Journal articles on the topic 'Wings'
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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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Dao, Thanh Tien, Thi Kim Loan Au, Soo Hyung Park, and Hoon Cheol Park. "Effect of Wing Corrugation on the Aerodynamic Efficiency of Two-Dimensional Flapping Wings." Applied Sciences 10, no. 20 (October 21, 2020): 7375. http://dx.doi.org/10.3390/app10207375.
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Many previous studies have shown that wing corrugation of an insect wing is only structurally beneficial in enhancing the wing’s bending stiffness and does not much help to improve the aerodynamic performance of flapping wings. This study uses two-dimensional computational fluid dynamics (CFD) in aiming to identify a proper wing corrugation that can enhance the aerodynamic performance of the KUBeetle, an insect-like flapping-wing micro air vehicle (MAV), which operates at a Reynolds number of less than 13,000. For this purpose, various two-dimensional corrugated wings were numerically investigated. The two-dimensional flapping wing motion was extracted from the measured three-dimensional wing kinematics of the KUBeetle at spanwise locations of r = (0.375 and 0.75)R. The CFD analysis showed that at both spanwise locations, the corrugations placed over the entire wing were not beneficial for improving aerodynamic efficiency. However, for the two-dimensional flapping wing at the spanwise location of r = 0.375R, where the wing experiences relatively high angles of attack, three specially designed wings with leading-edge corrugation showed higher aerodynamic performance than that of the non-corrugated smooth wing. The improvement is closely related to the flow patterns formed around the wings. Therefore, the proposed leading-edge corrugation is suggested for the inboard wing of the KUBeetle to enhance aerodynamic performance. The corrugation in the inboard wing may also be structurally beneficial.
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Medved, Victor, James H. Marden, Howard W. Fescemyer, Joshua P. Der, Jin Liu, Najmus Mahfooz, and Aleksandar Popadić. "Origin and diversification of wings: Insights from a neopteran insect." Proceedings of the National Academy of Sciences 112, no. 52 (December 14, 2015): 15946–51. http://dx.doi.org/10.1073/pnas.1509517112.
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Winged insects underwent an unparalleled evolutionary radiation, but mechanisms underlying the origin and diversification of wings in basal insects are sparsely known compared with more derived holometabolous insects. In the neopteran species Oncopeltus fasciatus, we manipulated wing specification genes and used RNA-seq to obtain both functional and genomic perspectives. Combined with previous studies, our results suggest the following key steps in wing origin and diversification. First, a set of dorsally derived outgrowths evolved along a number of body segments including the first thoracic segment (T1). Homeotic genes were subsequently co-opted to suppress growth of some dorsal flaps in the thorax and abdomen. In T1 this suppression was accomplished by Sex combs reduced, that when experimentally removed, results in an ectopic T1 flap similar to prothoracic winglets present in fossil hemipteroids and other early insects. Global gene-expression differences in ectopic T1 vs. T2/T3 wings suggest that the transition from flaps to wings required ventrally originating cells, homologous with those in ancestral arthropod gill flaps/epipods, to migrate dorsally and fuse with the dorsal flap tissue thereby bringing new functional gene networks; these presumably enabled the T2/T3 wing’s increased size and functionality. Third, “fused” wings became both the wing blade and surrounding regions of the dorsal thorax cuticle, providing tissue for subsequent modifications including wing folding and the fit of folded wings. Finally, Ultrabithorax was co-opted to uncouple the morphology of T2 and T3 wings and to act as a general modifier of hindwings, which in turn governed the subsequent diversification of lineage-specific wing forms.
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Harbig, R. R., J. Sheridan, and M. C. Thompson. "The role of advance ratio and aspect ratio in determining leading-edge vortex stability for flapping flight." Journal of Fluid Mechanics 751 (June 16, 2014): 71–105. http://dx.doi.org/10.1017/jfm.2014.262.
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AbstractThe effects of advance ratio and the wing’s aspect ratio on the structure of the leading-edge vortex (LEV) that forms on flapping and rotating wings under insect-like flight conditions are not well understood. However, recent studies have indicated that they could play a role in determining the stable attachment of the LEV. In this study, a numerical model of a flapping wing at insect Reynolds numbers is used to explore the effects of these parameters on the characteristics and stability of the LEV. The word ‘stability’ is used here to describe whether the LEV was attached throughout the stroke or if it was shed. It is demonstrated that increasing the advance ratio enhances vorticity production at the leading edge during the downstroke, and this results in more rapid growth of the LEV for non-zero advance ratios. Increasing the wing aspect ratio was found to have the effect of shortening the wing’s chord length relative to the LEV’s size. These two effects combined determine the stability of the LEV. For high advance ratios and large aspect ratios, the LEV was observed to quickly grow to envelop the entire wing during the early stages of the downstroke. Continued rotation of the wing resulted in the LEV being eventually shed as part of a vortex loop that peels away from the wing’s tip. The shedding of the LEV for high-aspect-ratio wings at non-zero advance ratios leads to reduced aerodynamic performance of these wings, which helps to explain why a number of insect species have evolved to have low-aspect-ratio wings.
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DWIVEDI, Y. D., ABHISHEK MOHAPATRA, T. BLESSINGTON, and Md IRFAN. "Experimental Flow Field Investigation of the Bio-Inspired Corrugated Wing for MAV Applications." INCAS BULLETIN 13, no. 2 (June 4, 2021): 37–50. http://dx.doi.org/10.13111/2066-8201.2021.13.2.5.
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This is an experimental flow field study of a bio-inspired corrugated finite wing from the dragonfly intended to assess the flow behavior over the wing and compare it with a wing of the same geometry with filled corrugation, at low Reynolds numbers 46000 and 67000. The work purpose is to explore the potential application of such types of wings for Micro Air Vehicles (MAVs) or micro sized Unmanned Air Vehicles (UAVs). Two types of wings are taken into account: first wing was a bio-inspired corrugated wing which was obtained from the mid span of the dragonfly, and the second wing was the same geometry with filled corrugation. Both wings were fabricated by using 3-D printing machine. The tufts were glued at three different locations i.e. at center, 30%, and 60% of the semi-span towards the right side of the wing at the trailing edge. The boundary layers were measured by using boundary layer rakes inside the open-end low speed wing tunnel with varied angles of attack. The results of the tuft flow visualization showed that the flow pattern at different span locations was different at different angles of attack and different wing velocities (Reynolds number). The fluctuations of the two different wings at the same angle of attack and Reynolds number were found different. Also, the directions of the flow for both wings were found to be different at different span locations. The boundary layer measurement results for both wings were found to be different at the same angles of attack and Reynolds numbers. The flow pattern also showed that the wing’s upper as well as lower surface behaved differently on the same wing under the same measurement conditions. The results showed that the corrugated wing outperformed the conventional wing at low Reynolds number and the stall angle of the corrugated wing was more than the conventional wing.
6
Wang, Dou, Qinfeng Lin, Chao Zhou, and Jianghao Wu. "Aerodynamic performance of a self-propelled airfoil with a non-zero angle of attack." Physics of Fluids 34, no. 3 (March 2022): 031901. http://dx.doi.org/10.1063/5.0082283.
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In the natural world, numerous flying creatures generate both thrust and lift by flapping their wings. Aerodynamic mechanisms of forward flight with flapping wings have received much attention from researchers. However, the majority of previous studies have simplified the forward-flight motion of flapping wings to be uniform, and there has been no detailed evaluation of the validity of this simplification. Motivated by this, aerodynamic characteristics of a self-propelled flapping wing with a non-zero angle of attack were investigated. The results showed that the asymmetric leading-edge vortex produced in the wing's upstroke and downstroke leads to transient thrust, driving the self-propelled wing to move with variable forward velocities. Compared to the uniform forward-flight cases, significant losses in lift and severe changes in the flow field were observed in self-propelled flapping wings. In addition, the changes in the aerodynamic performance—including the forward propulsion speed, lift, and power efficiency—of the self-propelled flapping wing with changes in various dimensionless parameters were also investigated. The heaving amplitude was shown to have significant effects on lift and propulsion speed of the self-propelled flapping wing, while the effects of ratio between the airfoil density and fluid density as well as the Reynolds number, were relatively small. In most conditions, when the Strouhal number was in the range 0.2–0.4, the self-propelled flapping wing performed well in terms of both lift generation and propulsive efficiency. These research results suggest that it is necessary to consider the fluctuating forward speed in aerodynamic modeling of propulsive flapping wings.
