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American Aviation AA-1 Yankee showing the wing's straight leading edge

The leading edge is the part of the wing that first contacts the air;^[1]^[2] alternatively it is the foremost edge of an airfoil section.^[3] The first is an aerodynamic definition, the second a structural one. As an example of the distinction, during a tailslide, from an aerodynamic point of view, the trailing edge becomes the leading edge and vice versa but from a structural point of view the leading edge remains unchanged.

Overview

The structural leading edge may be equipped with one or more of the following:

Associated terms are leading edge radius and leading 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. As wing sweep is conventionally measured at the 25% chord line^[3] an unswept wing may have a swept or tapered leading edge. Some aircraft, like the General Dynamics F-111, have swing-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 the Space Shuttle Columbia during re-entry on February 1, 2003.^{[citation needed]}

Sail boats

When sailing into the wind, the dynamics that propel a sailboat 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 of vortex 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 the mast aft rig.

References

^ Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 176. ISBN 9780850451634.
^ Crane, Dale: Dictionary of Aeronautical Terms, third edition, page 305. Aviation Supplies & Academics, 1997. ISBN 1-56027-287-2
^ ^a ^b ^c Kumar, Bharat (2005). An Illustrated Dictionary of Aviation. New York: McGraw Hill. ISBN 0-07-139606-3.
^ Collie, S.J.; M.G. Gerritsen; M.J. O'Sullivan. "Numerical simulation of the turbulent flow past upwind yacht sails" (PDF). Archived from the original (PDF) on August 30, 2011. Retrieved December 10, 2011.

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[1] Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 176. ISBN 9780850451634.

[Crane-2] Crane, Dale: Dictionary of Aeronautical Terms, third edition, page 305. Aviation Supplies & Academics, 1997. ISBN 1-56027-287-2

[Kumar-3] Kumar, Bharat (2005). An Illustrated Dictionary of Aviation. New York: McGraw Hill. ISBN 0-07-139606-3.

[4] Collie, S.J.; M.G. Gerritsen; M.J. O'Sullivan. "Numerical simulation of the turbulent flow past upwind yacht sails" (PDF). Archived from the original (PDF) on August 30, 2011. Retrieved December 10, 2011.

