Reply #4: This is an old concept but has been difficult to achieve

[FLPanhandle]

As explained to me by a helicopter pilot: With a single main rotor, the blades traveling with the direction of motion are moving through the air faster (generating more lift) than the blades rotating backwards. At high speeds this causes an imbalance that will eventually rotate the aircraft out of level flight.

With two counter rotating main rotors each side of the aircraft has a forward and backward moving blade balancing the effect.

Simple in concept but mechanically and with blade pitch control and air flow dynamics it's been a tough puzzle to solve. What's cool about this is that the concept will be applied to all future helicopters (commercial and military). Coast Guard helicopters will be able to get on scene much faster and return much faster.