Small Wing Research Articles

Aerodynamic characteristics of variously modified leading-edge protuberanced (LEP) wind turbine blades under various turbulent intensities

A series of wind tunnel tests were performed to investigate the effect of turbulent inflows on the aerodynamic characteristics of variously modified leading-edge protuberanced (LEP) wing configurations at various turbulence intensities. A self-developed passive grid made of parallel arrays of round bars was placed at different locations of the wind tunnel to generate desired turbulence intensity. The aerodynamic forces acting over the baseline straight leading-edge model and the modified small, medium and high LEP wing configurations were obtained from the surface pressure measurements made over the wing at different turbulence intensities using MPS4264 Scanivalve simultaneous pressure scanner corresponding to a sampling frequency of 700Hz. All the test models were tested for a wide range of angles of attack ranging between −45° ≤ α ​≤ ​45° at turbulence intensities varying between 0.51% ​≤ ​TI ​≤ ​4.92%. Results reveal that the time-averaged mean coefficient of lift (CL) increases with the increase in the turbulence intensity associated with smooth stall characteristics rendering the modified LEP test models advantageous. Furthermore, based on the surface pressure coefficients the underlying dynamics behind the stall delay tendency were discussed. Additionally, attempts were made to statistically quantify the aerodynamic forces using standard deviation at both the pre-stall and the post-stall angles.

What does not kill it does not always make it stronger: High temperatures in pyriproxyfen treatments produce Aedes aegypti adults with reduced longevity and smaller females

Abstract Aedes aegypti control in Brazil comprises integrated actions, in which larvicide application is a supplementary measure. Despite the importance of analyzing the effects of temperature on the efficiency of larvicides to control mosquito populations, there is still a lack of information regarding the sublethal effect of larvicides. We hypothesized that mosquitoes which survived pyriproxyfen exposure, during their immature development, have small body sizes and live less than mosquitoes that were not exposed to this larvicide. We investigated the sublethal effects of five different pyriproxyfen concentrations (0.0001; 0.001; 0.01; 0.1 and 1 mg.L−1), under three different temperatures (20, 25 and 30 °C). As we increased the larvicide concentration, less larvae survived and developed into adults. However, at 30 °C the survival was higher than at 25 °C and 20 °C comparing the concentrations of 0.001 mg.L−1 and 0.01 mg.L−1 (10% and 16% high, respectively). Mosquito survivors to pyriproxyfen exposure, in all thermal conditions, had shorter adult life spans than mosquitoes not exposed to pyriproxyfen during the larval stage. The females exposed at 30 °C showed smaller wings than females from experiments at 20 °C. These findings provide evidence that the biological parameters of the adult lifespan and wing centroid size are impaired due to larval exposure to pyriproxyfen, even at high temperatures. Reduced longevity and small wing size are fitness costs to survive this larvicide exposure. These findings provide support to assess resistance development to larvicides through future generations and contribute to the discussion on improving the rational application of larvicides.

When does diet matter? The roles of larval and adult nutrition in regulating adult size traits in Drosophila melanogaster

Adult body size is determined by the quality and quantity of nutrients available to animals. In insects, nutrition affects adult size primarily during the nymphal or larval stages. However, measures of adult size like body weight are likely to also change with adult nutrition. In this study, we sought to explore the roles of nutrition throughout the life cycle on adult body weight and the size of two appendages, the wing and the femur, in the fruit fly Drosophila melanogaster. We manipulated nutrition in two ways: by varying the protein to carbohydrate content of the diet, called macronutrient restriction, and by changing the caloric density of the diet, termed caloric restriction. We employed a fully factorial design to manipulate both the larval and adult diets for both diet types. We found that manipulating the larval diet had greater impacts on all measures of adult size. Further, macronutrient restriction was more detrimental to adult size than caloric restriction. For adult body weight, a rich adult diet mitigated the negative effects of poor larval nutrition for both types of diets. In contrast, small wing and femur size caused by poor larval diet could not be increased with the adult diet. Taken together, these results suggest that appendage size is fixed by the larval diet, while those related to body composition remain sensitive to adult diet. Further, our studies provide a foundation for understanding how the nutritional environment of juveniles affects how adults respond to diet.

