Reducing Trailing Edge Flap Deflection Requirements in Swashplateless Primary Control Via a Moveable Horizontal Tail

Achieving primary control of helicopters through the use of trailing edge flaps holds significant promise in eliminating the swashplate and its related components—a system that is complex, heavy, a significant source of drag, and subject to demanding maintenance requirements. However, the predicted deflections that trailing edge flaps serving in this role must reach to achieve high speed flight are currently beyond the stroke capability of existing smart-material actuators that could be used. A method of reducing the required trailing edge flap deflections through fixed frame moments input via a moveable horizontal tail is developed and demonstrated to significantly reduce the required trailing edge flap deflections on a UH-60 helicopter. This study models a UH-60 rotor with blades undergoing rigid rotations about an offset hinge and includes advanced UH-60 rotor and fuselage geometry in conjunction with the moveable tail. A moveable horizontal tail is demonstrated to reduce required cyclic trailing edge flap deflections on a UH-60 with nondimensional rotating natural frequency (νθ) of 2.1/rev and pitch index (θPre) of 20° at a forward speed of 130 knots (μ = 0.3) to deflections within the capability of current actuators (±5°), and without prohibitive vehicle attitude and performance penalties.