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MARIN, Florin Bogdan, Daniela Laura BURUIANA, Viorica GHISMAN, and Mihaela MARIN. "Deep neural network modeling for CFD simulation of drone bioinspired morphing wings." INCAS BULLETIN 15, no. 4 (December 2, 2023): 149–57. http://dx.doi.org/10.13111/2066-8201.2023.15.4.12.
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In this paper we present a deep neural network modelling using Computational Fluid Dynamics (CFD) simulations data in order to optimize control of bioinspired morphing wings of a drone. Drones flight needs to consider variation in aerodynamic conditions that cannot all be optimized using a fixed aerodynamic profile. Nature solves this issue as birds are changing continuously the shape of their wings depending of the aerodynamic current requirements. One important issue for fixed wing drone is the landing as it is unable to control and most of the time consequences are some damages at the nose. An optimized shape of the wing at landing will avoid this situation. Another issue is that wings with a maximum surface are sensitive to stronger head winds; while wings with a small surface allowing the drone to fly faster. A wing with a morphing surface could adapt its aerial surface to optimize aerodynamic performance to specific flight situations. A morphing wing needs to be controlled in an optimized manner taking into account current aerodynamics parameters. Predicting optimized positions of the wing needs to consider (CFD) prior simulation parameters. The scenarios for flight require an important number of CFD simulation to address different conditions and geometric shapes. We compare in this paper neural network architecture suitable to predict wing shape according to current conditions. Deep neural network (DNN) is trained using data resulted out of CFD simulations to estimate flight conditions.
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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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Salcedo, Mary K., and John J. Socha. "Circulation in Insect Wings." Integrative and Comparative Biology 60, no. 5 (September 1, 2020): 1208–20. http://dx.doi.org/10.1093/icb/icaa124.
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Synopsis Insect wings are living, flexible structures composed of tubular veins and thin wing membrane. Wing veins can contain hemolymph (insect blood), tracheae, and nerves. Continuous flow of hemolymph within insect wings ensures that sensory hairs, structural elements such as resilin, and other living tissue within the wings remain functional. While it is well known that hemolymph circulates through insect wings, the extent of wing circulation (e.g., whether flow is present in every vein, and whether it is confined to the veins alone) is not well understood, especially for wings with complex wing venation. Over the last 100 years, scientists have developed experimental methods including microscopy, fluorescence, and thermography to observe flow in the wings. Recognizing and evaluating the importance of hemolymph movement in insect wings is critical in evaluating how the wings function both as flight appendages, as active sensors, and as thermoregulatory organs. In this review, we discuss the history of circulation in wings, past and present experimental techniques for measuring hemolymph, and broad implications for the field of hemodynamics in insect wings.
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Mazharmanesh, Soudeh, Jace Stallard, Albert Medina, Alex Fisher, Noriyasu Ando, Fang-Bao Tian, John Young, and Sridhar Ravi. "Effects of uniform vertical inflow perturbations on the performance of flapping wings." Royal Society Open Science 8, no. 6 (June 2021): 210471. http://dx.doi.org/10.1098/rsos.210471.
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Flapping wings have attracted significant interest for use in miniature unmanned flying vehicles. Although numerous studies have investigated the performance of flapping wings under quiescent conditions, effects of freestream disturbances on their performance remain under-explored. In this study, we experimentally investigated the effects of uniform vertical inflows on flapping wings using a Reynolds-scaled apparatus operating in water at Reynolds number ≈ 3600. The overall lift and drag produced by a flapping wing were measured by varying the magnitude of inflow perturbation from J Vert = −1 (downward inflow) to J Vert = 1 (upward inflow), where J Vert is the ratio of the inflow velocity to the wing's velocity. The interaction between flapping wing and downward-oriented inflows resulted in a steady linear reduction in mean lift and drag coefficients, C ¯ L and C ¯ D , with increasing inflow magnitude. While a steady linear increase in C ¯ L and C ¯ D was noted for upward-oriented inflows between 0 < J Vert < 0.3 and J Vert > 0.7, a significant unsteady wing–wake interaction occurred when 0.3 ≤ J Vert < 0.7, which caused large variations in instantaneous forces over the wing and led to a reduction in mean performance. These findings highlight asymmetrical effects of vertically oriented perturbations on the performance of flapping wings and pave the way for development of suitable control strategies.
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Schmidt, Eduardo O., Laura D. Baravalle, and Adriana R. Rodríguez-Kamenetzky. "Spectroscopic study of the [O iii]λ5007 profile in Seyfert 1 galaxies." Monthly Notices of the Royal Astronomical Society 502, no. 3 (January 27, 2021): 3312–28. http://dx.doi.org/10.1093/mnras/stab167.
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ABSTRACT The spectra of active galactic nuclei usually exhibit wings in some emission lines, such as [O iii]λλ5007, 4959, with these wings generally being blueshifted and related to strong winds and outflows. The aim of this work was to analyse the [O iii] emission lines in broad-line Seyfert 1 (BLS1) galaxies in order to detect the presence of wings, and to study the [O iii] line properties and their possible connection with the central engine. In addition, we attempted to compare the black hole mass distribution in both BLS1 galaxies with symmetric and blue-asymmetric [O iii] profiles. For this purpose, we carried out a spectroscopic study of a sample of 45 nearby southern BLS1 galaxies from the Six Degree Field Galaxy survey. The [O iii] emission lines were well-fitted using a single Gaussian function in 23 galaxies, while 22 objects presented a wing component and required a double-Gaussian decomposition. By computing the radial velocity difference between the wing and core centroids (i.e. Δv), we found 18 galaxies exhibiting blueshifted wings, 2 objects presenting red wings, and 2 galaxies showing symmetric wings (Δv = 0). Moreover, Δv was slightly correlated with the black hole mass. In addition, we computed the radial velocity difference of the blue-side full extension of the wing relative to the centroid of the core component through the blue emission parameter, which revealed a correlation with black hole mass, in agreement with previous results reported for narrow-line galaxies. Finally, in our sample, similar black hole mass distributions were observed in both BLS1 galaxies with symmetric and blueshifted asymmetric [O iii] profiles.
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Pratiwi, Henny. "THE EFFECTS OF ANGLE OF ATTACK, REYNOLD NUMBERS AND WINGLET STRUCTURE ON THE PERFORMANCE OF CESSNA 172 SKYHAWK." Angkasa: Jurnal Ilmiah Bidang Teknologi 10, no. 1 (May 23, 2018): 61. http://dx.doi.org/10.28989/angkasa.v10i1.206.
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This research aims to investigate the effects of angle of attack, Reynold numbers and winglet structure on the performance of Cessna 172 Skyhawk aircraft with winglets variation design. Winglets improve efficiency by diffusing the shed wingtip vortex, which reducing the drag due to lift and improving the wing’s lift over drag ratio. In this research, the specimens are the duplicated of Cesnna 172 Skyhawk wing with 1:40 ratio made of balsa wood. There are three different winglet designs that are compared with the one without winglet. The experiments are conducted in an open wind tunnel to measure the lift and drag force with Reynold numbers of 25,000 and 33,000. It can be concluded that the wings with winglets have higher lift coefficient than wing without winglet for both Reynold numbers. It was also found that all wings with winglets have higher lift-to-drag ratio than wings without winglet where the blended 45o cant angle has the highest value.
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Wang, Q., J. F. L. Goosen, and F. van Keulen. "A predictive quasi-steady model of aerodynamic loads on flapping wings." Journal of Fluid Mechanics 800 (July 13, 2016): 688–719. http://dx.doi.org/10.1017/jfm.2016.413.
