State-space unsteady aerodynamic theories for rotating wings in two and three dimensions

A high quality two-dimensional incompressible finite-state induced-flow model is presented. The model for the flow around thin airfoils with arbitrary airfoil motions is derived directly from potential flow theory. Solutions of the compact, closed-form finite-state equations are in excellent agreement with theories of Theodersen, Wagner and others. This hierarchical model works very efficiently with only few states. A theory, previously developed in three dimensions, is extended to induced flow off of the lifting disk in all three velocity components. Results of finite state model in three dimensions are compared with results of the vortex-lattice model.