ON THE CUTTING EDGE: Silent Running
NYers are used to helicopters racing across the sky to cover a breaking news event or hovering overhead to update the status of a major traffic snarl – and even to film aerial cut away shots for TV shows and movies that are supposed to be taking place in NYC but are really being filmed in Toronto. And city officials are used to getting complaints from NYers about the noise.
Both sides will be happy with Eurocopter’s new noise-reducing Blue Edge rotor blade, which brings down the noise level of the spinning blades to 3 or 4 decibels, reports Wired magazine' “Autopia” blog:
[T]he company also introduced something called Blue Pulse technology. Also designed to reduce helicopter noise, the Blue Pulse system uses three flap modules in the trailing edge of each rotor blade. Piezoelectric motors move actuate the flaps 15 to 40 times per second in reduce the “slap noise” often heard when a helicopter is descending.
Both of these technologies are able to reduce noise by minimizing the blade-vortex interaction of the main rotor on a helicopter. Blade-vortex interaction is the source of the pulsating sound most of us are familiar with when helicopters fly overhead. The noise is created when a rotor blade hits the wake vortex left behind from the blade in front of it. …
The company says the goal is to create more environmentally friendly helicopters from both a noise and emissions standpoint.
This cockpit recording of Eurocopter’s EC155 with and without the Blue Edge rotor shows the drastic difference in noise-level:
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