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Quasi-steady aerodynamic models play an important role in evaluating aerodynamic performance and conducting design and optimization of flapping wings. The kinematics of flapping wings is generally a resultant motion of wing translation (yaw) and rotation (pitch and roll). Most quasi-steady models are aimed at predicting the lift and thrust generation of flapping wings with prescribed kinematics. Nevertheless, it is insufficient to limit flapping wings to prescribed kinematics only since passive pitching motion is widely observed in natural flapping flights and preferred for the wing design of flapping wing micro air vehicles (FWMAVs). In addition to the aerodynamic forces, an accurate estimation of the aerodynamic torque about the pitching axis is required to study the passive pitching motion of flapping flights. The unsteadiness arising from the wing’s rotation complicates the estimation of the centre of pressure (CP) and the aerodynamic torque within the context of quasi-steady analysis. Although there are a few attempts in literature to model the torque analytically, the involved problems are still not completely solved. In this work, we present an analytical quasi-steady model by including four aerodynamic loading terms. The loads result from the wings translation, rotation, their coupling as well as the added-mass effect. The necessity of including all the four terms in a quasi-steady model in order to predict both the aerodynamic force and torque is demonstrated. Validations indicate a good accuracy of predicting the CP, the aerodynamic loads and the passive pitching motion for various Reynolds numbers. Moreover, compared to the existing quasi-steady models, the presented model does not rely on any empirical parameters and thus is more predictive, which enables application to the shape and kinematics optimization of flapping wings.
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Rogalla, Svana, Liliana D'Alba, Ann Verdoodt, and Matthew D. Shawkey. "Hot wings: thermal impacts of wing coloration on surface temperature during bird flight." Journal of The Royal Society Interface 16, no. 156 (July 2019): 20190032. http://dx.doi.org/10.1098/rsif.2019.0032.
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Recent studies on bird flight propose that hotter wing surfaces reduce skin friction drag, thereby improving flight efficiency (lift-to-drag ratio). Darker wings may in turn heat up faster under solar radiation than lighter wings. We used three methods to test the impact of colour on wing surface temperature. First, we modelled surface temperature based on reflectance measurements. Second, we used thermal imaging on live ospreys ( Pandion haliaetus ) to examine surface temperature changes with increasing solar irradiance. Third, we experimentally heated differently coloured wings in a wind tunnel and measured wing surface temperature at realistic flight speeds. Even under simulated flight conditions, darker wings consistently became hotter than pale wings. In white wings with black tips, the temperature differential produced convective currents towards the darker wing tips that could lead to an increase in lift. Additionally, a temperature differential between wing-spanning warm muscles and colder flight feathers could delay the flow separation above the wing, increasing flight efficiency. Together, these results suggest that wing coloration and muscle temperature both play important roles in modulating wing surface temperature and therefore potentially flight efficiency.
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Marino, L. "Induced-drag reduction of wing–wings and wings–ground configurations." Aeronautical Journal 108, no. 1088 (October 2004): 523–30. http://dx.doi.org/10.1017/s000192400000035x.
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Abstract The problem of induced drag reduction during formation flight is revisited by means of a simple aerodynamic model based on lifting line theory. The optimum configuration for minimum induced drag is analysed both in and out of the ground effect and the influence of the main geometrical and aerodynamic parameters is considered. The results are discussed and compared with existing numerical and experimental data.
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Meresman, Yonatan, and Gal Ribak. "Elastic wing deformations mitigate flapping asymmetry during manoeuvres in rose chafers (Protaetia cuprea)." Journal of Experimental Biology 223, no. 24 (November 9, 2020): jeb225599. http://dx.doi.org/10.1242/jeb.225599.
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ABSTRACTTo manoeuvre in air, flying animals produce asymmetric flapping between contralateral wings. Unlike the adjustable vertebrate wings, insect wings lack intrinsic musculature, preventing active control over wing shape during flight. However, the wings elastically deform as a result of aerodynamic and inertial forces generated by the flapping motions. How these elastic deformations vary with flapping kinematics and flight performance in free-flying insects is poorly understood. Using high-speed videography, we measured how contralateral wings elastically deform during free-flight manoeuvring in rose chafer beetles (Protaetia cuprea). We found that asymmetric flapping during aerial turns was associated with contralateral differences in chord-wise wing deformations. The highest instantaneous difference in deformation occurred during stroke reversals, resulting from differences in wing rotation timing. Elastic deformation asymmetry was also evident during mid-strokes, where wing compliance increased the angle of attack of both wings, but reduced the asymmetry in the angle of attack between contralateral wings. A biomechanical model revealed that wing compliance can increase the torques generated by each wing, providing higher potential for manoeuvrability, while concomitantly contributing to flight stability by attenuating steering asymmetry. Such stability may be adaptive for insects such as flower chafers that need to perform delicate low-speed landing manoeuvres among vegetation.
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Kumar, Ashutosh, and Raghvendra Gautam. "Design of Elevons, Wings, and Performance Investigation for A Blended Wing Body UAV." International Journal of Engineering and Advanced Technology 11, no. 1 (October 30, 2021): 60–69. http://dx.doi.org/10.35940/ijeat.a3152.1011121.
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Objectives: To study a hybrid VTOL- Blended wing body design for its wings and elevons and perform CFD simulations with the wings. The steps for designing wing configuration and Elevon positioning involve different variables giving rise to a large number of design possibilities for a control surface. In the current study methods, have been proposed for the selection of optimized wing configuration and elevons positioning and validated with simulations model. Methods: Meta-heuristic methods like genetic algorithms are used for arriving at favorable solutions and Matlab coding is written for the initial draft of wing geometry, selected geometries are iterated in XFLR5 for stability and control, and later validated with simulations around the fluid domain. Elevons are control surfaces generally installed in tailless aircraft at the wing's trailing edge. It applies to roll and pitching force to wings as it combines the functionality of both pitching and rolling control. Design space was mathematically plotted and solved using MATLAB to decide elevons, wing configuration, and their positions.Findings: Initial selection of wing geometry, aoa, and structural design for maneuverability and stability for the enhanced aerodynamic performance of BWB UAV. In this presented paper drag coefficient of the designed BWB UAV comes out to be precisely around 0.02216 using computational modeling. Variation curve of Lift and drag coefficient with aspect ratio and angle of attack. Post-processing results of pressure forces and velocity profile on Wings accurately validate the proposed method of control surface optimization. Novelty: Designed BWB UAV has increased lift to drag ratio, reduced weight of airframe which improves performance. The Design phase is highly iterative, Through this research paper, an attempt has been made to develop a methodology for selection and investigation of control surfaces against requirements that makes BWB UAV more helpful for practical use and increasing the lift and endurance efficiency of the hybrid VTOL- Blended wing body aircraft.
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Kruyt, Jan W., GertJan F. van Heijst, Douglas L. Altshuler, and David Lentink. "Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio." Journal of The Royal Society Interface 12, no. 105 (April 2015): 20150051. http://dx.doi.org/10.1098/rsif.2015.0051.
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Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the wing that elevates lift. Previous studies have demonstrated that this vortex and high lift can be reproduced by revolving the animal wing at the same angle of attack. How do flapping and revolving animal wings delay stall and reduce power? It has been hypothesized that stall delay derives from having a short radial distance between the shoulder joint and wing tip, measured in chord lengths. This non-dimensional measure of wing length represents the relative magnitude of inertial forces versus rotational accelerations operating in the boundary layer of revolving and flapping wings. Here we show for a suite of aspect ratios, which represent both animal and aircraft wings, that the attachment of the leading edge vortex on a revolving wing is determined by wing aspect ratio, defined with respect to the centre of revolution. At high angle of attack, the vortex remains attached when the local radius is shorter than four chord lengths and separates outboard on higher aspect ratio wings. This radial stall limit explains why revolving high aspect ratio wings (of helicopters) require less power compared with low aspect ratio wings (of hummingbirds) at low angle of attack and vice versa at high angle of attack.
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Jemitola, P. O., G. Monterzino, and J. Fielding. "Wing mass estimation algorithm for medium range box wing aircraft." Aeronautical Journal 117, no. 1189 (March 2013): 329–40. http://dx.doi.org/10.1017/s0001924000008022.
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Abstract A procedure for defining an empirical formula for the mass estimation of the fore and aft wings field Uof a medium range box wing aircraft is described. The procedure is based upon the work of Howe for estimating the wing mass of conventional cantilever wing aircraft. The paper outlines the procedure used to relate conventional cantilever wings to box wing aircraft wings. Using a vortex lattice tool, finite element methods and regression analysis, the modification performed on the coefficient in Howe’s method to enable its use on a medium range box wing aircraft is outlined. The results show that the fore and aft wings would use the same correction coefficient and that the aft wing would therefore be lighter than the fore wing on a medium range box wing aircraft.
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Ye, Ruiqi, Ziming Liu, Jin Cui, Chenyang Wang, and Yirong Wu. "Aerodynamic Analysis of Hovering Flapping Wing Using Multi-Plane Method and Quasi-Steady Blade Element Theory." Applied Sciences 14, no. 10 (May 17, 2024): 4258. http://dx.doi.org/10.3390/app14104258.
