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In this paper, a numerical analysis of a biomimetic unmanned aerial vehicle (UAV) is presented. Its wings feature three grids at the tip similar to the primary feathers of birds in order to modify the lift distribution over the wing and help in reducing the induced drag. Numerical analysis using computational fluid dynamics (CFD) is presented to analyze the aerodynamic effects of the changes in dihedral and angle of attack (with respect of the rest of the wing) of these small grids at the tip. The aerodynamic performances (lift, drag, and efficiency) and rolling capabilities are obtained under different flight conditions. The effects of changing the dihedral are small. However, the change in the grid angle of attack increases aerodynamic efficiency by up to 2.5 times when the UAV is under cruise flight conditions. Changes to the angle of attack of the grids also provide increased capabilities for rolling. Finally, boundary values of the pressure coefficient and non-dimensional velocity contours are presented on the surfaces of the UAV, in order to relate the aerodynamic results to the aerodynamic patterns observed over the wing. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this research paper is to recover the autonomous flight performance of a mini unmanned aerial vehicle (UAV) via stochastically optimizing the wing over certain parameters (i.e. wing taper ratio and wing aspect ratio) while there are lower and upper constraints on these redesign parameters. Design/methodology/approach: A mini UAV is produced in the Iskenderun Technical University (ISTE) Unmanned Aerial Vehicle Laboratory. Its complete wing can vary passively before the flight with respect to the result of the stochastic redesign of the wing while maximizing autonomous flight performance. Flight control system (FCS) parameters (i.e. gains of longitudinal and lateral proportional-integral-derivative controllers) and wing redesign parameters mentioned before are simultaneously designed to maximize autonomous flight performance index using a certain stochastic optimization strategy named as simultaneous perturbation stochastic approximation (SPSA). Found results are used while composing UAV flight simulations. Findings: Using stochastic redesign of mini UAV and simultaneously designing mini ISTE UAV over previously mentioned wing parameters and FCS, it obtained a maximum UAV autonomous flight performance. Research limitations/implications: Permission of the directorate general of civil aviation in the Republic of Türkiye is essential for real-time UAV autonomous flights. Practical implications: Stochastic redesign of mini UAV and simultaneously designing mini ISTE UAV wing parameters and FCS approach is very useful for improving any mini UAV autonomous flight performance cost index. Social implications: Stochastic redesign of mini UAV and simultaneously designing mini ISTE UAV wing parameters and FCS approach succeeds confidence, highly improved autonomous flight performance cost index and easy service demands of mini UAV operators. Originality/value: Creating a new approach to recover autonomous flight performance cost index (e.g. satisfying less settling time and less rise time, less overshoot during flight trajectory tracking) of a mini UAV and composing a novel procedure performing simultaneous mini UAV having passively morphing wing over certain parameters while there are upper and lower constraints and FCS design idea. [ABSTRACT FROM AUTHOR]

In the wild, gliding birds dodge obstacles or predators by folding and twisting their wings swiftly to perform a rapid roll. Accordingly, the authors strive to explore the feasibility of improving the roll rate of drones through this bird‐inspired morphing method, by using the asymmetric sweepback of wings to simulate the contraction of birds' wings and the deflection of the aileron to imitate wing torsion. Moreover, the effects of wing morphing on the centroid, inertia matrix, and aerodynamic characteristics of the drone are explored herein, and a nonlinear dynamic model is established. Furthermore, a novel cooperative strategy that combines wing morphing with aileron deflection for roll control is introduced, and a flight controller based on this cooperative strategy is developed. Finally, the superiority of the cooperative strategy and the accuracy of the dynamic modeling have been validated in the outdoor flights of the morphing wing drone. [ABSTRACT FROM AUTHOR]

As unmanned vehicles become smaller and more autonomous, it is becoming feasible to use them in large groups with comparatively few human operators. Design and analysis of such distributed systems are complicated by the many interactions among agents and phenomena of human behavior. In particular, human susceptibility to fatigue and cognitive overload can introduce errors and uncertainty into the system. In this paper, we demonstrate how advanced computational tools can help to overcome these engineering difficulties by optimizing multirobot, multioperator surveillance systems for cost, speed, accuracy, and stealth according to diverse user preferences in multiple case studies. The tool developed is a graphical user interface that returns the optimal number and mix of diverse agent types as a function of the user's trade‐off preferences. System performance prediction relies on a multiagent simulation with submodels for human operators, fixed‐wing unmanned aerial vehicles (UAVs), quadrotor UAVs, and flapping wing UAVs combined in different numbers. [ABSTRACT FROM AUTHOR]

The presented study offers a comprehensive insight in design and application of the Kalman filters for improvement of control efficiency of small unmanned aerial vehicles with fixed wing. The presented control scheme of the UAV includes its model, a servo drive model, and an optimal proportional-integral-derivative (PID) controller for the selected flight speed. Subsequently, process noise and measurement noise components were introduced into the whole constructed UAV model. The process noise was formed by disturbances caused by horizontal and vertical airflow in the atmosphere. The measurement noise contained deterministic and stochastic errors of the inertial measurement unit (IMU) UAV sensors and engine noise. The obtained results showed that the designed optimal Kalman filter was able to eliminate the influence of interfering signals from the control process and increased the phase safety, controllability, and stability of UAV control as a lean design can be applied in real-time control systems like Pixhawk PX4. [ABSTRACT FROM AUTHOR]

