Wing Unmanned Aerial Vehicle Research Articles

Design of a tilting mechanism for a VTOL flying wing UAV

In this paper, the detailed design of a mechanism for the transition from vertical to horizontal flight of a Vertical Take-off and Landing (VTOL) fixed wing Unmanned Aerial Vehicle (UAV) is presented. The UAV, which is being developed in the framework of the MPU research project, under the designation MPU RX-4, is a lightweight, all electric driven UAV with a flying wing layout. The MPU RX-4 is capable of performing both conventional flight, like a regular fixed wing aerial vehicle, as well as vertical hovering, like a multicopter, adapting on different operational demands. To achieve that, the development of a robust transition procedure from one flight phase to the other is required. This procedure is based on mechanisms capable of altering the flying characteristics of the UAV. More specifically, these mechanisms should be designed in order to change the orientation of the thrust vectors from horizontal to vertical and vice versa. MPU RX-4 uses a configuration of three electric motors (two mounted on the canards, and one in the main body) in order to perform both flight phases. For the transition from the hovering phase to the level flight, the two frontal motors have to be tilted from the vertical position to the horizontal, and the rear motor to be nested in its proprietary position, using four external hatches. Two separate mechanisms are designed, one for the canards’ tilting movement and another one for the extension and retraction of the rear motor hatches. Finite Element Analysis is carried out for the structural sizing of the mechanism (i.e. internal loads, linkages cross-section, joints sizing). The aerodynamic loads, acting on the mechanisms, are derived from Computational Fluid Dynamics analysis performed for the various flight phases (hovering, level flight and transition) of the UAV. Finally, the designed mechanisms are presented as integrated parts of the prototype UAV.

Aerodynamic and stability analysis of a VTOL flying wing UAV

The stability analysis of an aerial vehicle is an of great importance integral part of its design procedure. It is of even greater importance in the case of tailless aircraft, which are prone to stability issues. In the present study, the aerodynamic and stability characteristics of a Vertical Take-off and Landing (VTOL) fixed wing Unmanned Aerial Vehicle (UAV), designated as MPU RX-4, are investigated. The MPU RX-4 has a flying wing layout and is capable of performing, both conventional flight, like a regular fixed wing aerial vehicle, as well as vertical hovering, like a multicopter, adapting on different operational demands and achieving rapid field deployment. In this study, the preliminary design phase of the MPU RX-4 is presented and the aerial vehicle’s aerodynamic performance, as well as, its stability and control behavior are assessed using both semi-empirical correlations, specifically modified for lightweight flying wing UAVs, and Computational Fluid Dynamics (CFD) analyses. These correlations are employed to estimate the non-dimensional aerodynamic coefficients for various flight conditions (e.g. cruise, loiter, maximum speed, etc.) of the MPU RX-4 flight envelope. Furthermore, the correlations are validated with dedicated CFD analyses in order to assure their level of accuracy. Finally, the MPU RX-4 stability and control derivatives, and the required control surfaces deflection for steady level flight are computed, in order to assess its overall aerodynamic performance and flight characteristics.

Kriging Aerodynamic Modeling and Multi-Objective Control Allocation for Flying Wing UAVs With Morphing Trailing-Edge

Flexible skin and continuous deformable control surface are the basic of adaptive wing technology for future aircraft. This paper presents a continuous morphing trailing-edge and its control allocation method for the flying wing Unmanned Aerial Vehicle (UAV). Firstly, we apply the Kriging method to establish the aerodynamic model of the morphing trailing-edge, with the initial sample points generated by the non-uniform optimal Latin Hypercube Sampling (LHS). Then, based on the Kriging model, the multi-objective control allocation problem is converted into a standard optimization form. To solve such problem, we design a Comprehensive Multi-Objective Particle Swarm Optimization (C-MOPSO) algorithm and an improved Hierarchical MOPSO (H-MOPSO) algorithm, in which multiple optimization objectives are prioritized and hierarchically optimized using the PSO algorithm. As for performance analysis, an attitude angle tracking flight control system is established to validate the effectiveness of our proposed control allocation methods. Simulation results show that both the C-MOPSO and H-MOPSO methods have similar performance in attitude angle tracking, while H-MOPSO achieves better multi-objective allocation performance.