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In the design of flapping-wing micro-size air vehicles capable of hovering, wings serve as the primary source of hovering power, making the analysis of aerodynamics and aerodynamic efficiency crucial. Traditional quasi-steady models treat the wings as single rigid plane, neglecting the deformable characteristics of flexible wings. This paper proposes a multi-plane method that, in conjunction with various design parameters of flexible wings in a two-dimensional plane, analyzes their deformation characteristics under the assumption of multiple planes in three-dimensional space, and describes the deformation of wings during flapping. By combining the quasi-steady aerodynamic model, aerodynamic analysis of the deformed wings can be conducted. The relationship between the slack angle, wing flapping position, and wing deformation are analyzed, along with their effects on aerodynamics and aerodynamic efficiency. Experiments validate the deformation patterns of wings during flapping and compare the simulated aerodynamic forces with measured ones. The results indicate that wing deformation can be accurately described by adjusting the parameters in the multi-plane method and that the aerodynamic analysis using this method closely approximates the average lift results. Additionally, the multi-plane method establishes a connection between wing morphology and aerodynamic forces and efficiency, providing valuable insights for aerodynamic analysis.
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Xin, Hua, Zhang Ji, and Ming Lei. "The Bionic Wing with Winglet in Near Space Aerodynamic Analysis." Applied Mechanics and Materials 644-650 (September 2014): 1939–42. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.1939.
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With reference to a certain type of flying drones with imitation airfoil design a seagull flat wings and on the basis of its wing tip winglet in this paper. Through to the numerical simulation of two wings, it is concluded that the bionic wing aerodynamic performance is superior to the conventional airfoil wing, after adding wing tip winglet bionic wings effectively reduced the downwash velocity, reduce the induced drag, makes the wing aerodynamic performance is improved. Provide theoretical reference for the design of the uav wing
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Reid, Heidi, Huimin Zhou, Miles Maxcer, Robert KD Peterson, Jia Deng, and Mark Jankauski. "Toward the design of dynamically similar artificial insect wings." International Journal of Micro Air Vehicles 13 (January 2021): 175682932199213. http://dx.doi.org/10.1177/1756829321992138.
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Flapping wing deformation influences the aerodynamics of insect flight. This deformation is dictated by the dynamical properties of the insect wing, particularly its vibration spectra and mode shapes. However, researchers have not yet developed artificial insect wings with vibration spectra and mode shapes that are identical to their biological counterparts. The goal of the present work is to develop artificial insect wings that are both isospectral and isomodal with respect to real insect wings. To do so, we characterized hawkmoth Manduca sexta wings using experimental modal analyses. From these results, we created artificial wings using additive manufacturing and heat molding. Between artificial and real wings, the first two natural frequencies differ by 7% and 16% respectively, with differences of 16% and 131% in gains evaluated at those natural frequencies. Vibration modes are similar as well. This work provides a foundation for more advanced wing design moving forward.
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Wu, Jiang Hao, Chao Zhou, and Yan Lai Zhang. "A Novel Design in Micro-Air-Vehicle: Flapping Rotary Wings." Applied Mechanics and Materials 232 (November 2012): 189–93. http://dx.doi.org/10.4028/www.scientific.net/amm.232.189.
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A novel design in micro-air-vehicle using flapping rotary wings with different wing spanwise length and area is proposed. With the wings flapping, produced thrust makes the wings rotation. Furthermore, lift force from rotary wings increases and overcomes the MAV weight. On the basis of this principle, a mechanical model is made and sample experiments of averaged lift measurement in different wing length and area and angle of attack are executed. It is shown that the maximum averaged lift produced by micro flapping rotary wings can reach to 80mN approximately close to the weight of MAV.
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TUCKER, VANCE A. "Pitching Equilibrium, Wing Span and Tail Span in a Gliding Harris' Hawk, Parabuteo Unicinctus." Journal of Experimental Biology 165, no. 1 (April 1, 1992): 21–41. http://dx.doi.org/10.1242/jeb.165.1.21.
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1. The centre of area of the wings of a Harris' hawk gliding freely in a wind tunnel moved forward 0.09 wing chord lengths when the hawk increased its wing span from 0.68 to 1.07 m. The movement of the centre of area probably produces a positive pitching moment that, if unopposed, would cause the bird's head to rise. The tail remained folded until wing span reached 87% of maximum and then began to spread. This behaviour is also typical of gliding birds in nature, which spread their tails when the wings are near maximum span. Tail spreading probably produces a negative pitching moment that compensates for the forward movement of the wings at maximum span. 2. As the tail spread, its centre of area moved backwards. This movement, together with the increase in tail area, can keep the centre of area of the combined wings and tail from moving forward, even at maximum wing span. 3. The tail can generate an estimated 10% of the hawk's total lift at maximum wing span and 5 % or less at shorter wing spans. 4. I moved the centre of area of the hawk's wings forward experimentally by clipping 76 mm from primary feathers 6–10 and 38 mm from primary feather 5. The effect of this operation on the hawk's behaviour indicated that the forward movement of the centre of area of the wings caused a positive pitching moment. The hawk pitched up more in flight. It held its wings at shorter than normal spans, which partially compensated for the effects of clipping by moving the centre of area of the wings backwards. It also spread its tail at shorter than normal spans, which would compensate for an increase in the pitching moment of the wings.
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Gong, C. L., Z. J. Yuan, Q. Zhou, G. Chen, and Z. Fang. "Numerical Investigation of Unsteady Flows Past Flapping Wings with Immersed Boundary-Lattice Boltzmann Method." Journal of Mechanics 34, no. 2 (July 24, 2017): 193–207. http://dx.doi.org/10.1017/jmech.2017.56.
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AbstractBiomimetic motions are helpful to underwater vehicles and new conception airplanes design. The lattice Boltzmann method with an immersed boundary method technique is used to reveal the propulsion and lift enhancement mechanism of biomimetic motions. The flow past a sphere and an ellipsoidal flapping wing were validated respectively by comparing with other numerical methods. Then a single flapping wing and three flapping wings in a tandem arrangement are accomplished respectively. It founds that the mean thrust coefficient of three plate wings is bigger than the one of the single plate wing. Three ellipsoidal wings and single ellipsoidal wing are compared. It shows that the single ellipsoidal wing has larger thrust coefficients than the three ellipsoidal wings. Ellipsoidal flapping wing and plate wing were further compared to investigate the influence of wing shape. It indicates the mean thrust coefficient of the ellipsoidal wing is bigger than the plate wing.
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Berg, C., and J. Rayner. "The moment of inertia of bird wings and the inertial power requirement for flapping flight." Journal of Experimental Biology 198, no. 8 (January 1, 1995): 1655–64. http://dx.doi.org/10.1242/jeb.198.8.1655.
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The agility and manoeuvrability of a flying animal and the inertial power required to flap the wings are related to the moment of inertia of the wings. The moments of inertia of the wings of 29 bird species and three bat species were determined using wing strip analysis. We also measured wing length, wing span, wing area, wing mass and body mass. A strong correlation (r2=0.997) was found between the moment of inertia and the product of wing mass and the square of wing length. Using this relationship, it was found that all birds that use their wings for underwater flight had a higher than average moment of inertia. Assuming sinusoidal wing movement, the inertial power requirement was found to be proportional to (body mass)0.799, an exponent close to literature values for both metabolic power output and minimum power required for flight. Ignoring wing retraction, a fairly approximate estimate showed that the inertial power required is 11­15 % of the minimum flight power. If the kinetic energy of the wings is partly converted into aerodynamic (useful) work at stroke reversal, the power loss due to inertial effects may be smaller.
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Andrews, SA, and RE Perez. "Analytic study of the conditions required for longitudinal stability of dual-wing aircraft." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 232, no. 5 (May 11, 2017): 958–72. http://dx.doi.org/10.1177/0954410017704215.
