Definition
A type of aileron in which the leading edge of the up-going aileron projects below the wing's lower surface into the airflow, increasing drag on the descending wing to help offset adverse yaw during a turn.
Plain English
An aileron designed so that when it deflects up, part of its front edge sticks down into the air below the wing. This added drag on the wing that's rolling downward helps the airplane turn more cleanly without the nose swinging the wrong way.
Context Anchor
Seen in aircraft control-surface design, maintenance, inspection, and discussions of how an airplane rolls into a turn.
Derivation
Named after Leslie George Frise, a British aeronautical engineer who designed this aileron arrangement in the 1920s. Knowing it's a proper name (not a technical word) prevents readers from trying to decode 'frise' as if it described the part.
Why Pilots Care
The added drag helps cancel adverse yaw, reducing the amount of rudder coordination needed during roll maneuvers and improving overall handling.
Intuition Check
Do not read “Frise” as “freeze.” It is a person’s name, not a reference to ice or cold weather. A Frise aileron is still an aileron; the special feature is the way its front edge creates drag when the surface moves upward.
Example Sentence 1
The technician inspected the hinge line of the Frise aileron to confirm the leading edge was free to project into the airflow when deflected upward.
Example Sentence 2
During preflight, the mechanic checked the Frise aileron hinges to confirm the leading edge would protrude correctly on upward deflection.