Lift to Drag Ratio Formula

Equation for calculate lift to drag ratio is,

$\mathrm{LD_max}=\frac{1}{2}·\sqrt{\frac{\pi ·A·ϵ}{C_{\mathrm{D,0}}}}$

where,
A = aspect ratio
ϵ = span efficiency factor, a number less than but close to unity for long, straight edged wings
C_D,0 = zero-lift drag coefficient
π = pi (3.141592653589793)
L/D Ratio = Lift to drag ratio