Air Vehicle Wing Research Articles

Wave propagation analysis of micro air vehicle wings with honeycomb core covered by porous FGM and nanocomposite magnetostrictive layers

Recently, nano- and micro air vehicles have been intensely attractive among researchers due to their small size and ultralightweight. Hence, in this article, wave propagation of micro air vehicle wings is studied based on mathematical modeling as the main novelty of this article. In addition, assuming porous functionally graded materials (FGM) and magnetostrictive nanocomposite layers for the wing for improving the stiffness and control of the wave propagation is another important innovation of this study. The effects of size are considered based on strain gradient theory and the Halpin-Tsai model is employed for calculating the effective material characteristic of the magnetostrictive nanocomposite layer. For modeling the structure mathematically, refined zigzag theory (RZT) is used. According to Hamilton's principle, the governing equations are gained and solved by exact solutions for obtaining the phase velocity, cut-off, and escape frequencies. In this novel work, influences of dispersion kinds of GPLs, various core and face sheets thickness, damping of structure, porosity constant, FG index, auxetic honeycombs core characteristics, size parameters, and magnetic field are investigated on wave propagation of the micro air vehicle wings. It is found that by imposing the magnetic field on the magnetostrictive layer, the wave velocity is enhanced.

Computational Aerodynamics Study of Competing Conceptual Designs for Advanced Tactical Fighter Aircraft

Advanced tactical fighter (ATF) configurations are bound to perform high angle of attack (AoA) maneuvers. However, existing conceptual design tools available in aerospace industry are based on empirical or potential flows that cannot predict aerodynamic data in nonlinear regimes. High-fidelity computational fluid dynamics algorithms have to be incorporated during conceptual design phase for better assessment between competing configurations. In this research, steady state aerodynamic analysis is conducted to compare four conceptual designs of advanced tactical fighters through Reynolds-averaged Navier–Stokes (RANS) simulations. Prior to the study, two validation test cases were conducted based on ONERA M6 Wing and benchmark unmanned combat air vehicle (UCAV) design to assess the computational setup for the problem. Pressure based solver is used to model the flow field in subsonic, transonic and supersonic regimes at sea level for all four competing designs. The quantitative results include the aerodynamic forces and the longitudinal stability coefficient comparisons among the models and its components. The qualitative analyses include pressure distribution, eddy shedding and behavior of vortices at varying flow angle. Additionally, the empirical estimation for interpolation and post-stall extrapolation are carried out for further flight performance studies.

Lift Study of a Flapping MAV Wing Design Based on Bat Wings

Bio-inspiration is a design ideation method that uses observations found in nature to solve a mechanical problem. In this study, a simulation study of a micro air vehicle (MAV) wing design that is based on bat wings was done and validated experimentally. The wing model was generated using an in vivo observation where the margin wing shape was traced and then used to generate a flat wing with a margin shape of a batwing. The lift of the wing was studied at 4m/s wind speed with a flapping angle of 55°, and at the angle of attack from 0° to 35°. The simulation was done using ANSYS V1.6 software and the experimental study was done using an open circuit subsonic wind tunnel. It was observed that the wing has a stall angle of 25° and a CLmax of 3.2. The result also shows that the difference between the simulation and the observation result to be small with 0.2% at the smallest point and 5% at the largest point. This shows that the simulation model was valid and can be used for future wing design.

Kinematics, Deformation, and Aerodynamics of a Flexible Flapping Rotary Wing in Hovering Flight

