Large Wingspan Research Articles

Design and Experimental Verification of a Roll Control Strategy for Large Wingspan Flapping-Wing Aerial Vehicle

Design and Experimental Verification of a Roll Control Strategy for Large Wingspan Flapping-Wing Aerial Vehicle

Simplified Coupled Calculation Method for Aeroelasticity of Large Flexible Aircraft

Large flexible aircraft have the characteristics of large wingspan, low wing load, slow flight speed, and significant impact from gust loads. Therefore, the load and response issues of such aircraft have received widespread attention from scholars at home and abroad. This article establishes a simplified coupled calculation method for gust loads on large flexible aircraft, achieving coupled calculations of flight motion, structural deformation, and aerodynamic changes at different time steps. Due to the simple strip method used for aerodynamic modeling, this method is relatively fast compared to the CFD-CSD calculation method. In order to verify the accuracy of the method, the calculation results were compared with those of the standard calculation method. The comparative calculation results show that the simplified coupling calculation method is relatively accurate for this calculation example and can play an important role in engineering experiments with low requirements for calculation results.

Coupled Aerodynamics–Structure Analysis and Wind Tunnel Experiments on Passive Hinge Oscillation of Wing-Tip-Chained Airplanes

This study examines the wing hinge oscillations in an aircraft concept that employs multiple wings, or small aircraft, chained at the wing tips through freely rotatable hinges with minimal structural damping and no mechanical position-locking system. This creates a single pseudo long-span aircraft that resembles a flying chain oriented perpendicular to the flight direction. Numerical calculations were conducted using the vortex lattice method and modified equations for a multi-link rigid body pendulum. The calculations demonstrated good agreement with small-scale wind tunnel experiments, where the motion of the chained wings was tracked through color tracking, and the forces were measured using six-axis force sensors. The total CL/CD increased for the chained wings, even in the presence of hinge joint oscillations. Furthermore, numerical simulations assuming an unmanned airplane size corroborated the theoretical attainment of passive stability with high chained numbers (≥9 wings), without any structural damping and relying solely on aerodynamic forces. Guidelines for appropriate hinge axis angle δ and angle-of-attack regions for different chained wing numbers to maximize passive oscillation stability were obtained. The results showed that wing-tip-chained airplanes could successfully provide substantially large wing spans while retaining flexibility, light weight and CL/CD, without requiring active hinge rotation control.

Experimental Study on Modal Characteristics of Large Flexible Aircraft

High altitude long endurance unmanned aerial vehicle (UAV) is a type of UAV that operates at an altitude of around 10000 meters and can fly for several days, relying on solar panels.Usually, this type of aircraft has the structural characteristics of high aspect ratio, large wingspan, low wing load, and high flexibility.In engineering applications, it is often necessary to measure the vibration modes of such aircraft, and the modal measurements of such aircraft are often not accurately obtained.This article conducts relevant research on the issue of inaccurate measurement in modal experiments of such aircraft. By establishing a finite element model, the reasons for the inaccurate measurement of low order frequencies in modal experiments of such aircraft are analyzed, and the magnitude of data errors in different situations is quantitatively calculated.Based on the above research, this article proposes two methods for solving modal tests of such aircraft. This method has important guiding significance for ground modal testing of large flexible structures, which is beneficial for dynamic analysis and flight control research of such aircraft.

Control Design and Flight Test of Aerodynamics-Driven Monoplane–Biplane Morphing Aircraft

Increasing the aspect ratio of the wing of an aircraft reduces drag and increases its range and endurance. However, a large wingspan complicates takeoff and landing. Therefore, an aerodynamics-driven monoplane–biplane morphing (MBM) aircraft was proposed, which cruises as a high-aspect-ratio monoplane and takes off and lands as a biplane, switching between two patterns during flight. This concept of MBM was validated in our previous work via wind tunnel experiments. We further develop it beyond this phase and introduce its applications under real flight conditions here. We constructed a test plane with a wingspan of 6 m and conducted a series of flight experiments on it. To examine its performance and facilitate its initial flight test, we built aerodynamic and dynamic models of the aircraft to analyze its morphing behavior through simulations. The corresponding controller algorithm and hardware system were also developed. The successful implementation of these systems enables bidirectional morphing during flight from a large-span monoplane to a half-span biplane. The test results, comprising data and photographs, validated the success of these trials. The concept of MBM, the corresponding models, and the control algorithm for morphing were thus verified.