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Recent studies of new, fuel-efficient transport aircraft have considered designs, which make use of two principal lifting surfaces to provide the required lift as well as trim and static stability. Such designs include open tandem-wings as well as closed joined and box-wings. As a group, these aircraft can be termed dual-wing designs. This study developed a new analytic model, which takes into account the downwash from the two main wings and is sensitive to three important design variables: the relative areas of each wing, the streamwise separation of the wings, and the center of gravity position. This model was used to better understand trends in the dual-wing geometry on the stability, maneuverability, and lift-to-drag ratio of the aircraft. Dual-wing aircraft have been shown to have reduced the induced drag compared to the conventional designs. In addition, further drag reductions can be realized as the horizontal tail can be removed if the dual-wings have sufficient streamwise stagger to provide the moments necessary for trim and longitudinal stability. As both wings in a dual-wing system carry a significant fraction of the total lift, trends in such designs that led to longitudinal stability can differ from those of the conventional aircraft and have not been the subject of detailed investigation. Results from the analytic model showed that the longitudinal stability required either a reduction of the fore wing area or shifting the center of gravity forward from the midpoint of both wings' aerodynamic centers. In addition, for wing configurations of approximately equal fore and aft wing areas, increasing the separation between the two wings decreased the stability of the aircraft. The source of this unusual behavior was the asymmetric distribution of downwash upstream and downstream of the wing. These relationships between dual-wing geometry and stability will provide initial guidance on the conceptual design of dual-wing aircraft and aid in the understanding of the results of more complex studies of such designs, furthering the development of future transport aircraft.
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Machida, Kenji, and Tomoaki Oikawa. "Structure Analyses of the Wings of Anotogaster Sieboldii and Hybris Subjacens." Key Engineering Materials 345-346 (August 2007): 1237–40. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.1237.
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The wings of a dragonfly have many complicated structures. The configuration of the costal vein of the wings of a dragonfly is different from them of other insects. So, we paid attention to the configuration of the costal vein of the wings in this study. In order to know the functions and structures of the wings of a dragonfly, several 3-D models of the wing of Anotogaster Sieboldii were created, and calculated with the 3-D finite element method. In addition, we created a 3-D model of the wing of Hybris Subjacens which has the configuration of original wing, and compared the models of Anotogaster Sieboldii and Hybris Subjacens. As a result, it was clarified that the arch configuration of the costal vein controls the bending and the torsion of the wings.
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Phillips, Nathan, Kevin Knowles, and Richard J. Bomphrey. "Petiolate wings: effects on the leading-edge vortex in flapping flight." Interface Focus 7, no. 1 (February 6, 2017): 20160084. http://dx.doi.org/10.1098/rsfs.2016.0084.
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The wings of many insect species including crane flies and damselflies are petiolate (on stalks), with the wing planform beginning some distance away from the wing hinge, rather than at the hinge. The aerodynamic impact of flapping petiolate wings is relatively unknown, particularly on the formation of the lift-augmenting leading-edge vortex (LEV): a key flow structure exploited by many insects, birds and bats to enhance their lift coefficient. We investigated the aerodynamic implications of petiolation P using particle image velocimetry flow field measurements on an array of rectangular wings of aspect ratio 3 and petiolation values of P = 1–3. The wings were driven using a mechanical device, the ‘Flapperatus’, to produce highly repeatable insect-like kinematics. The wings maintained a constant Reynolds number of 1400 and dimensionless stroke amplitude Λ * (number of chords traversed by the wingtip) of 6.5 across all test cases. Our results showed that for more petiolate wings the LEV is generally larger, stronger in circulation, and covers a greater area of the wing surface, particularly at the mid-span and inboard locations early in the wing stroke cycle. In each case, the LEV was initially arch-like in form with its outboard end terminating in a focus-sink on the wing surface, before transitioning to become continuous with the tip vortex thereafter. In the second half of the wing stroke, more petiolate wings exhibit a more detached LEV, with detachment initiating at approximately 70% and 50% span for P = 1 and 3, respectively. As a consequence, lift coefficients based on the LEV are higher in the first half of the wing stroke for petiolate wings, but more comparable in the second half. Time-averaged LEV lift coefficients show a general rise with petiolation over the range tested.
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Rajamurugu, Natarajan, Mohit Satyam, Manoj V, V. Nagendra, S. Yaknesh, and M. Sundararaj. "Investigation of Static Aeroelastic Analysis and Flutter Characterization of a Slender Straight Wing." International Journal of Automotive and Mechanical Engineering 21, no. 2 (June 20, 2024): 11203–19. http://dx.doi.org/10.15282/ijame.21.2.2024.3.0866.
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This research aims to investigate the static aeroelastic characteristics of a slender straight 2D wing using aerodynamic strip theory. The finite element method is employed to determine the wing's divergence speed and aileron effectiveness, while Galerkin's method, based on the principle of virtual work is used to obtain the influence coefficient of the straight wing. The application of aerodynamic strip theory and finite span correction is utilized to establish a correlation between elastic twist and lift coefficient. Subsequently, a computational tool in MATLAB is formulated to derive an approximate solution for the static aeroelastic equilibrium equations concerning slender straight wings. An investigation is conducted into the impact of various elastic axis positions on the divergence speed and its implications for structural integrity are analyzed. It was observed in the study that the incorporation of finite span correction into the strip theory led to a 15% augmentation in the divergence speed of the slender wing. Validation of the mathematical model of the slender wing is performed through computational analyses conducted using ANSYS software. The flutter analysis examines parameters such as the distance between the elastic and aerodynamic axes, the sweep position, and the wing span. A MATLAB code is presented in the research article to explore the influence of these parameters on the flutter speed of a slender wing. Through an investigation of the interplay between these parameters and the flutter speed, the study strives to enhance comprehension of the fundamental mechanisms governing flutter occurrence in slender wings. The current research reveals that the flutter speed is notably affected by both the eccentricity and span of the wing. Specifically, a reduction in eccentricity leads to a 1.5% enhancement in flutter speed, while increasing the sweep angle from 15 to 30 degrees for a wing with a 15ft span results in a 2.54% increase in flutter speed. Moreover, wings spanning from 5ft to 15ft exhibit a 5% rise in flutter speed. These findings offer valuable insights for the design of more efficient and stable wings.
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Kabir, A., A. S. M. Al-Obaidi, and F. W. Y. Myan. "Review and aerodynamic analysis of NACA 2415 morphing wing for variable span and scale morphing concepts using CFD analysis." Journal of Physics: Conference Series 2523, no. 1 (July 1, 2023): 012033. http://dx.doi.org/10.1088/1742-6596/2523/1/012033.
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Abstract Morphing wings made a significant advancement in aircraft engineering by improving aerodynamic performance for better fuel efficiency and are still under research. This paper reviewed and investigated some morphing wing types including the variable sweep, trailing edge, leading edge, variable span, variable chord, or scale, and airfoil morphing among others. Based on the review, two types of morphing wings were chosen for detailed investigation, and they were variable span and variable scale. Each morphing concept from the selected morphing wing types was implemented in airfoil wing configuration for aerodynamic performance analysis. Computational Fluid Dynamics (CFD) simulation is used to design and analyse morphing wing configurations of the chosen morphing concepts. In this research, two CFD analyses were investigated based on wing configuration; each consists of chosen morphing concept. Before the main CFD simulation of morphing wing analysis, CFD analysis of reference data of a typical NACA 2415 airfoil was verified. The lift coefficient of the morphing wing obtained from CFD analysis was compared with the unmorphed NACA airfoil wing to evaluate the morphing wing’s aerodynamic performance. It is concluded that there is an improvement in lift coefficients using the morphing concept cases, showing improved aerodynamic performance.
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Khaghaninia, S., S. Mohammadi, A. Srafrazi, K. Nejad, and R. Zahiri. "Geometric Morphometric Study on Geographic Dimorphism of Coding Moth Cydia Pomonella (Lepidoptera, Tortricidae) from North West of Iran." Vestnik Zoologii 45, no. 5 (January 1, 2011): e-20-e-28. http://dx.doi.org/10.2478/v10058-011-0028-z.
