Häntäroottori

Häntäroottori is a Finnish term that translates to "tail rotor" in English. It refers to the smaller rotor located on the tail of a helicopter. The primary function of the häntäroottori is to counteract the torque produced by the main rotor. As the main rotor spins, it generates a rotational force that would cause the helicopter's body to spin in the opposite direction. The häntäroottori spins in a direction that creates a thrust, pushing against this torque and keeping the helicopter stable.

In addition to counteracting torque, the häntäroottori also provides directional control. By varying the pitch of the häntäroottori blades, the pilot can change the amount of thrust it produces. This allows the pilot to yaw the helicopter, which means turning the nose left or right. Without a häntäroottori, most single-rotor helicopters would be uncontrollable.

The design and placement of the häntäroottori can vary. Some helicopters have a traditional häntäroottori with visible blades, while others use enclosed fenestron or NOTAR (No Tail Rotor) systems. The fenestron is a ducted fan system, and NOTAR uses a stream of air directed through the tail boom. Despite these variations, the fundamental purpose of counteracting torque and providing yaw control remains the same. The häntäroottori is a critical component for the safe and effective operation of most helicopters.