antitorquejärjestelmä

An antitorque system is a mechanism used in rotorcraft, most commonly helicopters, to counteract the torque produced by the main rotor. The main rotor's rotation creates a reactive torque that tries to spin the helicopter's fuselage in the opposite direction. Without an antitorque system, the helicopter would be uncontrollable.

The most common antitorque system is the tail rotor. This is a smaller rotor mounted on the tail boom, rotating vertically. It generates a sideways thrust that opposes the main rotor's torque. The pilot controls the pitch of the tail rotor blades to adjust the amount of thrust, which in turn controls yaw (rotation around the vertical axis).

Another type of antitorque system is the NOTAR (No Tail Rotor) system. This system uses a ducted fan within the tail boom, which expels air to provide directional control. The air is directed out of vents on the sides of the tail boom, creating a thrust that counters the main rotor torque. NOTAR systems are generally quieter and safer than tail rotors, as there are no exposed spinning blades.

Fenestron is a type of ducted fan antitorque system that is enclosed within a shroud at the rear of the helicopter. It offers improved safety and reduced noise compared to conventional tail rotors. Coaxial rotors, where two main rotors spin in opposite directions on the same mast, also cancel out each other's torque without the need for a separate antitorque system. Tandem rotors, with two main rotors positioned one behind the other, also achieve a similar effect.