Wing polar

Wings of small aspect ratio

For a geometrically flat wing it is possible to assume:

. (4.11)

This expression can be received if it assumes that the sucking force is not realized on the wing leading edge. The formula can be transformed to the following form if it neglects the non-linear additive () we have:

, (4.12)

In such form the formula is used in practice (it coincides to the formula for a flat wing of large aspect ratio)

(For a wing of small aspect ratio , and ; comparing with a wing of large aspect ratio we shall notice that ).

Polar of the first type is called the dependence between coefficients of aerodynamic lift and drag force . As well as induced drag coefficient the polar depends on twist presence on a wing. Therefore we shall separately consider polar for a flat wing and polar for a wing having twist, and we shall conduct the qualitative analysis.

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