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Encyclopedia > Swept wing
The swept wing of an Airbus A320 (British Midland A320-200)
The swept wing of an Airbus A320 (British Midland A320-200)

A swept-wing is a wing planform used on high-speed aircraft. A swept-wing is a wing that is bent "backwards", instead of being at right angles to the fuselage. The swept wing of a British Midland Airbus A320-200 (G-MIDS). ... The swept wing of a British Midland Airbus A320-200 (G-MIDS). ... A planform or plan view is a vertical orthographic projection of an object on a horizontal plane, like a map. ... An Airbus A380, currently the worlds largest airliner An aircraft is any vehicle or craft capable of atmospheric flight. ...

Contents

Speed of sound

The swept wing is used in airplanes that spend a portion of their flight time in the transonic speed range. They were initially used only on fighter aircraft, but have since become almost universal on jets, including airliners and business jets. As an aircraft approaches the speed of sound, an effect known as wave drag starts to appear. The air reaches supersonic speed locally over an area on the top of the wing, and this local supersonic region ends in an oblique shock wave, which becomes nearly normal on the wing's upper surface. The losses of the normal shock wave increase drag. The shock can be made more oblique by having the profile of the aircraft change as slowly as possible (high fineness ratio). Instead of changing the profile it is possible to do this indirectly by swing wings or extending the wings with anti-shock bodies, which have low effect at low speeds. These methods also tilt the shock in another direction (which is not visible in the cut view of a profile) especially with forward swept wings: the shock is near the trailing edge. Sweep back in conjunction with taper is useful only if the wing is swept forward. Transonic is an aeronautics term referring to a range of velocities just below and above the speed of sound. ... This article or section does not cite its references or sources. ... Jet aircraft with condensation trail Jet aircraft are aircraft with jet engines. ... An Airbus A340 airliner operated by Air Jamaica An airliner is a large fixed-wing aircraft whose primary function is the transportation of paying passengers. ... Business jet, private jet or, in slang, bizjet is a term describing a jet aircraft, usually of modest size, designed for transporting small groups of business people for commercial reasons at a time convenient to their business needs. ... The speed of sound is a term used to describe the speed of sound waves passing through an elastic medium. ... Wave drag is an aerodynamics term that refers to a sudden and very powerful form of drag that appears on aircraft flying at high-subsonic speeds. ... Introduction The shock wave is one of several different ways in which a gas in a supersonic flow can be compressed. ... A swing-wing is a type of pivoted wing planform that attempts to combine the advantages of a swept wing at high speeds, while avoiding its problems at lower speeds. ... Junkers patent drawing from March 1944. ...


For supersonic flight the leading edge needs either to be sharp or swept back. The Lockheed F-104 Starfighter is a high-performance supersonic interceptor aircraft, capable of high speeds and climb rates. ... The Aérospatiale-BAC Concorde supersonic transport (SST), along with the Tupolev Tu-144, was one of only two models of supersonic passenger airliners to have seen commercial service. ...


History

This effect was known in the 1930s, but due to the fairly low speeds of most aircraft, it was largely of academic interest. Large engines at the front of the aircraft made it difficult to obtain a reasonable fineness ratio, and although wings could be made thin and broad, doing so made them considerably less strong. The British Supermarine Spitfire deliberately used as thin a wing as possible for lower high-speed drag, but later paid a high price for it in a number of aerodynamic problems such as control reversal. German design instead opted for thicker wings, accepting the drag for greater strength and increased internal space for landing gear, fuel and weapons. This article or section does not cite its references or sources. ... The Supermarine Spitfire was a single-seat fighter used by the RAF and many Allied countries in World War II. Produced by Supermarine, the Spitfire was designed by R.J. Mitchell, who continued to refine it until his death in 1937. ... Control reversal is an adverse affect on the controllability of aircraft. ...

The swept wing of a Boeing 747 (Thai Airways International Boeing 747-400)
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The swept wing of a Boeing 747 (Thai Airways International Boeing 747-400)

A practical solution had already been offered in 1936, by German engineers at a public aeronautics meeting in Italy. In their presentation they noted that the wing "thickness" for these calculations was measured along the direction of the airflow, as opposed to along the line of the chord. A thick wing could be made "effectively thinner" by rotating it at an angle relative to the airflow, sweeping it back. With planes starting to approach only 400km/h at the time, the presentation was soon forgotten. Image File history File links Download high resolution version (2100x1555, 887 KB) Thai Airways International Boeing 747-400 (HS-TGB) taking off from London Heathrow Airport, England. ... Image File history File links Download high resolution version (2100x1555, 887 KB) Thai Airways International Boeing 747-400 (HS-TGB) taking off from London Heathrow Airport, England. ... Cross section of an airfoil showing chord In reference to aircraft, chord refers to the distance between the front and back of a wing, measured in the direction of the normal airflow. ...