The paper investigates the aerodynamic performance and power requirement characteristics of wing sections integrated with high-lift airfoil to support the operation of solar-powered Unmanned Aerial vehicle (UAV). The flight mission is aimed to simulate the operation of solar-powered UAVs under low -speed environment. The research focuses on studying the aerodynamic effect of nonsolar UAV wing model and solar UAV wing model for the varying angle of attack. The UAV wing models are tested using a subsonic wind tunnel to validate the aerodynamic characteristics at low-speed condition. The aerodynamic parameters such as coefficient of lift (Cl), coefficient of drag (Cd), coefficient of pressure (Cp), and the total power required to accelerate the solar UAV are studied to maintain steady level flight. The solar UAV and non-solar UAV wing models were subjected to a computational process to examine the pressure and velocity distributions for the aerodynamic performance analysis. Evident results show that the solar cells positioned at the flow separation region of the UAV wing model produces an aerodynamic efficiency rate of 5.45% and required 37.13W of minimum power compared to non-solar UAV at the Reynolds number of 9.8 × 106. [ABSTRACT FROM AUTHOR]

In recent years, the air-drop launch technology of near-space UAVs has attracted much attention. Between downfall from the carrier and the flight control system's initiation, the UAV presents free-fall movement. This free-fall process is very important for the control effect of the flight control system and is also crucial for the safety of the UAV and the carrier. Focus is required on two important dynamic parameters of the UAV: the moment of inertia and the center of mass position. In this paper, we used a quasi-steady model proposed by predecessors to address the flat-plate falling problem with modifications to describe the freely falling motion of the wing. Computational fluid dynamics (CFD) were used to simulate the free-fall movement of the wing with various parameters, and the wing release behavior was analyzed to check the quasi-steady model. Research shows that the movement characteristics of the falling wing are mostly reflected in the longitudinal plane, and the developed quasi-steady analytical model can more accurately describe the dynamic behavior of free-fall to some extent. By using CFD methods, we further investigated the aerodynamic performance of the free-fall wing. The results show that the wing mainly presents tumbling and fluttering motion. Changing the moment of inertia around the tumbling axis changes the tumbling frequency and the time point as the wing enters tumbling. In contrast, changing the position of the center of mass significantly changes the form of falling and makes the free-fall motion more complex. Therefore, it is necessary to carefully configure the center of mass in the UAV design process. [ABSTRACT FROM AUTHOR]

Integrating the operation of airborne wind energy systems safely into the airspace requires a systematic qualification process. It seems likely that the European Union Aviation Safety Agency will approve commercial systems as unmanned aircraft systems within the "specific" category, requiring risk-based operational authorization. In this paper, we interpret the risk assessment methodology for airborne wind energy systems, going through the ten required steps of the recommended procedure and discussing the particularities of tethered energy-harvesting systems. Although the described process applies to the entire field of airborne wind energy, we detail it for a commercial flexible-wing airborne wind energy system. We find that the air risk mitigations improve the consolidated specific assurance and integrity level by a factor of two. It is expected that the framework will increase the safety level of commercial airborne wind energy systems and ultimately lead to operation approval. [ABSTRACT FROM AUTHOR]

In this study, a performance-based calculation tool was developed to ease the process of exploring different conceptual aircraft conditions. The study aims to minimize human errors when calculating aircraft performance parameters manually. The parametric design tool, which will aid in designing unmanned aircraft, was built using Microsoft Excel. It was developed for the purpose of saving time and excessive effort that hand calculations require. Based on the criteria mentioned in the SAE aero design competition, five conceptual designs for the unmanned aircraft were drafted. One of the main criteria of this competition is creating an aircraft with a high payload fraction and a low empty weight. Using this Excel spreadsheet, we computed the values of thrust force, lift coefficient, drag coefficient, dynamic pressure, and drag force acting on the unmanned aircraft, allowing us to analyze and compare the performances of the different conceptual designs. To make sure that the Excel spreadsheet was reliable, it was tested and verified by comparing it with hand calculations. [ABSTRACT FROM AUTHOR]

Innovative design intricacies of new generation of UAVs, necessitate formulation of control laws utilizing intelligent techniques which are independent of underlying dynamic model besides being robust to changing environment. In current research, a novel control architecture is presented for maximizing glide range of the UAV which bears an unconventional design. To handle the control complexities emerging due to the unique design of the UAV, a distinct RL technique named 'optimal dynamic programming' is proposed which besides being computationally acceptable also effectively controls the entire flight regime of the UAV. The proposed methodology has been specifically modified to configure the problem in continuous state and control space domains. The efficacy of the results and performance characteristics, demonstrated the ability of the presented algorithm to dynamically adapt to the changing environment, thereby making it suitable for UAV applications. Nonlinear simulations performed under different environmental conditions demonstrated the effectiveness of the proposed methodology over the conventional classical approaches. [ABSTRACT FROM AUTHOR]

Considering the deployment characteristics of the folding wing, this paper proposed three deployment modes, synchronous deployment, fixed-axis–non-fixed-axis stepwise deployment, and non-fixed-axis–fixed-axis stepwise deployment, to obtain the optimal deployment scheme of the orthogonal biaxial folding wing of Unmanned Aerial Vehicles (UAVs) at different airspeeds. On this basis, combined with the folding wing deployment action, the Lagrange method was used to establish the aerodynamic model of the folding wing, and the Fluent simulation software was used to simulate the aerodynamic simulation of multiple deployment modes of the orthogonal biaxial folding wing, which analyze the influence of the UAV deployment mode and airspeed towards the driving torque of the folding wing. Based on the driving moment of the folding wing, the optimal deployment mode at different airspeeds was obtained. The comparison of simulation results shows that when the airspeed is less than 40 m/s, the optimal deployment mode is synchronous deployment. When the airspeed is greater than or equal to 40 m/s, the optimal deployment mode is non-fixed-axis–fixed-axis stepwise deployment. The accuracy of the folding wing aerodynamics model can be proven according to the comparison of the simulation results with the theoretical results. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In preparation for the battlefields of the future, using unmanned aerial vehicles (UAV) loaded with multisensors to track dynamic targets has become the research focus in recent years. According to the air combat tracking scenarios and traditional multisensor weighted fusion algorithms, this paper contains designs of a new data fusion method using a global Kalman filter and LSTM prediction measurement variance, which uses an adaptive truncation mechanism to determine the optimal weights. The method considers the temporal correlation of the measured data and introduces a detection mechanism for maneuvering of targets. Numerical simulation results show the accuracy of the algorithm can be improved about 66% by training 871 flight data. Based on a mature refitted civil wing UAV platform, the field experiments verified the data fusion method for tracking dynamic target is effective, stable, and has generalization ability. [ABSTRACT FROM AUTHOR]

