Wing Shape Research Articles

Optimizing airfoil shape for small, low speed, unmanned gliders: A homemade investigation

Motivated by an interest to increase the efficiency of static airfoils, the objective of this study was to optimize airfoil lift generation based solely on airfoil shape. Enhancing the lift generated by airfoils without flaps can lead to longer flight times for unmanned gliders and possibly reduce fuel requirements for ground and air vehicles (1,2,3). We employed a Bernoullian model of airfoil lift generation to predict an optimized wing shape which was then constructed and compared with five others in a wind tunnel. We assembled airfoils from Styrofoam and conducted experiments in a small wind tunnel, measuring air speeds with a handheld anemometer. Our Bernoullian model related lift generation to the ratio of surface areas above and below an airfoil’s chord, and because this ratio was maximized in our optimal airfoil, we predicted that this wing would generate more lift force than the other tested wings with lower ratios. However, we identified a variety of confounding variables including imperfections in wing constructions, turbulent airflow and air resistance within the wind tunnel, and low resolution of the anemometer, all of which contributed to unpredicted and unreliable results. Moreover, we concluded that our mathematical model was not rigorous enough to be generalized to a wider set of experimental conditions. Despite these shortcomings, our results did point to a correlation between airfoil shape and lift generation, and will allow for more informed, less error prone future studies.

Wing morphology is related to niche specialization and interaction networks in stenodermatine bats (Chiroptera: Phyllostomidae)

Abstract Plant–animal interactions constitute some of the most important ecological processes for the maintenance of tropical forests. Bats are the only group of mammals capable of true flight and have been recognized as important dispersers of pioneer and secondary successional plant species. Although progress has been made in the study of Neotropical bats, morphological variation of the wing and its influence on niche separation between species is unknown. We evaluated relationships among habitat structures of selected Colombian tropical dry forest patches, the diet through interaction networks, and wing morphology of 11 species of bats in the Stenodermatinae subfamily (297 individuals) using geometric morphometry in a phylogenetic context. The results indicate that the phylogenetic signal for wing size is greater than for wing shape, thus providing some evidence for evolutionary convergence. Wing shape variation was associated primarily with the distal anatomical tip of the third finger and the joint between the humerus and the radius and ulna. Species with wide, short wings, as in the genus Artibeus had generalist diets and less nested positions within the interaction networks. In contrast, species with elongated and pointed wings, such as Sturnira and Platyrrhinus, had specialized diets and more nested positions within the interaction networks. We argue that wing shape variation may play an important role as a source of interspecific variation leading to food specialization within tropical bat communities.

Optimization of the Bionic Wing Shape of Tidal Turbines Using Multi-Island Genetic Algorithm

In this study, we improved the energy acquisition efficiency of tidal turbines with bionic airfoils by optimizing the seagull, long-eared owl, sparrowhawk, and two-dimensional airfoils, thereby obtaining a better lift–drag ratio. We used Isight software to integrate the Integrated Computer Engineering and Manufacturing (ICEM) software and used Fluent simulation software, batch operation file, and multi-island genetic algorithm to maximize the lift–drag ratio as the objective function for optimizing the original airfoil. The optimized upper airfoil profile was distributed upward from the starter wing, and the thickness of the upper wing was the greatest. Meanwhile, the lower airfoil profile was thinner and more curved. The thickness of the three airfoils was distributed backward from the front of the wing, with the maximum thickness at the front, and the maximum camber was distributed backward from the front. The three optimized wings exhibited a maximum lift–drag ratio at an angle of attack of approximately 5°, with the sparrowhawk wing having a maximum lift–drag ratio of 80.87 at an angle of attack of 6°, the seagull wing having a maximum lift–drag ratio of 76.82 at an angle of attack of 4°, and the long-eared owl wing having a maximum lift–drag ratio of 68.43 at an angle of attack of 5°.

Mixed support for an alignment between phenotypic plasticity and genetic differentiation in damselfly wing shape.

