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1
Harbig, R. R., J. Sheridan, and M. C. Thompson. "Relationship between aerodynamic forces, flow structures and wing camber for rotating insect wing planforms." Journal of Fluid Mechanics 730 (July 30, 2013): 52–75. http://dx.doi.org/10.1017/jfm.2013.335.
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AbstractWing deformation is observed during the flight of some insect species; however, the effect of these distorted wing shapes on the leading edge vortex (LEV) is not well understood. In this study, we investigate the effect of one of these deformation parameters, (rigid) wing camber, on the flow structures and aerodynamic forces for insect-like wings, using a numerical model of an altered fruit fly wing revolving at a constant angular velocity. Both positive and negative camber was investigated at Reynolds numbers of 120 and 1500, along with the chordwise location of maximum camber. It was found that negatively cambered wings produce very similar LEV structures to non-cambered wings at both Reynolds numbers, but high positive camber resulted in the formation of multiple streamwise vortices at the higher Reynolds number, which disrupt the development of the main LEV. Despite this, positively cambered wings were found to produce higher lift to drag ratios than flat or negatively cambered wings. It was determined that a region of low pressure near the wing’s leading edge, combined with the curvature of the wing’s upper surface in this region, resulted in a vertical tilting of the net force vector for positively cambered wings, which explains how insects can benefit from wing camber.
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Walker, Simon M., Adrian L. R. Thomas, and Graham K. Taylor. "Deformable wing kinematics in the desert locust: how and why do camber, twist and topography vary through the stroke?" Journal of The Royal Society Interface 6, no. 38 (December 16, 2008): 735–47. http://dx.doi.org/10.1098/rsif.2008.0435.
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Here, we present a detailed analysis of the wing kinematics and wing deformations of desert locusts ( Schistocerca gregaria , Forskål) flying tethered in a wind tunnel. We filmed them using four high-speed digital video cameras, and used photogrammetry to reconstruct the motion of more than 100 identified points. Whereas the hindwing motions were highly stereotyped, the forewing motions showed considerable variation, consistent with a role in flight control. Both wings were positively cambered on the downstroke. The hindwing was cambered through an ‘umbrella effect’ whereby the trailing edge tension compressed the radial veins during the downstroke. Hindwing camber was reversed on the upstroke as the wing fan corrugated, reducing the projected area by 30 per cent, and releasing the tension in the trailing edge. Both the wings were strongly twisted from the root to the tip. The linear decrease in incidence along the hindwing on the downstroke precisely counteracts the linear increase in the angle of attack that would otherwise occur in root flapping for an untwisted wing. The consequent near-constant angle of attack is reminiscent of the optimum for a propeller of constant aerofoil section, wherein a linear twist distribution allows each section to operate at the unique angle of attack maximizing the lift to drag ratio. This implies tuning of the structural, morphological and kinematic parameters of the hindwing for efficient aerodynamic force production.
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Traub, L. W., R. Waghela, and K. A. Bordignon. "Characterisation of a highly staggered spanwise cambered biplane." Aeronautical Journal 119, no. 1212 (February 2015): 203–28. http://dx.doi.org/10.1017/s0001924000010344.
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AbstractAn investigation is presented to elucidate the performance of a staggered, spanwise cambered biplane. The spanwise camber yielded wings forming a ‘∧’ or ‘∨’ when viewed streamwise. The configuration is examined in terms of its aerodynamic and stability characteristics. The feasibility of negating the requirement for a conventional empennage is explored. Geometric variation encompassed front and back wing anhedral/dihedral angles yielding 49 combinations. Evaluation of the geometry was accomplished using both wind tunnel testing and numerical simulation. The results indicated that front wing dihedral in conjunction with aft wing anhedral was most beneficial, such that the benefit of wake spacing was maximised. Aerodynamic benefit was indicated compared to a conventional empennage geometry. The greatest disparity in behaviour of the fore and aft wing anhedral/dihedral distribution was in the high lift regime, where the nature of the stall varied. Simulations to establish the viability of the geometry in terms of controllability were also conducted and indicated that the configuration is viable.
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Traub, Lance W. "Lift Prediction of Spanwise Cambered Delta Wings." Journal of Aircraft 36, no. 3 (May 1999): 515–22. http://dx.doi.org/10.2514/2.2486.
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Traub, Lance W. "Aerodynamic Characteristics of Spanwise Cambered Delta Wings." Journal of Aircraft 37, no. 4 (July 2000): 714–24. http://dx.doi.org/10.2514/2.2657.
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Wootton, R. J., K. E. Evans, R. Herbert, and C. W. Smith. "The hind wing of the desert locust (Schistocerca gregaria Forskal). I. Functional morphology and mode of operation." Journal of Experimental Biology 203, no. 19 (October 1, 2000): 2921–31. http://dx.doi.org/10.1242/jeb.203.19.2921.
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Detailed morphological investigation, mechanical testing and high-speed cinematography and stroboscopic examination of desert locusts, Schistocerca gregaria, in flight show that their hind wings are adapted to deform cyclically and automatically through the wing stroke and that the deformations are subtly dependent on the wings' structure: their shape, venation and vein design and the local properties of the membrane. The insects predominantly fly fast forwards, generating most force on the downstroke, and the hind wings generate extra lift by peeling apart at the beginning of the downstroke and by developing a cambered section during the stroke's translation phase through the ‘umbrella effect’ - an automatic consequence of the active extension of the wings' expanded posterior fan. Bending experiments indicate that most of the hind wing is more rigid to forces from below than from above and demonstrate that the membrane acts as a stressed skin to stiffen the structure.
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Forster, K. J., and T. R. White. "Numerical Investigation into Vortex Generators on Heavily Cambered Wings." AIAA Journal 52, no. 5 (May 2014): 1059–71. http://dx.doi.org/10.2514/1.j052529.
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Wrist, Andrew H., and James P. Hubner. "Aerodynamic comparisons of flexible membrane micro air vehicle wings with cambered and flat frames." International Journal of Micro Air Vehicles 10, no. 1 (May 29, 2017): 12–30. http://dx.doi.org/10.1177/1756829317705327.
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Flexible membrane wings at the micro air vehicle scale can experience improved lift/drag ratios, delays in stall, and decreased time-averaged flow separation when compared to rigid wings. This research examines the effect of frame camber on the aerodynamic characteristics of membrane wings. The frames for the wings were 3D printed using a polymer-based material. The membranes are silicone rubber. Tests were conducted at Re ∼50,000. Aerodynamic force and moment measurements were acquired at angles-of-attack varying from −4 to 24°. Additionally, digital image correlation data were acquired to assess time-averaged shapes of the membrane wings during wind tunnel tests. An in-house program was developed to average the deflection plots from the digital image correlation images and produce time-averaged shapes. Lifting-line theory based on the time-averaged shapes was then used to calculate theoretical lift and induced drag coefficients, showing that the time-average shape of the membrane under load contributes extensively to the aerodynamic performance. The results show that introducing camber to the frames of membrane wings increases aerodynamic efficiency.
