Dualrotor

Dualrotor refers to systems that use two rotors to generate lift or propulsion. In rotorcraft, two principal configurations are common: coaxial dual-rotor, where two rotors are mounted on the same vertical axis and rotate in opposite directions, and tandem dual-rotor, where two large rotors are mounted on separate fore and aft positions along the fuselage.

Coaxial dual-rotor systems balance aerodynamic torque without a tail rotor, allowing a more compact airframe and potentially higher lift. However, they involve increased mechanical complexity, heavier gearboxes and drive systems, and careful synchronization to minimize vibrations and rotor interference. Coaxial designs are associated with many Kamov helicopters, such as the Ka-50 and Ka-52, which use counter-rotating rotors to achieve control and stability in a compact airframe.

Tandem rotor designs provide high lift and payload capacity with good longitudinal stability, due to the separation of the lift surfaces and the ability to balance weight fore and aft. They typically require a longer aircraft and larger rotor discs, with complex synchronization and control requirements to manage rotor interactions. Notable tandem-rotor examples include the Boeing CH-47 Chinook and the Sea Knight variants, which use front and rear rotors to achieve heavy-lift capabilities without a tail rotor.

In modern aviation, dual-rotor concepts are employed in specialized military and civilian rotorcraft, and in some UAV and experimental platforms. The choice between coaxial and tandem configurations depends on mission requirements, payload, airspace, and manufacturing considerations.