The Flapping Rotary Wing (FRW) is a micro air vehicle wing layout coupling flapping, pitching, and rotating motions. It can gain benefits in high lift from a fast passive rotating motion, which is tightly related to the passive pitching motion directly caused by wing flexible deformation. Therefore, flexible deformation is crucial for the wing kinematics and aerodynamic performance of an FRW. In this paper, we explored the effect of flexibility on wing kinematics and aerodynamics on the basis of a mechanical FRW model. A photogrammetric method was adopted to capture motion images according to which wing orientations and deformations were reconstructed. Corresponding aerodynamic force was computed using computational fluid dynamic method, and wing kinematics and deformations were used as simulation inputs. The experimental measurements presented the real orientation and deformation pattern of a real FRW. The wing passive deformation of a high-intensity FRW was found to be mainly caused by inertial force, and a linear positive spanwise twist was observed in the FRW. The effects of wing deformation on aerodynamic force production and the underlying mechanism were addressed. Results showed that lift augment, rotating moment enhancement, and power efficiency improvement can be achieved when a wing becomes flexible. Wing spanwise twist mainly accounts for these changes in aerodynamics, and increment in spanwise twist could further contributes to aerodynamic improvement.

Fabrication of a Unmanned Air Vehicle Wing for Better Endurance

Fabrication of a Unmanned Air Vehicle Wing for Better Endurance

Nano-mechanical properties and structural of a 3D-printed biodegradable biomimetic micro air vehicle wing

The biomimetic micro air vehicles (BMAV) are unmanned, micro-scaled aircraft that are bio-inspired from flying organisms to achieve the lift and thrust by flapping their wings. The main objectives of this study are to design a BMAV wing (inspired from the dragonfly) and analyse its nano-mechanical properties. In order to gain insights into the flight mechanics of dragonfly, reverse engineering methods were used to establish three-dimensional geometrical models of the dragonfly wings, so we can make a comparative analysis. Then mechanical test of the real dragonfly wings was performed to provide experimental parameter values for mechanical models in terms of nano-hardness and elastic modulus. The mechanical properties of wings were measured by nanoindentre. Finally, a simplified model was designed and the dragonfly-like wing frame structure was bio-mimicked and fabricated using a 3D printer. Then mechanical test of the BMAV wings was performed to analyse and compare the wings under a variety of simplified load regimes that are concentrated force, uniform line-load and a torque. This work opened up the possibility towards developing an engineering basis for the biomimetic design of BMAV wings.

Aerodynamic comparisons of flexible membrane micro air vehicle wings with cambered and flat frames

Flexible membrane wings at the micro air vehicle scale can experience improved lift/drag ratios, delays in stall, and decreased time-averaged flow separation when compared to rigid wings. This research examines the effect of frame camber on the aerodynamic characteristics of membrane wings. The frames for the wings were 3D printed using a polymer-based material. The membranes are silicone rubber. Tests were conducted at Re ∼50,000. Aerodynamic force and moment measurements were acquired at angles-of-attack varying from −4 to 24°. Additionally, digital image correlation data were acquired to assess time-averaged shapes of the membrane wings during wind tunnel tests. An in-house program was developed to average the deflection plots from the digital image correlation images and produce time-averaged shapes. Lifting-line theory based on the time-averaged shapes was then used to calculate theoretical lift and induced drag coefficients, showing that the time-average shape of the membrane under load contributes extensively to the aerodynamic performance. The results show that introducing camber to the frames of membrane wings increases aerodynamic efficiency.

An experimental study of elastic properties of dragonfly-like flapping wings for use in biomimetic micro air vehicles (BMAVs)

This article studies the elastic properties of several biomimetic micro air vehicle (BMAV) wings that are based on a dragonfly wing. BMAVs are a new class of unmanned micro-sized air vehicles that mimic the flapping wing motion of flying biological organisms (e.g., insects, birds, and bats). Three structurally identical wings were fabricated using different materials: acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and acrylic. Simplified wing frame structures were fabricated from these materials and then a nanocomposite film was adhered to them which mimics the membrane of an actual dragonfly. These wings were then attached to an electromagnetic actuator and passively flapped at frequencies of 10–250Hz. A three-dimensional high frame rate imaging system was used to capture the flapping motions of these wings at a resolution of 320 pixels×240 pixels and 35000 frames per second. The maximum bending angle, maximum wing tip deflection, maximum wing tip twist angle, and wing tip twist speed of each wing were measured and compared to each other and the actual dragonfly wing. The results show that the ABS wing has considerable flexibility in the chordwise direction, whereas the PLA and acrylic wings show better conformity to an actual dragonfly wing in the spanwise direction. Past studies have shown that the aerodynamic performance of a BMAV flapping wing is enhanced if its chordwise flexibility is increased and its spanwise flexibility is reduced. Therefore, the ABS wing (fabricated using a 3D printer) shows the most promising results for future applications.