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ENNOS, A. ROLAND, and ROBIN J. WOOTTON. "FUNCTIONAL WING MORPHOLOGY AND AERODYNAMICS OF PANORPA GERMANICA (INSECTA: MECOPTERA)." Journal of Experimental Biology 143, no. 1 (May 1, 1989): 267–84. http://dx.doi.org/10.1242/jeb.143.1.267.
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The functional wing morphology of the wings of the scorpion fly Panorpa germanica L. was investigated using a combination of light microscopy, high-speed cinematography, wing manipulation and mechanical testing In rising forward flight the wings are flapped 40° out of phase along a shallow stroke plane, the forewings leading. Aerodynamic analysis suggests that unsteady effects are important in flight During the downstroke, both wings are straight and cambered, the chord being parallel to the body axis, which is angled 45° upwards from horizontal. Both wings are supinated at lower stroke reversal, the hindwing to a much greater extent, and flex ventrally halfway along their length for the first half of the upstroke. Flexion is parallel to the chord in the hindwing, but is oblique in the forewing, so distal forewing areas are supinated relative to proximal areas The behaviour of the wings is related to their structure. Spars at the leading and trailing edges of both wings support the wing during the downstroke, and flexion during the upstroke is facilitated by buckling of the weak ventral thyridium region. The oblique flexion seen in the forewing is due to its relatively longer leading edge spar The differences between the wings are, in turn, related to their pitch control mechanisms. The forewing has a well-developed clavus, like that of the forewing of a locust, and pitch is altered by relative movement of this and the leading edge, but only within a narrow range. Oblique flexion is necessary to invert the aerofoil. The weaker and less well-developed clavus of the hindwing, more similar to that of the Diptera, allows a greater degree of supination, effected largely by wing inertia. No oblique flexion is necessary
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Traub, Lance W. "Analytic Drag Prediction for Cambered Wings with Partial Leading Edge Suction." Journal of Aircraft 46, no. 1 (January 2009): 312–19. http://dx.doi.org/10.2514/1.38558.
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Knight, Jason, Simon Fels, Benjamin Beazley, George Haritos, and Andrew Lewis. "Fluid–Structure Interaction of Symmetrical and Cambered Spring-Mounted Wings Using Various Spring Preloads and Pivot Point Locations." Applied Mechanics 2, no. 3 (August 27, 2021): 591–612. http://dx.doi.org/10.3390/applmech2030034.
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The fluid–structure interaction of a pivoting rigid wing connected to a spring and subjected to freestream airflow in a wind tunnel is presented. Fluid–structure interactions can, on the one hand, lead to undesirable aerodynamic behaviour or, in extreme cases, to structural failure. On the other hand, improved aerodynamic performance can be achieved if a controlled application within certain limitations is provided. One application is the reduction of drag of road vehicles at higher speeds on a straight, while maintaining downforce at lower speeds during cornering. Conversely, another application concerns increased downforce at higher windspeeds, enhancing vehicle stability. In our wind tunnel experiments, the angle of incidence of the spring-mounted wing is either increased or decreased depending on the pivot point location and spring torque. Starting from a specified initial angle, the aerodynamic forces overcome a pre-set spring preload at incrementally increased freestream velocity. Reynolds numbers at a range of Re = 3 × 104 up to Re = 1.37 × 105 are considered. The application of a symmetrical NACA 0012 and a cambered NACA 6412 airfoil are tested in the wind tunnel and compared. For both airfoils mounted ahead of the aerodynamic centre, stable results were achieved for angles above 15 and below 12 degrees for the symmetrical airfoil, and above 25 and between 10 and −2 degrees for the cambered airfoil. Unsteady motions were observed around the stall region for both airfoils with all spring torque settings and also below −2 degrees for the cambered airfoil. Stable results were also found outside of the stall region when both airfoils were mounted behind the aerodynamic centre, although the velocity ranges were much smaller and highly dependent on the pivot point location. An analysis is reported concerning how changing the spring torque settings at each pivot point location effects performance. The differences in performance between the symmetrical and cambered profiles are then presented. Finally, an evaluation of the systems’ effects was conducted with conclusions, future improvements, and potential applications.
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Lambert, Thomas, and Grigorios Dimitriadis. "Induced Drag Calculations with the Unsteady Vortex Lattice Method for Cambered Wings." AIAA Journal 55, no. 2 (February 2017): 668–72. http://dx.doi.org/10.2514/1.j055135.
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Chu, Julio, and John E. Lamar. "Force and pressure study of thick cambered/twisted 58 deg delta wings." Journal of Aircraft 25, no. 1 (January 1988): 69–75. http://dx.doi.org/10.2514/3.45543.
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Senthil Kumar, M., R. Vijayanandh, N. Kaviarasan, R. Dinesh Kumar, I. Adrin Issai Arasu, and R. Kanmaniraja. "Numerical and Experimental Investigation on the Aerodynamic performance of roller Airfoil." International Journal of Engineering & Technology 7, no. 4.10 (October 2, 2018): 637. http://dx.doi.org/10.14419/ijet.v7i4.10.21302.
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Prevailing norm is a fixed wing in a conventional aircraft, but the prospect appears bright for developing wings that could yield better aerodynamic properties with a change in the form and shape, this may have a wider application in future aviation. The main objective of this paper is to probe such a morphing technology in wings to improve their aerodynamic performance while operating at various cruise conditions. The airfoil is equipped with a rolling mechanism on its upper surface, operated by custom- designed controllers. This roller airfoil model will generate higher lift at low angles of attack and substantially increase flight performance, leading to the evolution of a create multiple-regime, aerodynamically efficient aircraft. This paper aims to compare the performance enhancement of roller airfoil over a conventional airfoil, by increasing the velocity at the upper surface of the airfoil to increase the lift to drag ratio using typical engineering analyses. The cambered airfoil chosen here is NACA 4412. Morphing concept brings about the improvement due to a reduction in lift-induced drag by promoting large laminar flow run on the upper surface of the wing.
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Pelletier, Alain, and Thomas J. Mueller. "Low Reynolds Number Aerodynamics of Low-Aspect-Ratio, Thin/Flat/Cambered-Plate Wings." Journal of Aircraft 37, no. 5 (September 2000): 825–32. http://dx.doi.org/10.2514/2.2676.
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Roy, Aritras, R. Vinoth Kumar, and Rinku Mukherjee. "Experimental validation of numerical decambering approach for flow past a rectangular wing." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 9 (April 6, 2020): 1564–82. http://dx.doi.org/10.1177/0954410020916311.
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Experimental investigation on two rectangular wings with NACA0012 and NACA4415 profiles is performed at different Reynolds numbers to understand their aerodynamic behaviours at a high α regime. In-house developed numerical code VLM3D is validated using this experimental result in predicting the aerodynamic characteristics of a rectangular wing with cambered and symmetrical wing profile. The sectional coefficient of lift ([Formula: see text]) obtained from the numerical approach is used to study the variation in spanwise lift distribution. The lift and moment characteristics obtained from wind tunnel experiments are plotted, and change in the maximum coefficient of lift ([Formula: see text]) and stall angle ( α stall) are studied for both of the wing sections. A significant addition to the novelty of the present experiments is to provide some comparison of the numerical induced drag coefficient, [Formula: see text] with experimentally fitted model coefficients using least square technique. A novel method is used to examine the aerodynamic hysteresis at high angles of attack. The area included in the lift- Re curve loop is a measure of aerodynamic efficiency, and its variation with angle of attack and wing plan forms is studied.
