An elliptical wing is a wing planform whose leading and trailing edges each approximate two segments of an ellipse. It is not to be confused with annular wings, which may be elliptically shaped.
Relatively few aircraft have adopted the elliptical wing, an even-smaller number of which attained mass production; the majority of aircraft that did use this feature were introduced during the 1930s and 1940s. Perhaps the most famous aircraft to feature an elliptical wing is the Supermarine Spitfire, a Second World War-era British fighter aircraft. Another example was the Heinkel He 70 "Blitz", a German fast mail plane and reconnaissance bomber; early versions of the He 111 bomber also used such a wing configuration before a simpler design was adopted for economic reasons.
Theoretically, the most efficient way to create lift is to generate it in an elliptical spanwise distribution across the wing.[1] There is no inherent superiority to pure elliptical shapes and wings with other planforms can be optimized to give elliptical spanwise lift distributions.
The basic elliptical wing shape has disadvantages:
For a wing to have an elliptical area distribution, it is not necessary for both the leading and trailing edges to be curved. If one of these is straight, as in the semi-elliptical planform, the wing may still have an elliptical area distribution. Several aircraft of this type have been produced; one of the most successful being the American Seversky P-35.
During the postwar era, the semi-elliptical wing profile was extensively studied for its ground effect properties; it was postulated that it would be suitable for ground-effect vehicles (which operate close to the water, in ground effect, to avoid the higher induced drag that occurs out of ground effect). The low level of induced drag produced by a semi-elliptical wing would be beneficial for these vehicles.[6]
The British theoretical aerodynamicist Frederick Lanchester was perhaps the first person to write in detail about the elliptical wing, having done so during 1907. Ludwig Prandtl independently rediscovered this in Lifting-line theory (1917–1918). Despite this head-start, the elliptical wing was initially viewed as more a theoretical concept than one for practical application, in part due to the overriding needs to compromise between an aircraft aerodynamic properties and its other design aspects. It would be quite some time before practical use of the planform would be made.
The first aircraft to use the elliptical wing was the Bäumer Sausewind, a German light sports aircraft that performed its maiden flight on 26 May 1925. Its designers, the Günther brothers, later joined the German aircraft manufacturer Heinkel to apply their designs, including the elliptical wing, to several projects undertaken by the firm. During the early 1930s, Heinkel developed a fast mail plane and reconnaissance bomber, the Heinkel He 70 "Blitz", which had the elliptical wing. It proved to have excellent performance for the era, establishing eight world records relating to speed over distance, having reportedly attained a maximum speed of