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Geometric Morphometric Study on Geographic Dimorphism of Coding MothCydia Pomonella(Lepidoptera, Tortricidae) from North West of IranDuring years 2003-2004, nine geographical populations of codling moth Cydia pomonella (Linnaeus) from 4 north western provinces of Iran were collected. By preparing 575 images from fore wings and 564 from hind wings, a total of 15 and 11 landmarks were determined for fore and hind wings, respectively. With transforming of landmark's geometrical data into partial warp scores, 26 and 18 scores were obtained for fore and hind wings, respectively. Canonical correlation analysis (CCA) revealed significant correlation between environmental parameters and wing shape variables. Among environmental parameters, wind speed showed the highest correlation with wing shape variables whereas, the correlation between latitude, relative humidity as well as amount of precipitation and wing shape variables was low. Considering the effect of various environmental parameters on wing shape, wind speed was determined as important parameter affecting geographic dimorphism. Among the populations collected from different regions, two geographic population pairs; Meshkinshahr-Mahneshan and Zandjan-Khoramdareh were selected as representative of low and high windy regions, respectively. Relative warp analysis (RWA) of fore and hind wings shape variables in the areas with high and low wind showed shorter and wider fore wings as well as slender and narrower hind wings in populations from high windy regions compared with populations from low wind regions. Centroid size of fore and hind wings in high windy area populations were smaller compared with those from low windy ones as revealed by t-test. The results showed aerodynamic shape and small size of wings are as adapted traits for powerful flight and its control in high windy regions.
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Bluman, James E., Madhu K. Sridhar, and Chang-kwon Kang. "Chordwise wing flexibility may passively stabilize hovering insects." Journal of The Royal Society Interface 15, no. 147 (October 2018): 20180409. http://dx.doi.org/10.1098/rsif.2018.0409.
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Insect wings are flexible, and the dynamically deforming wing shape influences the resulting aerodynamics and power consumption. However, the influence of wing flexibility on the flight dynamics of insects is unknown. Most stability studies in the literature consider rigid wings and conclude that the hover equilibrium condition is unstable. The rigid wings possess an unstable oscillatory mode mainly due to their pitch sensitivity to horizontal velocity perturbations. Here, we show that a flapping wing flyer with flexible wings exhibits stable hover equilibria. The free-flight insect flight dynamics are simulated at the fruit fly scale in the longitudinal plane. The chordwise wing flexibility is modelled as a linear beam. The two-dimensional Navier–Stokes equations are solved in a tight fluid–structure integration scheme. For a range of wing flexibilities similar to live insects, all eigenvalues of the system matrix about the hover equilibrium have negative real parts. Flexible wings appear to stabilize the unstable mode by passively deforming their wing shape in the presence of perturbations, generating significantly more horizontal velocity damping and pitch rate damping. These results suggest that insects may passively stabilize their hover flight via wing flexibility, which can inform designs of synthetic flapping wing robots.
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Hawkes, Elliot W., and David Lentink. "Fruit fly scale robots can hover longer with flapping wings than with spinning wings." Journal of The Royal Society Interface 13, no. 123 (October 2016): 20160730. http://dx.doi.org/10.1098/rsif.2016.0730.
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Hovering flies generate exceptionally high lift, because their wings generate a stable leading edge vortex. Micro flying robots with a similar wing design can generate similar high lift by either flapping or spinning their wings. While it requires less power to spin a wing, the overall efficiency depends also on the actuator system driving the wing. Here, we present the first holistic analysis to calculate how long a fly-inspired micro robot can hover with flapping versus spinning wings across scales. We integrate aerodynamic data with data-driven scaling laws for actuator, electronics and mechanism performance from fruit fly to hummingbird scales. Our analysis finds that spinning wings driven by rotary actuators are superior for robots with wingspans similar to hummingbirds, yet flapping wings driven by oscillatory actuators are superior at fruit fly scale. This crossover is driven by the reduction in performance of rotary compared with oscillatory actuators at smaller scale. Our calculations emphasize that a systems-level analysis is essential for trading-off flapping versus spinning wings for micro flying robots.
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Gursul, I. "Recent developments in delta wing aerodynamics." Aeronautical Journal 108, no. 1087 (September 2004): 437–52. http://dx.doi.org/10.1017/s0001924000000269.
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Abstract Recent developments in delta wing aerodynamics are reviewed. For slender delta wings, recent investigations shed more light on the unsteady aspects of shear-layer structure, vortex core, breakdown and its instabilities. For nonslender delta wings, substantial differences in the structure of vortical flow and breakdown may exist. Vortex interactions are generic to both slender and nonslender wings. Various unsteady flow phenomena may cause buffeting of wings and fins, however, vortex breakdown, vortex shedding, and shear layer reattachment are the most dominant sources. Dynamic response of vortex breakdown over delta wings in unsteady flows can be characterised by large time lags and hysteresis, whose physical mechanisms need further studies. Unusual flow–structure interactions for nonslender wings in the form of self-excited roll oscillations have been observed. Recent experiments showed that substantial lift enhancement is possible on a flexible delta wing.
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Ortega-Jimenez, Victor Manuel, Antonio Martín-Alcántara, Ramon Fernandez-Feria, and Robert Dudley. "On the autorotation of animal wings." Journal of The Royal Society Interface 14, no. 126 (January 2017): 20160870. http://dx.doi.org/10.1098/rsif.2016.0870.
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Botanical samaras spin about their centre of mass and create vertical aerodynamic forces which slow their rate of descent. Descending autorotation of animal wings, however, has never been documented. We report here that isolated wings from Anna's hummingbirds, and also from 10 species of insects, can stably autorotate and achieve descent speeds and aerodynamic performance comparable to those of samaras. A hummingbird wing loaded at its base with the equivalent of 50% of the bird's body mass descended only twice as fast as an unloaded wing, and rotated at frequencies similar to those of the wings in flapping flight. We found that even entire dead insects could stably autorotate depending on their wing postures. Feather removal trials showed no effect on descent velocity when the secondary feathers were removed from hummingbird wings. By contrast, partial removal of wing primaries substantially improved performance, except when only the outer primary was present. A scaling law for the aerodynamic performance of autorotating wings is well supported if the wing aspect ratio and the relative position of the spinning axis from the wing base are included. Autorotation is a useful and practical method that can be used to explore the aerodynamics of wing design.
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Krishna, Swathi, Moonsung Cho, Henja-Niniane Wehmann, Thomas Engels, and Fritz-Olaf Lehmann. "Wing Design in Flies: Properties and Aerodynamic Function." Insects 11, no. 8 (July 23, 2020): 466. http://dx.doi.org/10.3390/insects11080466.
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The shape and function of insect wings tremendously vary between insect species. This review is engaged in how wing design determines the aerodynamic mechanisms with which wings produce an air momentum for body weight support and flight control. We work out the tradeoffs associated with aerodynamic key parameters such as vortex development and lift production, and link the various components of wing structure to flight power requirements and propulsion efficiency. A comparison between rectangular, ideal-shaped and natural-shaped wings shows the benefits and detriments of various wing shapes for gliding and flapping flight. The review expands on the function of three-dimensional wing structure, on the specific role of wing corrugation for vortex trapping and lift enhancement, and on the aerodynamic significance of wing flexibility for flight and body posture control. The presented comparison is mainly concerned with wings of flies because these animals serve as model systems for both sensorimotor integration and aerial propulsion in several areas of biology and engineering.
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Pan, Dingyi, Jian Deng, Xueming Shao, and Zubin Liu. "On the Propulsive Performance of Tandem Flapping Wings with a Modified Immersed Boundary Method." International Journal of Computational Methods 13, no. 05 (August 31, 2016): 1650025. http://dx.doi.org/10.1142/s0219876216500250.
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The modified immersed boundary method is introduced and applied to study the propulsive mechanism of a tandem flapping wings system. The effects of tandem wings distance and phase lag between the two flapping wings are investigated. Thrust force of the upstream wing is nearly constant and close to the magnitude of single flapping wing system. Thrust force of second wing is influenced by the distance and phase lag. With specific parameters, the second wing can obtain a maximum thrust which is larger than the one of first wing. The flow structures of the wake flow are classified into three different formations, and they are correlated to the trends of thrust force. The effects of distance and phase lag are coupled other than isolated. It is possible to lower down the power consumption of this tandem flapping wings system and enhance the total thrust force of the system at the same time.
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Son, Nguyen Hong, Hoang Thi Bich Ngoc, Dinh Van Phong, and Nguyen Manh Hung. "Experiments and numerical calculation to determine aerodynamic characteristics of flows around 3D wings." Vietnam Journal of Mechanics 36, no. 2 (June 10, 2014): 133–43. http://dx.doi.org/10.15625/0866-7136/36/2/3405.
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The report presents method and results of experiments in wind tunnel to determine aerodynamic characteristics of 3D wings by measuring pressure distribution on the wing surfaces. Simultaneously, a numerical method by using sources and doublets distributed on panel elements of wing surface also is carried out to calculate flows around 3D wings. This computational method allows solving inviscid problems for wings with thickness profile. The experimental and numerical results are compared to each other to verify the built program that permits to extend the range of applications with the variation of wing profiles, wing planforms, and incidence angles.
