著者

浅井 圭介 ASAI Keisuke

出版者

航空宇宙技術研究所

雑誌

航空宇宙技術研究所報告 = Technical Report of National Aerospace Laboratory TR-797 (ISSN:03894010)

巻号頁・発行日

vol.797, pp.21, 1984-01

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The objective of the present paper is to discuss the application of nonplanar wings such as Whitcomb’s winglet to new subsonic transport airplanes. A simple numerical method has been developed to calculate the minimum induced drag for a wing of an arbitrary nonplanar configuration, using the Trefftz-plane(far-field) analysis and the Lagrangean multiplier technique. For a series of wing/winglet combinations and several more complex forms such as curved wings, the value of the induced drag efficiency parameter‘l/e’is evaluated and compared with that of a conventional planar wing. When comparing the induced drag benefits, it is assumed that both wings have the same‘extended’wing planform rather than the‘projected’one. And, to take account of the trade-offs between wing aerodynamic efficiency and wing structural weight, the wing root bending moment as well as the wing total lift are kept constant. With these constraints, the drag performances for both wings could be compared without any ambiguity associated with structural weight and wing surface skin friction. The results obtained show that the minimum induced drag of every nonplanar wing analyzed here is not less than that of a planar wing except in the case of relatively small values of restricted wing root bending moment. Thus, it is concluded that a planar wing is superior to a nonplanar wing from the view point of cruise drag performance.