Unsteady lifting surface theory applied to a propeller and helicopter rotor

This thesis is concerned with the development of a theory for determining the aerodynamic forces for unsteady, compressible subsonic flow on a propeller and helicopter rotor. The acceleration potential method was used in developing the basic equations and the method has been programmed for the propeller on a computer and some results are given. The integral equations was solved by the doublet-lattice method, which consists of placing "load" lines at certain locations on the chord and satisfying the down-vash condition at other selected positions. The examples presented include the spanvise and chordwise loading on a rotating propeller for incompressible flow, an example of compressible flow calculations and finally, a calculation illustrating the loss of aerodynamic damping of a propeller blade due to the passage of the blade over its own wake.