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An Extension of Bennett’s Formula for the Profile-Drag Power of Helicopter Rotors

Published online by Cambridge University Press:  04 July 2016

H. Wittenberg*
Affiliation:
Department of Aeronautics, Technological University, Delft

Extract

In ref. 1 Bennett derived the well-known expression for the power required to overcome the profile drag of the rotor blades for a helicopter in forward flight:

The power given by (1) is composed of two parts: the contribution of the torque of the profile drag with respect to the rotor axis and that of the drag of the rotor blades due to the forward motion (H-force).

Several methods for performance calculation of helicopters require the two parts of the profile-drag power separately, as they make use of the equation for the equilibrium of forces in the direction of flight, to which the rotor drag gives a contribution. In this note expressions for the two parts of the total profile-drag power are derived using the same method as indicated in the original work of Bennett. Numerical results are given.

Type
Technical Notes
Copyright
Copyright © Royal Aeronautical Society 1960

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References

1.Bennett, J. A. J. (1933). Zeit. Flugtechn. und Motorluftsch, No. 17, 1933. English translation:—Rotary-Wing Aircraft. Aircraft Engineering, pp. 6567, 79, March 1940.Google Scholar