel test of 1/4-scale aircraft, the mean chord is 15 cm, the wing span is 80 cm, the attack angle is 5', the air speed is 28 m/s, the pressure is 10 times of the atmosphere, and the temperature is the same as the standard condition. The measured lift and drag forces are 400 N and 35 N, respectively. The schematic diagram of test results at different attack angles are shown in Figure 3. a. L Ср θα 50 10° Figure 3 (a) Determine the lift and drag coefficients. (6 marks) (b) Determine the speed of real-size flight that the wind tunnel test simulates. (4 marks) (c) Determine the maximum weight of the real-size aircraft of which a cruise flight can be sustained by the speed obtained in part (b). (5 marks) (d) Determine the output power of engine of the real-size aircraft in the cruise flight in part (e). (5 marks) () Suppose the aircraft is initially in cruise flight at a = 5º. Someone claims if the pilot increases a to 8º and keep the same output power of engine in part (d), the aircraft will ascend. Do you agree? Justify your answer. (5 marks)