The relationship between genetic differentiation and phenotypic plasticity can provide information on whether plasticity generally facilitates or hinders adaptation to environmental change. Here, we studied wing shape variation in a damselfly (Lestes sponsa) across a latitudinal gradient in Europe that differed in time constraints mediated by photoperiod and temperature. We reared damselflies from northern and southern populations in the laboratory using a reciprocal transplant experiment that simulated time-constrained (i.e. northern) and unconstrained (southern) photoperiods and temperatures. After emergence, adult wing shape was analysed using geometric morphometrics. Wings from individuals in the northern and southern populations differed significantly in shape when animals were reared in their respective native environment. Comparing wing shape across environments, we found evidence for phenotypic plasticity in wing shape, and this response differed across populations (i.e. G × E interactions). This interaction was driven by a stronger plastic response by individuals from the northern population and differences in the direction of plastic wing shape changes among populations. The alignment between genetic and plastic responses depended on the specific combination of population and rearing environment. For example, there was an alignment between plasticity and genetic differentiation under time-constrained, but not under non-time-constrained conditions for forewings. We thus find mixed support for the hypothesis that environmental plasticity and genetic population differentiation are aligned. Furthermore, although our laboratory treatments mimicked the natural climatic conditions at northern and southern latitudes, the effects of population differences on wing shape were two to four times stronger than plastic effects. We discuss our results in terms of time constraints and the possibility that natural and sexual selection is acting differently on fore- and hindwings.

Design and preliminary application of outdoor flying pigeon-robot

Control at beyond-visual ranges is of great significance to animal-robots with wide range motion capability. For pigeon-robots, such control can be done by the way of onboard preprogram, but not constitute a closed-loop yet. This study designed a new control system for pigeon-robots, which integrated the function of trajectory monitoring to that of brain stimulation. It achieved the closed-loop control in turning or circling by estimating pigeons' flight state instantaneously and the corresponding logical regulation. The stimulation targets located at the formation reticularis medialis mesencephali (FRM) in the left and right brain, for the purposes of left- and right-turn control, respectively. The stimulus was characterized by the waveform mimicking the nerve cell membrane potential, and was activated intermittently. The wearable control unit weighted 11.8 g totally. The results showed a 90% success rate by the closed-loop control in pigeon-robots. It was convenient to obtain the wing shape during flight maneuver, by equipping a pigeon-robot with a vivo camera. It was also feasible to regulate the evolution of pigeon flocks by the pigeon-robots at different hierarchical level. All of these lay the groundwork for the application of pigeon-robots in scientific researches.

High and lowland dependent wing phenotypic variation of the dark blue tiger butterfly, Tirumala septentrionis (Butler, 1874) (Lepidoptera: Nymphalidae) with FE-SEM wing scales nanomorphology

Butterflies display remarkable variation in wing shape and size, which is associated with tremendous ecological diversity. In butterflies, wing color patterns have been extensively studied, but wing shape and size diversity is less understood. In the present study, we investigated the altitude-specific wing asymmetry (right and left wings), sexual asymmetry, and wing covariation (proximal-distal and anterior-posterior wing organization) of Tirumala septentrionis (Butler, 1874). Using the geometric morphometric (GMM) method, we discovered that broad and expanded wings were found in lowland areas, whereas long and more rounded slender wings were found in highland areas. Furthermore, the ANOVA analysis, found significant (p < 0.05) altitude-specific shape and size differences in forewings and hindwings of both sexes. Thus, compared to size variations, the shape can be utilized as a valuable tool to distinguish sex (male and female), wing asymmetry (right and left) as well as altitudes (high and lowlands) specific variations of T. septentrionis. Furthermore, we noticed that lowland butterfly population had more asymmetric wings than the highland in the wing asymmetry analysis. We suspected that the unique wing morphology observed in the highland T. septentrionis population favored long-distance flight (indication of a migratory population). In contrast, the lowland population wing morphology indicated a newly colonized butterfly population. In addition to GMM analysis, we documented the FE-SEM wing scale morphology of T. septentrionis collected from two different altitudes. Interestingly, we observed that there is no difference in scale morphology related to altitude variations. Finally, we concluded that altitude-specific variations were observed mainly on wing shape and size, rather than the wing scales. These morphological variations were primarily associated with an adaptive response like migration, host searching, flight energy management and so on.

Aerostructural evaluation of bioinspired chordwise flexible flapping wing

This study relates the structural deformation and the unsteady aerodynamics involved for lift production in bioinspired nanocomposite flapping wings. The sectional chord deformation effects on theoretically supported aerodynamic lift are addressed. Digital image correlation setup and L-shape mechanism are developed and synchronized for wing deformation and aerodynamic forces measurement respectively. DIC system with estimated resolution of 0.159 mm/pixel and L-shape mechanism with net uncertainty of ± 0.72 % verify the measurement accuracy for low Reynolds number flapping wing experiments and alike miniature aero-structures. The flapping wing shape is investigated at 25%, 50% and 75% wing-span to study the effect of sectional chord deformation on lift components obtained from Theodorsen theory. Circulatory lift is dominant at mid-downstroke while Non-circulatory lift is dominant at the beginning of flapping cycle due to inertial effects.

