Definition
The unequal lift produced by the two wings of an airplane in a turn, caused by the outside wing traveling faster through the air than the inside wing. The faster wing generates more lift, which tends to roll the airplane further into the bank.
Plain English
In a turn, the outer wing moves faster than the inner wing, so it makes more lift. That extra lift on one side is the difference the term is naming.
Context Anchor
Encountered when learning level turns, especially when discussing why an airplane may want to keep increasing its bank during a turn.
Derivation
‘Differential’ comes from Latin differentia, meaning ‘a difference.’ Here it points to the difference in lift between the two wings — not equal, but uneven — which is exactly what produces the rolling effect in a turn.
Why Pilots Care
This effect tends to steepen the bank angle during a turn, requiring the pilot to apply opposite aileron to maintain a constant bank.
Analogy
It is like two runners going around a track side by side: the runner on the outside lane has to cover more distance. In a turn, the outside wing covers more distance too, so it moves a little faster and can make more lift.
Intuition Check
Differential lift does not mean a special type of lift. It means an unequal amount of lift between the left and right wings.
Example Sentence 1
In a steep left turn, differential lift causes the right wing to produce more lift than the left, which tends to steepen the bank.
Example Sentence 2
The pilot maintains coordinated flight by counteracting differential lift through appropriate control pressures.