Propeller locations study of a generic delta wing UAV model

PurposeThis study aims to investigate the effects of propeller locations on the aerodynamic characteristics of a generic 55° swept angle sharp-edged delta wing unmanned aerial vehicle (UAV) model.Design/methodology/approachA generic delta-winged UAV model has been designed and fabricated to investigate the aerodynamic properties of the model when the propeller is placed at three different locations. In this research, the propeller has been placed at three different positions on the wing, namely, front, middle and rear. The experiments were conducted in a closed-circuit low-speed wind tunnel at speeds of 20 and 25 m/s corresponding to 0.6 × 106 and 0.8 × 106 Reynolds numbers, respectively. The propeller speed was set at constant 6,000 RPM and the angles of attack were varied from 0° to 20° for all cases. During the experiment, two measurement techniques were used on the wing, which were the steady balance measurement and surface pressure measurement.FindingsThe results show that the locations of the propeller have significant influence on the lift, drag and pitching moment of the UAV. Another important observation obtained from this study is that the location of the propeller can affect the development of the vortex and vortex breakdown. The results also show that the propeller advance ratio can also influence the characteristics of the primary vortex developed on the wing. Another main observation was that the size of the primary vortex decreases if the propeller advance ratio is increased.Practical implicationsThere are various forms of UAVs, one of them is in the delta-shaped planform. The data obtained from this experiment can be used to understand the aerodynamic properties and best propeller locations for the similar UAV aircrafts.Originality/valueTo the best of the author’s knowledge, the surface pressure data available for a non-slender delta-shaped UAV model is limited. The data presented in this paper would provide a better insight into the flow characteristics of generic delta winged UAV at three different propeller locations.

Spatial Variation in Coastal Dune Evolution in a High Tidal Range Environment

Coastal dunes have global importance as ecological habitats, recreational areas, and vital natural coastal protection. Dunes evolve due to variations in the supply and removal of sediment via both wind and waves, and on stabilization through vegetation colonization and growth. One aspect of dune evolution that is poorly understood is the longshore variation in dune response to morphodynamic forcing, which can occur over small spatial scales. In this paper, a fixed wing unmanned aerial vehicle (UAV), is used to measure the longshore variation in evolution of a dune system in a megatidal environment. Dune sections to the east and west of the study site are prograding whereas the central portion is static or eroding. The measured variation in dune response is compared to mesoscale intertidal bar migration and short-term measurements of longshore variation in wave characteristics during two storms. Intertidal sand bar migration is measured using satellite imagery: crescentic intertidal bars are present in front of the accreting portion of the beach to the west and migrate onshore at a rate of 0.1–0.2 m/day; episodically the eastern end of the bar detaches from the main bar and migrates eastward to attach near the eastern end of the study area; bypassing the central eroding section. Statistically significant longshore variation in intertidal wave heights were measured using beachface mounted pressure transducers: the largest significant wave heights are found in front of the dune section suffering erosion. Spectral differences were noted with more narrow-banded spectra in this area but differences are not statistically significant. These observations demonstrate the importance of three-dimensionality in intertidal beach morphology on longshore variation in dune evolution; both through longshore variation in onshore sediment supply and through causing longshore variation in near-dune significant wave heights.