A dynamic cell recruitment process drives growth of the Drosophila wing by overscaling the vestigial expression pattern

Organs mainly attain their size by cell growth and proliferation, but sometimes also grow through recruitment of undifferentiated cells. Here we investigate the participation of cell recruitment in establishing the pattern of Vestigial (Vg), the product of the wing selector gene in Drosophila. We find that the Vg pattern overscales along the dorsal-ventral (DV) axis of the wing imaginal disc, i.e., it expands faster than the DV length of the pouch. The overscaling of the Vg pattern cannot be explained by differential proliferation, apoptosis, or oriented-cell divisions, but can be recapitulated by a mathematical model that explicitly considers cell recruitment. When impairing cell recruitment genetically, we find that the Vg pattern almost perfectly scales and adult wings are approximately 20% smaller. Conversely, impairing cell proliferation results in very small wings, suggesting that cell recruitment and cell proliferation additively contribute to organ growth in this system. Furthermore, using fluorescent reporter tools, we provide direct evidence that cell recruitment is initiated between early and mid third-instar larval development. Altogether, our work quantitatively shows when, how, and by how much cell recruitment shapes the Vg pattern and drives growth of the Drosophila wing.

Evaluation of drag force of a thrip wing by using a microcantilever

Tiny flight-capable insects such as thrips utilize a drag-based mechanism to generate a net vertical force to support their weight, owing to the low associated Reynolds number. Evaluating the drag generated by such small wings is of considerable significance to understand the flight of tiny insects. In this study, a self-sensing microcantilever was used to measure the drag force generated by an actual wing of a thrip. The wing of a thrip was attached to the tip of the microcantilever, and the microcantilever along with the wing was affixed perpendicular to a constant airflow at the middle of a bench-top wind tunnel. The drag generated by the wing under airflow velocities in the range of 0–4.8 m/s was obtained. In addition, the drag generated by the wing was verified by performing a three-dimensional computational fluid dynamics analysis. At a biological average wing tip velocity of 0.7 m/s, the difference between the measured drag force (290 nN) and calculated drag force (300 nN) was merely 3.3%. This new approach of evaluating the drag force generated by tiny insects could contribute to enhancing the understanding of microscale flight.

Bionic Stiffener Layout Optimization with a Flexible Plate in Solar-Powered UAV Surface Structure Design

A cellular-based evolutionary topology optimization scheme over a small curvature big contour wing surface is proposed for the design of an ultralight surface structure. Using this method, a ground-structure technique is first applied to obtain homogeneous mesh generation with a predefined weight value over the design domain. Secondly, the stiffener path’s description is guided by a modified map L system topology method that simulates the growth of the bionic branch, and the structural components are obtained by the specified searching method according to weights of the previous mesh vertexes. Thirdly, an optimal curved stiffener layout is achieved using an agent-based algorithm to create individual instances of designs based on a small number of input parameters. These parameters can then be controlled by a genetic algorithm to optimize the final design according to goals like minimizing weight and structural weakness. A comparison is implemented for long-span panel stiffener layout generation between an initial straight case and a bionic optimal case via our method, thereby indicating the significant improvement of the buckling loads by steering the stiffener’s path. Finally, this bionic method is applied to the wing box structure design and achieves remarkable weight loss at last.

Numerical Analysis and Experimental Measurements of a Small Horizontal Wind Turbine Blade Profile for Low Reynolds Numbers

