e AR} Hence D_i = \frac{L^2}{\frac{1}{2} \rho_0 V_e^2 S \pi e AR} Where: AR \, is the aspect ratio , C_{Di} \, is the induced drag coefficient (see Lifting-line theory ), C_L \, is the lift coefficient , D_i \, is the induced drag, e \, is the Oswald efficiency number by