Development of an Adaptive Fuzzy Extended Kalman Filter (AFEKF) and an Adaptive Fuzzy Unscented Kalman Filter (AFUKF) for the state estimation of unmanned aerial vehicles (UAVs) were presented in this paper based on real flight data of a fixed wing airplane. The Adaptive Neuro Fuzzy extension helps to estimate the values of the EKF's and UKF's Rk covariance matrix at each sampling instant when measurement update step is carried out. The ANFIS monitors the EKF's and UKF's performances attempt to eliminate the gap between theoretical and real innovation sequences' covariance. The investigations show that AFUKF can provide better performance in accuracy and less error than the AFEKF in case of real flight data for maneuvering fixed wing UAVs. [ABSTRACT FROM AUTHOR]

Conventional aircraft use discrete flight control surfaces to maneuver during flight. The gaps and discontinuities of these control surfaces generate drag, which degrades aerodynamic and power efficiencies. Morphing technology aims to replace conventional wings with advanced wings that can change their shape to control the aircraft with the minimum possible induced drag. This paper presents MataMorph-3, a fully morphing unmanned aerial vehicle (UAV) with camber-morphing wings and tail stabilizers. Although previous research has presented successful designs for camber-morphing wing core mechanisms, skin designs suffered from wrinkling, warping, or sagging problems that result in reduced reliability and aerodynamic efficiency. The wing and tail stabilizers of MataMorph-3 feature hybrid ribs with solid leading-edge sections that house servomotors, and compliant trailing-edge sections with integrated flexible ribbons that are connected to the servomotors to camber-morph the ribs. Thin laminated carbon fiber composite skin slides smoothly over the compliant rib sections upon morphing, guided by innovative trailing-edge sliders and skin-supporting linkage mechanisms strategically located between the ribs. Sample prototypes were built and tested to show the effectiveness of the proposed design solutions in enabling smooth camber-morphing. The proposed design provides a better alternative to stretchable skins in morphing airplane designs through the concept of skin sliding. [ABSTRACT FROM AUTHOR]

Static aeroelastic analysis of a flexible morphing wing design for an unmanned aerial vehicle (UAV) subjected to different flight mission profiles is investigated. The considered morphing wing design, accounting for wing flexural and torsional stiffness as well as rigid body dynamics for varied flight scenarios, was developed using a consistent lumped mass approach. Specifically, a two-dimensional strip model is used to calculate the quasi-steady aerodynamic forces and moments acting on the morphed wing. The resulting aeroelastic equations are then integrated numerically using a fourth order Runge–Kutta scheme to establish the time history of the wing for the considered various flight scenarios. Discrete gust input in the time domain is introduced to simulate the wing response to this perturbation. The presented numerical results provide an effective physical insight into the behavior of the morphed wing under different geometrical configurations and are useful for the design of the actuation system, flight controller, and gust alleviation. [ABSTRACT FROM AUTHOR]

In the paper hereby, design of a single stage Fowler flap is proposed. The flap is meant to increase lifting abilities of a straight wing at low speeds. It is applicable to small-sized remotely controlled unmanned aerial vehicles widely available to hobbyists. The design process included thorough analysis of flow around a wing foil in case of both retracted and deployed flap. To obtain aerodynamic coefficients values at different angles of attack and Reynolds numbers was a primary goal. In addition, a linkage mechanism was developed to make it possible for the flap to move along a complex path. Various plots and charts are depicted thereafter with sole purpose of providing better understanding of the idea. [ABSTRACT FROM AUTHOR]

Composite materials are widely used in aerospace applications due to their good mechanical properties such as low density and good resistance. Due to their versatility it is possible to design different configurations making it difficult to find the optimal option. The objective of this work is to compare different laminates on the wing surface, the advantage of using structural elements such as spars and ribs, also to see the influence on the results of different load simplifications. In the study, the finite element analysis technique is used to find the best characteristics regarding resistance, deformation, and failure modes under the established conditions. The analysis showed that the best load simplification is a decreasing distributed load along the pressure center, the best surface laminate is [45/0/0/45] with carbon fiber cloth with a maximum displacement of 15.27 mm, the spar presented a 29.6% decrease in maximum displacement and the ribs did not represent a significant change in the structural response. [ABSTRACT FROM AUTHOR]

In this article, a novel surface‐mounted type wideband monopole antenna for VHF band unmanned aerial vehicle (UAV) communication is presented. The proposed antenna constitutes a planar monopole structure such that taper‐feeding configuration is adopted for wideband impedance matching and the radiation element of the antenna is formed on the vertical and horizontal parts of the narrow tail wing of the UAV to obtain monopole‐like radiation pattern. After designing the antenna, simulation was performed in the VHF band of 0.11‐0.17 GHz and the results showed the characteristics of the monopole. Because the antenna size of VHF band is too large to be tested, after 1/7 size scaling, the simulation and the measurement were performed in the frequency band of seven times the original band. The results show that the 10 dB return‐loss band is 0.732‐1.242 GHz (52.0%), the average gain in the H‐plane is −0.23 dBi, and the radiation patterns are very similar to those of the monopole antenna. [ABSTRACT FROM AUTHOR]

