Awing-body model is tested in a wind tunnel with a flow of 100 m/s at standard sea-level conditions the wing area is 1.5 m2 and the mean aerodynamic chord length is 0.45 m. measurements of lift force, l, and moment about the center of gravity, mg are made using the wind tunnel force balance b1 (a) when the lift is zero, the moment about the center of gravity is measured to be, mcg =-12.4 nm. at another angle of attack, the force balance measurements give, l = 3675 n and m 20.67 nm calculate the location of the aerodynamic center (3 marks) and the moment coefficient about the aerodynamic center. (3 marks) b1 (b) a lead mass is added to the rear of the model which moves the center of gravity rearward by 20% of the mean wing chord. calculate mg when l = 4000 n (4 marks) b1 (c) the lead mass is removed and a horizontal tail without an elevator is added to the model. the distance from the airplane center of gravity to the aerodynamic center of the tail is 1.0 m. the area of the tail is 0.4 m2 and the tail-setting angle is 2.0°. the tail has a lift-curve slope of 0.12 per degree. experimental measurements give the downwash in terms of angle of attack, e= 0.42a, i. e. the downwash is zero for zero angle of attack, e = 0 for the case where the angle of attack, a = 5.0°, and the lift, l= 4134 n: (i) calculate mcgc (4 marks) (ii) determine whether the model possesses longitudinal static stability (4 marks) (iii calculate the location of the neutral point and the static margin if h=0.26 (4 marks) bl (d) an elevator is added to the horizontal tail with the property ac /as =0.04 per degree calculate the elevator deflection angle required to trim the aircraft at an angle of attack of 8.0°