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Drag Polar

Total drag coefficient is the sum of parasite drag and lift-induced drag — the fundamental performance relationship for an airframe.

Formula

CD=CD0+CL2πeARC_D = C_{D0} + \dfrac{C_L^2}{\pi e AR}

Variables

C_DTotal drag coefficient
C_{D0}Zero-lift (parasite) drag
C_LLift coefficient
eOswald efficiency
ARAspect ratio

Example

CD0=0.02, CL=0.5, e=0.8, AR=8: CD = 0.02 + 0.25/(20.1) ≈ 0.032

Did You Know?

The drag polar plots drag against lift — every airframe has one, and it sets the best glide and cruise speeds.

dragdrag polarperformanceaerodynamics

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