# Flight Controls and the Vertical Axis

in Physics

The vertical axis of an airplane runs from top to bottom through the middle of the airplane, passing through the center of gravity. Movement around this axis is known as yaw, and control around this axis is called directional control. Movement around this axis is controlled by the rudder, or in the case of the Beechcraft Bonanza in Figure 3-67, by the ruddervators.

Figure 3-67. Ruddervators on a Beechcraft Bonanza provide pitch control.

The feet of the pilot are on the rudder pedals, and pushing on the left or right rudder pedal makes the rudder move left or right. When the right rudder pedal is pushed, the trailing edge of the rudder moves to the right, and the nose of the airplane yaws to the right. The rudder pedals of a Cessna 182 can be seen in Figure 3-68.

Figure 3-68. Cessna 182 control wheel and rudder pedals.

Even though the rudder of the airplane will make the nose yaw to the left or the right, the rudder is not what turns the airplane. For what is called a coordinated turn to occur, both the ailerons and rudder come into play. Let’s say we want to turn the airplane to the right. We start by turning the control wheel to the right, which raises the right aileron and lowers the left aileron and initiates the banking turn. The increased lift on the left wing also increases the induced drag on the left wing, which tries to make the nose of the airplane yaw to the left. To counteract this, when the control wheel is moved to the right, a small amount of right rudder is used to keep the nose of the airplane from yawing to the left. Once the nose of the airplane is pointing in the right direction, pressure on the rudder is no longer needed. The rudder of a Piper Cherokee Arrow can be seen in Figure 3-70.

Figure 3-70. Rudder on a Piper Cherokee Arrow.