Synthesized Unsteady Airfoil Data with Applications to Stall Flutter Calculations

A compact, semi-analytic method is presented for synthesizing and calculating unsteady two-dimensional airfoil data. The method extends the α, A, B concept while avoiding the need for extensive tabular data. The results of synthesizing the unsteady data of a NACA 0012 airfoil in the form of certain nonlinear functions and appropriate constants are presented. The method is sufficiently general to permit meaningful approximations to the unsteady data of airfoils for which only static data exist. Preliminary results show the synthesized data to be as accurate as the established tabular form of the data. Examples of measured CN and CM loop reconstructions and stall flutter predictions are presented.