The lift coefficient, also: lift coefficient, is a dimensionless coefficient for the dynamic buoyancy of a body in flow of a fluid. It is an important parameter in the characterization of profiles in the fluid dynamics. In formulas is usually chosen the abbreviation for the lift coefficient in the German language, in English texts it is ( l for lift ) or.
The lift resulting from the buoyancy force, normalized to the ram and the reference surface ( reference surface profiles at the blade surface, the end face is selected in vehicles ):
The lift is as other aerodynamic coefficients, eg the drag, depending on the orientation of the body in the flow, expressed by the angle of attack. The ratio between the two above-mentioned Beiwerten depending on the angle of attack is given by the polar diagram, also briefly called Polar. This relationship is clearly different for different profile shapes.
As in profile polars the values of the infinitely long wing are always shown, has the value of the extended wing are adjusted using the following formula ( reduction, as the break is always):
With the aspect ratio (lambda ).