What is a Rudder?
If you've ever looked at the tail end of a plane, you've probably
noticed the large tail assembly,
which is used to help maintain the position of the plane. One
important part of the tail assembly is the rudder, a long,
vertical, teardrop-shaped flap which controls the yaw of the plane.
Yaw is the rotation of the plane around a vertical axis; otherwise
explained, the rotation to the left or right. The rudder is
operated by a set of foot pedals, which cause the rudder to rotate
left or right. If a pilot wanted to turn to the right, he would
press down on the right rudder pedal, turning the rudder right.
A pilot has to be careful while turning, because used alone, the
rudder is not useful; a rudder change alone would send the plane
into a skid, where it moves forwards, while turned at an angle
relative to its motion. Therefore, the set of actions described
in the introduction to the control section
must be used.
As the rudder position changes, the airflow around the tail
assembly comes off at an angle, changing the
forces on the tail (think action-reaction).
The air has a small tendency to stick to the surface of the wing
(viscosity), which causes it to follow the path of the wing as it
moves. The air hitting the front of the tail is moving in a
straight line, but when the rudder is at an angle, the air curves
around the tail. From Newton's Third Law, the force of the rudder
disturbing the air's path is reciprocated, with the air pushing
back on the rudder, causing the plane to change its course.