Helicopter Axes of Flight – Control Around the Vertical Axis

in Physics

For a single main rotor helicopter, control around the vertical axis is handled by the anti-torque rotor (tail rotor) or from the fan’s airflow on a NOTAR type helicopter. Like in an airplane, rotation around this axis is known as yaw. The pilot controls yaw by pushing on the anti-torque pedals located on the cockpit floor, in the same way the airplane pilot controls yaw by pushing on the rudder pedals. To make the nose of the helicopter yaw to the right, the pilot pushes on the right anti-torque pedal. When viewed from the top, if the helicopter tries to spin in a counterclockwise direction because of the torque of the main rotor, the pilot will also push on the right anti-torque pedal to counteract the main rotor torque. By using the anti-torque pedals, the pilot can intentionally make the helicopter rotate in either direction around the vertical axis. The anti-torque pedals can be seen in Figure 3-91.

Figure 3-90. Three axes of rotation for a helicopter.

Figure 3-90. Three axes of rotation for a helicopter.

Some helicopters have a vertical stabilizer, such as those shown in Figures 3-90 and 3-92. In forward flight, the vertical stabilizer creates a force that helps counteract the torque of the main rotor, thereby reducing the power needed to drive the anti-torque system located at the end of the tail boom.

Figure 3-91. Helicopter cockpit controls.

Figure 3-91. Helicopter cockpit controls.

Figure 3-92. Agusta A-109 banking to the right.

Figure 3-92. Agusta A-109 banking to the right.

 

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