Model of Unsteady Aerodynamic Coefficients of a Delta Wing Aircraft at High Angles of Attack

Several approaches for modelling the longitudinal aerodynamic coefficients of a fighter aircraft at high angles of attack, including the unsteady effects are presented. A traditional approach where the model of the coefficient arises in the form of the steady and unsteady effects, the unsteady effect being modelled by means of transfer functions. The second approach uses an internal variable descriptive of the flow field: the vortical state of the flow on the wing. An example of application of this method through neural network model is described. NOMENCLATURE α angle of attack β side slip angle δ control surface position Λ wing sweep angle Ω rotation rate p,q,r roll rate, pitch rate, yaw rate x vortex burst location CN normal force coefficient CL lift coefficient Cm pitch moment coefficient s Laplace variable