Identification of an unsteady aerodynamic model at high angles of attack

A state-space representation for unsteady aerodynamics up to stall range is presented in this paper. The model consists of the description of the state of flow separation and vortex burst, and the determination of aerodynamic coefficients from the state and input variables. First order differential equations a,re used to model the dynamics of flow separation and vortex burst, and the Taylor scries expansions in terms of input variables are used for the determination of aerodynamic coefficients, resembling the current representation of stability derivatives. The minimum meansquare error approach is used to identify the unknown parameters in the model from wind tunnel data. The identifiability of the parameters and the performance of the model are demonstrated by using the wind tunnel measurements of an airfoil, a flat delta wing and, finally, a realistic aircraft. The results show that within the framework of the proposed model, it is possible to analyze more complex unsteady aerodynamic problems in high angle-of-attack regime for an aircraft.