Oswald Span Efficiency Factor Calculator

Aircraft Drag Polar Modeling: Calculate Oswald span efficiency ($e_0$), planform factor ($e_{plan}$), and induced drag coefficient factor ($K$).

Aspect Ratio $AR$:

Taper Ratio $\lambda = c_t / c_r$:

Quarter-Chord Sweep $\Lambda$ (°):

Wingtip Device:

Fuselage Interference Class:

Oswald Factor ($e_0$)

Aerodynamic Rating: --

Drag Polar Factor ($K$)

C_Di = K · C_L²

Wing Planform Efficiency ($e_{plan}$)

Optimum taper: ~0.35 - 0.45

Induced Drag Multiplier

+-- %

Ideal Elliptic K: --

Raymer & Howe Formulations:

• Drag polar equation: $C_D = C_{D0} + K C_L^2 = C_{D0} + \frac{C_L^2}{\pi AR e_0}$.

• Oswald $e_0$ combines inviscid non-elliptic span efficiency ($e_{plan}$) with viscous profile drag increase at high lift coefficients.

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