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Engels, Thomas, Henja-Niniane Wehmann, and Fritz-Olaf Lehmann. "Three-dimensional wing structure attenuates aerodynamic efficiency in flapping fly wings." Journal of The Royal Society Interface 17, no. 164 (March 2020): 20190804. http://dx.doi.org/10.1098/rsif.2019.0804.
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The aerial performance of flying insects ultimately depends on how flapping wings interact with the surrounding air. It has previously been suggested that the wing's three-dimensional camber and corrugation help to stiffen the wing against aerodynamic and inertial loading during flapping motion. Their contribution to aerodynamic force production, however, is under debate. Here, we investigated the potential benefit of three-dimensional wing shape in three different-sized species of flies using models of micro-computed tomography-scanned natural wings and models in which we removed either the wing's camber, corrugation, or both properties. Forces and aerodynamic power requirements during root flapping were derived from three-dimensional computational fluid dynamics modelling. Our data show that three-dimensional camber has no benefit for lift production and attenuates Rankine–Froude flight efficiency by up to approximately 12% compared to a flat wing. Moreover, we did not find evidence for lift-enhancing trapped vortices in corrugation valleys at Reynolds numbers between 137 and 1623. We found, however, that in all tested insect species, aerodynamic pressure distribution during flapping is closely aligned to the wing's venation pattern. Altogether, our study strongly supports the assumption that the wing's three-dimensional structure provides mechanical support against external forces rather than improving lift or saving energetic costs associated with active wing flapping.
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Shi, Xing, Xianwen Huang, Yao Zheng, and Susu Zhao. "Effects of cambers on gliding and hovering performance of corrugated dragonfly airfoils." International Journal of Numerical Methods for Heat & Fluid Flow 26, no. 3/4 (May 3, 2016): 1092–120. http://dx.doi.org/10.1108/hff-10-2015-0414.
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Purpose – The purpose of this paper is to explore the effects of the camber on gliding and hovering performance of two-dimensional corrugated airfoils. While the flying mechanism of natural flyers remains a myth up to nowadays, the simulation serves as a minor step toward understanding the steady and unsteady aerodynamics of the dragonfly flight. Design/methodology/approach – The lattice Boltzmann method is used to simulate the flow past the cambered corrugated dragonfly airfoil at low Reynolds numbers. For gliding flight, the maximum camber, the distance of the location of maximum camber point from the leading edge and Reynolds number are regarded as control variables; for hovering flight, the maximum camber, the flapping amplitude and trajectory are considered as control variables. Then corresponding simulations are performed to evaluate the implications of these factors. Findings – Greater gliding ratio can be reached by increasing the maximum camber of the dragonfly wing section. When the location of the maximum camber moves backward along the wing chord, large scale flow separation can be delayed. These two effects result in better gliding performances. For hovering performances, it is found that for different flapping amplitudes along an inclined plane, the horizontal force exerted on the airfoils increases with the camber, and the drag growths first but then drops. It is also found that the elliptic flapping trajectory is most sensitive to the camber of the cambered corrugated dragonfly wing section. Originality/value – The effects of the camber on gliding and hovering performance of the cambered dragonfly wing section are explored in detail. The data obtained can be helpful when designing micro aerial vehicles.
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Meresman, Yonatan, and Gal Ribak. "Allometry of wing twist and camber in a flower chafer during free flight: How do wing deformations scale with body size?" Royal Society Open Science 4, no. 10 (October 2017): 171152. http://dx.doi.org/10.1098/rsos.171152.
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Intraspecific variation in adult body mass can be particularly high in some insect species, mandating adjustment of the wing's structural properties to support the weight of the larger body mass in air. Insect wings elastically deform during flapping, dynamically changing the twist and camber of the relatively thin and flat aerofoil. We examined how wing deformations during free flight scale with body mass within a species of rose chafers (Coleoptera: Protaetia cuprea ) in which individuals varied more than threefold in body mass (0.38–1.29 g). Beetles taking off voluntarily were filmed using three high-speed cameras and the instantaneous deformation of their wings during the flapping cycle was analysed. Flapping frequency decreased in larger beetles but, otherwise, flapping kinematics remained similar in both small and large beetles. Deflection of the wing chord-wise varied along the span, with average deflections at the proximal trailing edge higher by 0.2 and 0.197 wing lengths compared to the distal trailing edge in the downstroke and the upstroke, respectively. These deflections scaled with wing chord to the power of 1.0, implying a constant twist and camber despite the variations in wing and body size. This suggests that the allometric growth in wing size includes adjustment of the flexural stiffness of the wing structure to preserve wing twist and camber during flapping.
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Cheney, Jorn A., Jonathan P. J. Stevenson, Nicholas E. Durston, Masateru Maeda, Jialei Song, David A. Megson-Smith, Shane P. Windsor, James R. Usherwood, and Richard J. Bomphrey. "Raptor wing morphing with flight speed." Journal of The Royal Society Interface 18, no. 180 (July 2021): 20210349. http://dx.doi.org/10.1098/rsif.2021.0349.
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In gliding flight, birds morph their wings and tails to control their flight trajectory and speed. Using high-resolution videogrammetry, we reconstructed accurate and detailed three-dimensional geometries of gliding flights for three raptors (barn owl, Tyto alba ; tawny owl, Strix aluco , and goshawk, Accipiter gentilis ). Wing shapes were highly repeatable and shoulder actuation was a key component of reconfiguring the overall planform and controlling angle of attack. The three birds shared common spanwise patterns of wing twist, an inverse relationship between twist and peak camber, and held their wings depressed below their shoulder in an anhedral configuration. With increased speed, all three birds tended to reduce camber throughout the wing, and their wings bent in a saddle-shape pattern. A number of morphing features suggest that the coordinated movements of the wing and tail support efficient flight, and that the tail may act to modulate wing camber through indirect aeroelastic control.
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Harvey, C., V. B. Baliga, P. Lavoie, and D. L. Altshuler. "Wing morphing allows gulls to modulate static pitch stability during gliding." Journal of The Royal Society Interface 16, no. 150 (January 2019): 20180641. http://dx.doi.org/10.1098/rsif.2018.0641.
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A gliding bird's ability to stabilize its flight path is as critical as its ability to produce sufficient lift. In flight, birds often morph the shape of their wings, but the consequences of avian wing morphing on flight stability are not well understood. Here, we investigate how morphing the gull elbow joint in gliding flight affects their static pitch stability. First, we combined observations of freely gliding gulls and measurements from gull wing cadavers to identify the wing configurations used during gliding flight. These measurements revealed that, as wind speed and gusts increased, gulls flexed their elbows to adopt wing shapes characterized by increased spanwise camber. To determine the static pitch stability characteristics of these wing shapes, we prepared gull wings over the anatomical elbow range and measured the developed pitching moments in a wind tunnel. Wings prepared with extended elbow angles had low spanwise camber and high passive stability, meaning that mild perturbations could be negated without active control. Wings with flexed elbow angles had increased spanwise camber and reduced static pitch stability. Collectively, these results demonstrate that gliding gulls can transition across a broad range of static pitch stability characteristics using the motion of a single joint angle.
