ailerons

Ailerons are hinged control surfaces on the trailing edge of aircraft wings that control roll. They are typically arranged as a pair, one on each wing, so that they move in opposite directions when the pilot operates the control stick or yoke.

When the left aileron deflects upward and the right aileron downward, lift on the left wing decreases while lift on the right wing increases. This creates a rolling moment that tilts the aircraft about its longitudinal axis. The roll rate depends on wing design, airspeed, and dihedral, and is influenced by aerodynamic stability and gravity. Adverse yaw can occur as drag differs between the wings during a roll.

Most conventional airplanes place ailerons near the wingtips, though some designs use inboard surfaces or multiple panels. To improve control in certain flight regimes, aircraft may employ differential ailerons that move unequally, spoilerons that assist or substitute for ailerons, or other combined systems. Modern fly-by-wire and hydraulic systems can enhance control feel, integrate with stability augmentation, and provide gust suppression.

History and development: ailerons emerged in the early 20th century as a practical alternative to wing-warping. They were rapidly adopted during the 1910s and became the standard method of roll control on most fixed-wing aircraft. The Wright brothers used wing-warping in their early flights, but hinged ailerons became dominant in subsequent designs.

In contemporary aviation, ailerons remain fundamental to roll control on fixed-wing aircraft, with various implementations tailored to aircraft size, speed, and mission requirements. Some large or specialized aircraft also use spoiler-based systems to share or replace traditional aileron functions.