“Can I get L₁ on?” Providing consistent handling qualities on Calspan’s variable-stability learjet

This paper presents a handling qualities assessment of Calspan’s variable-stability Lear- jet aircraft augmented with an L₁ adaptive flight control law. The variable-stability capability of the aircraft was used to alter its apparent dynamics while in flight, allowing the validation of the L₁ flight control law against a set of off-nominal aircraft configurations, some of them with aggressive tendencies to adverse pilot-aircraft interaction. All of these off-nominal configurations were opaque to the control law, and no fault detection and isolation methods were employed. The results demonstrate that the L₁ flight control law was able to recover consistent and safe handling qualities across all configurations. The evaluation also included a series of straight-in landings with two different aircraft configurations. Results which demonstrate the ability of the L₁ flight control law to significantly restore the flying qualities of a baseline Learjet model are presented in the companion paper [1]. The flight tests were conducted by the U.S. Air Force Test Pilot School at Edwards Air Force Base, CA.