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Siliang, Du, and Tang Zhengfei. "The Aerodynamic Behavioral Study of Tandem Fan Wing Configuration." International Journal of Aerospace Engineering 2018 (October 30, 2018): 1–14. http://dx.doi.org/10.1155/2018/1594570.
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The fan wing aircraft is a new concept based on a new principle, especially its wing which is based on a unique aerodynamic principle. A fan wing can simultaneously generate lift and thrust. In order to further improve its aerodynamic characteristics without changing its basic geometric parameters, two fan wings are installed along the longitudinal body, which is the composition of a tandem fan wing aircraft. Through numerical simulation, the lift and thrust of the fan wings were calculated with the distance, height, and installation angle of the front and rear fan wings changed, and the aerodynamic characteristic interaction rule between the front and rear fan wings was analyzed. In addition, the wind test model of a tandem fan wing was designed, and the results of the wind tunnel test and numerical calculation results were compared to verify the preliminary setup. The results show that at a certain height, distance, and installation angle, aerodynamic characteristics of a tandem fan wing have more advantages compared to the single fan wing. Therefore, the tandem fan wing aircraft’s advantages have good prospects for development and application.
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HEINRICH, BERND. "Is ‘Reflectance’ Basking Real?" Journal of Experimental Biology 154, no. 1 (November 1, 1990): 31–43. http://dx.doi.org/10.1242/jeb.154.1.31.
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Various kinds of butterflies raise both (or sometimes one) of their pairs of wings while basking with their body at approximately right angles to the incident solar radiation and with their wings held at an acute angle to the incident sunlight. I here test the effects of wing posture on thoracic temperature in so-called ‘reflectance’ basking. 1. Butterflies with pale yellow or white dorsal wing surfaces held with their wings at 45, 90 or 180° with respect to each other (or 22–23, 45 and 90°with respect to the solar radiation) heated to mean thoracic temperatures (Tth) of 38.2, 39.5 and 39.9°C, respectively, in direct sunlight. These closely similar values of T^ are significantly different (P < 0.02) from each other, but the difference is in the opposite direction to that predicted by the solar reflectance hypothesis. 2. The Tth of butterflies tested under a sun lamp in the laboratory showed the same trend of Tth with wing angle. Reflectance from the wings thus makes little or no practical contribution to the animal's heating response. 3. Butterflies with wings at 45° that were heated from above with a sun lamp showed an immediate increase in Tth when turned at right angles to a gentle air stream. Thoracic temperature immediately declined when they were again turned to face the air stream. 4. Those butterflies that were at right angles to the air stream showed an immediate increase in Tth when the wings were raised from 180 to 45°, and their Tth again declined to previous values when the wings were again lowered. However, little or no effect of wing angle on Tth was observed when the wing angle of butterflies parallel to the air stream was altered. These results indicate that wing elevation in basking butterflies does not increase Tth by way of solar reflection from the wings. Instead, the raised wings increase Tth by reducing convective cooling. ‘Reflectance’ basking is a form of dorsal basking used by species of butterflies that perch above vegetation rather than above a heated substratum.
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Combes, S. A., and T. L. Daniel. "Shape, flapping and flexion: wing and fin design for forward flight." Journal of Experimental Biology 204, no. 12 (June 15, 2001): 2073–85. http://dx.doi.org/10.1242/jeb.204.12.2073.
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SUMMARY Both kinematics and morphology are critical determinants of performance in flapping flight. However, the functional consequences of changes in these traits are not yet well understood. Traditional aerodynamic studies of planform wing shape have suggested that high-aspect-ratio wings generate more force per area and perform more efficiently than low-aspect-ratio wings, but these analyses may neglect critical components of flapping flight such as unsteady fluid dynamics and wing or fin flexion. In this paper, we use an unsteady potential flow analysis that incorporates wing flexion to test predictions of optimal wing shape under varying degrees of unsteady motion and wing flexion. We focus on forward flapping flight and examine the effects of wing/fin morphology and movements on thrust generation and efficiency. We test the model by comparing our predictions with kinematic data derived from the aquatic flight of the ratfish Hydrolagus colliei. Our analyses show that aspect ratio and the proportion of area in the outer one-fifth of the wing can characterize wing shape in terms of aero- or hydrodynamic performance. By comparing the performance of wings that vary in these two parameters, we find that traditional predictions of optimal wing shape are valid only under limited circumstances (when flapping frequency is low, wings are stiff or wings are tapered at the tips). This indicates a complex relationship between locomotor traits and performance and helps explain the diversity of wing kinematics and morphologies observed in nature.
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Kumar, David, Vemuri Shyam Kumar, Tigmanshu Goyal, P. M. Mohite, and S. Kamle. "Modal Analysis of Hummingbird Inspired MAV Flapping Wings." Applied Mechanics and Materials 772 (July 2015): 435–40. http://dx.doi.org/10.4028/www.scientific.net/amm.772.435.
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Natural flyers are the best source of inspiration for making successful MAVs. Hummingbirds are known for their excellent flight characteristics such as long duration hovering, backward flying, high agility, etc. Giant hummingbird is chosen as the bio-inspiration for designing the wing. Wings are required to be light, strong, and fatigue resistant to be used for MAV applications. Carbon nanotubes (CNTs)/Polypropylene (PP) composite is chosen as the wing membrane material whereas carbon fiber (CF)/epoxy (E) composite is chosen for wing frame. Two types of wings are fabricated, one is CNTs/PP wing and another is CF/E frame with CNTs/PP membrane wing. Kinematics, structural dynamics, and aerodynamics are the main component of flapping flight studies. Modal analysis of fabricated wings is done using 3D visual image correlation (VIC-3D) and laser displacement sensor setup. In the end, the results of both type wings are compared with experimental results and a good correlation has been seen. The validation of results is done using Ansys.
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O’Callaghan, Felicity, Amir Sarig, Gal Ribak, and Fritz-Olaf Lehmann. "Efficiency and Aerodynamic Performance of Bristled Insect Wings Depending on Reynolds Number in Flapping Flight." Fluids 7, no. 2 (February 10, 2022): 75. http://dx.doi.org/10.3390/fluids7020075.
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Insect wings are generally constructed from veins and solid membranes. However, in the case of the smallest flying insects, the wing membrane is often replaced by hair-like bristles. In contrast to large insects, it is possible for both bristled and membranous wings to be simultaneously present in small insect species. There is therefore a continuing debate about the advantages and disadvantages of bristled wings for flight. In this study, we experimentally tested bristled robotic wing models on their ability to generate vertical forces and scored aerodynamic efficiency at Reynolds numbers that are typical for flight in miniature insects. The tested wings ranged from a solid membrane to a few bristles. A generic lift-based wing kinematic pattern moved the wings around their root. The results show that the lift coefficients, power coefficients and Froude efficiency decreased with increasing bristle spacing. Skin friction significantly attenuates lift production, which may even result in negative coefficients at elevated bristle spacing and low Reynolds numbers. The experimental data confirm previous findings from numerical simulations. These had suggested that for small insects, flying with bristled instead of membranous wings involved less change in energetic costs than for large insects. In sum, our findings highlight the aerodynamic changes associated with bristled wing designs and are thus significant for assessing the biological fitness and dispersal of flying insects.
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Larsen, Janet D., and Ned K. Garn. "Wings in the Intershaft Space Contribute to the Mueller-Lyer Illusion." Perceptual and Motor Skills 67, no. 3 (December 1988): 831–34. http://dx.doi.org/10.2466/pms.1988.67.3.831.
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The interference of the wings of the wings-in part of the Mueller-Lyer figure was examined for the version of the illusion in which one part of the figure is placed above the other. Wings were removed in pairs from either above or below the shaft of one of the two parts of the figure. Subjects indicated the apparent difference between the lengths of the shafts of the two parts of the figure. Removal of the wings between the shafts of the wings-in part of the figure reduced the amount of the illusion more than removal of the wings from outside the shafts. Removing wings from the wings-out part of the figure reduced the amount of illusion, but it made no difference whether the wing removal occurred between or outside the shafts.
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Kobelev, Vladimir. "Approximate static aeroelastic analysis of composite wings." Multidiscipline Modeling in Materials and Structures 15, no. 2 (February 21, 2019): 365–86. http://dx.doi.org/10.1108/mmms-02-2018-0019.
