Elliptical wing
Overview
 
An elliptical wing is a wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

 planform
Planform
In aviation, a planform is the shape and layout of a fixed-wing aircraft's fuselage and wing. Of all the myriad planforms used, they can typically be grouped into those used for low-speed flight, found on general aviation aircraft, and those used for high-speed flight, found on many military...

 shape that minimizes induced drag
Lift-induced drag
In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is a drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift and also in cars...

. Elliptical taper shortens the chord
Chord (aircraft)
In aeronautics, chord refers to the imaginary straight line joining the trailing edge and the center of curvature of the leading edge of the cross-section of an airfoil...

 near the wingtips in such a way that all parts of the wing experience equivalent downwash, and lift at the wing tips is essentially zero, improving aerodynamic
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...

 efficiency due to a greater Oswald efficiency number
Oswald efficiency number
The Oswald efficiency, similar to the span efficiency, is a correction factor that represents the change in drag with lift of a three dimensional wing or airplane, as compared with an ideal wing having the same aspect ratio and an elliptical lift distribution.-Definition:The Oswald efficiency is...

 in the induced drag equation.

The elliptical wing was first used on aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 in the 1930s, but has only seen limited use, for a number of reasons:
  • the compound curves involved are difficult and costly to manufacture,
  • the pure elliptical shape as a superior planform may be a myth.
Encyclopedia
An elliptical wing is a wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

 planform
Planform
In aviation, a planform is the shape and layout of a fixed-wing aircraft's fuselage and wing. Of all the myriad planforms used, they can typically be grouped into those used for low-speed flight, found on general aviation aircraft, and those used for high-speed flight, found on many military...

 shape that minimizes induced drag
Lift-induced drag
In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is a drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift and also in cars...

. Elliptical taper shortens the chord
Chord (aircraft)
In aeronautics, chord refers to the imaginary straight line joining the trailing edge and the center of curvature of the leading edge of the cross-section of an airfoil...

 near the wingtips in such a way that all parts of the wing experience equivalent downwash, and lift at the wing tips is essentially zero, improving aerodynamic
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...

 efficiency due to a greater Oswald efficiency number
Oswald efficiency number
The Oswald efficiency, similar to the span efficiency, is a correction factor that represents the change in drag with lift of a three dimensional wing or airplane, as compared with an ideal wing having the same aspect ratio and an elliptical lift distribution.-Definition:The Oswald efficiency is...

 in the induced drag equation.

The elliptical wing was first used on aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 in the 1930s, but has only seen limited use, for a number of reasons:
  • the compound curves involved are difficult and costly to manufacture,
  • the pure elliptical shape as a superior planform may be a myth. A truncated ellipse, same span, same area, has, for all practical purposes, the same induced drag. Trapeze planforms with 0.4 or 0.5 taper ratio are induced drag equivalent, too.
  • furthermore, the wing's uniform lift
    Lift (force)
    A fluid flowing past the surface of a body exerts a surface force on it. Lift is the component of this force that is perpendicular to the oncoming flow direction. It contrasts with the drag force, which is the component of the surface force parallel to the flow direction...

     distribution causes the entire span of the wing to stall
    Stall (flight)
    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...

     simultaneously, potentially causing loss of control with little warning. To compensate, aircraft such as the Supermarine Spitfire
    Supermarine Spitfire
    The Supermarine Spitfire is a British single-seat fighter aircraft that was used by the Royal Air Force and many other Allied countries throughout the Second World War. The Spitfire continued to be used as a front line fighter and in secondary roles into the 1950s...

     used a modified elliptical wing with washout
    Washout (aviation)
    Washout refers to a feature of wing design to deliberately reduce the lift distribution across the span of the wing of an aircraft. The wing is designed so that angle of incidence is higher at the wing roots and decreases across the span, becoming lowest at the wing tip...

    , though such compromises increase induced drag and reduce a wing’s efficiency. Note, though, that the typical tapered wing planform has to employ more washout than the elliptical planform wing to see similar stall performance, which puts the tapered wing at a disadvantage.


Few aircraft have used elliptical wings, and even fewer have seen mass production
Mass production
Mass production is the production of large amounts of standardized products, including and especially on assembly lines...

, most in the 1930s and 40s. The British
British people
The British are citizens of the United Kingdom, of the Isle of Man, any of the Channel Islands, or of any of the British overseas territories, and their descendants...

 Supermarine
Supermarine
Supermarine was a British aircraft manufacturer that became famous for producing a range of sea planes and the Supermarine Spitfire fighter. The name now belongs to an English motorboat manufacturer.-History:...

 Schneider Trophy
Schneider Trophy
The Coupe d'Aviation Maritime Jacques Schneider was a prize competition for seaplanes. Announced by Jacques Schneider, a financier, balloonist and aircraft enthusiast, in 1911, it offered a prize of roughly £1,000. The race was held eleven times between 1913 and 1931...

 racers of the early and mid 1930s were some of the most successful designs, and were the predecessors to the later Spitfire fighters. The German
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...

 Heinkel He 70
Heinkel He 70
The Heinkel He 70 was a German mail plane and fast passenger aircraft of the 1930s, that also saw use in auxiliary bomber and reconnaissance roles. It had a relatively brief commercial career before it was replaced by types which could carry more passengers...

 of the early 1930s was a fast mail plane and reconnaissance
Reconnaissance
Reconnaissance is the military term for exploring beyond the area occupied by friendly forces to gain information about enemy forces or features of the environment....

 bomber
Bomber
A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...

, and the predecessor to the Heinkel He 111
Heinkel He 111
The Heinkel He 111 was a German aircraft designed by Siegfried and Walter Günter in the early 1930s in violation of the Treaty of Versailles. Often described as a "Wolf in sheep's clothing", it masqueraded as a transport aircraft, but its purpose was to provide the Luftwaffe with a fast medium...

 bomber, early models of which used an elliptical wing. Almost all of the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 Republic P-47 Thunderbolt
P-47 Thunderbolt
Republic Aviation's P-47 Thunderbolt, also known as the "Jug", was the largest, heaviest, and most expensive fighter aircraft in history to be powered by a single reciprocating engine. It was heavily armed with eight .50-caliber machine guns, four per wing. When fully loaded, the P-47 weighed up to...

s used elliptical wings, except the last models, which used squared-off wingtips. In addition, several contemporary aircraft used a more conventional wing with elliptical wingtips in an attempt to gain some benefits without the added cost, but the aerodynamic benefit was found to be minimal.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK