Flight Evaluation of an Integrated Control and Display System for High-Precision Manual Landing Flare of Powered-Lift STOL Aircraft

This paper describes a combined display and control system to provide high-precision manual landing flare and touchdown, and presents the results of a preliminary flight evaluation using the NASA Quiet Short-Haul Research Aircraft (QSRA). A head-up display presents flare commands to the pilot, who executes a simple, repeatable nominal flare maneuver. Height and height rate errors relative to the desired trajectory are fed back to a low-authority (± 0.05g) direct-lift-control system that drives spoilers and throttles so as to null the errors resulting from gusts and pilot deviations. This integrated cockpit display and closed-loop control constitutes a trajectory augmentation system that extends the QSRA flight control from augmentation of attitude, flightpath angle, and airspeed (previously reported) to augmentation of the trajectory itself. The pilot can easily over-ride the low-authority closed-loop control, and a monitored simplex system is adequate for safety. Touchdown dispersion was achieved that is approximately equal to that obtained during aircraft carrier trials of this same aircraft (± 18 ft). The pilots were hooded to touchdown, and rated the flare and landing task as satisfactory to adequate using the Cooper-Harper scale. Additional work is needed to extend the statistical data base and to cover a greater range of atmospheric disturbances. Although these evaluations were performed in the context of STOL operations with a powered-lift transport (6-degree approach at lift coefficient 5 to landing in a 200-ft long touchdown zone on a 100-ft wide × 1700-ft long STOL runway), the results are considered broadly applicable to all highly-augmented vehicles with head-up displays operating in environments where high-precision guidance is available, whether ground-based or autonomous.