Definition
A high-speed aerodynamic condition in which deflecting an aileron produces a roll in the opposite direction to that intended. At high airspeeds, the aerodynamic load created by the deflected aileron twists the wing itself, changing the wing's angle of attack enough that the wing's reaction overpowers the aileron's own lift change, reversing the rolling moment.
Plain English
When an airplane is flying very fast, moving the control wheel to roll one way can actually make the airplane roll the other way, because the force on the aileron twists the wing instead of just tilting the airplane.
Context Anchor
Seen in high-speed flight and aircraft design discussions, especially when explaining speed limits and why wings must be stiff enough to resist twisting.
Derivation
‘Aileron’ comes from the French for ‘little wing,’ referring to the hinged surface on the trailing edge of the wing used for roll control. ‘Reversal’ simply means the effect is reversed — the airplane rolls opposite to the pilot's input. Knowing the aileron is a small surface attached to a much larger wing helps explain why, at high speed, the wing can twist and overpower the aileron's intended effect.
Why Pilots Care
It reduces or reverses roll authority at high speeds and must be prevented through wing design stiffness.
Grounding Statement
Picture a fast-moving wing twisting under air pressure so the aileron’s effect is partly turned against the pilot’s command.
Intuition Check
Aileron reversal does not mean the aileron itself moves backward. It means the airplane’s rolling response can reverse because the wing twists at high speed.
Example Sentence 1
At very high speeds, some early jet fighters experienced aileron reversal, so designers added spoilers to maintain roll control.
Example Sentence 2
Stiffer wing spars were added to the design to eliminate aileron reversal at cruise speeds.