Local and landscape scale woodland cover and diversification of agroecological practices shape butterfly communities in tropical smallholder landscapes

Abstract The conversion of biodiversity‐rich woodland to farmland and subsequent management has strong, often negative, impacts on biodiversity. In tropical smallholder agricultural landscapes, the impacts of agriculture on insect communities, both through habitat change and subsequent farmland management, is understudied. The use of agroecological practices has social and agronomic benefits for smallholders. Although ecological co‐benefits of agroecological practices are assumed, systematic empirical assessments of biodiversity effects of agroecological practices are missing, particularly in Africa. In Malawi, we assessed butterfly abundance, species richness, species assemblages and community life‐history traits on 24 paired woodland and smallholder‐managed farmland sites located across a gradient of woodland cover within a 1 km radius. We tested whether habitat type (woodland vs. farmland) and woodland cover at the landscape scale interactively shaped butterfly communities. Farms varied in the implementation of agroecological pest and soil management practices and flowering plant species richness. Farmland had lower butterfly abundances and approximately half the species richness than woodland. Farmland butterfly communities had, on average, a larger wingspan than woodland site communities. Surprisingly, higher woodland cover in the landscape had no effect on butterfly abundance in both habitats. In contrast, species richness was higher with higher woodland cover. Butterfly species assemblages were distinct between wood‐ and farmland and shifted across the woodland cover gradient. Farmland butterfly abundance, but not species richness, was higher with higher flowering plant species richness on farms. Farms with a higher number of agroecological pest management practices had a lower abundance of the dominant butterfly species, but not of rarer species. However, a larger number of agroecological soil management practices was associated with a higher abundance of rarer species. Synthesis and applications: We show that diversified agroecological soil practices and flowering plant richness enhanced butterfly abundance on farms. However, our results suggest that on‐farm measures cannot compensate for the negative effects of continued woodland conversion. Therefore, we call for more active protection of remaining African woodlands in tandem with promoting agroecological soil management practices and on‐farm flowering plant richness to conserve butterflies while benefiting smallholders.

New postcranial remains from the Lealt Shale Formation of the Isle of Skye, Scotland, showcase hidden pterosaur diversity in the Middle Jurassic

The Early to Middle Jurassic transition was significant in pterosaur evolution, during which these volant reptiles exploded in diversity alongside dinosaurs and other animals. It has long been thought, however, that pterosaurs did not develop large wingspans until after the Jurassic, a notion challenged by the recent discovery of Dearc sgiathanach in the Bathonian-aged Lealt Shale Formation of the Isle of Skye, Scotland, whose holotype specimen had an estimated wingspan greater than 2.5 m. We here report the discovery of a new pterosaur specimen from the Lealt Shale Formation, comprising a tibiotarsus, metatarsal, pedal phalanges and caudal vertebrae. The elongate tail vertebrae with ossified processes indicate that the specimen is a non-pterodactyloid pterosaur, albeit its fragmentary nature makes it difficult to determine whether it belongs to a new taxon. Its metatarsal and caudal vertebrae are considerably larger than corresponding bones in the Dearc holotype, indicating that it belonged to an even larger individual, thus demonstrating that pterosaurs with broad wingspans were not anomalous in the Middle Jurassic. The growing Middle Jurassic pterosaur record of Scotland and England, although mostly represented by isolated and fragmentary fossils, reveals a high diversity of clades, long obscured by the lack of well-preserved skeletons.

Design and Verification of a Large-Scaled Flapping-Wing Aircraft Named “Cloud Owl”

The bionic flapping-wing aircraft has the advantages of high flexibility and strong concealment; however, in the existing flapping-wing aircraft, the platform performance is influenced by the payload capacity, endurance, and durability; additionally, the mission capability is constrained, making it challenging to put into use in real-world scenarios. In response to this issue, this article offers a thorough design approach for a large-span flapping-wing aircraft, focusing on effective flapping wings, effective flapping mechanism design, and enhancement of flapping mechanism reliability, and ultimately realizing the design and verification of a new bionic flapping-wing aircraft with a large wingspan, called “Cloud Owl”. It has a wingspan of 1.82 m and weighs 980 g. The aircraft is capable of autonomous flight and remote control, and it can carry a range of mission-specific equipment. More than 200 flights have been made by “Cloud Owl” so far in Xi’an, Beijing, Tianjin, Tibet, Ganzi, and other places. It has evolved into a flapping-wing aircraft platform with exceptional stability, payload capacity, and long endurance.

