A low weight electro-hydraulic active damper to control main rotor vibrations on helicopters

Vibration control is a crucial aspect in helicopter to enhance the ride quality experienced by the crew and to increase the fatigue life of onboard instruments. This paper presents an innovative active solution to reduce vibrations, proposed by Elettronica Aster S.p.A., consisting in the substitution of the classic rigid struts supporting the gearbox/main rotor assembly with an electro-hydraulic actuator hosted within a compliant structure. This parallel design, obtained with a model-based approach, allows the actuator to reach an extremely high power density and bandwidth. The paper first introduces the layout and main characteristics, after the test bench used to perform certification tests is presented. Hence, the results of its model validation are shown. Finally, experimental results demonstrate the ability of the system to reduce vibrations by more than 10.5 dB at 25 Hz.