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ENNOS, A. ROLAND. "The Importance of Torsion in the Design of Insect Wings." Journal of Experimental Biology 140, no. 1 (November 1, 1988): 137–60. http://dx.doi.org/10.1242/jeb.140.1.137.
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A model insect wing is described in which spars of corrugated membrane which incorporate stiffening veins branch serially from a V-section leading edge spar. The mechanical behaviour of this model is analysed. The open, corrugated spars possess great resistance to bending, but are compliant in torsion. Torsion of the leading edge spar will result in torsion and relative movement of the rear spars. As a result camber will automatically be set up in the wing as it twists. Aerodynamic forces produced during the wing strokes will result in torsion and camber of the wing which should improve its aerodynamic efficiency. The effects of varying parameters of the wing model are examined. For given wing torsion, higher camber is given by spars branching from the leading edge at a lower angle, by spars which curve posteriorly, and by spars which diverge from each other. Wings of three species of flies were each subjected to two series of mechanical tests. Application of a force behind the torsional axis caused the wings to twist and to develop camber. Immobilizing basal regions of the leading edge greatly reduced compliance to torsion and camber, as predicted by the theoretical model. Aerodynamic forces produced during a half-stroke are sufficient to produce observed values of torsion and camber, and to maintain changes in pitch caused by inertial effects at stroke reversal.
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bin Md Shah, Mohd Zarif, Mohd Ridh bin Abu Bakar, and Bambang Basuno. "The Aerodynamics Analysis on Cambered Fuselage Model." Applied Mechanics and Materials 660 (October 2014): 492–97. http://dx.doi.org/10.4028/www.scientific.net/amm.660.492.
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There various factors gives influence in determining the fuselage shapes, such as the payload, cockpit, wing and tail placements or in manner up and down loading the payload for a cargo aircraft. These factors may come up the fuselage is no longer as symmetrical fuselage but represent as a cambered fuselage. As results the lift coefficient as well as its pitching moment coefficient is no longer equal to zero as the angle of attack goes to zero. Basically the manner how to determine the fuselage aerodynamics characteristics for cambered fuselage can be done in similar way as in the case of symmetrical fuselage by simply replacing the angle of attack α term with (α-αL=0), where αL=0 represent the angle of attack at zero lift. The present work use a similar manner in determining the zero lift angle of attack as it had been used in DATCOM software. To investigate the effect of camber on the aerodynamics characteristic fuselage, the present work use a fuselage model with a circular cross section where the location of center of the circle placed along the fuselage’s camber line. The fuselage’s camber line defined according to the definition of camber line of NACA airfoils. Aerodynamics analysis on over various fuselage models indicate that the maximum camber line thickness and their position give a significant influent to the fuselage aerodynamics characteristics.
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Cole, Julian D., and Norman D. Malmuth. "Wave drag due to lift for transonic airplanes." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, no. 2054 (February 8, 2005): 541–60. http://dx.doi.org/10.1098/rspa.2004.1376.
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Lift–dominated pointed aircraft configurations are considered in the transonic range. To make the approximations more transparent, two–dimensionally cambered untwisted lifting wings of zero thickness with aspect ratio of order one are treated. An inner expansion, which starts as Jones's theory, is matched to a nonlinear outer transonic theory as in Cheng and Barnwell's earlier work. To clarify issues, minimize ad hoc assumptions existing in earlier studies, as well as provide a systematic expansion scheme, a deductive rather than inductive approach is used with the aid of intermediate limits and matching not documented for this problem in previous literature. High–order intermediate–limit overlap–domain representations of inner and outer expansions are derived and used to determine unknown gauge functions, coordinate scaling and other elements of the expansions. The special role of switchback terms is also described. Non–uniformities of the inner approximation associated with leading–edge singularities similar to that in incompressible thin airfoil theory are qualitatively discussed in connection with separation bubbles in a full Navier–Stokes context and interaction of boundary–layer separation and transition. Non–uniformities at the trailing edge are also discussed as well as the important role of the Kutta condition. A new expression for the dominant approximation of the wave drag due to lift is derived. The main result is that although wave drag due to lift integral has the same form as that due to thickness, the source strength of the equivalent body depends on streamwise derivatives of the lift up to a streamwise station rather than the streamwise derivative of cross–sectional area. Some examples of numerical calculations and optimization studies for different configurations are given that provide new insight on how to carry the lift with planform shaping (as one option), so that wave drag can be minimized.
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Breslin, John P. "Chines-Dry Planing of Slender Hulls: A General Theory Applied to Prismatic Surfaces." Journal of Ship Research 45, no. 01 (March 1, 2001): 59–72. http://dx.doi.org/10.5957/jsr.2001.45.1.59.
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The ultimate goals of this two-part study are the advantages and de' ciencies of application of camber to dry-chine, stepped-planing forms. The present paper is limited to the correlation of a relatively new theory with existing data to qualify it for use in a later paper which will predict the hydrodynamic characteristics of practical forms without and with cambers. Following a brief account of the pertinent literature, a mathematical model is developed via slender-body theory. It is a generalization of M. P. Tulin's (1957) seminal analysis of flat, cambered, delta-wing waterplanes to include deadrise, together with a departure from the oversimpli' ed Wagnerian (1932) theory ' rst introduced by Vorus (1996). It is an independent, less complicated development which con'rms Vorus's result for his special case of straight-sided wedges. Detailed comparisons of all the hydrodynamic coefficients with data from model tests of prismatic hulls show that this theory is superior to that of Wagner. A very simple formula for maximum pressures is shown. Comparisons with the extensive theories of Zhao and Faltinsen are discussed. The theory is justi' ed for extension to more pragmatic forms within the scope of the theory.
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Waldrop, Lindsay D., Yanyan He, Tyson L. Hedrick, and Jonathan A. Rader. "Functional Morphology of Gliding Flight I: Modeling Reveals Distinct Performance Landscapes Based on Soaring Strategies." Integrative and Comparative Biology 60, no. 5 (August 7, 2020): 1283–96. http://dx.doi.org/10.1093/icb/icaa114.
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Synopsis The physics of flight influences the morphology of bird wings through natural selection on flight performance. The connection between wing morphology and performance is unclear due to the complex relationships between various parameters of flight. In order to better understand this connection, we present a holistic analysis of gliding flight that preserves complex relationships between parameters. We use a computational model of gliding flight, along with analysis by uncertainty quantification, to (1) create performance landscapes of gliding based on output metrics (maximum lift-to-drag ratio, minimum gliding angle, minimum sinking speed, and lift coefficient at minimum sinking speed) and (2) predict what parameters of flight (chordwise camber, wing aspect ratio [AR], and Reynolds number) would differ between gliding and nongliding species of birds. We also examine performance based on the soaring strategy for possible differences in morphology within gliding birds. Gliding birds likely have greater ARs than non-gliding birds, due to the high sensitivity of AR on most metrics of gliding performance. Furthermore, gliding birds can use two distinct soaring strategies based on performance landscapes. First, maximizing distance traveled (maximizing lift-to-drag ratio and minimizing gliding angle) should result in wings with high ARs and middling-to-low wing chordwise camber. Second, maximizing lift extracted from updrafts should result in wings with middling ARs and high wing chordwise camber. Following studies can test these hypotheses using morphological measurements.