Technology of photovoltaic cells and lithium batteries is developing rapidly. As a result, more and more attempts are made to build solar high altitude long endurance airplanes. Unfortunately, data on altitude impact on photovoltaic cells and batteries performance are not easily available. Moreover, acquisition cost of cells is still high. As a result, high altitude long endurance airplanes design is expensive and risky. Therefore, a tool for inexpensive testing of cells is needed. A small and very light unmanned aerial vehicle can be used for this purpose. It could fly as high as the envisaged high altitude long endurance airplane with a small number of cells and batteries, providing valuable information on them. The weight of such an experimental unmanned aerial vehicle could be minimized because long endurance would not be required, so heavy load of lithium batteries could be minimized, reducing also weights of other components. Wings of this unmanned aerial vehicle should enable installation of various types of photovoltaic cells including rigid ones. Therefore, it would be advantageous to apply an airfoil with a flat-upper-surface as large as possible. Unfortunately, flat-upper-surface airfoils are not popular in airfoils catalogs. Therefore, an attempt was undertaken to design an airfoil with 75% flat upper surface. The research focused on maximization of the lift-to-drag ratio and power factor assuming low Reynolds numbers conditions since it was designed for a small unmanned aerial vehicle for photovoltaic cells testing. This paper contains description of design methodology, design assumptions, and the obtained results. Moreover, the authors describe the experiment undertaken to verify the design. The wind tunnel and a semi-span model used for this experiment are presented together with the obtained results. The model has a similar structure to the envisaged structure of unmanned aerial vehicle, so flexibility of the wing is taken into account. [ABSTRACT FROM AUTHOR]

In this work, a 3D numerical study on the influence of the spanwise distribution of tubercles on a unmanned aerial vehicle wing is presented. The idea of using tubercles in aeronautics comes from the humpback whale (Megaptera novaeangliae) which has a characteristic flipper, with a spanwise scalloped leading edge, creating an almost sinusoidal shape, consisting of bumps called tubercles. The whale uses this layout in order to achieve high underwater maneuverability. Early experimental research showed a great potential in enhancing the 3D aerodynamic characteristics of a wing. Most of the existing experimental results concern infinite wings (2D) models and are accompanied with substantial loss in lift and increase in drag in pre-stall region. On the other hand, 3D finite models have displayed a better overall aerodynamic performance (increased lift and moment, but also, decreased drag). At a range of Reynolds number between 500,000 and 1,000,000 (based on the mean chord of the flipper), tubercles act as virtual fences, introducing a pair of counter rotating vortices that delays the stall of the flipper, a phenomenon that the whales exploit to perform sharp turns and catch their prey. The aforementioned Reynolds number range is the same as the operational Reynolds number for typical unmanned aerial vehicles. To assess the influence of the tubercles installation on UAV wings, a full 3D computational study is carried-out with the use of CFD tools which at a first phase are validated and calibrated with the available literature experimental data. Then, computations are performed for different spanwise tubercles distributions. The results show that there is a noticeable potential on controlling the flow on the wings of a UAV operating in a Reynolds number range between 500,000 and 1,000,000 (based on UAV's wing mean chord), which can lead to an aerodynamic performance and efficiency increase. [ABSTRACT FROM AUTHOR]

The development of low-altitude unmanned aerial vehicles (UAVs) has been proposed for many high-impact civilian-centered applications such as expanding telecommunication networks in remote locations, improved weather monitoring, and terrain surveying. Such missions, which can last anywhere from hours to days, rely on efficient, lightweight, and high-aspect ratio designs to minimize energy consumption. We investigate a method of aerodynamic control that also permits energy harvesting through surface texturing on aircraft wings using multifunctional kirigami composites. These kirigami skins produce 3D surface features when axially strained and have been manufactured using thin-film solar cells. Here, we show that when actuated, these 3D features increase the drag over the wings, which can be used to control yaw. Wind tunnel experiments were conducted to quantify the effects of kirigami actuation on aerodynamic lift, drag, and yaw moment. These results demonstrate excellent yaw-control capabilities and delayed aerodynamic stall, indicating that the actuated kirigami features may delay flow separation. The implied multifunctionality of these kirigami skins is ideal for low-altitude UAVs, which benefit from both lightweight energy sources and actuators. [ABSTRACT FROM AUTHOR]

In recent years, small unmanned aerial vehicles (SUAVs) have proven to be exceptionally useful. However, most of the commercially available drones are electric powered and therefore have a short endurance. Solar‐powered UAVs have recently received increased attention due to their ability to fly continuously for several days using solar energy. For this purpose, solar cells must show high efficiency, lightweight, and ultraflexibility to be fully compliant with the drone wings/body and avoid degrading their aerodynamic characteristics. Nevertheless, previous demonstrations used rigid/semi‐flexible cells. Herein, corrugated ultraflexible silicon solar cells (19% efficiency) with a smaller specific weight (645 g m−2, encapsulated) are considered and used. A theoretical comparison between the performances of the corrugated versus commercial semiflexible cells is conducted in terms of flight endurance in "AtlantikSolar" UAV. The results show that due to the ultralightweight of corrugated cells and their ability to expand at higher temperatures without bowing, an enhancement in the flight time up to 19% is achieved compared with the commercial cells which enable heavier payload (7 lbs) transportation. Finally, the corrugated cells (12.5 by 4 cm) are experimentally tested on a small‐sized drone under different conditions indoors and a 10% extended flight is reported. [ABSTRACT FROM AUTHOR]

