Lifting Surface Theory For A Helicopter Rotor In Forward Flight

A lifting surface theory has been developed for a helicopter rotor in forward flight for compressible and incompressible flow. The method utilizes the concept of the li near ized acceleration potential and makes use of the vortex lattice procedure. Calculations demon-strating the application of the method are given in terms of the lift distribution on a single rotor, a two-bladed rotor, and a rotor with swept-forward and swept-back tips. In addition, the lift on a rotor which is vibrating in a pitching mode at 4/rev is given. Compressibility effects and interference effects for a two-bladed rotor are discussed .