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A, Mugeshwaran, Guru Prasad Bacha, and Rajkumar S. "Design and experimental analysis of morphing wing based on biomimicry." International Journal of Engineering & Technology 7, no. 3.3 (June 8, 2018): 239. http://dx.doi.org/10.14419/ijet.v7i2.33.14160.
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In this paper narrate about the study of aerodynamics in the multi-section morphing wing variation of baseline configuration to camber con-figuration. In particularly NACA 0012, section tried to morph as NACA 9312 camber section to achieve the lift to drag ratio in the flight condition based on the bio-mimicry. The CAD model and fabricated morphing wing in geometry scale of 20 cm chord and a 36 cm wing-span, with aluminum material ribs divided into 6 sections. Each section was able to rotate approximately 6 degrees without causing a discon-tinuity in the wing surface and also in order avoid the control surface based on the bio mimicry the morphing wing was designed and tested. DC-motor located at main spar with the two equal gear ratio the rib section used to morph the wing through the linear mechanical linkages. The aluminum ribs section are made through the EDM-Wire cut machining process for capable to actuate the morphing wing. In each sec-tion morphing wing can able provide up to 10 percent variation in the symmetrical airfoil to the cambered airfoil. The experimental test of the morphing was carried out in the cascade tunnel by force balancing method and the lift and drag output are compared.
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Nangia, R. K., and M. E. Palmer. "A comparative study of two UCAV type wing planforms — performance and stability considerations." Aeronautical Journal 110, no. 1112 (October 2006): 641–58. http://dx.doi.org/10.1017/s0001924000001512.
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Abstract Currently there is a revival of interest in flying wings for military (and civil) use. The military context has arisen from the future ‘stealthy’ high altitude long endurance (HALE) and unmanned combat air vehicles (UCAV) aircraft. Questions on aerodynamics, control and structural efficiency arise. Compared with conventional wing/tail arrangements, flying wings have a special set of very different constraints. These are mentioned. Without a trim surface, the constraints on the wing pitching moment dictate the design camber and twist. Control power requirements can be high because of effectively short moment arms. The camber and twist are strongly dependent on trim stability margins. This aspect needs to be understood in detail when comparing different types of planforms. This paper covers three inter-related aspects – a wing design method, the suitability of solvers used with the method and a comparative study of two, typical UCAV planforms. This is inspired by the need to understand a variety of wings (in the public domain) that are, at first sight, aimed at similar missions. The main emphasis has been on developing and understanding cruise design camber and twist with Cm constraints of stable, neutral and unstable static margins. Spanwise lift and drag loadings have also been presented. Camber design has been via attained thrust methods and a modal approach. It is shown that starting from basic information such as the planform, we are able to predict the anticipated performance with sufficient confidence for comparative assessments of published project data. Further work is proposed in several areas.
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Alsaidi, Bashir, Woong Yeol Joe, and Muhammad Akbar. "Computational Analysis of 3D Lattice Structures for Skin in Real-Scale Camber Morphing Aircraft." Aerospace 6, no. 7 (July 7, 2019): 79. http://dx.doi.org/10.3390/aerospace6070079.
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Conventional or fixed wings require a certain thickness of skin material selection that guarantees structurally reliable strength under expected aerodynamic loadings. However, skin structures of morphing wings need to be flexible as well as stiff enough to deal with multi-axial structural stresses from changed geometry and the coupled aerodynamic loadings. Many works in the design of skin structures for morphing wings take the approach either of only geometric compliance or a simplified model that does not fully represent 3D real-scale wing models. Thus, the main theme of this study is (1) to numerically identify the multi-axial stress, strain, and deformation of skin in a camber morphing wing aircraft under both structure and aerodynamic loadings, and then (2) to show the effectiveness of a direct approach that uses 3D lattice structures for skin. Various lattice structures and their direct 3D wing models have been numerically analyzed for advanced skin design.
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Nguyen, Quoc V., Woei L. Chan, and Marco Debiasi. "Experimental investigation of wing flexibility on force generation of a hovering flapping wing micro air vehicle with double wing clap-and-fling effects." International Journal of Micro Air Vehicles 9, no. 3 (March 28, 2017): 187–97. http://dx.doi.org/10.1177/1756829317695565.
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Experimental investigation of wing flexibility on vertical thrust generation and power consumption in hovering condition for a hovering Flapping-Wing Micro Air Vehicle, namely FlowerFly, weighing 14.5 g with a 3 g onboard battery and having four wings with double wing clap-and-fling effects, was conducted for several wing configurations with the same shape, area, and weight. A data acquisition system was set up to simultaneously record aerodynamic forces, electrical power consumption, and wing motions at various flapping frequencies. The forces and power consumption were measured with a loadcell and a custom-made shunt circuit, respectively, and the wing motion was captured by high-speed cameras. The results show a phase delay of the wing tip displacement observed for wings with high flexible leading edge at high frequency, resulting in less vertical thrust produced when compared with the wings with less leading edge flexibility at the same flapping frequency. Positive wing camber was observed during wing flapping motion by arranging the wing supporting ribs. Comparison of thrust-to-power ratios between the wing configurations was undertaken to figure out a wing configuration for high vertical thrust production but less power consumption.
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Osterberg, N., and R. Albertani. "Investigation of self-deploying high-lift effectors applied to membrane wings." Aeronautical Journal 121, no. 1239 (March 30, 2017): 660–79. http://dx.doi.org/10.1017/aer.2017.10.
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ABSTRACTFlow separation followed by aerodynamic stall limits the operation of aircraft. Expanding the flight envelope of aircraft has been a goal of aerodynamicists for decades. This work presents findings from tests in the Oregon State University wind tunnel investigating the effectiveness of a passively actuated suction-surface flap on membrane wings. Experiments were conducted on a rigid plate and membrane wings with and without a pop-up flap. All wings had an aspect ratio of 2, while membrane pre-strain and Reynolds number were varied. An increase in lift at stall was observed for all testing conditions with flap deployment. The observed average increase in maximum lift varied from 5% to 15% for different test conditions. The variation in flap effectiveness is compared to membrane pre-strain, Reynolds number, and wing camber. A quadratic relationship between modelled camber and flap effectiveness is observed, and an optimal level of membrane camber is found to maximise flap effectiveness.
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Okamoto, M., K. Yasuda, and A. Azuma. "Aerodynamic characteristics of the wings and body of a dragonfly." Journal of Experimental Biology 199, no. 2 (February 1, 1996): 281–94. http://dx.doi.org/10.1242/jeb.199.2.281.
