2. An airplane weighing 73.6 kN has elliptic wings 15.23 m in span with no geometric twist and a planform area of 19.8 m2 . For a speed of 90 m/s in steady, level flight at sea level ( = 1.2256 kg/m3 ) calculate the value of the circulation in the plane of symmetry (o), the downwash velocity, w, the induced drag, D, i, the geometric angle of attack, , and the effective angle of attack, eff. Assume that L=0 = -1.2°.