A general aviation aircraft has a wing span b 18 meters and

A general aviation aircraft has a wing span b = 18 meters and an aspect ratio AR = 8. In a given equilibrium flight condition, at an equivalent airspeed Veq = 55 m/s, the lift and drag fores are L = 24 kN and D = 3kN, respectively.

(a) Find the life coefficient CL and the drag Coefficient CD

(b) A gust momentarily increases the angle of attack by 0.5 degrees, without changing the equivalent airspeed, resulting in an additional 4 kN of lift. Find the slope of the lift coefficient curve, expressed per degree

Solution

b = 18m
b/c = AR = 8
c = b/AR = 2.25
A = cb = 40.5
rho at sea level (rho) = 1.225
v = 55

Dynamic Pressure = 0.5*1.225*55^2 = 1852.8125
Cl = L/[DP * A] = 24*10^3/[75038.90] = 0.3198
Cd = D/[DP * A] = 0.03997

dCl/d(alpha) = dL/[DP * A]/d(alpha) = 0.1066 per degree