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The aerodynamic characteristics of the wings and body of a dragonfly and of artificial wing models were studied by conducting two types of wind-tunnel tests and a number of free-flight tests of gliders made using dragonfly wings. The results were consistent between these different tests. The effects of camber, thickness, sharpness of the leading edge and surface roughness on the aerodynamic characteristics of the wings were characterized in the flow field with Reynolds numbers (Re) as low as 103 to 104.
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Zhang, Yaqing, Wenjie Ge, Ziang Zhang, Xiaojuan Mo, and Yonghong Zhang. "Design of compliant mechanism-based variable camber morphing wing with nonlinear large deformation." International Journal of Advanced Robotic Systems 16, no. 6 (November 1, 2019): 172988141988674. http://dx.doi.org/10.1177/1729881419886740.
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The morphing wing with large deformation can benefit its flight performance a lot in different conditions. In this study, a variable camber morphing wing with compliant leading and trailing edges is designed by large-displacement compliant mechanisms. The compliant mechanisms are carried out by a hyperelastic structure topology optimization, based on a nonlinear meshless method. A laminated leading-edge skin is designed to fit the curvature changing phenomenon of the leading edge during deformation. A morphing wing demonstrator was manufactured to testify its deformation capability. Comparing to other variable camber morphing wings, the proposal can realize larger deflection of leading and trailing edges. The designed morphing wing shows great improvement in aerodynamic performance and enough strength to resist aerodynamic and structural loadings.
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Kinnas, Spyros A. "A General Theory for the Coupling Between Thickness and Loading for Wings and Propellers." Journal of Ship Research 36, no. 01 (March 1, 1992): 59–68. http://dx.doi.org/10.5957/jsr.1992.36.1.59.
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The incompressible, inviscid flow around a generally shaped wing in arbitrary inflow is analyzed as a perturbation expansion, with respect to wing thickness, superimposed on the zero thickness lifting-surface problem (also called the mean camber surface problem). The first-order term in that expansion is shown that can also be treated as a lifting-surface problem with the inflow normal to the lifting surface given as the sum of two velocities. The first of those velocities is the one induced by the wing thickness source distribution and is non-zero in the case of a non-planar wing or in the case of a propeller. The second velocity is due to the coupling between wing loading and thickness and is given as a function of the zero thickness vorticity distribution and the wing thickness distribution. The presented method, though applicable to general shape wings (without any assumptions on the magnitude of wing twist or camber) in arbitrary inflow, is shown to reduce to previous methods of evaluating the coupling between thickness and loading for two-dimensional foils and planar wings in uniform inflow. Finally, the presented method is applied for several wing and propeller blade geometries and the results are shown to be in very good agreement with those from applying an existing potential based panel method.
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Thielicke, William, and Eize J. Stamhuis. "The influence of wing morphology on the three-dimensional flow patterns of a flapping wing at bird scale." Journal of Fluid Mechanics 768 (March 4, 2015): 240–60. http://dx.doi.org/10.1017/jfm.2015.71.
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The effect of airfoil design parameters, such as airfoil thickness and camber, are well understood in steady-state aerodynamics. But this knowledge cannot be readily applied to the flapping flight in insects and birds: flow visualizations and computational analyses of flapping flight have identified that in many cases, a leading-edge vortex (LEV) contributes substantially to the generation of aerodynamic force. In flapping flight, very high angles of attack and partly separated flow are common features. Therefore, it is expected that airfoil design parameters affect flapping wing aerodynamics differently. Existing studies have focused on force measurements, which do not provide sufficient insight into the dominant flow features. To analyse the influence of wing morphology in slow-speed bird flight, the time-resolved three-dimensional flow field around different flapping wing models in translational motion at a Reynolds number of $22\,000<\mathit{Re}<26\,000$ was studied. The effect of several Strouhal numbers ($0.2<\mathit{St}<0.4$), camber and thickness on the flow morphology and on the circulation was analysed. A strong LEV was found on all wing types at high $\mathit{St}$. The vortex is stronger on thin wings and enhances the total circulation. Airfoil camber decreases the strength of the LEV, but increases the total bound circulation at the same time, due to an increase of the ‘conventional’ bound circulation at the inner half of the wing. The results provide new insights into the influence of airfoil shape on the LEV and force generation at low $\mathit{Re}$. They contribute to a better understanding of the geometry of vertebrate wings, which seem to be optimized to benefit from LEVs in slow-speed flight.
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Ozel, Cevdet, Emre Ozbek, and Selcuk Ekici. "A Review on Applications and Effects of Morphing Wing Technology on UAVs." International Journal of Aviation Science and Technology vm01, is01 (September 10, 2020): 30–40. http://dx.doi.org/10.23890/ijast.vm01is01.0105.
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Unmanned aerial vehicles (UAVs) have excelled with their ability to perform the intended task on or without personnel. In recent years, UAVs have been designed for civilian purposes as well as military applications. Morphing wings are changeable wing applications developed as a result of the need for a different lift and drag forces in various phases of the flight of aircraft. It is an application that enables altering the wing aspect ratio, wing airfoil, wing airfoil camber ratio, wing reference area and even different angles of attack are obtained in different parts of the wing. Although morphing wing application has just begun on today’s UAVs, modern airliners already have morphing wingtip devices such as Boeing 777-X’s. The benefits of the use of morphing wings for UAVs make this technology important. UAVs with morphing wing technology; may increase its payload ratio, may achieve a shorter take-off distance, may land and stop in shorter distance, may take-off where runway clearance is limited, has more efficient altitude change at lower engine RPMs, can obtain higher cruise speeds, may decrease its stall speed, may lower its drag if necessary, thus; saving energy and time. This study concludes a review of literature over morphing wing technology.
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Alsaidi, Bashir, Woong Yeol Joe, and Muhammad Akbar. "Simplified 2D Skin Lattice Models for Multi-Axial Camber Morphing Wing Aircraft." Aerospace 6, no. 8 (August 13, 2019): 90. http://dx.doi.org/10.3390/aerospace6080090.
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Conventional fixed wing aircraft require a selection of certain thickness of skin material that guarantees structural strength for aerodynamic loadings in various flight modes. However, skin structures of morphing wings are expected to be flexible as well as stiff to structural and coupled aerodynamic loadings from geometry change. Many works in the design of skin structures for morphing wings consider only geometric compliance. Among many morphing classifications, we consider camber rate change as airfoil morphing that changes its rate of the airfoil that induces warping, twisting, and bending in multi-axial directions, which makes compliant skin design for morphing a challenging task. It is desired to design a 3D skin structure for a morphing wing; however, it is a computationally challenging task in the design stage to optimize the design parameters. Therefore, it is of interest to establish the structure design process in rapid approaches. As a first step, the main theme of this study is to numerically validate and suggest simplified 2D plate models that fully represents multi-axial 3D camber morphing. In addition to that, the authors show the usage of lattice structures for the 2D plate models’ skin that will lead to on-demand design of advanced structure through the modification of selected structure.
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Rader, Jonathan A., Tyson L. Hedrick, Yanyan He, and Lindsay D. Waldrop. "Functional Morphology of Gliding Flight II. Morphology Follows Predictions of Gliding Performance." Integrative and Comparative Biology 60, no. 5 (September 10, 2020): 1297–308. http://dx.doi.org/10.1093/icb/icaa126.