Wind energy is an important contributor to the generation of electricity amongst the renewable sources, and per long-term political goals it is expected that this contribution will be further increased. For achieving this goal, optimized blades having increased aerodynamic performance must be designed especially for small horizontal wing turbines (SHWT). SHWT are exposed to a highly volatile, low Reynolds number, turbulent flow, where not only boundary layer transition phenomena are significant, but additionally, 3D flow effects are dominant, due to the relatively small length of the wind turbine blades. These blades are usually 1.5 to 3.5 m in diameter and produce 1 - 10 kW of electricity at their optimum design conditions which are closely related to the wind speed. In order to maximize the wind turbine blades efficiency, a thorough analysis of the complex aerodynamic effects that govern the flow has to be performed. In the current paper an assessment of the modelling of a wind turbine blade profile of a SHWT is investigated, with the use of Computational Fluid Dynamic (CFD) and validated with appropriate experiments. More specifically, a characteristic profile of an operating SHWT blade is selected and carefully picked transitional turbulence models are utilized for the CFD computations, for a wide range of angles of attack (AoA). The selected models are the 4-equation SST k-? turbulence model of Menter et al. (1994) and the turbulence model of Walters and Cokljat (2008) that adopts the laminar kinetic energy concept. Two relatively small Reynolds numbers are chosen for studying the flow, in order to take into account, the transient and complex flow phenomena that are present in real wind turbine operating conditions. For the validation of the computational results, existing literature data (Selig and McGranahan, 2004) are used in combination with the acquired experimental data from the appropriately designed experiments which were performed in the Laboratory of Fluid Dynamics and Turbomachinery (LFMT) facilities. The results show the existing potential of further optimizing the wind turbine blades and as a result enhancing their aerodynamic performance and efficiency.

Comparison of UAS-to-Ground Small-Scale Fading in Residential and Mountainous Desert Terrains

Small, consumer grade unmanned aerial systems (UAS) provide a cost-effective solution in many wireless communications applications where access to typical terrestrial based communications methods might not be feasible. In this work we characterize and model the small-scale wireless channel effects of the UAS-to-ground wireless channel in residential and mountainous desert terrains. In particular, we focus on constructing statistical models of the wireless channel for small rotary wing UAS flying at low altitudes (<130 meters). The results show that the mountainous desert terrain induces more fading than the residential terrain. Additionally, we provide Doppler spectrum models for the micro-Doppler effect caused by the UAS rotary wings. We validate the proposed channel models using filtered Gaussian noise techniques. The intent of the channel models presented here is to aide in the design of wireless communications systems that use consumer grade off-the-shelf UAS and radio hardware.

Boosting Aircraft Efficiency by Reversing the Load on the Horizontal Stabilizer

This work aims at finding how reversing the direction of THS force improves aircraft performance. In most airplanes, the trimmable horizontal stabilizer (THS) is subjected to downward air force. This downward force acts in the same direction as the weight and opposite to the lift. The produced extra lift can be used to increase the payload or extend the range of the aircraft by carrying more fuel. The proposed design is based on shifting the wings location forward in order to make the force on the THS upward instead of downward. However, the stability of the airplane will be adversely affected. To address this issue, modern control theory is applied to the airplane elevator so as to maintain longitudinal stability. An airplane model based on longitudinal dynamics was used to investigate the stability of the airplane. Both current and proposed designs are simulated first without controllers and then with active controllers. The longitudinal dynamics’ equations are used to design the controllers so as to make the aircraft stable. The payload gain due to the proposed design is calculated; For a typical airliner, it is found that up to 21% increase in payload can be achieved using the proposed design. The proposed design where the load on the THS becomes upward instead of downward results in improving flight efficiency; that is, we can choose between increasing payload, extending the range, reducing the thrust, or using a smaller wing, or any combination of these benefits. In all these cases, there is an operational advantage. This advantage is translated to cost savings or higher revenues.

A high performance altitude navigation system for small rotorcraft unmanned aircraft

An altitude navigation system is proposed for the small rotary wing unmanned aircraft to realize stable landing control. Based on the speeded up robust feature algorithm, the stereo vision system can get the feature matching points from the complex environment easily. With the consideration of tilt angle of SRUA system, the corresponding altitude estimation value can be generated by the parallax of ground points, and the stereo vision system can offer accurate altitude information without specialized landing marks. Meanwhile, with the analysis of the characteristic of the on-board altitude sensors, an adaptive weighted average filter algorithm has been developed to adjust the weights of onboard altitude sensors on line. Therefore, the navigation system can generate high performance altitude information even if some onboard sensors are invalid in the autonomous landing process. A series of static tests and autonomous landing tests verify the effectiveness of the altitude navigation system.