A prototype of Fixed Wing UAV for delivery of Medical Supplies

A prototype Unmanned Aerial Vehicle (UAV) is designed for the purpose of last mile delivery to supply medicines and vaccines. This work aims to ascertain that UAVs can be employed to decrease transportation times, increased power efficiency, and improved safety for transportation of necessary products. The prototype model is design to deliver 1 kg maximum payload up to 5 km with an endurance time of 30 minutes. The model is fabricated with a wing span of 1.5 m, Aspect ratio 7, and contains NACA 6 series airfoil shape as its cross section. During the transportation of payload, it has to fly beyond the line of sight which requires an autonomous Pixhawk flight controller installed in the model. Autonomous module aids in the safe flight avoiding the obstacles during the operation. To comply with government regulations for flying the model cruises at an altitude of 350 feet. After reaching the desired GPS destination, the payload is delivered to the target customer via parachute. However the model requires a runway length of 200 m for its takeoff and landing operation.

Optimization of composite wing spars for an unmanned aerial vehicle

In this paper, the weight optimizing of an unmanned aerial vehicle wing spar was designed by using composite material. The optimization parameters were considered, respectively: the wing mass, the location of the spars and ribs, and the spars mass. Determined the selecting of wing spars locations for optimizing spars design based on the minimum weight of the wing. Layer optimizing was used to reduce the weight of composite wing spars. The thickness of front spar and rear spar element such as web and flange were optimized by criterion of allowable normal stress and deflection. The analysis of stress-strain state for all variants were carried out in the FEMAP software package. As the result of analysis, the total weights of composite wing spars reduced 18.17% than the original spars.

Comparison of partly coupled and fully coupled Fluid-Structural interactions of UAV wing

Aircraft components are naturally elastic in nature and have their own natural frequency. Whenever the source frequency becomes equal to the object’s natural frequency, the objects may vibrate and deform and this might results in fluttering. The main objective of this article is to compare the fully coupled and partly coupled result of an unmanned aerial vehicle wing with combination of winglet. Modelling of structural and fluid domain is required to solve both fluid-structural interaction phenomena. The rectangular wing with elliptical winglet model has been analyzed at different altitude in 0.1 to 0.5 mach range using finite element analysis and computational fluid dynamics tools. The deformation and stress variation exists in a rectangular wing with elliptical winglet model caused by aero elastic effects. The resulting stress variation and structural deformation respect to the corresponding flow are fully studied and affirmed.

A Review on Applications and Effects of Morphing Wing Technology on UAVs

Unmanned aerial vehicles (UAVs) have excelled with their ability to perform the intended task on or without personnel. In recent years, UAVs have been designed for civilian purposes as well as military applications. Morphing wings are changeable wing applications developed as a result of the need for a different lift and drag forces in various phases of the flight of aircraft. It is an application that enables altering the wing aspect ratio, wing airfoil, wing airfoil camber ratio, wing reference area and even different angles of attack are obtained in different parts of the wing. Although morphing wing application has just begun on today’s UAVs, modern airliners already have morphing wingtip devices such as Boeing 777-X’s. The benefits of the use of morphing wings for UAVs make this technology important. UAVs with morphing wing technology; may increase its payload ratio, may achieve a shorter take-off distance, may land and stop in shorter distance, may take-off where runway clearance is limited, has more efficient altitude change at lower engine RPMs, can obtain higher cruise speeds, may decrease its stall speed, may lower its drag if necessary, thus; saving energy and time. This study concludes a review of literature over morphing wing technology.

Design of a Pesticide Spraying Quadcopter

Today, coupled with technological development, UAV (Unmanned Aerial Vehicle) systems show an important improvement in civil area applications. UAV systems have active tasks with cost-effective solutions in several areas like defense, logistics, engineering and agriculture. Especially in agricultural applications, UAV system usage contributes to improvement of the critical parameters of this sector as efficiency and sustainability. Thus, in agricultural areas, improvement and usage of unmanned systems are of importance. In this study, a remote-control rotary wing UAV system that has the ability to perform irrigation and spraying and its design, production and application processes are discussed. The designed, verified and all test operations completed UAV system is planned to be used in remote control liquid rejection in the agricultural area.