Design and Application of Zero Poisson Large Deformation Superstructure

The variant wing can adapt to more complicated operating environment. There often need large thickness deformation and wingspan change in the process of wing deformation. Meanwhile, the deformation process should not affect other components, which requires that both the wing structure and the outer panel cover have the function of zero poisson’s ratio and large deformation. For this reason, this work designed a two-dimensional poisson’s ratio structure based on the topology optimization and variable density method. Then, optimization design method was adopted to meet the demand of zero poisson’s ratio and large deformation of wing cover. Furthermore, the equivalent elastic tensor of zero poisson’s ratio structure with large deformation was predicted using energy homogenization method, and the mechanical properties of zero poisson’s ratio structure were verified. Finally, numerical simulation method was conducted to predict the mechanical properties of zero poisson’s ratio wing covering lattice structure. To summarize, a kind of wing cover structure with zero poisson’s ratio and large deformation in this study was obtained and the application of this structure in aerospace was also demonstrated.

Multi-objective Optimization Design of Solar UAV Overall Parameters

Based on the design background of solar UAV, this paper introduces the characteristics of this kind of UAV, such as high flying height, large wingspan, large structural deformation and low wing load. The mathematical model of multi-objective optimization for this type of UAV is established, and the multi-objective genetic algorithm is used to optimize the design. The optimization results of the aircraft design are obtained by computer. Finally, the summary parameters and basic design drawings of this kind of aircraft are given. The results show that multi-objective optimization can be used in the design of solar UAV, and the optimal combination of the overall parameters of this kind of UAV can be obtained to avoid design defects and improve design efficiency. After the optimization design, the overall performance of the aircraft has been improved. This method has a certain reference value for the design of new aircraft.

An Adaptive Launch Control for Balloon-Borne UAVs with Large Wingspans

Near space has attracted major countries’ attention due to the fact that it is a new cognitive space of Earth and acts as an important national security space. Near-space solar-powered unmanned aerial vehicles (UAVs) are becoming a focus of research in the aviation field. However, it is difficult for solar-powered UAVs to climb such high heights and achieving optimal cruising levels is challenging. A balloon-borne-based aircraft that rises with the help of a balloon avoids difficult climbing processes and initiates a new research direction in the near-space aviation domain. Simultaneously, the special mode of taking off poses a great challenge for the pull-up control of balloon-borne aircraft, especially for large wingspan aircraft. In this paper, we propose an adaptive launch control for the pull-up process of large-scale balloon-borne-based aircraft. First, the flight control of the pull-up process for a large-scale balloon-borne-based aircraft is analyzed. Then, a flight dynamic model considering elastic deformation is established. Finally, an adaptive aircraft pull-up control algorithm is proposed. We evaluate it by performing simulation experiments and comparing it with the latest control algorithm utilized in physical experiments. The experiment’s results demonstrate the effectiveness of the proposed algorithm with respect to overcoming challenges in controlling pull-up processes and its superiority compared to the latest control algorithm.

Integration of propelled yaw control on wing tips: a practical approach to the Icaré solar-powered glider

In this practical approach to distributed propulsion, the solar-powered manned motorglider icaré 2 has been used as a testbed for wingtip propulsion. The large wingspan and slow cruising speed of icaré 2 are highly suitable to assess the influence and potential of propellers at the wingtips for yaw control. The paper describes the work of a multidisciplinary team consisting of researchers, engineers, pilots and students, starting from the initial idea to use propellers at the wingtips of icaré 2 up to the actual flight test campaign. First, the design and development of the modular wingtip pods are described to house the propeller, electric motor, battery and further sensors and control systems. Furthermore, the modifications required for integrating the wingtip pods on the aircraft itself are outlined and the electrical and mechanical interfaces are defined and described. To obtain a permit to fly for the new configuration of the aircraft, several tests on system level of the wingtip pods needed to be conducted and documented for the authorities. Finally, the flight test campaigns carried out to date are outlined and described including the planning, lessons learned and results.

A key design parameter proposal for aerodynamically efficient subsonic blended wing body

