THE QUIET HELICOPTER « FROM RESEARCH TO REALITY »

Every helicopter manufacturer became aware of environmental constraints over the last ten years and is now attempting to integrate noise reduction devices in the design of future helicopters so that they will remain well below the ICAO noise limits. EUROCOPTER, TURBOMECA and ONERA developed an ambitious research program intended to develop a demonstrator helicopter whose overall noise level should be 8 EPNdB below the ICAO standards. Our strategy was to balance the reduction of the whole helicopter noise sources: the main rotor, the tail rotor and the engine, but also the RPM variations. For this purpose, the "Quiet Helicopter" demonstrator of Dauphin-type was equipped with new main and tail rotors as well as sound-proofed air intakes. This paper is intended to depict the development of these different elements and the associated technologies. After a review of the development of each component on this demonstrator, the results obtained in flight are presented. The initial noise reduction objectives were reached. They were even exceeded thanks to rotor speed variations. This flight test demonstration proves that the quiet helicopter concept is now achievable and the technological fall-outs are already available for future products.