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Abstract The evolution of wing morphology among birds, and its functional consequences, remains an open question, despite much attention. This is in part because the connection between form and function is difficult to test directly. To address this deficit, in prior work, we used computational modeling and sensitivity analysis to interrogate the impact of altering wing aspect ratio (AR), camber, and Reynolds number on aerodynamic performance, revealing the performance landscapes that avian evolution has explored. In the present work, we used a dataset of three-dimensionally scanned bird wings coupled with the performance landscapes to test two hypotheses regarding the evolutionary diversification of wing morphology associated with gliding flight behavior: (1) gliding birds would exhibit higher wing AR and greater chordwise camber than their non-gliding counterparts; and (2) that two strategies for gliding flight exist, with divergent morphological conformations. In support of our first hypothesis, we found evidence of morphological divergence in both wing AR and camber between gliders and non-gliders, suggesting that wing morphology of birds that utilize gliding flight is under different selective pressures than the wings of non-gliding taxa. Furthermore, we found that these morphological differences also yielded differences in coefficient of lift measured both at the maximum lift to drag ratio and at minimum sinking speed, with gliding taxa exhibiting higher coefficient of lift in both cases. Minimum sinking speed was also lower in gliders than non-gliders. However, contrary to our hypothesis, we found that the maximum ratio of the coefficient of lift to the coefficient of drag differed between gliders and non-gliders. This may point to the need for gliders to maintain high lift capability for takeoff and landing independent of gliding performance or could be due to the divergence in flight styles among gliders, as not all gliders are predicted to optimize either quantity. However, direct evidence for the existence of two morphologically defined gliding flight strategies was equivocal, with only slightly stronger support for an evolutionary model positing separate morphological optima for these strategies than an alternative model positing a single peak. The absence of a clear result may be an artifact of low statistical power owing to a relatively small sample size of gliding flyers expected to follow the “aerial search” strategy.
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Heryawan, Yudi, Hoon Cheol Park, Nam Seo Goo, Kwang Joon Yoon, and Yung Hwan Byun. "Structural Design, Manufacturing, and Wind Tunnel Test of a Small Expandable Wing." Key Engineering Materials 306-308 (March 2006): 1157–62. http://dx.doi.org/10.4028/www.scientific.net/kem.306-308.1157.
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This paper describes design, manufacturing, and wind tunnel test of a motor-driven small-scale expandable wing for MAV class vehicles. The bird-like expandable wing has been developed for investigating the influence of aspect ratio change on the lift and drag of the wing. As a typical bird wing, the wing is separated into inner and outer wings. The wing model consists of the linkage system made of carbon composite strip/rod and the remaining part covered with carbon composite sheet and multiple LIPCAs (Lightweight Piezo-Composite Actuators) mimicking wing feathers. The LIPCA actuator was used to control wing camber, which created additional lift. Wind tunnel tests were conducted to investigate the changes in lift and drag during wing folding and expansion, and to observe the influence of LIPCA actuation on the wing. In the tests, effects of the wing fold/expansion and actuation of LIPCA on changes in lift and drag were quantitatively identified.
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Kang, Chang-kwon, and Wei Shyy. "Scaling law and enhancement of lift generation of an insect-size hovering flexible wing." Journal of The Royal Society Interface 10, no. 85 (August 6, 2013): 20130361. http://dx.doi.org/10.1098/rsif.2013.0361.
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We report a comprehensive scaling law and novel lift generation mechanisms relevant to the aerodynamic functions of structural flexibility in insect flight. Using a Navier–Stokes equation solver, fully coupled to a structural dynamics solver, we consider the hovering motion of a wing of insect size, in which the dynamics of fluid–structure interaction leads to passive wing rotation. Lift generated on the flexible wing scales with the relative shape deformation parameter, whereas the optimal lift is obtained when the wing deformation synchronizes with the imposed translation, consistent with previously reported observations for fruit flies and honeybees. Systematic comparisons with rigid wings illustrate that the nonlinear response in wing motion results in a greater peak angle compared with a simple harmonic motion, yielding higher lift. Moreover, the compliant wing streamlines its shape via camber deformation to mitigate the nonlinear lift-degrading wing–wake interaction to further enhance lift. These bioinspired aeroelastic mechanisms can be used in the development of flapping wing micro-robots.
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Item, Cem C., and Oktay Baysal. "Wing Section Optimization for Supersonic Viscous Flow." Journal of Fluids Engineering 120, no. 1 (March 1, 1998): 102–8. http://dx.doi.org/10.1115/1.2819632.
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To improve the performance of a highly swept supersonic wing, it is desirable to have an automated design method that also includes a higher fidelity to the flow physics. With this impetus, an aerodynamic optimization methodology incorporating the thin-layer Navier-Stokes equations and sensitivity analysis had previously been developed. Prior to embarking upon the full wing design task, the present investigation concentrated on the identification of effective optimization problem formulations and testing the feasibility of the employed methodology, by defining two-dimensional test cases. Starting with two distinctly different initial airfoils, two independent optimizations resulted in shapes with similar features: cambered, parabolic profiles with sharp leading- and trailing-edges. Secondly, an outboard wing section normal to the subsonic portion of the leading edge, which had a high normal angle-of attack, was considered. The optimization resulted in a shape with twist and camber that eliminated the adverse pressure gradient, hence, exploiting the leading-edge thrust. The wing section shapes obtained in all the test cases included the features predicted by previous studies. This was considered as a strong indication that the flow field analyses and sensitivity coefficients were computed and provided to the present gradient-based optimizer correctly. Also, from the results of the present study, effective optimization problem formulations could be deduced to start a full wing shape optimization.
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Forouzi Feshalami, Behzad, MH Djavareshkian, AH Zaree, Masoud Yousefi, and AA Mehraban. "The role of wing bending deflection in the aerodynamics of flapping micro aerial vehicles in hovering flight." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 10 (October 30, 2018): 3749–61. http://dx.doi.org/10.1177/0954410018806081.
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Scientists have been improving the aerodynamic performance of flapping micro aerial vehicles by drawing inspiration from birds and insect flight. In this research study, first, the flapping mechanism of the black-headed gull is designed and then it is constructed in order to investigate the effects of wing bending deflection on the aerodynamic performance. Thrust generation, power consumption and power loading are considered as performance parameters. Three wings representing different underlying structures, namely flexible membrane, rigid membrane and airfoil, are fabricated with the same planform to investigate the roles of flexibility, thickness and camber. Experiments are performed for flapping frequencies ranging from 1.5 Hz to 6 Hz, 10 degrees angle of attack and no wind tunnel velocity (hovering flight). The results indicate that the aerodynamic performance is improved by using the bending deflection mechanism in comparison with the simple flapping mechanism. Moreover, we can conclude that the performance of the airfoil wing is superior to flexible and rigid wings.
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Bhayu, Prasetiyo Radius, Quoc-Viet Nguyen, Hoon Cheol Park, Nam Seo Goo, and Doyoung Byun. "Artificial Cambered-Wing for a Beetle-Mimicking Flapper." Journal of Bionic Engineering 7, S4 (December 2010): S130—S136. http://dx.doi.org/10.1016/s1672-6529(09)60226-2.