Investigation and Improvement of Pusher-Propeller Installation Effect for Flying Wing UAV

This paper presents a collaborative experimental and numerical research to investigate the influences of the installation of propeller on aircraft aerodynamic performance, and two approaches to mitigate the propeller installation effect are also analyzed. The configuration under investigation is based on a real flying wing unmanned aerial vehicle with a two-bladed pusher-propeller mounted on the aft part of its associated airframe. Reynolds-averaged Navier Stokes simulations coupled with a structured finite-volume cell-vertex based solver are applied to propeller uninstalled and installed configurations, and the numerical results are shown to be in good agreement with the experimental data. The comparative results obtained through prop-uninstalled and prop-installed cases show that the installation of the pusher-propeller leads to the decline of the maximum lift-drag ratio due to aerodynamic interactions between the propeller and airframe. Detailed analysis of the numerical results highlighted that the low pressure areas on the aft part of the airframe generated by the installation of the pusher-propeller will result in an increase of the base drag and hence a decline of the maximum lift-drag ratio. The feasibilities of center shaft extension and the modification of airframe geometry to mitigate the propeller installation effect are verified by numerical simulations, and results showed that proper propeller–airframe spacing and good designs of airframe geometry can effectively improve the flow characteristic and reduce the drag induced by propeller installation effect.

A semi-analytical approach for flutter analysis of a high-aspect-ratio wing

AbstractWe present a hybrid, semi-analytical approach to perform an eigenvalue-based flutter analysis of an Unmanned Aerial Vehicle (UAV) wing. The wing has a modern design that integrates metal and composite structures. The stiffness and natural frequency of the wing are calculated using a Finite Element (FE) model. The modal parameters are extracted by applying a recursive technique to the Lanczos method in the FE model. Subsequently, the modal parameters are used to evaluate the flutter boundaries in an analytical model based on the p-method. Two-degree-of-freedom bending and torsional flutter equations derived using Lagrange’s principle are transformed into an eigenvalue problem. The eigenvalue framework is used to evaluate the stability characteristics of the wing under various flight conditions. An extension of this eigenvalue framework is applied to determine the stability boundaries and corresponding critical flutter parameters at a range of altitudes. The stability characteristics and critical flutter speeds are also evaluated through computational analysis of a reduced-order model of the wing in NX Nastran using the k- and pk-methods. The results of the analytical and computational methods are found to show good agreement with each other. A parametric study is also carried out to analyse the effects of the structural member thickness on the wing flutter speeds. The results suggest that changing the spar thickness contributes most significantly to the flutter speeds, whereas increasing the rib thickness decreases the flutter speed at high thickness values.

Aerodynamic characterization of an Albatross wing for Bio-inspired unmanned aerial vehicle

The aerodynamic efficiency of any flying object depends largely on the shape of its wing. Albatross, the largest flying bird in terms of the aerodynamic efficiency, is researching the wing structure of birds. The wing of a flange is first modelled and comparable with other influenced wing types as well as to the conventional geometric shapes which includes the delta, elliptical and rectangular wing types. These studies will help to understand the effect of wing shape on aerodynamic efficiency of the UAVs. Airfoil and flight speed analyses are carried out under the same terms, taking into account the same aspect ratio (AR), span of the wing and its area. There is now growing need for UAVs with different military and civil capabilities for a fixed-wing aircraft. The novel ideas and concepts for developing the Unmanned Aerial Systems is gaining a lot of attention on the current era of development includes the autonomous missions, such as maritime and spatial exploration. It is important to note this will help to provide the pathways for production of an efficient drone with high aerodynamic efficiency.

Autonomous Recovery of a Fixed-Wing UAV Using a Line Suspended Between Two Multirotor UAVs

This article presents an autonomous recovery system for fixed wing unmanned aerial vehicles (UAVs) which is using a line suspended between two multirotor UAVs to catch a line with a hook hanging from a fixed-wing UAV. This method of recovery is particularly suitable for recovery in space constrained areas such as on small ships. A control system is presented for the proposed recovery concept and the concept is validated through experiments. The results include 17 test runs to characterize control accuracy, followed by three successful recoveries. With the selected equipment and tuning values, the multirotors were able to track the fixed-wing UAV with a mean error of 0.8 m at the moment the catch would have happened in the 17 test runs. The margins for missing for the three recoveries were 1.0-2.1 m showing that this recovery method is robust.