A high-throughput multispectral imaging system for museum specimens

We present an economical imaging system with integrated hardware and software to capture multispectral images of Lepidoptera with high efficiency. This method facilitates the comparison of colors and shapes among species at fine and broad taxonomic scales and may be adapted for other insect orders with greater three-dimensionality. Our system can image both the dorsal and ventral sides of pinned specimens. Together with our processing pipeline, the descriptive data can be used to systematically investigate multispectral colors and shapes based on full-wing reconstruction and a universally applicable ground plan that objectively quantifies wing patterns for species with different wing shapes (including tails) and venation systems. Basic morphological measurements, such as body length, thorax width, and antenna size are automatically generated. This system can increase exponentially the amount and quality of trait data extracted from museum specimens.

Responsiveness and Adaptability of Housing Spatial Design to New Emerging Functions: The Case of COVID-19 Pandemic

The paper aims to measure the ability of housing design in Palestine to respond to any emerging functions and needs and the ability to adapt to new and possible sudden lifestyle changes. Four different interior house types were analyzed, two refer to the traditional approach of the closed plan, and another two types refer to the modern approaches of the open plan in terms of adaptation to new needs. These needs are adaptability to work from home, flexibility to change, separate or merge functions, and the adaptability to respond to health issues like quarantine. The study adopts the method of architectural analysis and questionnaire to measure people's opinions about all types in terms of sudden functions. The study takes the COVID-19 pandemic conditions as a case study. The main finding of the study is establishing a relationship between style of housing spatial design and the ability for adapting sudden changes in lifestyle. It shows that the traditional designs adapt to most changing lifestyles successfully, the independent guest room was converted into an office or guaranteed room. Moreover, the modern open plan house design with a T shape of the day wing is the best choice for adapting to the post-COVID-19.

Linear and Geometrically Nonlinear Structural Shape Sensing from Strain Data

An aircraft’s shape must be measured during flight to implement active shape controls such as active trim shape, divergence, and sonic boom controls. A basis function method for linear as well as geometrically nonlinear structural shape sensing is proposed in this study. Basis functions can be mode shapes, linear static deformation shapes, and/or geometrically nonlinear static deformation shapes. The proposed basis function method is validated using a high-aspect-ratio wing, a swept test plate, and the National Aeronautics and Space Administration X-59 aircraft. A large structural deformation of a high-aspect-ratio wing is successfully captured using the proposed basis function method with less than 0.3% prediction error at the wing-tip section. The basis function method gives excellent deformation prediction, even with stress concentration. Performance of the basis functions is compared using the X-59 stabilator sample case. In most of the sample load cases, static deformations give a better correlation with the target deformation than do mode shapes. Wing shape sensing with sparse strain data are also demonstrated in this study using the X-59 aircraft. Predicted structural deformations match reasonably with the target deformations, even without strain gauges on some structural components. The predicted deformations have a good match with the target deformations.

Has long‐distance flight ability been maintained by pigeons in highly insular habitats?

AbstractAimA reduction in dispersal ability has been thought to be a general trend for island land birds. However, recent studies have indicated that long‐distance dispersal among island habitats may be maintained in island pigeon populations. Here, we investigated whether pigeons could maintain their long‐distance dispersal ability to move among islands within the archipelago, even in highly insular conditions, by comparing two subspecies of Japanese wood pigeon distributed on islands with different levels of insularity.LocationThe Ogasawara, Izu and Nansei Islands in the north‐western Pacific Ocean.TaxonJapanese wood pigeon (Columba janthina).MethodsWe compared the hand‐wing index related to dispersal potential between the two subspecies: C. j. janthina and C. j. nitens. We performed phylogenetic analyses with likelihood and Bayesian frameworks and estimated population genetic structure using the principal component analyses and individual admixture analyses based on the genotype likelihood of MIG‐seq SNPs. We calculated divergence times of the two subspecies using Bayesian and PSMC models for MIG‐seq SNPs and whole genome data, respectively.ResultsC. j. nitens had a wing shape that was better suited for long‐distance flight than that of C. j. janthina. Both subspecies maintained sufficient gene flow among the islands within their habitat archipelagos, with no evidence of isolation by distance. The divergence time of the two subspecies was 0.67 (95%CI: 0.33–0.97) million years ago, which was sufficient to reduce dispersiveness compared to other cases of island land birds.Main ConclusionLong‐distance flight can be maintained under highly insular conditions despite long‐term isolation from the ancestral populations. This indicates that the strategy of maintaining dispersal ability may also be possible in island systems, where organisms have repeatedly and globally shown reduced dispersal ability. Although further studies are required to reveal its evolutionary processes, our study provides an exceptional case for island birds' biogeography.

