Topic
Lift-induced drag
About: Lift-induced drag is a research topic. Over the lifetime, 2861 publications have been published within this topic receiving 41094 citations.
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30 Aug 2004
TL;DR: In this paper, the authors presented a methodology for minimizing total drag of a high-altitude, long endurance reconnaisance vehicle across its mission by optimal scheduling of flaps and fuel pumping.
Abstract: The paper presents a methodology for minimizing total drag of a high-altitude, long endurance reconnaisance vehicle across its mission by optimal scheduling of flaps and fuel pumping. The methodology accounts for profile and induced drag and includes the effects to drag of trimming the vehicle. The use of conventional, rigidarticulating flaps are considered, in addition to conformal flaps which provide a smooth, continuous camber change and allow for flap twisting. Numerical results are demonstrated on a Lockheed Martin SensorCraft concept that is characterized by a 30 degree wing sweep, a fuel fraction of nearly 60 %, and a constant altitude cruise in which CL varies roughly from 0.5 to 1.2. The results have shown that significant reductions in drag can be achieved with optimal scheduling of flaps and fuel pumping. Drag predictions have been translated to mission range through integration of the Breguet range equation. Results show that between a 5 and 15 % increase in range can be achieved.
10 citations
01 Jan 2012
TL;DR: In this paper, numerical simulation of the flow fields of a rotating variable-sweep wing-body and a shearing VAE was conducted, and the aerodynamic characteristics and its mechanism were analyzed.
Abstract: In order to explore the methods of morphing aircraft variable-sweep and their aerodynamic characteristics,numerical simulation of the flow fields of a rotating variable-sweep wing-body and a shearing variable-sweep wing-body was conducted,and the aerodynamic characteristics and its mechanism were analyzed.Numerical simulation method of viscous compressible flow and hybrid grid of prism-hexahedron were used.The results demonstrate that: shearing variable-sweep has better characteristics than rotating variable-sweep in that the former has better lift-to-drag ratio and drag when flying at a speed in the range from M∞ 0.3 to M∞ 0.8,and the main reason is distinct flow field structure caused by the different variable-sweep methods.
10 citations
TL;DR: In this paper , the aerodynamic and structural investigation of the winglet is done experimentally and the modification is done in the winglets to improve the lift force capacity and minimize the drag effect.
10 citations
Patent•
09 Dec 2009
TL;DR: In this article, an upper winglet and a lower winglet are used as an end plate to block bottom wing surface air current from flowing to the upper wing surface, which has the advantages of weakening wingtip eddy diffusion and trailing vortex intensity, downwash field of wingtips of wings and induced drag.
Abstract: The invention relates to a wingtip eddy diffusion device, comprising an upper winglet and a lower winglet which play the role of an end plate to block bottom wing surface air current from flowing to the upper wing surface; the upper winglet and the lower winglet are both of symmetrical airfoil profile; the symmetrical airfoil profile can avoid intense shock wave under supercritical air current condition, extra wave drag; certain deflection exists in wingtips of corresponding wings of the two winglets, thus improving lifting force of wings. The invention has the advantages of weakening wingtip eddy diffusion and trailing vortex intensity, downwash field of wingtips of wings and induced drag.
10 citations
TL;DR: In this article, the aerodynamic resistance acting on the legs counts up to 1/3 of the total drag in speed skating, due to the fact that the athletes minimize their frontal area keeping the trunk parallel to the air flow.
Abstract: In sports where high speed is reached and drag is the main force acting on the athlete's body, the posture highly influences the total drag. In speed skating, due to the fact that the total drag is proportional to the frontal area, the athletes minimize their frontal area keeping the trunk parallel to the air flow. In this study it is shown that the aerodynamic resistance acting on the legs counts up to 1/3 of the total drag. In order to reduce the drag, rough textiles with different patterns have been used in sport suits. However, a certain number of parameters need to be considered in order to optimize the aerodynamic performance of a textile. These parameters are: speed, diameter of the leg, yaw angle, distance between the legs and roughness of the textile. This study shows a quantitative effect of the different parameters on the aerodynamic performances of textiles. Tests have been carried out on cylinder models and c D -speed curves for each case have been acquired. The contemporary effect of roughne...
10 citations