Design and mechanical analysis of a 3D-printed biodegradable biomimetic micro air vehicle wing

The biomimetic micro air vehicles (BMAV) are unmanned, micro-scaled aircraft that are bio-inspired from flying organisms to achieve the lift and thrust by flapping their wings. There are still many technological challenges involved with designing the BMAV. One of these is designing the ultra-lightweight materials and structures for the wings that have enough mechanical strength to withstand continuous flapping at high frequencies. Insects achieve this by having chitin-based, wing frame structures that encompass a thin, film membrane. The main objectives of this study are to design a biodegradable BMAV wing (inspired from the dragonfly) and analyze its mechanical properties. The dragonfly-like wing frame structure was bio-mimicked and fabricated using a 3D printer. A chitosan nanocomposite film membrane was applied to the BMAV wing frames through casting method. Its mechanical performance was analyzed using universal testing machine (UTM). This analysis indicates that the tensile strength and Young's modulus of the wing with a membrane is nearly double that of the wing without a membrane, which allow higher wing beat frequencies and deflections that in turn enable a greater lifting performance.

Vortex structure on twist-morphing micro air vehicle wings

Vortex formation has numerous influences on the aerodynamic characteristics of fixed-wing micro air vehicle wings. Despite the mature understanding of vortices on fixed-wing and flapping micro air vehicle wings, the behavior of vortices over the morphing micro air vehicle wing has not been fully explored. Thus, the current work is conducted to investigate the influence of vortex structure over a series of twist-morphing micro air vehicle wings. Twist morphing micro air vehicle and baseline wings are simulated through fluid–structure interaction analysis. The validation results for each wing exhibited good correlation in the overall lift coefficient distribution trend. The vortex formation results show that vortex formations are significantly altered throughout angle of attack changes. For a given angle of attack cases below the stall angle, each morphing wing exhibited higher intensities of tip vortex structure formations and leading edge vortex–tip vortex interactions compared to the baseline wings. Stronger leading edge vortex–tip vortex interactions improved the low-pressure region over the morphing wing surface and further induce better lift performance. In fact, the morphing wing with higher morphing force induces better lift performance.

Numerical study on the flow characteristics of micro air vehicle wings at low Reynolds numbers

The aerodynamic characteristics around a micro air vehicle wing with an inverse-Zimmerman configuration are numerically investigated by an in-house programmed solver particularly dedicated for aircrafts operating in low Reynolds number regime. The complex three-dimensional aerodynamic performance was investigated in terms of force generation and flow structures visualization. Results show that the flow around the low aspect ratio MAV wing is characterized by complex three-dimensional separation-dominated flow. The flow fields exhibit separation, reattachment, secondary separation, secondary reattachment, and strong interaction between the separated boundary layer and wingtip vortices. In addition, the effect of tip-attached vertical stabilizers on flow structure and aerodynamic forces is addressed in this paper. The stabilizers significantly influence both the flow structure and aerodynamic forces via reducing the strength of wingtip vortices and shedding and interacting of wingtip vortices. Eventually, the unsteadiness of the aerodynamics revealed that higher angle of attack will result in stronger unsteady phenomena as demonstrated by the oscillating forces.

