GRC1: An Advanced Five-Bladed Bearingless Main Rotor Dynamics and Acoustics from Draft to Flight Test

Funded by the European research program Clean Sky Green Rotorcraft (GRC), a new five-bladed bearingless main rotor demonstrator has been developed and tested between 2014 and 2016 at Airbus Helicopters, hereafter denoted as GRC1 rotor. While inheriting rotor controls, control cuff, flexbeam and lead-lag damper from the Bluecopter™ main rotor, the rotor blade itself was developed from scratch within the research project. Main target was to achieve an ecofriendly design by simultaneously reducing acoustic signature, fuel consumption and vibratory loads while optimizing manufacturing costs. This could be achieved by proper balancing the requirements of the technical disciplines acoustics, aerodynamics, dynamics, loads, performance and handling qualities. While these targets have been achieved, demonstrated by ground and flight tests, excellent agreement between numerical predictions and test results was achieved. This paper provides an overview on the aeromechanics, acoustics and performance aspects after summarizing the evolution of bearingless main rotors at Airbus Helicopters.