Contribution to the Aerodynamics of Rotating-Wing Aircraft

G. Sissingh
naca-tm-921
December 1939


The conventional calculating methods for rotors of rotating-wing aircraft with hinged blades are extended and refined. The chief defect of the investigations up to now was the assumption of a more or less arbitrary "mean" drag coefficient for a section of the blade. This defect is remedied through replacement of the constant coefficient by a function of higher order which corresponds to the polar curve of the employed profile. In that way it is possible to extend the theory to include the entire range from "autogiro" without power input to the driven "helicopter" with forward-titled rotor axis. The treatment includes the twisted rectangular blade and a nontwisted tapered blade. The investigation is based on Wheatley's report (reference 10), which in turn is an extension of the well-known studies of Glauert (references 1, 3, 5) and Lock (reference 2). In the interests of clarity, the principal points of view of these analyses will be briefly reviewed.

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