Editing Flight control surfaces (section)

===Secondary effects of controls===

====Ailerons====
{{Main|Adverse yaw}}
The ailerons primarily cause roll. Whenever lift is increased, [[induced drag]] is also increased so when the aileron control is moved to roll the aircraft to the left, the right aileron is lowered which increases lift on the right wing and therefore increases induced drag on the right wing. Using ailerons causes [[adverse yaw]], meaning the nose of the aircraft yaws in a direction opposite to the aileron application. When moving the aileron control to bank the wings to the left, adverse yaw moves the nose of the aircraft to the ''right''. Adverse yaw is most pronounced in low-speed aircraft with long wings, such as gliders. It is counteracted by the pilot using the rudder pedals. [[Differential ailerons]] are ailerons which have been rigged such that the downgoing aileron deflects less than the upward-moving one, causing less adverse yaw.

====Rudder====
The rudder is a fundamental control surface which is typically controlled by pedals rather than at the stick. It is the primary means of controlling yaw—the rotation of an airplane about its vertical axis. The rudder may also be called upon to counter-act the adverse yaw produced by the roll-control surfaces.

If rudder is continuously applied in level flight the aircraft will yaw initially in the direction of the applied rudder – the primary effect of rudder. After a few seconds the aircraft will tend to bank in the direction of yaw. This arises initially from the increased speed of the wing opposite to the direction of yaw and the reduced speed of the other wing. The faster wing generates more lift and so rises, while the other wing tends to go down because of generating less lift. Continued application of rudder sustains rolling tendency because the aircraft flying at an angle to the airflow - skidding towards the forward wing. When applying right rudder in an aircraft with [[Dihedral (aircraft)|dihedral]] the left hand wing will have increased angle of attack and the right hand wing will have decreased angle of attack which will result in a roll to the right. An aircraft with [[Dihedral (aircraft)#Anhedral|anhedral]] will show the opposite effect.
This effect of the rudder is commonly used in model aircraft where if sufficient dihedral or polyhedral is included in the wing design, primary roll control such as ailerons may be omitted altogether.