An aircraft in steady level flight is shown in below figure. The forces acting on it are (i) the weight, W, acting at the centre of gravity, G (ii) the lift, L, acting vertically upwards, through the...

An aircraft in steady level flight is shown in below figure. The forces acting on it are (i) the weight, W, acting at the centre of gravity, G (ii) the lift, L, acting vertically upwards, through the centre of pressure, C (iii) thrust acting horizontally forwards, (iv) the drag D, acting horizontally backwards and (v) a small vertical balancing force at the tail plane. Its line of action is 9 m behind the centre of gravity.

 In a particular case when W = 129 kN, D = 15 kN, find the tailplane load in magnitude and direction and magnitude of lift. Assuming the position of the centre of gravity to be fixed, find the tailplane load (a) when the centre of pressure and the centre of gravity coincide and (b) when the line of action of the lift is 200 mm in front of the centre of gravity (4.04 kN downwards, 121.64 kN, 1.33 kN downwards and 1.25 kN upwards.)