Definition
An aileron rigging arrangement in which the up-going aileron deflects through a greater angle than the down-going aileron on the opposite wing. This unequal travel is built into the control linkage to reduce adverse yaw — the tendency of the aircraft to yaw away from the direction of a turn when the ailerons are deflected.
Plain English
The two ailerons don't move the same amount when you roll the aircraft. The one going up moves further than the one going down. This is done on purpose to keep the nose from swinging the wrong way when you start a turn.
Context Anchor
Seen in flight-control system descriptions, aircraft maintenance manuals, control rigging checks, and explanations of how ailerons help turn the airplane.
Derivation
Differential' comes from the Latin 'differre,' meaning 'to differ' or 'to carry apart.' Here it simply means the two ailerons travel by different amounts — not the same distance up as down.
Why Pilots Care
Reduces adverse yaw in turns, producing more coordinated flight with less need for rudder correction.
Grounding Statement
Picture starting a left bank: the right aileron goes down a little, while the left aileron goes up more, helping the airplane bank without the nose swinging as strongly to the right.
Intuition Check
“Travel” does not mean where the airplane goes. Here it means how far a control surface moves. “Differential” does not mean a separate part. It means the two ailerons move by different amounts.
Example Sentence 1
The aircraft's differential aileron travel reduces the amount of rudder needed to keep turns coordinated.
Example Sentence 2
Proper differential aileron travel helped the trainer roll smoothly into turns with minimal rudder input.