Helicopter manufacturers are exploring a number of technologies to reduce noise, both that perceived from the ground and inside the cabin. European manufacturers are working on several demonstration programs to reduce noise by changing the helicopter’s airframe dynamics.
According to Rogelio Ferrer, an expert at Eurocopter’s research department in Marignane, France, “the main rotor, the tail rotor and the engine, in that order, are the three major noise sources” for those on the ground. Bob Meissbach, Mesa, Ariz.-based MD Helicopters’ director of engineering and integration, said this also depends on the flight phase. “At flyover, a traditional tail rotor will be the first source, although a quiet-technology tail rotor or a Notar [MD Helicopters’ antitorque technology] leaves the first place to the main rotor. At takeoff and climb, this depends on how quickly the maneuver is performed; the more aggressive the maneuver, the more antitorque the helicopter needs, the more tail rotor noise,” he said.
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