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Drag Polar Calculator

Work out drag polar instantly with clear inputs, formula shown and shareable results.

About Drag Polar Calculator

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)).

Formula

Drag polar

CD = CD0 + CL^2 / (pi x AR x e); (L/D)max = 1 / (2 x sqrt(K x CD0))

Worked example

With the default values below, Drag Polar Calculator returns Total drag coefficient of 0.03694. Change any input above and every figure here is recalculated in your browser.

Inputs used

Zero-lift drag coefficient
0.024
Lift coefficient
0.5
Aspect ratio
7.5
Span efficiency
0.82

Results

Total drag coefficient
0.03694
Induced drag coefficient
0.01294
Lift-to-drag ratio
13.536
Maximum achievable L/D
14.187

Step by step

  1. 1Values used
  2. 2Drag polar
  3. 3Total drag coefficient= 0.03694
  4. 4Induced drag coefficient= 0.01294
  5. 5Lift-to-drag ratio= 13.536
  6. 6Maximum achievable L/D= 14.187

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • 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.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

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.

Frequently Asked Questions

Where does maximum L/D occur?

At the lift coefficient where induced drag equals zero-lift drag, CL = sqrt(CD0 / K). That condition is also best glide speed.

Is the parabolic polar accurate?

It is good through the normal cruise and climb range but breaks down near the stall and at transonic speeds where compressibility drag appears.

Related Calculators

Drag Polar Calculator – Calculate Total drag coefficient