The effect of habitat amount on flight‐related traits in the butterflyHamadryas februais sex‐dependent

AbstractMobility in flying animals can be assessed by variations in morpho–ecological traits such as body, thorax and wing sizes, wing shape and the proportion between body mass and wing area. Habitat loss and fragmentation can promote phenotypic plasticity and microevolutionary divergencies in natural populations. In this context, sexual differences in physiology and behaviour can impose different selection pressure on morphological aspects related to flight.We evaluated the relative impact of forest patch area and habitat amount in shaping flight‐related morpho–ecological traits of the tropical butterflyHamadryas februa. We find a marked sexual dimorphism in the species, with females being larger, having larger thorax, higher wing loadings and larger wing total area than males. These trait values indicate females as the more dispersive sex. We show that habitat amount modulates body mass allocations in both sexes, leading to an increase in thorax mass with decreasing habitat amount. The effect of habitat amount was more pronounced in females, which increased total mass and wing loading while decreasing thorax allocation with decreasing habitat amount. This outcome suggests that females increase abdominal mass in response to a reduction in habitat amount. The focal forest patch increasing area was linked to increases in hindwing lengths in both females and males.We advocate that both landscape metrics (i.e., habitat amount and patch area) should be considered in studies evaluating landscapes' impacts on insect mobility. We discuss results in terms of the species' sexual differences in flight behaviour and the relative importance of both landscape metrics.

Numerical study of the risk of thrombosis in the left atrial appendage of chicken wing shape in atrial fibrillation.

Atrial fibrillation (AF) is a common and life-threatening disease. For the patients with AF, more than 90% of the thrombi are formed in the left atrial appendage (LAA), thrombus dislodgement can cause vascular embolism, making them is becoming a high-risk group for stroke. Therefore, identifying the patients with high risk of thrombosis is crucial for advanced stroke warning. To better investigate the mechanism behind thrombus formation in the LAA, this study reconstructed the 3-D Left Atrium (LA) models of six AF volunteer patients by corresponding Computed Tomography (CT) images. Combine the advantages of Computational Fluid Dynamics (CFD), the blood flow field in LA both in AF and sinus heart rate states were studied. The risk of thrombus was evaluated based on the blood viscosity, shear rate thrombus prediction model and Time Average Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), and Relative Residence Time (RRT) values. The results showed that the left atrium had lower blood flow velocity and TAWSS values at the LAA in both AF and sinus rhythm, thus the LAA is the most thrombogenic region in the LA. Besides, the RRT value of LAA was generally higher in AF than in sinus rhythm. Therefore, AF carries a higher risk of thrombosis.

Bird extinctions threaten to cause disproportionate reductions of functional diversity and uniqueness

Abstract Human activities are driving rapid defaunation of Earth's ecosystems through increasing rates of extinction. However, the ecological consequences of species loss remain unclear, in part due to the limited availability of high‐resolution functional trait data. To address this, we assess how predicted extinctions will reshape avian functional diversity quantified using a multidimensional trait space, or morphospace, reflecting variation in eight key morphological traits closely linked to ecological function across 9943 (&gt;99%) extant bird species. We show that large regions of this morphospace are represented by very few species and, thus, vulnerable to species loss. We also find evidence that species at highest risk of extinction are both larger and functionally unique in terms of ecological trait dimensions unrelated to size, such as beak shape and wing shape. Although raw patterns suggest a positive relationship between extinction risk and functional uniqueness, this is removed when accounting for phylogeny and body mass, indicating a dominant role for clade‐specific factors, including the combination of larger average body size and higher extinction risk in the non‐passerine clade. Regardless of how a threat is related to uniqueness, we show using simulations that the loss of currently threatened bird species would result in a greater loss of morphological diversity than expected under random extinctions. Our results suggest that ongoing declines of threatened bird species may drive a disproportionately large loss of morphological diversity, with potentially major consequences for ecosystem functioning. Read the free Plain Language Summary for this article on the Journal blog.

CFD Analysis of Heat Transfer Enhancement of Shell Side Fluid Flow Over Inline, Non-circular Leading-Edge Wing Shape Tube

CFD Analysis of Heat Transfer Enhancement of Shell Side Fluid Flow Over Inline, Non-circular Leading-Edge Wing Shape Tube

Sex- and size-dependent variation in wing morphology of the cuckoo wasp Trichrysis cyanea (Hymenoptera: Chrysididae)

Intraspecific variation and sexual dimorphism in wing shape and size is common in winged insects. The exact patterns, however, differ among taxa and are related to the selection pressure acting on specific traits. Cuckoo wasps (Chrysdidae) are hymenopterans that have evolved a complex parasitoid or cleptoparasitic life-style. For the first time, we studied the intraspecific variation in wing shape and size in the model species, Trichysis cyanea, a common Palearctic cuckoo wasp. This involved geometric morphometrics combined with a novel, non-invasive way of obtaining images, to study the shape and size of the forewings of males and females. We found clear sexual dimorphism in both wing shape and size, possibly related to fecundity (as wing size typically correlates with body size in many insects) and increased manoeuvrability of females for searching for their host's nesting holes. This study increases our knowledge of the biology of T. cyanea in terms of a better understanding of the evolution of parasitism and corresponding adaptations in this hymenopteran family.

