VORTAC (electronic navigation system). An electronic navigation system used by both military and civilian aircraft. The name VORTAC is the combination of the names of two types of navigation equipment: VOR, very-high-frequency omnirange navigation equipment, and TACAN, a military pulse-type tactical navigation system. VOR and TACAN equipment are colocated at a VORTAC station, and signals from both systems are transmitted simultaneously.
Military aircraft use the TACAN system for determining their direction and distance from the VORTAC station. Civilian aircraft determine their direction from the station by the VOR and their distance from the station by the distance-measuring portion of TACAN. This distance is shown in the aircraft by the distance measuring equipment (DME).
vortex. A whirling motion in a fluid. The coriolis force caused by the rotation of the earth causes water to flow out of a drain in a vortex. Air that spills over the wing tips of an airplane spins in the form of vortices. A tornado is an extremely strong vortex of air.
vortex dissipator (turbine powered aircraft component). A high-velocity stream of compressor bleed air blown from a nozzle into an area where vortices are likely to form. Vortex dissipators destroy the vortices that would otherwise suck debris from the ground into engines mounted in pods below the wings.
vortex generators (aerodynamics). Small rectangular, low aspect ratio airfoils mounted on the upper surface of the wings of some high-speed airplanes. Vortex generators are mounted in pairs, and the air spilling over their upper ends forms swirls, or vortices. These vortices pull high-energy air down to the surface of the wing. Vortex generators prevent the air separating from the surface of the wing.