Robust Use of Horizontal Stabilator in Feedback Control on a UH-60 Black Hawk

The present study proposes an augmentation to the existing control mixing on the UH-60 Black Hawk to utilize the
horizontal stabilator as an available control effector in the feedback loop to compensate for locked-in-place failure
in the main rotor swashplate actuators. This modification has previously been shown to work in an adaptive sense,
where once failure is detected the control mixing is remapped in flight. Now it is shown to perform well when the
defined mixing includes the stabilator for all time, including the undamaged case, removing the need to detect and
identify specific failures on the aircraft. Further investigation considered the benefit of allowing for more or less
longitudinal authority to be given to the stabilator in different flight conditions, which include main rotor swashplate
actuators locked-in-place, in the context of handling qualities ratings for the aircraft in pitch attitude and vertical
rate response. Post-failure, the aircraft is demonstrated to retain level 1 performance in the pitch axis, whereas only
aft actuator failure remains level 1 in the vertical rate response. Both cases show general improvement in handling
qualities ratings with increased authority given to the horizontal stabilator. Finally, the aircraft is simulated flying a
trajectory to a recoverable aircraft state, where the descent rate and forward speed are appropriate for a rolling landing.

Reference

Vayalali, P., Mckay, M., Krishnamurthi, J., and, Gandhi, F., "Robust Use of Horizontal Stabilator in Feedback Control on a UH-60 Black Hawk ,"

Proceedings of the 75th Vertical Flight Society Annual Forum, Philadelphia, Pennsylvania, May 13-16, 2019.