Composite materials are often preferred in many industries such as aviation and automotive since they have many advantageous properties such as high specific strength, high corrosion resistance and ability to absorb vibration. In this study, a research for structural behaviour is theoretically done on an unmanned aerial vehicle wing composed of composite materials and metallic materials. Two different wing geometries are considered in the study. The first of these is the wing geometry without control surfaces that are flap and aileron. This wing geometry is mentioned as Model 1. The second of these is the wing geometry with flap, aileron and related components. The second wing geometry is mentioned as Model 2. New wing models composed of different material systems are created and analysed under different loads in order to develop reference wing model. These loads are the loads calculated under level flight cruise conditions and maximum static pressure loading conditions. In this way, the optimum configurations of the wing models are obtained. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to present a novel approach based on the artificial bee colony (ABC) algorithm aiming to achieve maximum acceleration and maximum endurance for morphing unmanned aerial vehicle (UAV) design. Design/methodology/approach: Some of the most important issues in the design of UAV are the design of thrust system and determination of the endurance of the UAV. Although propeller selection is very important for the thrust system design, battery selection has the utmost importance for the determination of UAV endurance. In this study, the calculations of maximum acceleration and endurance required by ZANKA-II during the flight are considered simultaneously. For this purpose, a model based on the ABC algorithm is proposed for the morphing UAV design, aiming to achieve the maximum acceleration and endurance. In the proposed model, the propeller diameter, propeller pitch and battery values used in morphing UAV's power system design are selected as the input parameters; maximum acceleration and endurance are selected as the output parameters. To obtain the maximum acceleration and endurance, the optimum input parameters are determined through the ABC algorithm-based model. Findings: Considerable improvements on maximum acceleration and endurance of morphing UAV with ABC algorithm-based model are obtained. Research limitations/implications: The endurance and acceleration due to the thrust are two separate parameters that are not normally proportional to each other. In this study, optimization of UAV's endurance and acceleration is considered with equal importance. Practical implications: Using artificial intelligence techniques causes fast and simple optimization for determination of UAV's endurance and acceleration with equal importance. In the simulation studies with ABC algorithm, satisfactory results are obtained. Social implications: The results of the study have showed that the proposed approach could be an alternative method for UAV designers. Originality/value: Providing a new and efficient method saves time and reduces cost in calculations of maximum acceleration and endurance of the UAV. [ABSTRACT FROM AUTHOR]

In this paper, the multi-objective, multifidelity optimization of a wing fence on an unmanned aerial vehicle (UAV) near stall is presented. The UAV under consideration is characterized by a blended wing body (BWB), which increases its efficiency, and a tailless design, which leads to a swept wing to ensure longitudinal static stability. The consequence is a possible appearance of a nose-up moment, loss of lift initiating at the tips, and reduced controllability during landing, commonly referred to as tip stall. A possible solution to counter this phenomenon is wing fences: planes placed on top of the wing aligned with the flow and developed from the idea of stopping the transverse component of the boundary layer flow. These are optimized to obtain the design that would fence off the appearance of a pitch-up moment at high angles of attack, without a significant loss of lift and controllability. This brings forth a constrained multi-objective optimization problem. The evaluations are performed through unsteady Reynolds-Averaged Navier–Stokes (URANS) simulations. However, since controllability cannot be directly assessed through computational fluid dynamics (CFD), surrogate-derived gradients are used. An efficient global optimization framework is developed employing surrogate modeling, namely regressive co-Kriging, updated using a multi-objective formulation of the expected improvement. The result is a wing fence design that extends the flight envelope of the aircraft, obtained with a feasible computational budget. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to present a novel approach based on the differential search (DS) algorithm integrated with the adaptive network-based fuzzy inference system (ANFIS) for unmanned aerial vehicle (UAV) winglet design. Design/methodology/approach: The winglet design of UAV, which was produced at Faculty of Aeronautics and Astronautics in Erciyes University, was redesigned using artificial intelligence techniques. This approach proposed for winglet redesign is based on the integration of ANFIS into the DS algorithm. For this purpose, the cant angle (c), the twist angle (t) and taper ratio (λ) of winglet are selected as input parameters; the maximum value of lift/drag ratio (Emax) is selected as the output parameter for ANFIS. For the selected input and output parameters, the optimum ANFIS parameters are determined by the DS algorithm. Then the objective function based on optimum ANFIS structure is integrated with the DS algorithm. With this integration, the input parameters for the Emax value are obtained by the DS algorithm. That is, the DS algorithm is used to obtain both the optimization of the ANFIS structure and the necessary parameters for the winglet design. Thus, the UAV was reshaped and the maximum value of lift/drag ratio was calculated based on new design. Findings: Considerable improvements on the max E are obtained through winglet redesign on morphing UAVs with artificial intelligence techniques. Research limitations/implications: It takes a long time to obtain the optimum Emax value by the computational fluid dynamics method. Practical implications: Using artificial intelligence techniques saves time and reduces cost in maximizing Emax value. The simulation results showed that satisfactory Emax values were obtained, and an optimum winglet design was achieved. Thus, the presented method based on ANFIS and DS algorithm is faster and simpler. Social implications: The application of artificial intelligence methods could be used in designing more efficient aircrafts. Originality/value: The study provides a new and efficient method that saves time and reduces cost in redesigning UAV winglets. [ABSTRACT FROM AUTHOR]

