Helicopter – Noise

Ambience: Medium helicopter hovering, Medium helicopter taxiing, Medium Helicopter moving to take-off point, Medium helicopter taxiing

We’re listening to the distinctive sound of a helicopter in flight. I’m Jim Metzner and this is the Pulse of the Planet. William Warmbrodt is Chief of the Aeromechanics Branch at Ames Research Center. He explains what it is that makes helicopters so noisy and what might be done to make them quieter.

“Helicopters generate their lift through the spinning of rotor blades. The spinning blades generate aerodynamic pressures and forces that create acoustic waves. These acoustic waves are what we call noise as we hear them while standing on the ground. The challenge is to develop the technology so that we can, in fact, significantly reduce, if not eliminate, annoying noise sources when a rotor is flying in edgewise flight.”

ambience: Medium Helicopter moving to take-off point

Edgewise flight refers to when a helicopter is moving forward, backward or to the sides, flying in the more or less the same plane that its main blade is turning.

ambience: Medium helicopter hovering

“When a helicopter or other edgewise-flying aircraft descends, the wake system that the rotor generates actually passes back through that spinning rotor disk. In doing so, it generates substantial aerodynamic impulses that create very large noise sources. These noise sources get radiated into the neighborhoods, into the communities. These sources are directional in nature and in some directions they are very, very loud. We are currently trying to develop various different technologies to be able to substantially reduce and minimize the acoustic strength of these noise sources as they propagate to the ground, so that people will experience what would hopefully be someday considered a quiet helicopter.”

We’ll hear more about helicopters in future programs. Please check out our website at pulseplanet.com. Pulse of the Planet is made possible by the National Science Foundation with additional support from NASA. I’m Jim Metzner.

Helicopter - Noise

The sound of a helicopter is instantly recognizable. But what causes it to be so noisy?
Air Date:09/18/2007
Scientist:
Transcript:

Ambience: Medium helicopter hovering, Medium helicopter taxiing, Medium Helicopter moving to take-off point, Medium helicopter taxiing

We’re listening to the distinctive sound of a helicopter in flight. I’m Jim Metzner and this is the Pulse of the Planet. William Warmbrodt is Chief of the Aeromechanics Branch at Ames Research Center. He explains what it is that makes helicopters so noisy and what might be done to make them quieter.

“Helicopters generate their lift through the spinning of rotor blades. The spinning blades generate aerodynamic pressures and forces that create acoustic waves. These acoustic waves are what we call noise as we hear them while standing on the ground. The challenge is to develop the technology so that we can, in fact, significantly reduce, if not eliminate, annoying noise sources when a rotor is flying in edgewise flight.”

ambience: Medium Helicopter moving to take-off point

Edgewise flight refers to when a helicopter is moving forward, backward or to the sides, flying in the more or less the same plane that its main blade is turning.

ambience: Medium helicopter hovering

“When a helicopter or other edgewise-flying aircraft descends, the wake system that the rotor generates actually passes back through that spinning rotor disk. In doing so, it generates substantial aerodynamic impulses that create very large noise sources. These noise sources get radiated into the neighborhoods, into the communities. These sources are directional in nature and in some directions they are very, very loud. We are currently trying to develop various different technologies to be able to substantially reduce and minimize the acoustic strength of these noise sources as they propagate to the ground, so that people will experience what would hopefully be someday considered a quiet helicopter.”

We’ll hear more about helicopters in future programs. Please check out our website at pulseplanet.com. Pulse of the Planet is made possible by the National Science Foundation with additional support from NASA. I’m Jim Metzner.