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+{{Short description|Part of the wing that contacts the air first}}
 {{other uses}}
+{{Use mdy dates|date=April 2023}}
+{{Use American English|date=April 2023}}
 [[File:leading edge.jpg|thumb|Cross section of an aerodynamic surface with the leading edge emphasised]]
+[[File:AmericanAviationAA-1YankeeClipper05.jpg|thumb|[[Grumman American AA-1|American Aviation AA-1 Yankee]] showing the wing's straight leading edge]]
 [[File:Space Shuttle Buran - Flickr - KlausNahr (13).jpg|thumb|The leading edge of the [[Buran space shuttle]] transported to the [[Technik Museum Speyer]]]]
-The '''leading edge''' of an [[airfoil]] surface such as a [[wing]] is its foremost edge and is therefore the part which first meets the oncoming air.<ref name="Crane">Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, 1997. {{ISBN|1-56027-287-2}}</ref><ref name=Kumar>{{cite book |title=An Illustrated Dictionary of Aviation |last=Kumar |first=Bharat |year=2005|publisher= McGraw Hill|location=New York |isbn=0-07-139606-3}}</ref>
+The '''leading edge''' is the part of the wing that first contacts the air;<ref>{{cite book |title=A Dictionary of Aviation |first=David W. |last=Wragg |isbn=9780850451634 |edition=first |publisher=Osprey |year=1973 |page=176}}</ref><ref name="Crane">Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, 1997. {{ISBN|1-56027-287-2}}</ref> alternatively it is the foremost edge of an [[airfoil]] section.<ref name=Kumar>{{cite book |title=An Illustrated Dictionary of Aviation |last=Kumar |first=Bharat |edition= |year=2005|publisher= McGraw Hill|location=New York |isbn=0-07-139606-3}}</ref>  The first is an aerodynamic definition, the second a structural one.
+As an example of the distinction, during a [[tailslide]], from an aerodynamic point of view, the [[trailing edge]] becomes the leading edge and vice versa but from a structural point of view the leading edge remains unchanged.
-==Characteristics==
+==Overview==
+The structural leading edge may be equipped with one or more of the following:
+* [[Deicing boot|Leading edge boots]]
+* [[Leading edge cuff]]s
+* [[Leading edge extension]]s
+* [[Leading edge slats]]
+* [[Leading edge slot]]s
+* [[Krueger flaps]]
+* [[Stall strips]]
+* [[Vortex generator]]s.
+Associated terms are [[leading edge radius]] and [[Stagnation point|leading edge stagnation point]].<ref name=Kumar/>
-===Sweep===
-Seen in plan the leading edge may be straight, curved, kinked or a combination of these. A straight leading edge may be swept or unswept, while curves or kinks always mean that part of the leading edge is swept.
-On a swept wing the sweep angle may differ from that of the wing, as [[swept wing|wing sweep]] is conventionally measured at the airfoil 25% [[Chord (aircraft)|chord]] line.<ref name=Kumar/> However on a [[delta wing]] the leading edge sweep defines the wing sweep.
+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.  As [[swept wing|wing sweep]] is conventionally measured at the 25% [[Chord (aircraft)|chord]] line<ref name=Kumar/> an unswept wing may have a swept or tapered leading edge. Some aircraft, like the [[General Dynamics F-111]], have [[swing-wing]]s 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 the [[Space Shuttle Columbia]] during re-entry on February 1, 2003.{{cn|date=April 2024}}
-===Radius and stagnation point===
-A rounded leading edge helps to maintain a smooth airflow at varying angles of incidence to the airflow. Most subsonic airfoils therefore have a rounded leading edge. The degree of rounding is characterised by the profile radius at that point.
-The airflow divides to pass either above or below the wing. The [[stagnation point]] on the leading edge profile is the point at which the flow divides and there is no flow either up or down. As the angle of incidence varies, the stagnation point will move a little up or down accordingly.<ref name=Kumar/>
-Airfoils optimised for supersonic flight have a sharp leading edge to minimise drag. Aircraft which must operate efficiently at both subsonic and supersonic speeds often compromise on a tightly-rounded leading edge.
-===Droop=== <!--The "Leading-edge droop" article redirects here -->
-When a wing is pitched up to a high angle of attack, the airflow above the wing can break away and the wing then stalls. Drooping the leading edge reduces the angle at which the airflow strikes the wing and helps to maintain smooth airflow and hence lift at higher angles and lower airspeeds.
-The problem is often most acute on the outer wing section near the tip, so leading-edge droop is often applied to the outer section only.
-Leading-edge droop can cause excessive drag in normal flight, so variable-position [[leading-edge droop flap]]s are sometimes used. An alternative to variable droop is the [[Krueger flap]], which runs along below the leading edge and drops forwards and down when deployed to open a slot under the leading edge.
-===Thermal effects===
-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 the [[Space Shuttle Columbia]] during re-entry on February 1, 2003.
-==Leading edge devices==
-The leading edge of an aircraft wing may be equipped with one or more devices or [[leading edge extension|extensions]] for various purposes:
-* [[Leading edge cuff|Cuffs]]
-* [[Deicing boot]]s
-* Flaps, including [[Leading-edge droop flap|droop flaps]] and [[Krueger flap]]s
-* [[Leading edge root extension]]s (LERX)
-* [[Leading edge slats|Slats]]
-* [[Leading edge slot|Slots]]
-* [[Stall strips]]
-* [[Vortilon]] vortex generators
 ==Sail boats==
-When sailing into the wind, the dynamics that propel a [[sailboat]] 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 of [[vortex shedding]] from the edges of the sail.<ref>{{cite web |url=http://syr.stanford.edu/JWEIA557.pdf |title=Numerical simulation of the turbulent flow past upwind yacht sails |author1=Collie, S.J. |author2=M.G. Gerritsen |author2-link=Margot Gerritsen |author3=M.J. O'Sullivan |access-date=December 10, 2011 |archive-url=https://web.archive.org/web/20110830095917/http://syr.stanford.edu/JWEIA557.pdf |archive-date=August 30, 2011 |url-status=dead }}</ref>  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 the [[mast aft rig]].
+When sailing into the wind, the dynamics that propel a [[sailboat]] 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 of [[vortex shedding]] from the edges of the sail.<ref>{{cite web |url=http://syr.stanford.edu/JWEIA557.pdf |title=Numerical simulation of the turbulent flow past upwind yacht sails |author1=Collie, S.J. |author2=M.G. Gerritsen |author3=M.J. O'Sullivan |accessdate=December 10, 2011 |archive-date=August 30, 2011 |archive-url=https://web.archive.org/web/20110830095917/http://syr.stanford.edu/JWEIA557.pdf |url-status=dead }}</ref>  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 the [[mast aft rig]].
 ==References==
@@ Line 50: / Line 36: @@
 {{Aircraft components}}
+[[Category:Aircraft aerodynamics]]
 [[Category:Aircraft wing design]]