Reduction of a nymphal instar in a dampwood termite: heterochronic shift in the caste differentiation pathways

BackgroundGenerally in termites, alates differentiate through multiple nymphal instars which gradually develop wing buds. However, in a dampwood termite, Hodotermopsis sjostedti, alates molt directly from a single nymphal instar with short wing buds. In this study, to examine the mechanism underlying the wing formation during the alate differentiation in H. sjostedti, histological and morphological observations were carried out on the developmental process of wing formation during the nymphal instar, in comparison with those in Zootermopsis nevadensis, which has two nymphal instars. Furthermore, the expression patterns of genes that are thought to be responsible for wing formation, i.e., wing-patterning genes and genes encoding hormone-related factors, were quantified during alate differentiation and compared between the two species.ResultsThe results showed that, in H. sjostedti, wings were formed in a complicatedly folded shape, not only inside the wing buds as seen in Z. nevadensis, but also under the dorsal thoracic cuticle, where the wing tips shifted toward the median thoracic part. Accordingly, the wing expansion pattern also differed from that in Z. nevadensis. Furthermore, the results of real-time qRT-PCR on overall expression profiles of wing-patterning genes and hormone-related genes suggest that the single nymphal instar in H. sjostedti well resembles to the second nymphal instar in Z. nevadensis. In particular, significant upregulation of vestigial (vg) and downregulation of Krüppel homolog 1 (Kr-h1) that were observed at the second nymphal instar in Z. nevadensis apparently occurred during the single nymphal instar in H. sjostedti.ConclusionThe developmental events for wing formation are compacted into a single nymphal instar in H. sjostedti, and as a result, the unique wing formation is seen to compensate for the spatial restriction inside small wing buds, leading to the completion of functional wings.

In search of the real Pseudomallada prasinus (Neuroptera, Chrysopidae).

Three sympatric morphs of Pseudomallada prasinus (Burmeister, 1839) were hybridized in search of reproductively separated species. In addition, 26 morphological and biological traits were recorded for living and preserved specimens of the three morphotypes. Cross-breeding experiments showed that the prasinoid morph "marianus" is a different species from either the "greenhead" or "sulfurhead" morphs. All three are morphologically and biologically distinct. "Greenhead" and "sulfurhead" are small to medium sized and deposit eggs singly, without obligatory diapause in the second instar. In most specimens of these two smaller "prasinus" morphs there is a red or brown suture below the antennae, which can fade with age or preservation. P. "marianus" is a large species, depositing bundled eggs, with an obligatory diapause in about half of the L2. In none of the collected or reared P. "marianus" was a red or brown suture below the eyes observed. The forewing sizes of the type specimens of Chrysopa prasina Burmeister, 1839, C. coerulea Brauer, 1851, and C. marianus Navás, 1915 differ significantly from those of C. aspersa Wesmael, 1841 and other, later synonymized type specimens such as C. sachalinensis Matsumura, 1911, C. burri Navás, 1914, C. caucasica Navás, 1914, or C. vernalis Navás, 1926. This strongly suggests that the "marianus" morph is the real P. prasinus and the "greenhead" and "sulfurhead" morphs correspond to P. aspersus or one of the later synonymized species with smaller wing size.Pseudomallada marianus (Navás, 1905) is confirmed as a synonym of P. prasinus, depositing bundled eggs, whereas smaller prasinoid morphs, depositing single eggs, are not P. prasinus-and are morphologically distinct from P. abdominalis (Brauer, 1856). Pseudomallada aspersus (Wesmael, 1841) is a valid species, but at this point it is not possible to assign it to one of the prasinoid morphs because most of the live color traits are not discernible in old type specimens. A diagnostic description of the "real" P. prasinus can separate almost all P. prasinus specimens, even in museum collections, from P. aspersus (likely to be the "greenhead" morph) and the Mediterranean "sulfurhead".

Do the enlarged hind legs of male thick-legged flower beetles contribute to take-off or mating?

