Work out drag polar instantly with clear inputs, formula shown and shareable results.
The parabolic drag polar splits drag into a lift-independent part and an induced part that grows with the square of lift coefficient: CD = CD0 + K x CL squared, with K = 1/(pi x AR x e). Maximum L/D occurs where the two parts are equal and equals 1 / (2 x sqrt(K x CD0)).
Drag polar
CD = CD0 + CL^2 / (pi x AR x e); (L/D)max = 1 / (2 x sqrt(K x CD0))
Aviation results are planning estimates only. Always verify take-off, landing, fuel, weight and balance figures against the certified Aircraft Flight Manual, current performance charts and applicable aviation regulations before flight.
At the lift coefficient where induced drag equals zero-lift drag, CL = sqrt(CD0 / K). That condition is also best glide speed.
It is good through the normal cruise and climb range but breaks down near the stall and at transonic speeds where compressibility drag appears.