singlerotor

Singlerotor is a term used to describe rotorcraft configurations that employ a single main rotor to provide lift, in contrast to multi-rotor systems that use two or more major rotors. In common usage, the phrase is most often applied to conventional helicopters with one main rotor and a tail rotor to counteract torque. The term may also appear when contrasting single-rotor designs with coaxial, tandem, or tiltrotor arrangements.

Operation and control: The main rotor is driven by a powerplant through a main transmission. Pilot input via the cyclic and collective controls changes lift distribution and rotor plane tilt; anti-torque is provided by a tail rotor, a fenestron (ducted tail rotor), or NOTAR system. Yaw control is achieved by varying anti-torque thrust while maintaining overall stability.

Advantages and limitations: Singlerotor configurations provide mechanical simplicity, lower weight and maintenance, and generally higher propulsive efficiency for a given rotor diameter. They are well suited to civil and light military helicopters. Limitations include the need for an anti-torque device to counteract engine torque, which adds drag, noise, and maintenance requirements, and potential vibration and control challenges at extreme flight regimes.

Examples: Notable single-rotor helicopters include the Robinson R22 and R44 families, the Bell 206 JetRanger family, and the Airbus Helicopters H125 (formerly EC130). These aircraft use a single main rotor with a tail-anti-torque system and are widely used for training, light transport, and aerial work.

See also: Coaxial rotor, Tandem rotor, Tiltrotor, Helicopter, Anti-torque.