Sensing Unsteady Pressure on MAV Wings: A New Method for Turbulence Alleviation

Experiments at low Reynolds numbers were performed on a pressure tapped NACA 2313 wing in a 3 x 2 x 9 meter wind tunnel under nominally smooth (Ti = 1.2%) and turbulent (Ti = 7.2%) flows at a mean flow velocity of 8ms-1(Re ≈120,000). The NACA 2313 wing is a replica of Micro Air Vehicle (MAV) wing of the Flash 3D aircraft used at RMIT University for research purposes. Unsteady surface pressures were measured to understand if the information could be adopted for resolving turbulence-induced perturbations and to furthermore use it in a turbulence mitigation system. Two span-wise locations of chord-wise pressure were acquired when tested under the two different flow conditions. It was discovered that at both span-wise locations, a local Coefficient of Pressure (Cp) held high correlation to the chord-wise Cp integration and allowed for a linear relationship to be formed between the two variables. The defined relationship provided a 95% confidence for angles of attack below stall and was used to estimate the integrated chord-wise pressure coefficient at a particular span wise location. The relationship between a single pressure tap and the integrated Cp of that chord-wise section was valid for the two different span-wise locations with similar defining equations. As one pressure tap is sufficient to adequately estimate the integrated Cp on a chord-wise wing section, a limited amount of pressure taps across the wings span approximates the pressure distribution across the span and eventually approximates the flight perturbations. Being a novel method of sensing aircraft disturbance, applications are not restricted to MAV. The methodology presented could very well be applied to larger aircraft to reduce the effects of turbulence within the terminal area and can provide other means of active stabilization.

Air Vehicle Wing Production:Depth Classification Version of CC

A depth classification version of CC for compound Subjects going with the Host Subject Air Vehicle Wing Production is given. The methodology for the design of freely-faceted scheme for classification has been used. A large number of the isolates Constituting the different schedules for the classification of subjects going with each of the different Host Subjects for the production of the different parts and sub-assemblies of an aircraft such as Wing, Fuselage, Nose cone, Control system, and Landing system have common array divisions. Eight provisional schedules of such array divisions of isolates relevant to Subjects in the field of aircraft production are presented and their use in the formation of isolate numbers illustrated with examples. The schedules of common array divisions given are: Directional relation, Location, Shape of edge, Attributes of surface, Shape (General), Mach Number, Range of dimension, and Matetrial of construction. A provisional schedule of common organ isolates is also given. The Numerical Device is explained. The use of these devices help, in conforming to the; Canon of Helpful Sequence, the Canon of Consistent Sequence, the Canon of Scheduled Mnemonics, ,and the Law of Parsimony, in schedule building. In this way, the enumeration of isolates in the schedules has been reduced by about fifty percent. An Alphabetical Index to the schedules and a lift of twelve examples of subjects classified according to the scheme for classification are given.

Computational aerodynamic analysis on perimeter reinforced (PR)-compliant wing

Implementing the morphing technique on a micro air vehicle (MAV) wing is a very challenging task, due to the MAV’s wing size limitation and the complex morphing mechanism. As a result, understanding aerodynamic characteristics and flow configurations, subject to wing structure deformation of a morphing wing MAV has remained obstructed. Thus, this paper presents the investigation of structural deformation, aerodynamics performance and flow formation on a proposed twist morphing MAV wing design named perimeter reinforced (PR)-compliant wing. The numerical simulation of two-way fluid structure interaction (FSI) investigation consist of a quasi-static aeroelastic structural analysis coupled with 3D incompressible Reynolds-averaged Navier–Stokes and shear-stress-transport (RANS–SST) solver utilized throughout this study. Verification of numerical method on a rigid rectangular wing achieves a good correlation with available experimental results. A comparative aeroelastic study between PR-compliant to PR and rigid wing performance is organized to elucidate the morphing wing performances. Structural deformation results show that PR-compliant wing is able to alter the wing’s geometric twist characteristic, which has directly influenced both the overall aerodynamic performance and flow structure behavior. Despite the superior lift performance result, PR-compliant wing also suffers from massive drag penalty, which has consequently affected the wing efficiency in general. Based on vortices investigation, the results reveal the connection between these aerodynamic performances with vortices formation on PR-compliant wing.

