Flight Assessment of Pilot Behavior with Smart-Cue and Smart-Gain Concepts Active

*Modern fly-by-wire airframes are often designed to have relaxed static stability or unstable configurations in the pitch axis. Augmentation is then used to obtain the desired response and corresponding handling qualities. When control surface rate limiting is encountered, the pilot may be instantaneously exposed to the reduced stability or unstable configuration. The Smart-Cue and Smart-Gain concepts were developed as a means to alleviate pilot-vehicle system loss of control in the presence of control surface actuator rate limiting. Both concepts exploit the measure of dynamic distortion, i.e., the difference between the actual and an ideal aircraft control system response. This paper examines the cruise pitch axis flight test evaluations conducted using the Calspan Corporation Learjet II In-Flight Simulator. In this paper, the results from three test pilots will be examined. In general terms, the pilot group included a low gain, high gain, and golden arm pilot. These pilots evaluated various Smart-Cue and Smart-Gain implementations while performing a continuous closed-loop sum-of-sines tracking task. As revealed through pilot ratings and corresponding comments and analysis of pilot-vehicle system behavior, performance improvements were seen using the Smart-Gain alone and several Smart-Cue alone configurations. The standout configurations, however, were a combination the Smart-Cue and Smart-Gain. For two of the three pilots the performance and ratings with this combined configuration approached or matched those seen for the baseline (i.e., no rate limiting) configuration.