Definition
Small, deliberately created spirals of swirling air produced by vortex generators on a wing or control surface. These vortices energize the boundary layer, helping the airflow stay attached to the surface at higher angles of attack and delaying flow separation that would otherwise lead to a stall or loss of control effectiveness.
Plain English
Tiny, on-purpose swirls of air created by small fins on the wing. They stir up the air close to the surface so it keeps flowing smoothly along the wing instead of breaking away, which helps the wing keep working at slower speeds and steeper angles.
Context Anchor
Seen in slow-speed flight discussions and diagrams of vortex generators, especially when explaining how airflow can remain smoother over a wing or tail at low airspeed.
Derivation
A vortex (from the Latin vortex, meaning 'whirlpool' or 'whirling mass') is any spinning, spiral flow of air or fluid. 'Controlled' here means the vortices are deliberately created in a chosen size, location, and strength -- not random turbulence. The term emphasizes that these swirls are an engineered tool, not a side effect.
Why Pilots Care
They improve aileron and elevator response and lower the stall speed, allowing safer flight at low airspeeds and high angles of attack.
Grounding Statement
Picture a small fin on the wing making a tiny, useful swirl that helps nearby air keep following the wing instead of peeling away.
Intuition Check
Do not assume “controlled” means the pilot is actively steering each swirl. Here it means the airplane’s shape or a small device creates the swirl on purpose, in a predictable place.
Example Sentence 1
The vortex generators along the leading edge create controlled vortices that keep the airflow attached to the wing at high angles of attack.
Example Sentence 2
By creating controlled vortices over the wing, the airplane maintained aileron effectiveness well below normal approach speed.