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Theleading edge is the part of the wing that first contacts the air;[1][2] alternatively it is the foremost edge of anairfoil section.[3] The first is an aerodynamic definition, the second a structural one.
As an example of the distinction, during atailslide, from an aerodynamic point of view, thetrailing edge becomes the leading edge and vice versa but from a structural point of view the leading edge remains unchanged.
The structural leading edge may be equipped with one or more of the following:
Associated terms areleading edge radius andleading edge stagnation point.[3]
Seen in plan the leading edge may be straight or curved. A straight leading edge may be swept or unswept, the latter meaning that it is perpendicular to the longitudinal axis of the aircraft. Aswing sweep is conventionally measured at the 25%chord line[3] an unswept wing may have a swept or tapered leading edge. Some aircraft, like theGeneral Dynamics F-111, haveswing-wings where the sweep of both wing and leading edge can be varied.
In high-speed aircraft, compression heating of the air ahead of the wings can cause extreme heating of the leading edge. Heating was a major contributor to the destruction of theSpace Shuttle Columbia during re-entry on February 1, 2003.[citation needed]
When sailing into the wind, the dynamics that propel asailboat forward are the same that create lift for an airplane. The term leading edge refers to the part of the sail that first contacts the wind. A fine tapered leading edge that does not disturb the flow is desirable since 90% of the drag on a sailboat owing to sails is a result ofvortex shedding from the edges of the sail.[4] Sailboats utilize a mast to support the sail. To help reduce the drag and poor net sail performance, designers have experimented with masts that are more aerodynamically shaped, rotating masts, wing masts, or placed the mast behind the sails as in themast aft rig.
