An Analytical Formulation for Lifting Rotor Induced Power

A concise analytical formulation for lifting rotor induced power is developed based on a quadratic algebraic model expressed in terms of the principal rotor angle variables - collective pitch, angle of attack, and blade twist. The model coefficients, termed power constants, are based on non-uniform inflow and contain the principal induced power characteristics of a lifting rotor. The power model manifests the complex induced power characteristics missing from traditional uniform inflow theory. The model is expanded to include rotor shaft torque and H-force components to enable solving the rotor trim equations for the rotor angle variables and thus fully determine the rotor induced power for specified operating conditions. Uniform inflow power constants are provided to compare with and help interpret the non-uniform inflow model. The calculated results are compared with power constants obtained from regression analysis of full-scale rotor experimental data. Although the experimental data reflects airfoil drag and stall, the non-uniform inflow power constants were confirmed as generally accurate.