The volume of the hind femora in the adult male flower beetle Oedemera nobilis is 38 times greater than in adult females. To determine what advantage limbs with swollen femora might provide, the behaviour of these insects was analysed with high-speed videography. First, because large hind legs are often associated with jumping and take-off, the performance of this behaviour by the two sexes was determined. Take-off was generated by a series of small-amplitude wing beats followed by larger ones, with the hind legs contributing little or no propulsion. The mean acceleration time to take-off was not significantly different in males (46.2 ms) and females (45.5 ms), but the mean take-off velocity of males was 10% higher than in females. Second, to determine if enlarged hind legs were critical in specifically male behaviour, interactions between males and females, and between males were videoed. The male mounted a female and then encircled her abdomen between the enlarged femora and tibiae of both his hind legs. The joint between these leg parts acted like a mole wrench (vice grip) so that when the tibia was fully flexed, a triangular space of 0.3 mm2 remained, in which a female abdomen (cross-sectional area 0.9 mm2) could be compressed and restrained firmly without inflicting damage. The flexor tibiae muscle in a male hind femur was 5.9 times larger than the extensor. In interactions between males, attempts to achieve a similar entrapment were frequently thwarted by the pursued male extending his hind legs vertically.

The study on structural vulnerability analysis of small fixed wing UAV with hard landing

The study on structural vulnerability analysis of small fixed wing UAV with hard landing

Design of distributed propulsion system for general aviation airplane

In this paper, a small airplane is redesigned by using a distributed electrical propulsion (DEP) system. The design procedure is focused on the reduction of fuel consumption in cruise regime with constrained parameters of take-off/landing. In this case, a one half wing area compared to an original airplane is used. Take-off distance and minimum airspeed for landing is achieved by distributed propellers mounted on the leading edge of the wing. These propellers induce velocity on the wing and thereby increase local dynamic pressure, thus the required lift force can be reached with smaller wing area. Moreover, the distributed propellers are assumed as folded in cruise regime to minimize drag when the main combustion engine provides sufficient power.

Range of Detection of Small Air Objects by the Grounding Noise Receivers System

The paper considers the problem of detecting small air objects by a ground-based noise-tracking system with the concomitant definition of the detection range in conditions to the real noise-signal situation. As the receiving system, a group of receivers is chosen as well as -devices, which is designed as a linear discrete equidistant acoustic antenna. A small air object is represented by a Drone with a screw-ring propulsor in a push arrangement. For calculations was attracted the data about the loss to the expansion of the of acoustic waves front, data on spatial attenuation, on the influence of climatic factors and green plantations, as well as on the features of the c- and the terrain. The emergence of a significant interest in the use of acoustic means for detecting, positioning and detecting elements of small airspace movement has led to the development of directions for the creation of mobile noise reduction devices that implement the principles of detecting sources of specific noise for conventional hydroacoustics. Such objects can include unmanned flying vehicles of various purposes - helicopter (rotor) or airplane type (wing). The solution to this problem should be based on accurate information about the acoustic field of the source of specific noise and on the modes of motion of the object. Unfortunately, the information about the noise characteristics of airspace is extremely limited, but the widely available sources of information are mainly focused not on the advertising side of this issue. In this regard, the proposed material will be timely and timely, and the solution to the problem of detecting these objects with the associated definition of the range of noise detectors in the conditions of a given model of spatial noise load - represents the purpose of the work. It is proposed to identify small wing objects of airborne objects at altitudes and at speeds that correspond to their technical characteristics in normal refraction. The probability of false alarms using the Neumann-Pearson criteria should be no more than 0.01. Survey Sector - selected according to the directional characteristics of the receiving system with the possibility of mechanical scanning in the sector. The operating frequency band of the receiving system is formed, based on the frequency characteristics of noise and the range of working speeds of airspace. It is proposed to determine the sloping predicted range taking into account the energy and geometric range. Before calculations, losses data on the expansion of the front of the acoustic waves, the data on the spatial decay, the influence of climatic factors and green plantations, as well as features of the profile and features of the terrain, in the form of engineering structures should be drawn. Ref. 14, fig. 2, tabl. 1.

