Optimally scheduled deployments of miniature trailing-edge effectors for rotorcraft power reduction

Spanwise-segmented Miniature Trailing-Edge Effectors (MiTEs), essentially deployable Gurney flaps, were examined for rotorcraft power reduction. Four MiTEs, extending from 50-60%, 60-70%, 70-80% and 80-90% span, were considered and actuated at frequencies of 1/rev and 2/rev. A gradient-based optimization scheme was used to determine the optimal deployment of the MiTEs, while satisfying vehicle trim. Studies were based on a UH-60 type aircraft and the effect of the MiTEs was examined at moderate to very high speeds, and for low through high aircraft gross-weights. In the analysis lift and drag increments associated with MiTE deployment were added to airfoil properties of the base SC-1095 airfoil. At very high gross-weights, or a combination of moderate weight and very high speed, large reductions in rotor power of up to 40% were predicted, with the MiTEs working to alleviate rotor stall. The rotor disk angles of attack on the retreating side were significantly reduced, as was the drag over much of the retreating side. At moderate to low gross-weights and/or lower speeds, power reductions of up to 8.74% were still obtained, even when the baseline rotor was not stalled. In these cases the MiTEs more optimally redistributed the lift around the rotor disk, generally offloading of the outer rim of the rotor disk while moving lift inboard.