With the introduction of jets in the later half of World War II applying sweep became relevant. The German jet powered Messerschmitt Me 262 and rocket powered Messerschmitt Me 163 suffered from compressibility effects that made them very difficult to control at high speeds. In addition the speeds put them into the wave drag regime, and anything that could reduce this drag would increase the performance of their aircraft, notably the notoriously short flight times measured in minutes. A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... Combatants Major Allied powers: United Kingdom Soviet Union United States Republic of China and others Major Axis powers: Nazi Germany Italy Japan and others Commanders Winston Churchill Joseph Stalin Franklin Roosevelt Harry Truman Chiang Kai-Shek Adolf Hitler Benito Mussolini Hideki Tojo Casualties Military dead: 17,000,000 Civilian dead... The Messerschmitt Me 262 Schwalbe (German Swallow) was the worlds first operational jet-powered fighter. ... The Me 163 Komet was the only operational rocket fighter aircraft during WWII. It required a lengthy development process and entered the Second World War in a very limited fashion only in 1944. ... Fluid Dynamics Compressibility (physics) is a measure of the relative volume change of fluid or solid as a response to a pressure (or mean stress) change: . For a gas the magnitude of the compressibility depends strongly on whether the process is adiabatic or isothermal, while this difference is small in...


The result was a crash program to introduce new swept wing designs, both for fighters as well as bombers. A prototype test aircraft, the Messerschmitt Me P.1101, was built to research the tradeoffs of the design and develop general rules about what angle of sweep to use. None of the designs were ready for use by the time the war ended, but the P.1101 was captured by US forces and returned to the United States, where two additional copies with US built engines carried on the research as the Bell X-5. A bomber is a military aircraft designed to attack ground targets, primarily by dropping bombs. ... The uncompleted P.1101 prototype. ... The Bell X-5 was the first aircraft capable of changing the sweep of its wings in flight. ...


The introduction of the German swept-wing research to aeronautics caused a minor revolution, and almost all design efforts immediately underwent modifications in order to incorporate a swept-wing. A particularly interesting victim was the cancellation of the Miles M-52, a straight-wing design for an attempt on the speed of sound. When the swept-wing design came to light the project was cancelled, as it was thought it would have too much drag to break the sound barrier, but soon after the US nevertheless did just that with the Bell X-1. In 1945, NACA engineer Robert T. Jones developed the mathematical sweep theory that perfected the concept of swept wings and defined its ability to reduce shockwave effects at critical mach numbers. By the 1950s nearly every fighter used a swept wing. It was at this point that another problem discovered by the Germans came to light. Miles M.52 The Miles M.52 was a supersonic research aircraft project which was undertaken in top secret conditions between 1942 and 1945. ... The Bell X-1, originally XS-1 was the first aircraft to exceed the speed of sound in controlled, level flight. ... NACA may mean: National Advisory Committee for Aeronautics National Association for Campus Activities [1] Network of Aquaculture Centres in Asia-Pacific, an industry association of shrimp farmers and other aquaculture industries. ... Bobby Jones can refer to different people: Bobby Jones: a golf player Bobby Jones: a baseball player Bobby Jones: a basketball player Bobby Jones: a gospel singer This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Sweep theory is an aeronautical engineering description of the behavior of airflow over a wing when the wings leading edge encounters the airflow at an oblique angle. ...

The unswept wing of a Maule M-7-235B Super Rocket light aircraft
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The unswept wing of a Maule M-7-235B Super Rocket light aircraft

Image File history File links Download high-resolution version (1343x971, 164 KB) Maule M7-235B light aircraft (US registration N882JH) takes off at Kemble Airfield, Gloucestershire, England. ... Image File history File links Download high-resolution version (1343x971, 164 KB) Maule M7-235B light aircraft (US registration N882JH) takes off at Kemble Airfield, Gloucestershire, England. ...

