Leading edge

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Cross section of an aerodynamic surface with the leading edge emphasised Leading edge.jpg
Cross section of an aerodynamic surface with the leading edge emphasised
American Aviation AA-1 Yankee showing the wing's straight leading edge AmericanAviationAA-1YankeeClipper05.jpg
American Aviation AA-1 Yankee showing the wing's straight leading edge
The leading edge of the Buran space shuttle transported to the Technik Museum Speyer Space Shuttle Buran - Flickr - KlausNahr (13).jpg
The leading edge of the Buran space shuttle transported to the Technik Museum Speyer

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.



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.

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.

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A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expressed as its lift-to-drag ratio. The lift a wing generates at a given speed and angle of attack can be one to two orders of magnitude greater than the total drag on the wing. A high lift-to-drag ratio requires a significantly smaller thrust to propel the wings through the air at sufficient lift.

<span class="mw-page-title-main">Fixed-wing aircraft</span> Heavier-than-air aircraft with fixed wings generating aerodynamic lift

A fixed-wing aircraft is a heavier-than-air flying machine, such as an airplane, which is capable of flight using wings that generate lift caused by the aircraft's forward airspeed and the shape of the wings. Fixed-wing aircraft are distinct from rotary-wing aircraft, and ornithopters. The wings of a fixed-wing aircraft are not necessarily rigid; kites, hang gliders, variable-sweep wing aircraft and airplanes that use wing morphing are all examples of fixed-wing aircraft.

<span class="mw-page-title-main">Chord (aeronautics)</span> Imaginary straight line joining the leading and trailing edges of an aerofoil

In aeronautics, the chord is an imaginary straight line joining the leading edge and trailing edge of an aerofoil. The chord length is the distance between the trailing edge and the point where the chord intersects the leading edge. The point on the leading edge used to define the chord may be the surface point of minimum radius. For a turbine aerofoil the chord may be defined by the line between points where the front and rear of a 2-dimensional blade section would touch a flat surface when laid convex-side up.

<span class="mw-page-title-main">Aeroelasticity</span> Interactions among inertial, elastic, and aerodynamic forces

Aeroelasticity is the branch of physics and engineering studying the interactions between the inertial, elastic, and aerodynamic forces occurring while an elastic body is exposed to a fluid flow. The study of aeroelasticity may be broadly classified into two fields: static aeroelasticity dealing with the static or steady state response of an elastic body to a fluid flow, and dynamic aeroelasticity dealing with the body's dynamic response.

<span class="mw-page-title-main">Stall (fluid dynamics)</span> Abrupt reduction in lift due to flow separation

In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded. The critical angle of attack is typically about 15°, but it may vary significantly depending on the fluid, foil, and Reynolds number.

<span class="mw-page-title-main">Delta wing</span> Triangle shaped aircraft wing configuration

A delta wing is a wing shaped in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta (Δ).

<span class="mw-page-title-main">Angle of attack</span> Angle between the chord of a wing and the undisturbed airflow

In fluid dynamics, angle of attack is the angle between a reference line on a body and the vector representing the relative motion between the body and the fluid through which it is moving. Angle of attack is the angle between the body's reference line and the oncoming flow. This article focuses on the most common application, the angle of attack of a wing or airfoil moving through air.

<span class="mw-page-title-main">Leading-edge extension</span> Anti-stall control surface on aircraft

A leading-edge extension (LEX) is a small extension to an aircraft wing surface, forward of the leading edge. The primary reason for adding an extension is to improve the airflow at high angles of attack and low airspeeds, to improve handling and delay the stall. A dog tooth can also improve airflow and reduce drag at higher speeds.

<span class="mw-page-title-main">Vortex generator</span> Aerodynamic device

A vortex generator (VG) is an aerodynamic device, consisting of a small vane usually attached to a lifting surface or a rotor blade of a wind turbine. VGs may also be attached to some part of an aerodynamic vehicle such as an aircraft fuselage or a car. When the airfoil or the body is in motion relative to the air, the VG creates a vortex, which, by removing some part of the slow-moving boundary layer in contact with the airfoil surface, delays local flow separation and aerodynamic stalling, thereby improving the effectiveness of wings and control surfaces, such as flaps, elevators, ailerons, and rudders.

