Question

A wing-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 m^2 and the mean aerodynamic chord length is 0.45 m. Measurements of lift force, L, and moment about the center of gravity, MCG are made using the wind tunnel force balance.

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, ε = α 0.42 , i.e. the downwash is zero for zero angle of attack, 0
ε = 0

For the case where the angle of attack, α = 5.0°, and the lift, L= 4134 N:

(i) Calculate MCG
(ii) Determine whether the model possesses longitudinal static stability. Calculate Mo
(iii) Calculate the location of the neutral point and the static margin if h = 0.26.
(iv) An elevator is added to the horizontal tail with the property / 0.04 L E T
∂ ∂ = C δ per degree.

In two ways calculate the elevator deflection angle required to trim the aircraft at an angle of attack of 8.0°. Answer should be the same.

Answer 1