Over the last few decades, multirotor UAVs have become significantly popular because of their various applications. However, multirotors suffer from poor endurance performance as compared to other aircraft configurations with lifting surfaces. This limitation can be addressed by improving the technology of components or by developing design optimization approaches at the vehicle level. This paper presents a co-design approach for the multirotor structure and propulsive system to improve the vehicle's energetic efficiency while respecting dynamic performance requirements. For this purpose, the approach uses a bi-level formulation to optimize the design and control concurrently. The methodology offers the possibility to activate or not a passive fault tolerant strategy in the controller synthesis to be tolerant to single rotor failure. In contrast to conventional design approaches that sequentially design each part, the co-design approach leads to a better optimal solution by considering the interactions and couplings between design and control. With the proposed co-design approach, the results show the soundness of the proposed design methodology and a significant reduction in the consumed energy compared to a reference non-optimal design while maintaining the same requirements in terms of dynamic performance. [ABSTRACT FROM AUTHOR]

This paper focuses on the aerodynamics and design of an unmanned aerial vehicle (UAV) based on solar cells as a main power source. The procedure includes three phases: the conceptual design, preliminary design, and a computational fluid dynamics analysis of the vehicle. One of the main disadvantages of an electric UAV is the flight time; in this sense, the challenge is to create an aerodynamic design that can increase the endurance of the UAV. In this research, the flight mission starts with the attempt of the vehicle design to get at the maximum altitude; then, the UAV starts to glide and battery charge recovery is achieved due to the solar cells. A conceptual design is used, and the aerodynamic analysis is focused on a UAV as a gliding vehicle, with the calculations starting with the estimation of weight and aerodynamics and finishing this stage with the best glide angle. In fact, the aerodynamic analysis is obtained for a preliminary design; this step involves the wing, fuselage, and empennage of the UAV. In order to achieve the preliminary design, an estimation of aerodynamic coefficients, along with computational fluid dynamics analysis, is performed. [ABSTRACT FROM AUTHOR]

In this article, combined active flow control system and flight control system design for morphing unmanned aerial vehicles is applied for the first time for autonomous flight performance maximization. For this purpose, longitudinal and lateral dynamics modeling of morphing unmanned aerial vehicle having active flow control manufactured in Erciyes University, Faculty of Aeronautics and Astronautics, Model Aircraft Laboratory is considered in order to obtain simulation environments. Our produced morphing unmanned aerial vehicle is called as ZANKA-II, which has a mass of 6.5 kg, range of 30 km, endurance of 0.5 h, and ceiling altitude of 6000 m. von Karman turbulence modeling is used in order to model atmospheric turbulence during flight in both longitudinal and lateral simulation environments. A stochastic optimization method called as s imultaneous perturbation stochastic approximation is also applied for the first time in order to obtain optimum dimensions of morphing parameters (i.e. extension ratios of wingspan and tail span), optimum positions of blowers, and optimum magnitudes of longitudinal and lateral controllers' gains (i.e. P, I, and D gains) while minimizing cost index capturing terms for both longitudinal and lateral autonomous flight performances and there exist lower and upper constraints on all optimization variables in the literature. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is finding the optimal geometric parameters and developing of a method for optimizing a light unmanned aerial vehicle (UAV) wing, maximizing, at the same time, its endurance with the assumed parameters of aircraft mission. Design/methodology/approach: The research is based on the experience gained by the author's contribution to the project of building medium-altitude, long-endurance class, light UAV called "Samonit". The author was responsible for the structure design, wind tunnel tests and flight tests of the "Samonit" aircraft. Based on the experience, the author was able to develop an optimization process considering various disciplines involved in the whole aircraft design topics such as aerodynamics, flight mechanics, structural stiffness and weight, aircraft stability and maneuverability. The presented methodology has a multidisciplinary nature, as in the process of optimization both aerodynamic aspects and the influence of wing geometric parameters on the wing structure and weight and the aircraft payload were taken into account. The optimal wing configuration was obtained using the genetic algorithms. Findings: As a result, a set of wing geometrical parameters has been obtained that allowed for achieving twice as long endurance as compared with the initial one. Practical implications: Using the methodology presented in the paper, an aircraft designer can easily find the optimum wing configuration of a designed aircraft, satisfying the mission requirements in a best way. Originality/value: An original procedure has been developed, based on the actual design, wind tunnel tests and numerical calculations of "Samonit" aircraft, enabling the determination of optimum wing configuration for a small unmanned aircraft. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The demand of aerial photogrammetry has increased recently especially after the development of unmanned aerial vehicle system. This study explores the use of different UAV systems which comprised of conventional UAV, UAV RTK and UAV Lidar systems. This study also comprises of three experiments. The first experiment involved the mapping of Lingkaran Ilmu, UTM by using fixed wing Ebee UAV with 20megapixel digital camera. This first experiment used conventional UAV. The second experiment involved the fixed wing Ebee UAV equipped with real time kinematic (RTK) system on-board for mapping the study area. The last experiment is the used of octacopter UAV equipped with Riegl Lidar system for mapping the study area. The study area for all experiments is located in Lingkaran Ilmu of main campus Universiti Teknologi Malaysia, Johor Bahru, Johor, Malaysia. Ebee UAV and Ebee RTK UAV are flown in autonomous mode at 200 meters altitude. Both systems are used to capture high resolution aerial photo of the study area. Riegl UAV Lidar system is flown at 100 meter altitude for capture high resolution and point cloud data. GPS rapid static method was used for establishing ground control points (GCP) and check point (CP) in the study area. Three different GCP configuration was applied in geometry correction. Meanwhile, CPs is used for accuracy assessment where RMSE equation was employed. The 15CGP configuration produce more accurate result compared to another. Where, the planimetric RMSE values of Ebee UAV, Ebee RTK UAV and Riegl UAV Lidar are 0.21 m, 0.09 m and 0.15 m respectively. For height RMSE values for Ebbe, Ebee RTK and Octacopter Lidar are 0.34 m, 0.13 m and 0.07 m respectively. In conclusion, Ebee RTK UAV is identified as a system that can produce an accurate digital orthophoto compared to other systems while Riegl UAV Lidar system can produce highest accurate DEM and DTM compared to other systems in 15GCP configuration. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

