Design, development, and hover testing of a helicopter rotor blade chord extension morphing system

A rotor blade chord extension system was designed, fabricated and hover tested, using electromechanical and pneumatic actuation. A 1.5 in actuator stroke output in the spanwise direction was converted into chordwise motion of a trailing-edge plate (TEP), via a rigid link. On the hover stand, with a 20 V dc input, the electromechanical actuator was shown to fully extend and retract the plate at rotational speeds up to 385 RPM (which put the system at a centrifugal loading of 209.5 g, or 47.2% of that on a Black Hawk helicopter at 73% span). The configuration was changed to reduce the actuator force requirement for the pneumatic actuator. The rotor test facility allowed a maximum of 105 psi pressure input through the rotary union (significantly lower than the rating of the actuator). At these moderate pressure inputs, full TEP deployment was observed at 315 RPM (140.2 g, or 31.6% of that on a Black Hawk helicopter at 73% span). The model prediction of TEP displacement versus pressure showed good correlation with test results.