Question 1: The lift and drag coefficients of a symmetric airfoil are related to its aspect ratio (A,) by the following approximate formula: CL 2 sin(a) 1+ (1) C = Cpoo + (2) (A) a=Angle of attack Cpdrag coefficient of the infinite-span airfoil. A, aspect ratio (L/C) L = airfoil length C=airfoil chord Because the lift coefficient for any airfoil is limited to a maximum value (C), which depends on the airfoil geometry, there is a minimum speed, or stall speed, for the aircraft at which the induced lift just supports the weight of the aircraft. This minimum, or stall, speed is given by: 2W 1/2 CLmax PA (3) V = W = Weight of aircraft A=Lifting surface CLmax = Maximum lift coefficient p = Medium density