This helicopter is the business! Recently Sikorsky Aircraft was awarded the Collier Trophy for their revolutionary X2 Technology™ demonstrator.

The X2 holds a record for a helicopter that can fly at more than 300 mph. It's a remarkable machine with two main rotors stacked one atop the other and a pusher propeller on the tail. This technology and layout makes the X2 fast and nimble.
Enjoy!

Sikorsky’s advancing blade concept, like those from the former Soviet Union, address the issue by using a a pair of coaxial main rotors so there are always advancing blades on each side of the helicopter. As the forward speed of the X2 increases, the rotational speed of the main rotors is reduced but the dual advancing blades ensure sufficient lift to keep the helicopter flying. With the slower rotor speed and sufficient lift, the slower relative airspeed of the retreating blades is not a problem. [Source Wired.com] Read full article here.