A vortex generator is a device used to create a vortex along the surface of an aircraft’s wing, with the goal of assisting in the aircraft’s overall aerodynamic properties. Vortex generators are found on a variety of aircraft, including single and multi-engine pistons, corporate and commercial jets and high-performance military jets. The device takes the form of a vane or bump and is normally found on the upper surface of the wing. Some aircraft, mostly jets, also include at least one vortex generator per side on the tail. This helps maintain rudder effectiveness at low airspeeds.
Aerodynamic stalls occur as the aircraft’s angle of attack (AOA), or position of the leading surface of the wing relative to the horizon, exceeds a specified value. When this happens, the air flowing over the wing is unable to remain “stuck.” With jet aircraft featuring sweptback wings, the stall occurs at the wingtips and progresses toward the fuselage of the aircraft. This poses a major safety hazard, as the aircraft’s ailerons — the flaps that control bank — are located close to the wingtips. A series of vortex generators are placed along this outer portion of the wing, which prevents that early separation of airflow, allowing the aircraft to maintain control while operating at lower speeds.
For subsonic aircraft, the purpose of the vortex generator is to lower the wing’s stalling speed and delay the separation of air from the wing. Supersonic aircraft utilize vortex generators to inhibit high-speed issues such as shock-stall, which occurs when aircraft break the sound barrier. Small aircraft such as single-engine, propeller-driven airplanes may include vortex generators, as they often fly at extremely low airspeeds. Aircraft constructed before the advent of the vortex generator may have after-market kits available, which allow the aircraft’s owner to install these devices.
The use of vortex generators also allows light, multi-engine aircraft to increase their maximum takeoff weight. When a twin-engine aircraft is certified, it is required to demonstrate the ability to climb at a specific rate with one of the engines inoperative. The required rate of climb is inversely proportional to the airspeed at which the aircraft stalls. Installing a vortex generator on the wing decreases the aircraft’s stalling speed, therefore decreasing the required rate of climb for that specific make and model. The use of vortex generators generally does not affect the aircraft’s maximum landing weight, as this is most often a function of the structural limits of the aircraft’s design.