The Fixed wing UAV usage on Land use Mapping for gazetted Royal land in Malaysia

The study deals with the usage of fixed wing unmanned aerial vehicle (UAV) in verifying boundary for gazetted royal land, which the other sight of efficacy of UAV has been tested in area of urban planning. The specific flight planning had been arranged and tested to royal land of Pekan in order to identify the settlement (kampongs) boundaries. Royal land in Pekan was the significant land that existed since 1919, which established under the Royal land Enactment 1919. It accommodated more five thousand residents in the 919 hectares of area with five villages (kampongs). The combination method of aerial mapping and vector digitization in structured a spatial database have been conducted by combining both output from UAV and GIS. The finding shows the royal land boundary was clearly identified in UAV orthophoto; further refine output of its database in GIS data. The additional info building footprints in 5 kampongs land lots also appeared very well in final output. Result shows that, the simple conclusion on the efficacy of fixed wing UAV in managing a land in urban planning, it also proved the dependency of decision makers should oriented more on geospatial applications since it was reliable and able to be used in many planning aspects in order to ensure a sustainability and resiliency of living.

Effects of point cloud density, interpolation method and grid size on derived Digital Terrain Model accuracy at micro topography level

ABSTRACT The objective of this study was to evaluate the effects of the three dimensional (3D) point cloud density derived from Unmanned Aerial Vehicle (UAV) photogrammetry (using Structure from Motion (SfM) and Multi-View Stereopsis (MVS) techniques), the interpolation method for generating a digital terrain model (DTM), and the resolution (grid size (GS)) of the derived DTM on the accuracy of estimated heights in small areas, where a very accurate high spatial resolution is required. A UAV-photogrammetry project was carried out on 13 m × 13 m bare soil with a rotatory wing UAV at 10 m flight altitude (equivalent ground sample distance = 0.4 cm), and the 3D point cloud was derived. A stratified random sample (200 points in each square metre) was extracted and from the rest of the cloud, 15 stratified random samples representing 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, and 90% were extracted. Five replications of each percentage were extracted to analyse the effect of cloud density on DTM accuracy. For each of these 15 × 5 = 75 samples, DTMs were derived using four different interpolation methods (Inverse Distance Weighted (IDW), Multiquadric Radial Basis Function (MRBF), Kriging (KR), and Triangulation with Linear Interpolation (TLI)) and 15 DTM GS values (20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.67, 0.50, and 0.40 cm). Then, 75 × 4 × 15 = 4500 DTMs were analysed. The results showed an optimal GS value for each interpolation method and each density (most of the cases were equal to 1 cm) for which the Root Mean Square Error (RMSE) was the minimum. IDW was the interpolator that yielded the best accuracies for all combinations of densities and GS. Its RMSE when considering the raw cloud was 1.054 cm and increased by 3% when a point cloud with 80% extracted from the raw cloud was used to generate the DTM. When the point cloud included 40% of the raw cloud, RMSE increased by 5%. For densities lower than 15%, RMSE increased exponentially (45% for 1% of raw cloud). The GS minimizing RMSE for densities of 20% or higher was 1 cm, which represents 2.5 times the ground sample distance of the pictures used for developing the photogrammetry project.

Realtime Localization and Estimation of Loads on Aircraft Wings from Depth Images.