Ancient speciation of the papilionoid legume Luetzelburgia jacana, a newly discovered species in an inter‐Andean seasonally dry valley of Colombia

AbstractEcology, geography, morphology, and a combined phylogenetic analysis of DNA sequence variation support the recognition of the new species Luetzelburgia jacana (Leguminosae, Papilionoideae, vataireoid clade). This species is found in the inter‐Andean Rio Cauca Valley in Colombia. Phylogenetic analyses of nine plastid and nuclear DNA sequences from 44 accessions representing all known Luetzelburgia species show that L. jacana is sister to the rest of the genus and has a mean estimated stem age of ca. 4 Ma, much older than other Luetzelburgia species. Luetzelburgia jacana is distinguished by a combination of mostly 7–9‐foliolate, glabrous leaves with leaflets obtuse to shortly acute at the apex, flowers up to 9.6 mm long, and samaras bearing two small lateral wings on the seed chamber. Luetzelburgia jacana, along with two other earliest‐branching species in the genus, L. guaissara and L. trialata, are geographical outliers in the genus, with L. jacana having the northernmost distribution and L. guaissara and L. trialata having the southernmost distributions. These three earliest‐branching species are also ecological outliers within Luetzelburgia by occurring in wetter and less seasonal settings than other species. The discovery of L. jacana resolves these three earliest‐branching species in Luetzelburgia as ecologically transitional between most species of the vataireoid clade that inhabit wet forests and most species of Luetzelburgia that inhabit highly seasonal dry forests and woodlands.

A palmitoyltransferase Approximated gene Bm-app regulates wing development in Bombyx mori.

The silkworm Bombyx mori is an important lepidopteran model insect in which many kinds of natural mutants have been identified. However, molecular mechanisms of most of these mutants remain to be explored. Here we report the identification of a gene Bm‐app is responsible for the silkworm minute wing (mw) mutation which exhibits exceedingly small wings during pupal and adult stages. Compared with the wild type silkworm, relative messenger RNA expression of Bm‐app is significantly decreased in the u11 mutant strain which shows mw phenotype. A 10 bp insertion in the putative promoter region of the Bm‐app gene in mw mutant strain was identified and the dual luciferase assay revealed that this insertion decreased Bm‐app promoter activity. Furthermore, clustered regularly interspaced short palindromic repeats/RNA‐guided Cas9 nucleases‐mediated depletion of the Bm‐app induced similar wing defects which appeared in the mw mutant, demonstrating that Bm‐app controls wing development in B. mori. Bm‐app encodes a palmitoyltransferase and is responsible for the palmitoylation of selected cytoplasmic proteins, indicating that it is required for cell mitosis and growth during wing development. We also discuss the possibility that Bm‐app regulates wing development through the Hippo signaling pathway in B. mori.

Conceptual Design of a Reusable Unmanned Space Vehicle Using Multidisciplinary Optimization

In this paper, a conceptual design for a reusable unmanned space vehicle was studied with multiple objective functions. To achieve this goal, a multi-objective genetic algorithm was used, and the performance of the space vehicle was evaluated based on weight, propulsion, aerothermodynamics, and trajectory analysis. Minimization of weight and landing speed and maximization of the highest CL in the supersonic flight regime were selected as the objective functions. The maximum limits in the dynamic pressure and the heat flux were applied as constraints. All objective functions are in trade-off relationships with each other. The geometry that produced the smallest weight had a very small wing size. Also, the vehicle that had the maximum CL in the supersonic flight regime had a closer angle between the flow and the lower surface of the wing, which showed the highest CL on the flat surface. The vehicle design with the lowest landing speed had the largest wing, which generated sufficient lift.

Reinventing the wing: With electric propulsion and lots of propellers, planes can use smaller wings to fly efficiently

I remember distinctly the cool december day in 2013 at my company's headquarters in the Santa Cruz mountains when we met with researchers from NASA to plan tests for a novel propeller configuration for electric aircraft. Somehow, our Joby Aviation team, the NASA researchers, and colleagues from another small California business brainstormed our way into a much more ambitious program than any of us had expected when the meeting began.