NONLINEAR VORTEX FLOW-CONTROL FOR HIGH-ANGLE-OF-ATTACK MANEUVERING

The research covered in this paper explores the feasibility of expandi ng the flight envelope of a modified VISTA F-16 to higher angles-of-at tack through forebody vortex flow control. The forebody vortex system is controlled with a pneumatic (blowing) forebody control system. The vortex blowing system is driven by nonlinear control laws that are der ived using Variable Structure Control and describing function techniqu es. Nominal stability, robust stability, limit cycle, and nonlinear pe rformance analyses are performed to examine control system performance . Results reveal that additional yaw control power from the blowing co ntrol system provides significant improvement in high-a performance.