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. History 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 1917–1918. Despite this early 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, would subsequently join the German aircraft manufacturer Heinkel and apply their designs, including the elliptical wing, to several different projects undertaken by the firm. During the early 1930s, Heinkel developed a fast mail plane and reconnaissance bomber, the Heinkel He 70 "Blitz", which featured the elliptical wing. It proved to have excellent performance for the era, establishing eight individual world records relating to speed over distance, having reportedly attained a maximum speed of 377 km/h (222 mph). Shortly thereafter, Heinkel developed the He 111 bomber, which made its first flight on 24 February 1935. In comparison to the preceding He 70, it was a larger aircraft that initially masqueraded as a civil airliner despite having been developed from conception to provide the nascent Luftwaffe with a fast medium bomber; this deception was due to restrictions placed on Germany after the First World War that prohibited the development or deployment of bomber aircraft. Despite the type being produced in vast numbers before and during the Second World War, only the early production models of the He 111 were equipped with an elliptical wing. The chief reason for dropping the He 111's elliptical wing in favour of one with straight leading