Tandem-rotor aircraft

Single-rotor helicopters need a mechanism to neutralize the yawing movement produced by the single large rotor.

Advantages of the tandem rotor system are a larger center of gravity range and good longitudinal stability.

To achieve pitch, opposite collective is applied to each rotor; decreasing the lift produced at one end, while increasing lift at the opposite end, effectively tilting the helicopter forward or back.

[3] Tandem-rotor helicopters have the advantage of being able to hold more weight with shorter blades, since there are two sets.

Both configurations typically require the same power to achieve high-speed flight.

Boeing Vertol CH-46 Sea Knight
Animation of the rotors spinning
A Piasecki H-21 B in the early 1960s