Geometric Morphometric Wing Analysis of Avian Malaria Vector, Culiseta longiareolata, from Two Locations in Algeria.

The application of geometric morphometry on mosquito wings (Culicidae) is considered a powerful tool for evaluating correlations between the phenotype (e.g., shape) and environmental or genetic variables. However, this has not been used to study the wings of the avian malaria vector, Culiseta longiareolata. Therefore, the goal of this study is to investigate the intra-specific wing variations between male and female Cs. longiareolata populations in different types of larval habitats and climatic conditions in Algeria. A total of 256 Cs. longiareolata mosquito samples were collected from January 2020 to July 2021 in three cities (Annaba, El-Tarf, and Guelma) of northeastern Algeria that have two distinct climatic condition levels (sub-humid and sub-arid) and different types of larval habitats (artificial and natural). Nineteen (19) wing landmarks (LMs) were digitized and analyzed based on geometric morphometry. Our results revealed differences in the wing shape of female and male mosquito populations, indicating sexual dimorphism. Moreover, canonical variance analysis (CVA) showed that factors, such as climatic conditions and type of larval habitats, also affect the wing shape of female and male Cs. longiareolata mosquito populations. Furthermore, the wing shape of male populations was more distinct compared with female populations.

Detection of brown adipose tissue in rats with acute cold stimulation using quantitative susceptibility mapping.

Detection of brown adipose tissue in rats with acute cold stimulation using quantitative susceptibility mapping.

The leading-edge vortex over a swift-like high-aspect-ratio wing with nonlinear swept-back geometry

The leading-edge vortex (LEV) is a common flow structure that forms over wings at high angles of attack. Over the years, LEVs were exploited for augmenting the lift of man-made slender delta wings aircraft. However, recent observations suggested that natural flyers with high-aspect-ratio (high-AR) wings, such as the common swift (Apus apus), can also generate LEVs while gliding. We hypothesize that the planform shape and nonlinear sweep (increasing towards the wingtip) enable the formation and control of such LEVs. In this paper, we investigate whether a stationary LEV can form over a nonlinear swept-back high-AR wing inspired by the swift’s wing shape and evaluate its characteristics and potential aerodynamic benefit. Particle image velocimetry (PIV) measurements were performed in a water flume on a high-AR swept-back wing inspired by the swift wing. Experiments were performed at four spanwise sections and a range of angles of attack for a chord-based Reynolds number of . Stationary LEV structures were identified across the wingspan by utilizing the proper orthogonal decomposition (POD) method for angles of attack of 5∘–15∘. The size and circulation of the stationary LEV were found to grow towards the wingtip in a nonlinear manner due to shear layer feeding and spanwise transport of mass and vorticity within the LEV, thus confirming that nonlinear high-AR swept-back wings can generate stationary LEVs. Our results suggest that the common swift can generate stationary LEVs over its swept-back wings to glide slower and at a higher rate of descent, with the LEVs potentially supporting up to 60% of its weight.

A Polyimide Film-Based Simple Force Plate for Measuring the Body Mass of Tiny Insects

Insects exhibit excellent maneuvers such as running and flying despite their small bodies; therefore, their locomotion mechanism is expected to provide a design guideline for micromachines. Numerical simulations have been performed to elucidate this mechanism, whereby it is important to develop a model that is physically identical to the target insect's parts to reproduce kinematic dynamics. In particular, in flight, the shape and mass of wings, which flap at high frequencies, are significant parameters. However, small insects such as fruit flies have small, thin, and light wings; thus, their mass cannot be easily measured. In this study, we proposed a high-resolution and simple force plate to measure the mass of each part of a tiny insect. The device consists of a circular plate supported by flat spiral springs made of polyimide film, and a laser displacement meter that detects the displacement of the center of the plate. The simple plate fabrication process requires only a couple of minutes. A fabricated force plate with a sub-N/m spring constant achieved a resolution of less than 2 µg. As a demonstration, the wing mass of the fruit flies was measured. The experimental results suggest that the wings accounted for approximately 0.4% of the body mass.