Pitch Control Law Analysis and Flight Test Demonstration of an Executive Transport Aircraft

Gulfstream is using the Advanced Flight Controls Research and Development Program to develop flight controls technology, including a pitch axis flight control law design applicable to an executive transport aircraft. The program includes fly-by-wire modifications to an existing airframe and flight testing of the integrated system. The flight control law 3333development process utilized has been presented elsewhere. This paper describes results of flight testing, analysis of the flight data, and linear analysis results. Illustration is presented that the closed-loop aircraft meets the design requirements in the areas of civil certification, control science stability, piloted aircraft handling qualities, and aero-servoelastic coupling. The highly integrated design approach allows for simultaneous compliance with the criteria in these areas by operating on condition-specific linear properties of the aircraft rigid-body dynamics, the aircraft sensor and control system dynamics, including time delay, and the aircraft flexible body modes. With flight testing complete, the design data and design methods are verified by comparison with flight results. This paper also describes the extended linear analysis of the pitch control law with weight and center of gravity variations using linear matrix inequality optimization. Some of these analysis results are illustrated.