Sneaky Helicopter is Sneaky: Eurocopter’s Blue Edge

This wicked looking scythe of a rotor blade belongs to Eurocopter‘s new initiative to create a quieter, less noise polluting helicopter.  Called the Blue Edge, its distinctive shape makes a helicopter quieter by 3 or 4 decibels (remember that the decibel scale is a logarithmic one, so this is a bigger difference than it might seem).  Eurocopter’s new blades also use flaps on their trailing edges that pulse 15 to 40 times a second.

Wired says:

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.

Hit the jump for Eurocopter’s recording, comparing the sound of an Eurocopter EC155 with normal blades to one with the Blue Edge. 

Via Wired.