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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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Patent
30 Jul 2010
TL;DR: In this paper, an aircraft with an elongated fuselage and a lifting surface fastened to the fuselage has a device for controlling the torque around the yaw axis GZ of the aircraft in which aerodynamic forms that have devices to generate aerodynamic drag are fastened on each end of the lifting surface at non-zero distances from each side of a vertical plane of symmetry XZ.
Abstract: An aircraft having an elongated fuselage and a lifting surface fastened to the fuselage. The aircraft has a device for controlling the torque around the yaw axis GZ of the aircraft in which aerodynamic forms that have devices to generate aerodynamic drag are fastened to each end of the lifting surface at non-zero distances from each side of a vertical plane of symmetry XZ of the aircraft. The drag-generating devices are commanded to produce a different aerodynamic drag at each of the two ends to generate a yaw torque on the aircraft. The aerodynamic forms, for example, have winglets improving the aerodynamics of the lifting surface, and provided with aerodynamic drag generators.

19 citations

Proceedings ArticleDOI
24 Aug 1964
TL;DR: In this paper, the authors compared a variety of simple lifting forms in the Mach range from 5 to 20 and found that the use of flat lifting surfaces produces higher lift/drag ratios than circular, vee, "caret," and "isentropic compression" surfaces.
Abstract: The comparative performance and heat-transfer problems of a variety of simple lifting forms are investigated in the Mach range from 5 to 20. In general it is found that the use of flat lifting surfaces produces higher lift/drag ratios than circular, vee, "caret," and "isentropic compression" surfaces. An exception is the thin delta wing with underslung body for which a favorable interference effect is produced at the lower hypersonic speeds. Configuration limits within which the favorable interference is obtainable are established. As the Mach number advances beyond about 10, adverse viscous interactions develop to such an extent that the interference effect becomes unfavorable, and higher lift/drag ratios are achieved by flat-bottom wing-bodies. A comparison of the best of these wing-body combinations with thick wings and with merged wing-bodies of equal volume and planform area reveals only snmll differences in peak lift/drag ratio. All configurations suffer a major deterioration in lift/drag as the Mach number is increased and the Reynolds number is decreased in conformance to typical hypersonic flight trajectories, because of the growth of adverse viscous effects. An important factor in this performance degradation is the unexpectedly high pressure found on the lee side at the higher Mach numbers. Heat-transfer studies reveal several anomalies associated with the viscous interactions and with the interacting flow fields of wing and body. An analysis of the leading-edge region of a typical wing leads to the conclusion that the relatively sharp leading edges essential to high lift/drag ratio are not impractical if a combination of internal and radiative cooling techniques are employed. INTRODUCTION During the next decade there will be an upsurge of interest in the development of hypersonic vehicles capable of e fficient long-range flight within the earth's at mosphere. The speeds of interest range upward from 877 878 FOURTH CONGRESS AERONAUTICAL SCIENCES about Mach 6 for hypersonic t ransports and recoverable first-stage boosters to near-orbital speeds for boost-glide and advanced self-propelled types. In contrast to the extensive effort that has been and continues to be applied to the aerodynamics of turbojet vehicles in the speed range up to about Mach 3, research on efficient hypersonic forms is still in its infancy. As a first approach to the hypersonic problem it is pertinent to examine the principles and guidelines which have been established for the lower supersonic speeds. The oldest principle, which up to now has been used almost universally, is separation of the vehicle into discrete elements according to function—the wing for lifting, the fuselage for housing, and so on. As design speeds advanced, increasing refinement in the shape details of these elements and their relative configurational positions became necessary. The swept-wing principle was developed, followed by the transonic and supersonic area rules Il-3]. A direct application of these principles to hypersonic velocities is rather obviously invalid, and results in configurations in which the wing is so highly swept that it tends to be largely engulfed by the fuselage. Thus the old guidelines become virtually useless. At best, they may be interpreted as pointing toward a merging of the wing and body functions. This is evidenced in the lifting-bodies and blended wing-body forms which are of interest in current hypersonic research. These wingless slender body shapes are all very well for expendable missiles; however, the manned hypersonic vehicles of the future as currently visualized will be required to perform acceptably through the entire flight-speed regime including the conventional low-speed approach and landing. Clearly, then, either the slender body configurations must be equipped with variable geometry devices such as retractable wings, or we must develop fixed geometry configurations having sufficient span to be flyable at low speeds. Accordingly, winged configurations continue to be of great interest in hypersonic research, despite the fact that they cannot be fitted into the geometrical pat terns required by the old guiding principles. Toward the eventual establishment of new principles for the design of efficient hypersonic configurations we have studied the comparative performance and heat-transfer problems of a variety of simple wing, body, wing-body, and merged or blended forms in the speed range up to Mach 20. The aim of this paper is to review the principal result s obtained so far front these studies. TWO DIMENSIONAL PLATES The flat plate of zero thickness and infinite span is of special interest because its lift/drag characteristics represent: an upper limit to the efficiency attainable for hypersonic lifting forms and because it can be analyzed STUDIES OF HYPERSONIC CONFIGURATIONS 879