PurposeBlended wing body (BWB) is a very advantageous design in terms of low fuel consumption, low emission and low noise levels. Because of these advantages, the BWB is a candidate to become the commercial passenger aircraft of the future by providing a paradigm shift in conventional designs. This paper aims to propose a key design parameter for wing sizing of subsonic BWB and a performance parameter for calculating the lift/drag ratio values of BWBs.Design/methodology/approachThe parameter proposed in the study is based on the square/cube law, that is, the idea that the wetted area is proportional to the power of 2/3 of the weight. Data on the weight, wing area, wingspan, lift-to-drag (L/D) ratio for 19 BWB used in the analyzes were compiled from the published literature and a theoretical methodology was developed to estimate the maximum lift to drag ratio of BWBs. The accuracy of the proposed key design parameter was questioned by comparing the estimated L/Dmax values with the actual values.FindingsIn the current study, it is claimed that the wingspan/(take-off gross weight)(1/3) parameter provides an L/D efficiency coefficient regardless of aircraft size. The proposed key design parameter is useful both for small-scale BWB, that is unmanned aerial vehicles BWB and for large-scale BWB designs. Therefore, the b/Wg(1/3) parameter offers a dimensionless L/D efficiency coefficient for BWB designs of different scales. The wetted aspect ratio explains how low aspect ratio (AR)-BWB designs can compete with high AR-tube-and-wing designs. The key parameter is also useful for getting an idea of good or bad BWB with design and performance data published in the literature. As a result, reducing the blending area and designing a smaller central body are typical features of aerodynamically efficient BWB.Originality/valueAs the role of the square/cube law in the conceptual aircraft design stage has not been sufficiently studied in the literature, the application of this law to BWBs, a new generation of designs, makes the study original. Estimation of the wetted area ratio using only wingspan and gross weight data is an alternative and practical method for assessing the aerodynamic performance of the BWB. According to the model proposed in the current study, reducing the take-off gross weight of the BWBs using lighter building materials and designing with a larger wingspan (b) are the main recommendations for an aerodynamically efficient BWB.

Kinematics of wings from Caudipteryx to modern birds

This study seeks to better quantify the parameters that drove the evolution of flight from non-volant winged dinosaurs to modern birds. In order to explore this issue, we used fossil data to model the feathered forelimbs of Caudipteryx, the most basal non-volant maniraptoran dinosaur with elongated pennaceous feathers that could be described as forming proto-wings. In order to quantify the limiting flight factors, we created three hypothetical wing profiles for Caudipteryx with incrementally larger wingspans. We compared them with what revealed through fossils in wing morphology. These four models were analyzed under varying air speed, wing beat amplitude, and wing beat frequency to determine lift, thrust potential, and metabolic requirements. We tested these models using theoretical equations in order to mathematically describe the evolutionary changes observed during the evolution of modern birds from a winged terrestrial theropod like Caudipteryx. Caudipteryx could not fly, but this research indicates that with a large enough wing span, Caudipteryx-like animal could have flown. The results of these analyses mathematically confirm that during the evolution of energetically efficient powered flight in derived maniraptorans, body weight had to decrease and wing area/wing profile needed to increase together with the flapping angle and surface area for the attachment of the flight muscles. This study quantifies the morphological changes that we observe in the pennaraptoran fossil record in the overall decrease in body size in paravians, the increased wing surface area in Archaeopteryx relative to Caudipteryx, and changes observed in the morphology of the thoracic girdle, namely, the orientation of the glenoid and the enlargement of the sternum.

A window to the world of global insect declines: Moth biodiversity trends are complex and heterogeneous

Moths are the most taxonomically and ecologically diverse insect taxon for which there exist considerable time-series abundance data. There is an alarming record of decreases in moth abundance and diversity from across Europe, with rates varying markedly among and within regions. Recent reports from Costa Rica reveal steep cross-lineage declines of caterpillars, while other sites (Ecuador and Arizona, reported here) show no or only modest long-term decreases over the past two decades. Rates of decline for dietary and ecological specialists are steeper than those for ecologically generalized taxa. Additional traits commonly associated with elevated risks include large wingspans, small geographic ranges, low dispersal ability, and univoltinism; taxa associated with grasslands, aridlands, and nutrient-poor habitats also appear to be at higher risk. In temperate areas, many moth taxa limited historically by abiotic factors are increasing in abundance and range. We regard the most important continental-scale stressors to include reductions in habitat quality and quantity resulting from land-use change and climate change and, to a lesser extent, atmospheric nitrification and introduced species. Site-specific stressors include pesticide use and light pollution. Our assessment of global macrolepidopteran population trends includes numerous cases of both region-wide and local losses and studies that report no declines. Spatial variation of reported losses suggests that multiple stressors are in play. With the exception of recent reports from Costa Rica, the most severe examples of moth declines are from Northern Hemisphere regions of high human-population density and intensive agriculture.

Agro-Morphological Characterization of Three Cultivated Legumes: Two Varieties of Soybean (Glycine max L.) and One Variety of Mungbean (Vigna radiata L.)

