Nonlinear aerodynamic effects on static aeroelasticity of flexible missiles

The study presents a novel computationally efficient methodology for assessment of static aeroelastic effects on flexible missiles. The Nonlinear Strip Method (NSM) is based on the coupling of a structural modal model with a database of nonlinear aerodynamic force coefficients provided at strips over the missile’s length. An iterative process com-putes the local elastic angle of attack at each segment from the missile’s deformed shape. A segment’s aerodynamic force is computed from the segment’s angle of attack and the rigid force coefficient from the database. Generalized aerodynamic forces are computed from the segments’ aerodynamic forces and used to compute the deformed shape. The process is repeated to convergence. The advantage of the NSM is that it is based on a database of rigid aerodynamic force coefficients, which is typically available either from CFD analyses or wind-tunnel experiment. It accounts for nonlinear aerodynamics, with-out relying on computationally elaborate aeroelastic CFD-based analyses. The NSM can be used to compute the elastically deformed shape of a flexible missile and asses its effect on the missile’s stability early on in the design process. The methodology is demonstrated on a generic, flexible air-to-air missile configuration at Mach numbers of 1.2 and 2.0 and a range of angles of attack. A full nonlinear aeroelastic simulation in a CFD code is used to assess the accuracy of the NSM. A reference linear aeroelastic analysis, based on a panel code, is used to demonstrate the significance of accounting for nonlinear aerodynamics in computing missile stability at these flight conditions.