|
''Not to be confused with annular wings, which may be elliptically shaped'' An elliptical wing is a wing planform whose leading and trailing edges each approximate to segments of an ellipse. This shape theoretically minimizes induced drag by providing an elliptical spanwise lift distribution. ==Properties== Theoretically, the most efficient way to create lift is to generate it in an elliptical spanwise distribution across the wing.〔Clancy (1975) sections 5.17, 5.25 and 8.14〕 The elliptical wing meets this condition.〔Clancy (1975) section 8.14〕 Elliptical taper shortens the chord 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 efficiency due to a greater Oswald efficiency number in the induced drag equation. The elliptical wing has some disadvantages compared to a typical straight tapered wing: * The wing's uniform lift distribution causes the entire span of the wing to stall simultaneously, potentially causing loss of control with little warning. To improve the stalling characteristics and give the pilot some warning, aircraft such as the Supermarine Spitfire used a non-uniform aerofoil in which the wing towards the tips was both thinned and twisted to give washout.〔"Spitfire"", ''Aeroplane icons'' No. 14, Kelsey, 2013, Page33.〕〔'Smith, J.; "The development of the Spitfire and Seafire", ''Journal of the Royal Aeronautical Society'', 1947, Pages 343.〕 Such compromises depart from the theoretical elliptical lift distribution, increasing induced drag and reducing overall efficiency. * The compound curves involved are difficult and costly to manufacture. In practice, most elliptical wings are approximations, for example several sections of the Spitfire leading and trailing edges are arcs of circles. The superiority of the pure elliptical shape is only theoretical. Wings with other planforms can be optimized to give the necessary elliptical spanwise lift distribution. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Elliptical wing」の詳細全文を読む スポンサード リンク
|