To contribute to the restoration of tropical soils fertility, the agro-morphological and yield characteristics of three cultivated legumes [two beige seeded varieties of soybean (Glycine max L.): one from Côte d’Ivoire (BVCI) and the other, from Benin (BVB) and a green seeded mungbean variety (Vigna radiata L) from Côte d'Ivoire (MVCI)] were studied. The legumes seeds were sown and the resulting plants were monitored until harvest. The data relating to the plants phenological, morphological and yield parameters were statistically processed through one-way analysis of variance (ANOVA 1). The results of phenological observations indicated that the mungbean (MVCI) was earlier than both soybean varieties (BVCI followed by BVB). Morphologically, plants of the late soybean varieties (BVCI and BVB) were higher, more branched with a large wingspan, and produced more panicles than the early variety of mungbean (MVCI). In addition, mungbean variety (MVCI) produced long tapered pods containing small seeds while the soybean varieties produced shorter but wider pods containing large seeds. In terms of yied, both late soybean varieties (BVCI and BVB) produced large dry biomass, more pods with higher seed yield, dry weight and 100 seed weight than the early variety of mungbean (MVCI).
 Significance: The precocious nature of mungbean makes it an important plant for the fight against climate change, especially against drought. Due to their good branching and significant plant spread, both late varieties of soybean (BVCI and BVB) have high potential of being selected for soil protection and weed control, as well as for food production because of their high pod yield, seed and dry biomass.

Development of a Whale-Shark-Inspired Gliding Robotic Fish With High Maneuverability

In this article, we present the design and implementation of an innovative bioinspired gliding robotic fish and a gliding angle controller. Through mimicking a whale shark, the gliding robotic fish is designed with diversified control surfaces and a streamlined shape instead of the conventional wings with large wingspan aiming at both high maneuverability and distinguished gliding performance. The mechatronic design of the whale-shark-inspired gliding robotic fish is first provided. A dynamic model for gliding motion is established and the hydrodynamic analysis is performed via computational fluid dynamics simulation. The effects of both the deflection of the pectoral fins and the displacement of the movable mass on the gliding motion are analyzed. Then, based on the model and the analysis, a gliding angle control strategy is constructed via the backstepping methodology and the sliding mode methodology, aiming at the robustness of the control system to unknown perturbation. Afterward, a control allocation law is designed and solved by the Newton method. Simulations are conducted to evaluate the effectiveness of the proposed controller. Experiments are also executed to verify the dynamic model and illustrate the remarkable motion capability of the newly developed robot prototype. The results of this article supply clues to the improvement of the locomotive ability for the gliding robotic fish in both shape design and motion control.

Comparative Effects of Organic Cocoa Shell-Based and Inorganic NPK Fertilization on the Growth and Yield of Four Cassava Varieties

Looking of finding an alternative to the use of chemical fertilizers to increase yields of cassava (Manihot esculenta), trials were carried out in the Lamto zone in central Cote d’Ivoire. Thus, the effects of compost and ash from cocoa shell and NPK were tested on the agronomic parameters of cassava. The trial was conducted for two years with four varieties of cassava: Yace, Alleda agba, Six mois and Bonoua, grown on elementary plots treated with one of these fertilizers. The experimental design was complete randomized blocks with three replicates. Analysis of the results showed that the Six mois variety gave the longest stems (131, 67 cm) with the cocoa shell compost. The Bonoua variety, on the other hand, gave the largest diameter of the stem base (21.56 mm), a higher number of leaves (77.30) and a large wingspan (136.89 cm) with cocoa shell compost. The leaves developed by the plants of this variety were wider (19.30 cm) and longer (17.96 cm) with cocoa shell compost. Also, this Bonoua variety treated with shell compost yielded a high number of tuberized roots (5.11), high average weight per plant (5.83 kg/plant) and higher yield (58.29 t/ha). This compost of cocoa shell has also allowed a better conservation of the cultivated soils quality.

A glance at the deep past history of insects

A glance at the deep past history of insects

Unsteady aerodynamics investigation of deploying tandem-wing with different methods

In the rapidly deploying process of the unmanned aerial vehicle with folding wings, the aerodynamic characteristics could be largely different owing to the effects of deformation rate and the aerodynamic interference. The investigation on the unsteady aerodynamics is of great significance for the stability analysis and control design. The lifting-line method and the vortex-lattice method are improved to calculate the unsteady aerodynamics in the morphing stage. It is validated that the vortex-lattice method predicts the unsteady lift coefficient more appropriately than the lifting-line method. Different tandem wing configurations with deployable wings are simulated with different deformation rates during the morphing stage by the vortex-lattice method. As results indicated, the unsteady lift coefficient and the induced drag of the fore wing rise with the deformation rate increasing, but it is reversed for the hind wing. Additionally, the unsteady lift coefficient of the tandem wing configuration performs well with a larger stagger, a larger magnitude of the gap and a larger wingspan of the fore wing; however, the total induced drag has a larger value for the configuration that the two lifting surfaces with the same wingspans are closer to each other.