This paper deals with the development of a realtime structural health monitoring system for airframe structures to localize and estimate the magnitude of the loads causing deflections to the critical components, such as wings. To this end, a framework that is based on artificial neural networks is developed where features that are extracted from a depth camera are utilized. The localization of the load is treated as a multinomial logistic classification problem and the load magnitude estimation as a logistic regression problem. The neural networks trained for classification and regression are preceded with an autoencoder, through which maximum informative data at a much smaller scale are extracted from the depth features. The effectiveness of the proposed method is validated by an experimental study performed on a composite unmanned aerial vehicle (UAV) wing subject to concentrated and distributed loads, and the results obtained by the proposed method are superior when compared with a method based on Castigliano’s theorem.

Flight dynamics modeling of a flexible wing unmanned aerial vehicle

This paper shows the results of traditional aerodynamic analysis and the flexible flight dynamics modeling including the effects of structural motion for a flexible wing unmanned aerial vehicle. The influence of some design parameters such as wing flexibility, horizontal/vertical tail aerodynamics is investigated for aeroelasticity and flight dynamics of flexible aircraft. The research platform is an Unmanned Aerial Vehicle (UAV), made of composite material. Its wing span is 4 m and reaches a high aspect ratio, whose value is 18.9. For a traditional analysis, the Vortex Lattice Method (VLM) was used to obtain conventional aerodynamic and control derivatives. The flexible flight dynamics model is based on the work of Waszack and Schmidt. In this approach, it is used the mean-axes reference system and it is assumed that structural deformations is small and described by a set of eigenmodes. The dynamics model incorporates the first normal modes obtained by Ground Vibration Test (GVT) campaigns. A focus of the paper lies on providing a useful model for dynamics system identification and in-flight aeroelastic testing. A developed platform for in-flight system identification and the acquisition system is described. A flight path reconstruction process from a flight test campaign results is shown.

Printing electronics directly onto carbon fiber composites: unmanned aerial vehicle (UAV) wings with integrated heater for de-icing

Unmanned Aerial Vehicles (UAVs) are increasingly used to deliver items and gather information in remote areas. As a result, UAVs suffer from ice accumulation on their wings, which drastically affects their flight. However, the UAV industry is still relatively young and, thus, commercial solutions for de-icing on UAVs are limited. The use of carbon fiber composites is becoming increasingly ubiquitous for UAVs as well as many other industries such as military, construction, medical, automobile, sporting goods and aircraft systems. Carbon fiber is commercially available in various forms, including single yarns, braids and weaves, which are similar to traditional textiles. This paper presents a method to create a self-heating composite structure that can be integrated into UAV wings for de-icing by exploiting the thermal and electrical conductivity of carbon fiber. Extrusion printing is used to fabricate electrical contacts directly on the carbon fiber weave. Extrusion printing on textiles faces multiple challenges that are overcome in this paper. A method is presented to extrusion print conductive paste on textiles. Specifically, carbon fiber weaves. This manufacturing method is employed to fabricate carbon fiber-based heating devices, and they are characterized electrically and thermally.

Estimation of Small Unmanned Aerial Vehicle Lateral Dynamic Model with System Identification Approaches

Modeling of unmanned aerial vehicle (UAV) with system identification is very important in terms of its model-based effective control. The modeling of UAV is required for aircraft crashes, analyzing autonomous aircrafts, preventing external disturbances, pre-flight analysis. However, since UAV has nonlinear inherent dynamics including inherent chaoticity and fractality, it becomes difficult to obtain a mathematical model under external disturbance. In this study, some of the inherent nonlinear dynamics of UAV are linearized and the model of UAV is obtained by system identification approaches under external disturbance. The linearized lateral dynamics of a fixed wing UAV is used in this study. Further, the flight motion equations applied to fixed wing UAV have been utilized for obtaining the coefficients of lateral model for straight and level flight. The roll angles are calculated using transfer functions for aileron, rudder and deflections inputs. The autoregressive exogenous (ARX), autoregressive moving average with exogenous (ARMAX) and output error (OE) parametric system identification approaches are performed to estimate UAV lateral dynamic system response as using empirical input-output data sets. The accuracy of parametric model estimation and model degrees are compared for different external disturbance effects.