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PurposeThe purpose of this paper is to consider divergence of composite plate wings as well as slender wings with thin-walled cross-section of small-size airplanes. The main attention is paid to establishing of closed-form mathematical solutions for models of wings with coupling effects. Simplified solutions for calculating the divergence speed of wings with different geometry are established.Design/methodology/approachThe wings are modeled as anisotropic plate elements and thin-walled beams with closed cross-section. Two-dimensional plate-like models are applied to analysis and design problems for wings of large aspect ratio.FindingsAt first, the equations of elastic deformation for anisotropic slender, plate-like wing with the large aspect ratio are studied. The principal consideration is delivered to the coupled torsion-bending effects. The influence of anisotropic tailoring on the critical divergence speed of the wing is examined in closed form. At second, the method is extended to study the behavior of the large aspect ratio, anisotropic wing with box-like wings. The static equations of the wing with box-like profile are derived using the theory of anisotropic thin-walled beams with closed cross-section. The solutions for forward-swept wing with box-like profiles are given in analytical formulas. The formulas for critical divergence speed demonstrate the dependency upon cross-sectional shape characteristics and anisotropic properties of the wing.Research limitations/implicationsThe following simplifications are used: the simplified aerodynamic theory for the wings of large aspect ratio was applied; the static aeroelastic instability is considered (divergence); according to standard component methodology, only the component of wing was modeled, but not the whole aircraft; the simplified theories (plate-lime model for flat section or thin-walled beam of closed-section) were applied; and a single parameter that defines the rotation of a stack of single layers over the face of the wing.Practical implicationsThe simple, closed-form formulas for an estimation of critical static divergence are derived. The formulas are intended for use in designing of sport aircraft, gliders and small unmanned aircraft (drones). No complex analysis of airflow and advanced structural and aerodynamic models is necessary. The expression for chord length over the span of the wing allows for accounting a board class of wing shapes.Social implicationsThe derived theory facilitates the use of composite materials for popular small-size aircraft, and particularly, for drones and gliders.Originality/valueThe closed-form solutions for thin-walled beams in steady gas flow are delivered in closed form. The explicit formulas for slender wings with variable chord and stiffness along the wing span are derived.
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Dessena, Gabriele, Dmitry I. Ignatyev, James F. Whidborne, Alessandro Pontillo, and Luca Zanotti Fragonara. "Ground Vibration Testing of a Flexible Wing: A Benchmark and Case Study." Aerospace 9, no. 8 (August 10, 2022): 438. http://dx.doi.org/10.3390/aerospace9080438.
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Beam-like flexible structures are of interest in many fields of engineering, particularly aeronautics, where wings are frequently modelled and represented as such. Experimental modal analysis is commonly used to characterise the wing’s dynamical response. However, unlike other flexible structure applications, no benchmark problems involving high-aspect-ratio flexible wings have appeared in the open literature. To address this, this paper reports on ground vibration testing results for a flexible wing and its sub-assembly and parts. The experimental data can be used as a benchmark and are available to the aeronautical and structural dynamics community. Furthermore, non-linearities in the structure, where present, were detected. Tests were performed on the whole wing as well as parts and sub-assembly, providing four specimens. These were excited with random vibration at three different amplitudes from a shaker table. The modal properties of a very flexible high-aspect-ratio wing model, its sub-assembly and parts, were extracted, non-linear behaviour was detected and the experimental data are shared in an open repository.
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Dai, Shuhao, Hongli Ji, Chongcong Tao, Chao Zhang, and Jinhao Qiu. "Design and thermal protection performance analysis of insulated wing storage box for hypersonic variable-sweep aircraft." Journal of Physics: Conference Series 2764, no. 1 (May 1, 2024): 012043. http://dx.doi.org/10.1088/1742-6596/2764/1/012043.
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Abstract Utilizing variable-sweep wing technology can further enhance the flight performance of hypersonic aircraft in a wide range of high-altitude, high-speed environments. Existing research on hypersonic variable-sweep flying wings has mainly focused on aerodynamic shape design, with limited research on the internal thermal protection of the aircraft. This study firstly investigates the performance improvement of a hypersonic flying wing using variable-sweep technology through CFD simulations. Secondly, to address the high-temperature issues induced by variable-sweep wings, an insulated wing storage box with a corrugated structure is designed, incorporating a thermal insulation layer made of corrugated webs and insulating materials. Heat transfer simulations are conducted by applying thermal loads to the wing storage box to study the temperature distribution during the variable-sweep process. Finally, a comparison between the corrugated structure design and the non-corrugated structure design of the wing storage box is performed to analyze the thermal insulation performance of the insulation layer. The results show that the heated area of the wing storage box is primarily influenced by the wing’s sweep angle, and the corrugated thermal insulation layer can effectively reduce heat transfer efficiency, resulting in a 30% reduction in the external temperature of the wing storage box.
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Zhao, Liang, Qingfeng Huang, Xinyan Deng, and Sanjay P. Sane. "Aerodynamic effects of flexibility in flapping wings." Journal of The Royal Society Interface 7, no. 44 (August 19, 2009): 485–97. http://dx.doi.org/10.1098/rsif.2009.0200.
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Recent work on the aerodynamics of flapping flight reveals fundamental differences in the mechanisms of aerodynamic force generation between fixed and flapping wings. When fixed wings translate at high angles of attack, they periodically generate and shed leading and trailing edge vortices as reflected in their fluctuating aerodynamic force traces and associated flow visualization. In contrast, wings flapping at high angles of attack generate stable leading edge vorticity, which persists throughout the duration of the stroke and enhances mean aerodynamic forces. Here, we show that aerodynamic forces can be controlled by altering the trailing edge flexibility of a flapping wing. We used a dynamically scaled mechanical model of flapping flight ( Re ≈ 2000) to measure the aerodynamic forces on flapping wings of variable flexural stiffness (EI). For low to medium angles of attack, as flexibility of the wing increases, its ability to generate aerodynamic forces decreases monotonically but its lift-to-drag ratios remain approximately constant. The instantaneous force traces reveal no major differences in the underlying modes of force generation for flexible and rigid wings, but the magnitude of force, the angle of net force vector and centre of pressure all vary systematically with wing flexibility. Even a rudimentary framework of wing veins is sufficient to restore the ability of flexible wings to generate forces at near-rigid values. Thus, the magnitude of force generation can be controlled by modulating the trailing edge flexibility and thereby controlling the magnitude of the leading edge vorticity. To characterize this, we have generated a detailed database of aerodynamic forces as a function of several variables including material properties, kinematics, aerodynamic forces and centre of pressure, which can also be used to help validate computational models of aeroelastic flapping wings. These experiments will also be useful for wing design for small robotic insects and, to a limited extent, in understanding the aerodynamics of flapping insect wings.
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Zhang, Yixin, Xingjian Wang, Shaoping Wang, Wenhao Huang, and Qiwang Weng. "Kinematic and Aerodynamic Investigation of the Butterfly in Forward Free Flight for the Butterfly-Inspired Flapping Wing Air Vehicle." Applied Sciences 11, no. 6 (March 16, 2021): 2620. http://dx.doi.org/10.3390/app11062620.
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To ensure the stability of flight, the butterfly needs to flap its wings and simultaneously move its main body to achieve all kinds of flying motion, such as taking off, hovering, or reverse flight. The high-speed camera is used to record the swing of the abdomen, the movement of the wings, and the pitch angle of the body for butterflies during their free flight; the comprehensive biokinetic observations show that the butterfly’s wings and body are coupled in various flight states. The swing of the abdomen and the flap of the fore wing affect the pitch motion significantly. For theoretical analysis of the butterfly flight, a three-dimensional multi-rigid butterfly model based on real butterfly dimension is established, and the aerodynamic of the butterfly flight is simulated and analyzed via computational fluid dynamics methods to obtain an optimal kinematic model of butterfly forward flight. Moreover, the formation and development of three-dimensional vortex structures in the forward flight are also presented. The detailed structures of vortices and their dynamic behavior show that the wing’s flap and the abdominal swing play a key role in reorienting and correcting the “clap and peel” mechanism, and the force generation mechanisms are evaluated. The research indicates that longitudinal flight performance is mainly related to the kinematic parameters of the wing and body, and it can lead to the development of butterfly-inspired flapping wing air vehicles.