Disadvantages

When a swept-wing travels at high speed, the airflow has little time to react and simply flows over the wing. However at lower speeds some of the air is pushed to the side towards the wing tip. At the wing root, by the fuselage, this has little noticeable effect, but towards the tip the airflow is pushed sidewise not only by the wing, but the sidewise moving air beside it. At the tip the airflow is moving along the wing instead of over it, a problem known as spanwise flow.


The lift on a wing is generated by the airflow over it from front to rear. As an increasing amount travels spanwise, the amount flowing front to rear is reduced, leading to a loss of lift. Normally this is not much of a problem, but as the plane slows for landing the tips can actually drop below the stall point even at speeds where stalls should not occur. When this happens the tip stalls, and since the tip is swept to the rear, the net lift moves forward. This causes the plane to pitch up, leading to more of the wing stalling, leading to more pitch up, and so on. This problem came to become known as Sabre dance in reference to the number of North American F-86 Sabres that crashed on landing as a result. A stall is the slowing or stopping of a process. ... This article does not cite its references or sources. ... The North American F-86 Sabre was a subsonic combat aircraft developed for the US Air Force. ...


The solution to this problem took on many forms. One was the addition of a strip of metal known as a wing fence on the upper surface of the wing to redirect the flow to the rear (see the MiG-15 as an example), another closely related design was to add a dogtooth notch to the leading edge (Avro Arrow). Other designs took a more radical approach, including the XF-91 Thunderceptor's wing that grew thicker towards the tip to provide more lift there, and the British-favoured a crescent compound sweep or scimitar wing that reduced the sweep along the span, used on the Handley Page Victor, one of their V Bombers. Category: Aircraft components ... The Mikoyan-Gurevich MiG-15 (NATO reporting name Fagot) was a jet fighter developed for the USSR. History Design began under the bureau designation I-310, which first flew in 1947. ... Avro Arrow The A.V.Roe CF-105 Arrow was a delta-wing interceptor aircraft, designed and built in Toronto, Ontario, Canada by Avro Canada during a short period of time in the 1950s. ... The Republic XF-91 Thunderceptor was an mixed-propulsion interceptor using a jet engine for most flight, and a cluster of four small rocket engines for added thrust during climb and interception. ... The Handley Page Victor was a British jet bomber aircraft, one of the V bombers intended to carry Britains nuclear arsenal. ... The term V bomber was used for the Royal Air Force aircraft during the 1950s and 1960s that comprised the UKs strategic nuclear strike force. ...


Modern solutions to the problem no longer require "custom" designs such as these. The addition of leading edge slats and large compound flaps to the wings has largely resolved the issue. On fighter designs, the addition of leading edge extensions, included for high manoeuvrability, also serve to add lift during landing and reduce the problem. Slats are small aerodynamic surfaces on the leading edge of an airplane wing which, when deployed, allow the wing to operate at a higher angle of attack. ... Flaps are hinged surfaces on the trailing edge of an airplane wing which, when deployed, increase the lift (and drag) of a wing by changing the camber of the airfoil. ... Two F/A-18 Hornets on the carrier deck. ...


The swept-wing also has several more problems. One is that for any given length of wing, the actual span from tip-to-tip is shorter than the same wing that is not swept. Low speed drag is strongly correlated with the aspect ratio, the span compared to chord, so a swept wing always has more drag at lower speeds. Another concern is the torque applied by the wing to the fuselage, as much of the wing's lift lies behind the point where the wing root connects to the plane. Finally, while it is fairly easy to run the main spars of the wing right through the fuselage in a straight wing design to use a single continuous piece of metal, this is not possible on the swept wing because the spars will meet at an angle. The low aspect ratio wing of a Piper PA-28 Cherokee In aerodynamics, the aspect ratio is an airplanes wings span divided by its standard mean chord (SMC). ...


References

See also


  Results from FactBites:
 
Dictionary : Wing_types (327 words)
A small wing called a canard is often attached to the fuselage near the front on this type of aircraft.
The term "dihedral" is used to describe wings that are angled upward from the fuselage.
Dihedral is the angle at which the wings are slanted upward from the root of the wing (where it is attached to the fuselage) to the wing tip.
Swept wing (1215 words)
A swept-wing is a wing planform used on high-speed aircraft that spend a considerable portion of their flight time in the transonic.
In their presentation they noted that the wing "thickness" for these calculations was measured along the direction of the airflow, as opposed to along the line of the chord.
At the wing root, by the fuselage, this has little noticable effect, but as you move towards the tip the airflow is pushed sidewise not only by the wing, but the sidewise moving air beside it.
  More results at FactBites »

 
 

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