v t e Aircraft components and systems
Airframe structure	Aft pressure bulkhead Cabane strut Canopy Crack arrestor Cruciform tail Dope Empennage Fabric covering Fairing Flying wires Former Fuselage Hardpoint Interplane strut Jury strut Leading edge Lift strut Longeron Nacelle Rib Spar Stabilizer Stressed skin Strut T-tail Tailplane Trailing edge Triple tail Twin tail V-tail Vertical stabilizer Wing root Wing tip Wingbox
Flight controls	Aileron Airbrake Artificial feel Autopilot Canard Centre stick Deceleron Dive brake Dual control Electro-hydraulic actuator Elevator Elevon Flaperon Flight control modes Fly-by-wire Gust lock HOTAS Rudder Rudder pedals Servo tab Side-stick Spoiler Spoileron Stabilator Stick pusher Stick shaker Trim tab Wing warping Yaw damper Yoke
Aerodynamic and high-lift devices	Active Aeroelastic Wing Adaptive compliant wing Anti-shock body Blown flap Channel wing Dog-tooth Drag-reducing aerospike Flap Gouge flap Gurney flap Krueger flap Leading-edge cuff Leading-edge droop flap LEX Slats Slot Stall strips Strake Variable-sweep wing Vortex generator Vortilon Wing fence Winglet
Avionic and flight instrument systems	ACAS Air data boom Air data computer Aircraft periscope Airspeed indicator Altimeter Annunciator panel Astrodome Attitude indicator Compass Course deviation indicator EFIS EICAS Flight management system Glass cockpit GPS Head-up display Heading indicator Horizontal situation indicator INS ISIS Multi-function display Pitot–static system Radar altimeter TCAS Transponder Turn and slip indicator Variometer Yaw string
Propulsion controls, devices and fuel systems	Autothrottle Drop tank FADEC Fuel tank Gascolator Inlet cone Intake ramp NACA cowling NACA duct Self-sealing fuel tank Splitter plate Throttle Thrust lever Thrust reversal Townend ring War emergency power Wet wing
Landing and arresting gear	Aircraft tire Arrestor hook Autobrake Conventional landing gear Drogue parachute Landing gear Landing gear extender Oleo strut Tricycle landing gear Tundra tire
Escape systems	Ejection seat Escape crew capsule
Other systems	Aircraft lavatory Auxiliary power unit Bleed air system Deicing boot Emergency oxygen system Environmental control system Flight recorder Hydraulic system Ice protection system In-flight entertainment system Landing lights Navigation light Passenger service unit Ram air turbine