Hover testing of a Mach-scaled rotor with piezoelectric-bender-actuated trailing-edge flaps

Abstract

This paper presents the open-loop hover testing of a Mach- scaled (1/7-scale) rotor with piezoelectric bender actuated trailing-edge flaps. The flap motion generates new unsteady aerodynamic loads, which if correctly phased can be used to achieve active vibration suppression. The objective of the present tests is to demonstrate the open-loop control authority of the actuator-flap system. The model rotor was tested in hover condition on the University of Maryland rotor test rig. These tests were conducted using a Bell-412 Mach- scaled rotor hub. Trailing-edge flap deflections of ±5 to ±10 degrees were achieved in the 1 - 4/rev frequency range at 1800 RPM. The associated oscillatory rotor thrust per blade for 3/rev flap excitation was ±6.9 lbs (40% of steady rotor thrust per blade at 8 degrees collective). These results demonstrate the open-loop effectiveness of the actuator-flap system. Future work will include closed-loop control tests conducted in forward flight in the Glen L. Martin wind tunnel.