19 citations

Dissertation
01 Jan 2013
TL;DR: In this paper, an experimental study of the turbulent wake past different geometries is performed by increasing the complexity from axisymmetric bodies to road vehicles, and two kinds of coherent wake motions are likely to be observed.
Abstract: An experimental study of the turbulent wake past different geometries is performed by increasing the complexity from axisymmetric bodies to road vehicles. Whatever the geometry is, two kinds of coherent wake motions are likely to be observed. First, at timescales of the order of 5D/U, D and U being the characteristic size and velocity of the flow respectively, the wake may generate periodic oscillations. These coherent motions are usually associated with the interaction of two facing shear layers of opposite vorticity. As the corresponding frequencies rely at first order on the distance between the shear layers, two distinct frequencies are reported when the afterbody has a cross-flow aspect ratio different than 1. These unsteady global modes seem to weaken when the Reynolds number and the complexity of the geometry increase. The second type of coherent motions corresponds to the development of stationary cross-flow instabilities. They are linked to the symmetry breaking modes observed in laminar regimes and their domains of appearance are defined from geometry considerations in the cases of parallelepiped bodies in ground proximity. These instabilities are responsible for strong asymmetries in the instantaneous flow and may generate bistable dynamics with a characteristic time scale of the order of 1000D/U. The study of these phenomena, combined with sensitivity analyses to small perturbations, places the diminution of the cross-flow asymmetries of the instantaneous wake as a relevant strategy for drag reduction. In particular, it is found that both local and global pressure gradients on the sides of the body are source of streamwise vortices increasing the drag. Parabolic dependences between the drag and the cross-flow forces are reported suggesting similarities with the mechanisms of induced drag that are well-known in aeronautics. Consequently, as they often generate significant wake asymmetries, the development of the cross-flow instabilities is identified as a drag contributor. On the contrary, the part of the drag related to the periodic global modes seems to be negligible especially for complex geometries at high Reynolds number.

19 citations

01 Jan 1990
TL;DR: The most common configuration for slot ingestion in the literature involves tangential injection of air along a two-dimensional surface on which air constitutes the mainstream flow; attention is presently given to slot injection in low-speed and high-speed flows, as well as a discussion of aircraft applications and an evaluation of prospective possibilities for practical drag reduction systems.
Abstract: Slot injection systems on the surfaces of aerodynamic bodies have been noted to consistently furnish substantial local skin friction reductions which are predictable on the basis of current numerical methods. Only crude systems studies, however, have been thus far completed. The most common configuration for slot ingestion in the literature involves tangential injection of air along a two-dimensional surface on which air constitutes the mainstream flow; attention is presently given to slot injection in low-speed and high-speed flows, as well as a discussion of aircraft applications and an evaluation of prospective possibilities for practical drag-reduction systems.

19 citations

Journal ArticleDOI
TL;DR: In this paper, multi-objective genetic algorithms (MOGAs) have been applied to optimize an inverse design of a transonic wing shape, where the wing planform is optimized by solving a multidisciplinary optimization problem based on aerodynamic, structural, and fuel storing objectives and constraints.
Abstract: Multi-objective genetic algorithms (MOGAs) have been applied to optimize an inverse design of a transonic wing shape. First, the wing planform is optimized by solving a multidisciplinary optimization problem based on aerodynamic, structural, and fuel storing objectives and constraints. Second, three-dimensional target pressure distribution is optimized for the aerodynamic inverse design with the previously designed planform. Minimization of the profile drag and the induced drag is performed under constraints on lift and other design principles. Applying these two preprocessing procedures by using MOGAs, Pareto surfaces can be studied for tradeoffs among multiple objectives. Thus, a designer is able to choose a good compromise for wing planform and target pressures for the inverse design. Corresponding for wing surface geometry is obtained by Takanashi's inverse method, and a sample design result is given

19 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202344
2022105
202138
202046
201944
201849