Editing Leading-edge extension (section)

==Leading-edge root extension==
[[File:FA18 LEX.jpg|thumb|Condensation vortex flows along the LERX of an [[McDonnell Douglas F/A-18 Hornet|F/A-18]]]]
A leading-edge root extension (LERX) is a small [[fillet (mechanics)|fillet]], typically roughly triangular in shape, running forward from the leading edge of the [[wing root]] to a point along the fuselage. These are often called simply leading-edge extensions (LEX), although they are not the only kind. To avoid ambiguity, this article uses the term LERX.

On a modern [[fighter aircraft]], LERXes induce controlled [[aerodynamics|airflow]] over the wing at high [[angle of attack|angles of attack]], so delaying the stall and consequent loss of lift. In cruising flight, the effect of the LERX is minimal. However, at high angles of attack, as often encountered in a [[dogfight]] or during takeoff and landing, the LERX generates a high-speed [[vortex]] that attaches to the top of the wing. The vortex action maintains the attachment of the airflow to the upper-wing surface well past the normal [[stall (flight)|stall]] point at which the airflow separates from the wing surface, thus sustaining lift at very high angles.

LERX were first used on the [[Northrop F-5]] "Freedom Fighter" which flew in 1959,<ref>Green, W. and Swanborough, G.; ''The complete book of fighters'', Salamander, 1994</ref> and have since become commonplace on many combat aircraft. The [[F/A-18 Hornet]] has especially large examples, as does the [[Sukhoi Su-27]] and the [[CAC/PAC JF-17 Thunder]]. The Su-27 LERX help make some advanced maneuvers possible, such as the [[Pugachev's Cobra]], the [[Cobra Turn]] and the [[Kulbit]].

A long, narrow sideways extension to the fuselage, attached in this position, is an example of a [[chine (aircraft)|chine]].