The Europeans are perfecting one. Look at the blade:
This week Eurocopter unveiled its most recent effort to reduce helicopter noise with the radical-looking Blue Edge rotor blade. The new blade has been tested on one of the company’s EC155 helicopters and was shown to reduce noise 3 to 4 decibels, according to the company.
In addition to the Blue Edge rotor blade, the 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.