<span class="mw-page-title-main">Swept wing</span> Plane wing that angles backwards or forwards

A swept wing is a wing that angles either backward or occasionally forward from its root rather than in a straight sideways direction.

<span class="mw-page-title-main">Airfoil</span> Cross-sectional shape of a wing, blade of a propeller, rotor, or turbine, or sail

An airfoil or aerofoil is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine. Foils of similar function designed with water as the working fluid are called hydrofoils.

<span class="mw-page-title-main">Wingtip device</span> Aircraft component fixed to the end of the wings to improve performance

Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip devices which function in different manners, their intended effect is always to reduce an aircraft's drag by partial recovery of the tip vortex energy. Wingtip devices can also improve aircraft handling characteristics and enhance safety for following aircraft. Such devices increase the effective aspect ratio of a wing without greatly increasing the wingspan. Extending the span would lower lift-induced drag, but would increase parasitic drag and would require boosting the strength and weight of the wing. At some point, there is no net benefit from further increased span. There may also be operational considerations that limit the allowable wingspan.

<span class="mw-page-title-main">Leading-edge cuff</span> Fixed aerodynamic wing device

A leading-edge cuff is a fixed aerodynamic wing device employed on fixed-wing aircraft to improve the stall and spin characteristics. Cuffs may be either factory-designed or an after-market add-on modification.

<span class="mw-page-title-main">Vortex lift</span> Lift from highly sweptback aircraft wings

Vortex lift is that portion of lift due to the action of leading edge vortices. It is generated by wings with highly sweptback, sharp, leading edges or highly-swept wing-root extensions added to a wing of moderate sweep. It is sometimes known as non-linear lift due to its rapid increase with angle of attack. and controlled separation lift, to distinguish it from conventional lift which occurs with attached flow.

<span class="mw-page-title-main">Pitch-up</span>

In aerodynamics, pitch-up is an uncommanded nose-upwards rotation of an aircraft. It is an undesirable characteristic that has been observed mostly in experimental swept-wing aircraft at high subsonic Mach numbers or high angle of attack.

<span class="mw-page-title-main">Subsonic aircraft</span> Aircraft with a maximum speed less than the speed of sound

A subsonic aircraft is an aircraft with a maximum speed less than the speed of sound. The term technically describes an aircraft that flies below its critical Mach number, typically around Mach 0.8. All current civil aircraft, including airliners, helicopters, future passenger drones, personal air vehicles and airships, as well as many military types, are subsonic.

<span class="mw-page-title-main">Wing configuration</span> Describes the general shape and layout of an aircraft wing

The wing configuration of a fixed-wing aircraft is its arrangement of lifting and related surfaces.

<span class="mw-page-title-main">Trapezoidal wing</span> Aircraft wing shape

In aeronautics, a trapezoidal wing is a straight-edged and tapered wing planform. It may have any aspect ratio and may or may not be swept.

<span class="mw-page-title-main">Forces on sails</span>

Forces on sails result from movement of air that interacts with sails and gives them motive power for sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and sail-powered land vehicles. Similar principles in a rotating frame of reference apply to windmill sails and wind turbine blades, which are also wind-driven. They are differentiated from forces on wings, and propeller blades, the actions of which are not adjusted to the wind. Kites also power certain sailing craft, but do not employ a mast to support the airfoil and are beyond the scope of this article.

<span class="mw-page-title-main">Vortilon</span> Aerodynamic device

Vortilons are fixed aerodynamic devices on aircraft wings used to improve handling at low speeds.


  1. Wragg, David W. (1973). A Dictionary of Aviation (first ed.). Osprey. p. 176. ISBN   9780850451634.
  2. Crane, Dale: Dictionary of Aeronautical Terms, third edition, page 305. Aviation Supplies & Academics, 1997. ISBN   1-56027-287-2
  3. 1 2 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). Retrieved December 10, 2011.