From Aeroacoustics Basic Research to a Modern Low Noise Rotor Blade

In 2015, Airbus Helicopters unveiled the secrecy around its Dauphin successor and presented the all-new H160 helicopter. A special feature that immediately attracted attention was its unusual and revolutionary fore-aft swept main rotor blade. This design, which aims to significantly reduce the blade-vortex interaction noise signature and reduce high-speed forward flight power requirements, was first investigated in the 1990s. At this time, Deutsches Zentrum fur Luft-und Raumfahrt e.V. (German Aerospace Center, DLR) and Office National d'Etudes et Recherches Aerospatiales (The French Aerospace Lab, ONERA) formed a joint team to acoustically optimize a rectangular reference rotor blade. Based on state-of-the-art comprehensive rotor codes and a 50/50 work share, the Etude d'un Rotor Aeroacoustique Technologiquement Optimise (aeroacoustically optimized rotor, ERATO) rotor blade design was developed, patented worldwide, and tested both on a rotor test rig and in the wind tunnel. Airbus Helicopters (then Eurocopter) adopted the design, optimized hover and forward flight high-lift performance, and prepared it for serial production, as the Blue Edge (TM) rotor blade on the Airbus Helicopters H160 helicopter.