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Naranjo, A. García, I. Cowling, J. A. Green, and N. Qin. "Aerodynamic performance benefits of utilising camber morphing wings for unmanned air vehicles." Aeronautical Journal 117, no. 1189 (March 2013): 315–27. http://dx.doi.org/10.1017/s0001924000008010.
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Abstract This work considers the effects of camber morphing, both in magnitude and chord position, on the performance of a generic unmanned air vehicle (UAV). The focus is to maximise appropriate aerodynamic factors across the mission by optimising the wing camber. Specifically, the enhancement of range, endurance, and stall speed is sought by means of maximising their aerodynamic performance parameters, CL /CD , CL 3/2/CD , and CLmax respectively. An analysis of the effects of camber morphing is carried out using the vortex panel code, XFOIL, utilising aerofoils from the NACA four-digit family. The results are then adjusted to account for 3D flow factors such as induced drag, offering a more realistic appraisal of their effectiveness. Flight testing is then performed on four wings of fixed aerofoil sections, optimised for each performance characteristic, to validate the trends observed in the XFOIL data onboard a 1·64m span aircraft.
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Walker, Simon M., Adrian L. R. Thomas, and Graham K. Taylor. "Photogrammetric reconstruction of high-resolution surface topographies and deformable wing kinematics of tethered locusts and free-flying hoverflies." Journal of The Royal Society Interface 6, no. 33 (August 5, 2008): 351–66. http://dx.doi.org/10.1098/rsif.2008.0245.
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Here, we present a suite of photogrammetric methods for reconstructing insect wing kinematics, to provide instantaneous topographic maps of the wing surface. We filmed tethered locusts ( Schistocerca gregaria ) and free-flying hoverflies ( Eristalis tenax ) using four high-speed digital video cameras. We digitized multiple natural features and marked points on the wings using manual and automated tracking. Epipolar geometry was used to identify additional points on the hoverfly wing outline which were anatomically indistinguishable. The cameras were calibrated using a bundle adjustment technique that provides an estimate of the error associated with each individual data point. The mean absolute three-dimensional measurement error was 0.11 mm for the locust and 0.03 mm for the hoverfly. The error in the angle of incidence was at worst 0.51° (s.d.) for the locust and 0.88° (s.d.) for the hoverfly. The results we present are of unprecedented spatio-temporal resolution, and represent the most detailed measurements of insect wing kinematics to date. Variable spanwise twist and camber are prominent in the wingbeats of both the species, and are of such complexity that they would not be adequately captured by lower resolution techniques. The role of spanwise twist and camber in insect flight has yet to be fully understood, and accurate insect wing kinematics such as we present here are required to be sure of making valid predictions about their aerodynamic effects.
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Onishi, Minato, and Daisuke Ishihara. "Performance evaluation of the pixel wing model for the insect wing's camber." Journal of Advanced Simulation in Science and Engineering 8, no. 2 (2021): 163–72. http://dx.doi.org/10.15748/jasse.8.163.
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Willmott, A., and C. Ellington. "Measuring the angle of attack of beating insect wings: robust three-dimensional reconstruction from two-dimensional images." Journal of Experimental Biology 200, no. 21 (November 1, 1997): 2693–704. http://dx.doi.org/10.1242/jeb.200.21.2693.
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A robust technique for determining the angle of attack of insect wings from film of free flight has to date proved elusive. This report describes the development of two new methods ­ the Strips and Planes techniques ­ which were designed to overcome some of the limitations experienced in previous studies. The accuracy and robustness of these novel methods were tested extensively using simulated hawkmoth wing outlines generated for a realistic range of wing positions and torsion. The results were compared with those from two existing methods ­ the Symmetry and Landmarks procedures. The performance of the latter technique will be strongly species-dependent; it could not be successfully applied to hawkmoth flight because of practical difficulties in obtaining suitable landmarks. The Planes method was the least successful of the remaining techniques, especially during those phases of the wingbeat when the orientations of the two wings relative to the camera viewpoint were similar. The Symmetry and Strips methods were tested further to investigate the effects on their performance of introducing additional camber or wing motion asymmetry. The results showed clearly that the Strips method should be the technique of choice wherever the axis of wing torsion is close to the longitudinal axis of the wing. The procedure involves the experimenter matching a model wing divided into chordwise strips to the true wing outline digitized from high-speed film. The use of strips rather than the points digitized in previous studies meant that the analysis required only one wing outline to be digitized. Symmetry of motion between the left and right wings is not assumed. The implications of requiring human input to the Strips method, as opposed to the strictly numerical algorithms of the alternative techniques, are discussed. It is argued that the added flexibility that this provides in dealing with images which have typically been recorded in suboptimal conditions outweighs the introduction of an element of subjectivity. Additional observations arising from the use of the Strips analysis with high-speed video sequences of hawkmoth flight are given.
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Kim, Dong Hyun, Hyun Jung Kim, Il Kwon Oh, and Seok Soon Lee. "Nonlinear Aeroelastic Characteristics of a Laminated Composite Wing Considering Compressible Shock Wave Effects." Key Engineering Materials 334-335 (March 2007): 481–84. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.481.
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In this study, advanced computational analysis system for nonlinear static aeroelastic problems has been successfully developed by the composite structure (FEM)-fluid (CFD) combined method with internal iteration steps. Major focus of the present study is to investigate the static aeroelastic characteristics of laminated composite wings including the strong normal shock waves in the transonic and low-supersonic flow regions. The results importantly indicate that the effect of airfoil camber on the load distribution of laminated composite wing models can be nonlinear due to the variation of ply orientations.
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Heitzig, DNWM, BW van Oudheusden, D. Olejnik, and M. Karásek. "Effects of asymmetrical inflow in forward flight on the deformation of interacting flapping wings." International Journal of Micro Air Vehicles 12 (January 2020): 175682932094100. http://dx.doi.org/10.1177/1756829320941002.
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This study investigates the wing deformation of the DelFly II in forward flight conditions. A measurement setup was developed that maintains adequate viewing axes of the flapping wings for all pitch angles. Recordings of a high-speed camera pair were processed using a point tracking algorithm, allowing 136 points per wing to be measured simultaneously with an estimated accuracy of 0.25 mm. The measurements of forward flight show little change in the typical clap-and-peel motion, suggesting similar effectiveness in all cases. It was found that an air-buffer remains at all times during this phase. The wing rotation and camber reduction during the upstroke suggests low loading during the upstroke in fast forward flight. In slow cases a torsional wave and recoil is found. A study of the isolated effects showed asymmetric deformations even in symmetric freestream conditions. Furthermore, it shows a dominant role of the flapping frequency on the clap-and-peel, while the freestream velocity reduces wing loading outside this phase.
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Manzo, Justin, and Ephrahim Garcia. "Demonstration of anin situmorphing hyperelliptical cambered span wing mechanism." Smart Materials and Structures 19, no. 2 (January 14, 2010): 025012. http://dx.doi.org/10.1088/0964-1726/19/2/025012.
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