Numerical Virtual Flight Simulation of Quasi-Cobra Maneuver of a Fighter Aircraft

Abstract

By using a computational-fluid-dynamics-based numerical virtual flight (NVF) simulator, a simplified quasi-Cobra maneuver of a typical third-generation fighter is simulated and the unsteady aerodynamics, such as the dynamic forces and moments and the flow separation, are analyzed preliminarily. The NVF simulator integrates an unsteady Reynolds-averaged Navier–Stokes (RANS) solver on dynamic unstructured/hybrid grids, a rigid-body dynamics solver, and user-defined flight control system. To analyze the complex multiphysics coupling problem, four cases with increasing complexity are studied, including 1) static state simulation; 2) one-degree-of-freedom (1-DOF) forced pitchup; 3) 1-DOF pitchup by open-loop control of the elevators; and 4) three-degree-of-freedom (3-DOF) quasi-Cobra maneuvering. By applying a cosine function open-loop flight control law to the elevators and introducing a simplified vector thrust model, the fighter can pitch up to a high angle of attack from the cruising state, and then it can pitch down quickly, the whole process is similar to a Cobra maneuver. Even though the RANS simulations are not necessarily highly accurate for the large angle of attack, the multidisciplinary application in this work demonstrates the potential of the NVF simulator for the simulations of realistic poststall maneuvers.