When the unmanned aerial vehicle (UAV) is used for aerial spraying, the downwash airflow generated by the UAV rotor will interact with the crop canopy and form a conical vortex shape in the crop plant. The size of the vortex will directly affect the outcome of the spraying operation. Six one-way spraying were performed by the UAV in a rice field with different but random flying altitude and velocities within the optimal operational range to form different vortex patterns. The spraying reagent was clear water, which was collected by water sensitive paper (WSP), and then the WSP was analyzed to study the droplets deposition effects in different vortex states. The results showed that the formation of the vortex significantly influenced the droplet deposition. To be specific, the droplet deposition amount in the obvious-vortex (OV) state was about 1.5 times of that in the small-scale (SV) vortex state, and 7 times of that in the non-vortex (NV) state. In the OV state, the droplets mainly deposited directly below and on both sides of the route. The deposition amount, coverage rate and droplet size increased from top to bottom of the crops with the deposition amount, coverage rate, and volume median diameter (VMD) ranging 0.204–0.470 μL/cm2, 3.31%-7.41%, and 306–367μm, respectively. In the SV state, droplets mainly deposited in the vortex area directly below the route. The deposition amount in the downwind direction was bigger than that in the upwind direction. The maximum of deposition amount, coverage rate and droplet size were found in the middle layer of the crops, the range are 0.177–0.334μL/cm2, 2.71%-5.30%, 295–370μm, respectively. In the NV state, the droplet mainly performed drifting motion, and the average droplet deposition amount in the downwind non-effective region was 29.4 times of that in the upwind non-effective region and 8.7 times of the effective vortex region directly below the route. The maximum of deposition amount, coverage rate and droplet size appeared in the upper layer of the crop, the range are 0.006–0.132μL/cm2, 0.17%-1.82%, 120–309μm, respectively, and almost no droplet deposited in the middle and lower part of the crop. The coefficient of variation (CV) of the droplet deposition amount was less than 40% in the state of obvious-vortex and small-scale vortex, and the worst penetration appeared in the non-vortex amounting to 65.97%. This work offers a basis for improving the spraying performance of UAV. [ABSTRACT FROM AUTHOR]

This correspondence paper presents a framework for practical model construction and stable altitude control of an unmanned aerial vehicle with a parafoil-type wing (UAV-PW). To design a stable controller, we first construct a dynamical longitudinal model of the UAV-PW. Since there exist no aerodynamics data of the parafoil shape in our UAV-PW, aerodynamics coefficients balanced at the trimmed equilibrium are employed. The model accuracy is investigated by comparing the model outputs with the real test flight experimental data. Next, stable controller design conditions for the UAV-PW model with uncertainties are derived in terms of linear matrix inequalities (LMIs). By solving the LMI conditions, we design a stable controller that asymptotically stabilizes the UAV-PW model with the uncertainties on a considered operation domain. The experimental results demonstrate the viability of the model construction and the stable altitude control. [ABSTRACT FROM AUTHOR]

This paper investigates experimental evaluation via flight tests for applying adaptive neural network controller to a flying-wing type unmanned aerial vehicle experiencing partial wing-loss. For this, six-degree-of-freedom numerical model is constructed taking into account damage-induced changes to the unmanned aerial vehicle in aerodynamic coefficients, mass, center of gravity, and moments of inertia. Numerical simulations are performed to investigate the flight dynamics change and to verify the performance of the neural network based controller. During the flight test, main wing-loss is artificially generated by 22% or 33% area moment. The flight test verifies that the damaged unmanned aerial vehicle shows drastic roll behavior with the unstable longitudinal response, and the neural network based adaptive controller combined with feedback linearization successfully compensates for the wing damage. [ABSTRACT FROM AUTHOR]

Aircraft perform flight in multiple regimes with different speeds, Angles of Attack (AoA), sideslip angles, and at different altitudes. Designers usually choose the airfoil having the best performance for the cruise mode only or being able to stay suboptimal for all the flight regimes. It leads to a reduction in the maximum lift-to-drag ratio for certain regimes, as well as deterioration in the overall performance. That is why the adaptive wing with its ability to stay optimal for any of the flight regimes is a promising technology which could significantly improve the performance and maneuverability of the aircraft during the flight. In this work, we assess the performance of the wing with the traditional and adaptive mechanization of the flap and slat using computer simulation followed by the experiments in the wind tunnel environment. This work also provides the design of an adaptive wing with an adaptive flap and slat. All the investigations were performed for the two-dimensional airfoil under different Reynolds numbers and AoA. This paper demonstrates that an adaptive wing improves the lift-to-drag ratio and maneuverability of the aircraft for different flight regimes. The application of the adaptive wing mechanization could improve the lift-to-drag ratio by 20%-30% for certain regimes, thereby improving the range and time of operation. [ABSTRACT FROM AUTHOR]

