Conceptual Design of an Edgewise Mission Adaptive Rotor

As part of the Defense Advanced Research Projects Agency (DARPA) sponsored Mission Adaptive Rotor (MAR) Phase I program, Boeing developed conceptual designs of demonstration and objective edgewise Mission Adaptive Rotor (eMAR) systems that help meet DARPA goals for improved payload, range, noise and vibrations. Boeing has chosen the state-of-the art Apache CMRB (Composite Main Rotor Blade) rotor for the demonstration rotor and a scaled up version of the CMRB rotor together with a new-design low drag airframe for the objective rotorcraft. Preliminary conceptual designs of nine, blade installed adaptive devices were developed. These included four trailing edge flap, two leading edge droop, extended chord, Gurney flap, blade twist concepts. Computational Fluid Dynamics (CFD) and comprehensive analyses were used to guide the effort and evaluate the hover, forward flight, acoustic, and vibration benefits of the on-blade devices, active pitch links, and variable rotor speed. Trade studies and evaluation of the adaptive concepts, and blade integration and system integration studies were performed. Together with consideration of the aeromechanical benefits, they provided the basis for the downselect of adaptive concepts that were then used in the adaptive rotor conceptual design. Mission performance analysis was performed to evaluate the payload and range benefits. For both the demonstration and objective rotor configurations adaptation provides significant improvements in capability.