HIGH-PERFORMANCE LINEAR-QUADRATIC AND H-INFINITY DESIGNS FOR A SUPERMANEUVERABLE AIRCRAFT

Recent efforts by the NASA Langley Research Center have focused on expanding the flight envelope of the F/A-18 aircraft. Of particular concern has been the low speed, high angle-of-attack regime over which the conventional aerodynamic controls of the F/A-18 lose their effectiveness. To address this problem, the F18 high alpha research vehicle (HARV) was developed. This aircraft is essentially a modified F/A-18 that possesses thrust vectoring capabilities and hence increased maneuverability in this flight regime. In this paper, the linear-quadratic-Gaussian/loop-transfer-recovery and H infinity design methodologies are used to design high-performance controllers for the HARV at an operating point within the expanded envelope. In addition, this paper shows how the control redundancy of the HARV can be used to maintain nominal performance, as well as nominal stability, in situations where failures occur.