Poor lateral-directional stability due to the absence of vertical stabilizer is a great risk to the aircraft with flying wing layout. In this paper, an unmanned aerial vehicle with this kind of configuration is chosen as the research object. A threedimensional model of the unmanned aerial vehicle is established, and then the sensitivity analysis is performed to obtain the effects of main aerodynamic shape parameters on lateral-directional flying quality. The results show that the roll mode and spiral mode of the aircraft meet the requirements of Level 1 flying quality in MIL-F-8785C. But the Dutch roll mode is generally divergent, which means that the flying quality of the aircraft is unacceptable. Thus it can be seen that the Dutch roll mode is the key to the dynamic stability of the aircraft. Further studies show that increasing the value of wing aspect ratio or decreasing the values of dihedral angle and torsion angle are useful for improving the Dutch roll mode. It is valuable to reveal the influence mechanism of aerodynamic shape parameters on lateral-directional flying quality for the design of flying wing aircraft. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the aerodynamic design procedure of a mini unmanned aerial vehicle, intended to perform aerial reconnaissance at low altitude and low Reynolds number, was summarized. Design process was divided into two major parts: conceptual design phase and preliminary design phase. During the conceptual design, classical procedures and data from similar unmanned aerial vehicles already designed were employed to define the requirements related to unmanned aerial vehicle design. The preliminary design was performed using panel method where the emphasis was given on the design of the UAV wing, fuselage design and empennage. The wing planform parameters were determined through an aerodynamic optimization process using both genetic algorithms and artificial neural networks. Finally an aerodynamic analysis using panel method, Computational Fluid Dynamic simulations and wind tunnel testing was carried out. Unmanned aerial vehicle full configuration design process was consistent, where a comparison between the final obtained results was carried out and showed an agreement in terms of lift, drag and pitch moment coefficients. [ABSTRACT FROM AUTHOR]

Lift production is constantly a great challenge for flapping wing micro air vehicles (MAVs). Designing a workable wing, therefore, plays an essential role. Dimensional analysis is an effective and valuable tool in studying the biomechanics of flyers. In this paper, geometric similarity study is firstly presented. Then, the pw−AR ratio is defined and employed in wing performance estimation before the lumped parameter is induced and utilized in wing design. Comprehensive scaling laws on relation of wing performances for natural flyers are next investigated and developed via statistical analysis before being utilized to examine the wing design. Through geometric similarity study and statistical analysis, the results show that the aspect ratio and lumped parameter are independent on mass, and the lumped parameter is inversely proportional to the aspect ratio. The lumped parameters and aspect ratio of flapping wing MAVs correspond to the range of wing performances of natural flyers. Also, the wing performances of existing flapping wing MAVs are examined and follow the scaling laws. Last, the manufactured wings of the flapping wing MAVs are summarized. Our results will, therefore, provide a simple but powerful guideline for biologists and engineers who study the morphology of natural flyers and design flapping wing MAVs. [ABSTRACT FROM AUTHOR]

Winglets have an important effect in the use o f aircraft and of unmanned aerial vehicle (UA V). The expected effect in winglet usage is the increase of the lift coefficient and the decrease of the drag coefficient. These aspects play a very important role in determining aerodynamic performance. Many researches have been done in order to determine the most effective winglet designs to further explore the effects on aircraft and unmanned aerial vehicle (UA V). Based on that fact, in this study the use of winglet on UA V is discussed. This research has been conducted using a simulation software with turbulent model k-co SST. The freestream velocity used is 10 m /s (Re=2.3 x 104) with an angle of attack (α) = 0°, 2°, 4°, 6°, 8°, 10°,12°, 15°, 16°, 17° and 19°. Model specimens are airfoils Eppler 562 with and without winglet. Winglet used in this study are wingtip fences with forward and reanvard configuration. From the research, it has been found that the addition of winglet can minimize vorticity magnitude behind the wing especially forward wingtip fence. Forward wingtip fence results in a smaller vorticity area than plain wing and reanvard wingtip fence although the vorticities increase with the increase o f the angles of attack. In addition, the fonvard wingtip fence can prevent the formation of tip vortex better than the reanvard one. [ABSTRACT FROM AUTHOR]

One of the major challenges of Mini-Unmanned Aerial Vehicle flight is the unsteady interaction with turbulent environment while flying in lower levels of atmospheric boundary layer. Following inspiration from nature we expose a new system for angle of attack estimation based on pressure measurements on the wing. Such an equipment can be used for real-time estimation of the angle of attack during flight or even further building of wind velocity vector with additional equipment. Those information can find purpose in control and stabilization of the aircraft due to inequalities seen by the wing or even for various soaring strategies that rely on active control for energy extraction. In that purpose, flying wing aircraft has been used with totally four span-wise locations for local angle of attack estimation. In-flight angle of attack estimation from differential pressure measurements on the wing has been compared with magnetic sensor with wind vane. The results have shown that pressure ports give more reliable estimation of angle of attack when compared to values given by wind vane attached to a specially designed air-boom. Difference in local angle of attack at four span-wise locations has confirmed spatial variation of turbulence in low altitude flight. Moreover, theoretical law of energy dissipation for wind components described by Kaimal spectrum has shown acceptable match with estimated ones. [ABSTRACT FROM AUTHOR]

The stability of small unmanned air systems can be challenged by turbulence during low-altitude flight in cluttered urban environments. This paper explores the benefits of a tandem wing aircraft configuration with the implementation of a pressure-based phase-advanced turbulence sensory system on a small unmanned air system for gust mitigation. The objective was to utilise passive and active methods to minimise gust-induced perturbations. Experimentation in repeatable turbulence within a wind tunnel’s test section was conducted. The experiments focus on the roll axis, which is isolated through a specially designed roll-axis rig. The results show improvement over conventional aircraft. This work is part of a larger research project aimed at enabling safe, stable and steady small unmanned air systems flight in urban environments. [ABSTRACT FROM AUTHOR]