Analytical and Finite Element Modal Analysis of a Hyperelastic Membrane for Micro Air Vehicle Wings

Analytical and finite element models are developed for investigating the modal characteristics of a hyperelastic rubber latex membrane for micro air vehicle wings applications. A radially prestretched membrane specimen is attached to a thin, rigid circular ring and vibrated in vacuum and in air at atmospheric pressure. The natural frequencies of the membrane computed by analytical and finite element models are correlated well. The natural frequencies increase with mode and prestretch level of the membrane but decrease in air from those in vacuum due to the effect of added mass of air. The damping is low and has a very minimal effect on the frequencies but helps to reduce the amplitude of vibration. Aerodynamic pressure at different angles of attack and a freestream velocity is computed from the wind tunnel test data, and a finite element model is developed for investigating the effect of the aerodynamic pressure on the modal characteristics of the membrane. It is found that the effect of aerodynamic pressure on the natural frequencies of the membrane is not significant.

Experimental Structural Dynamic Characterization of the Hawkmoth (Manduca Sexta) Forewing

While many bio-inspired flapping wing micro air vehicle wing designs continue to be conceived and studied in earnest, a general consensus of which physical attributes of the biological entity are important for flight is still at-large. It is proposed herein that the eigenstructure of the wing should figure prominently among rigorous engineering metrics for guiding flapping wing micro air vehicle wing designs at the scales of large insects. With virtually no compelling work done in this area to date, the method and results of system identification tests for the forewings of a representative sample of hawkmoth ( Manduca Sexta) are presented, revealing the underlying structural nature of this incredibly agile flyer's wings. Despite their inherent biological variability, these wings show very little variability in eigenstructure which may suggest it as a critical attribute for robust flight. Further supporting this hypothesis, the wings of four other insect species are briefly examined and show remarkable similarity with the hawkmoth wing's eigenstructure.

Aerodynamic control of micro air vehicle wings using electroactive membranes

Dielectric elastomer materials are ideal candidates for developing high-agility micro air vehicles due to their electric field–induced deformation. Consequently, the aero-structural response and control authority of the dielectric elastomer material, VHB 4910, are characterized on an elliptical membrane wing. An experimental membrane wing platform was constructed by stretching VHB 4910 over a rigid elliptical wing-frame. The low Reynolds number (chord Reynolds number < 106) and aerodynamics of the elliptical wing were characterized when different electrostatic fields were applied to the membrane. We observe an overall increase in lift with maximum gains of 20% at an applied voltage of 4.5 kV and demonstrate the ability to delay stall. The time-averaged aerodynamic surface pressure is also investigated by comparing sting balance data and membrane deformation measured using visual image correlation. The experimental results are compared to a nonlinear finite element membrane model to further understand the effects of aerodynamic load and electric fields on membrane displacements. Model predictions of surface pressure provide insight into how the electrostrictive constitutive relations influence the fluid–structure interactions of the membrane. This is validated by comparing lift predictions from the model with time-averaged wind tunnel lift measurements near stall.

Deployment Dynamics of a Rolled Micro Air Vehicle Wing

In this study the structural deployment dynamics of a rollable micro air vehicle wing are investigated. The wing is composed of a single layer of woven, carbon-fiber composite and behaves like a tape-spring, remaining stiff in one direction (lift) while rolling easily in the other for storage. A finite element model is developed and evaluated for its comparison to an experimental model. A vacuum chamber is used to eliminate fluid effects on the structural deployment dynamics, which are recorded using a high-speed video camera. Modal testing and finite element updating are used to estimate unknown composite material properties for the analysis. A laser vibrometer is used to record wing mode shapes, and they are found to agree well with fitted mode shapes and their frequencies from the updated Abaqus finite element model. A wing deployment is simulated in Abaqus and compared with experimental deployments, and the time history displacements matched well. The deployment is found to be sensitive to the wing mount as well as to material properties, particularly damping.

Parametric Representation and Shape Optimization of Flapping Micro Air Vehicle Wings

The effects of wing planform on the aerodynamic performance of a rigid wing in forward flapping flight and hovering configurations were investigated in this paper. The planform design space was parameterized using a new, modified Zimmerman method based on low aspect ratio Zimmerman planform designs. The aerodynamic forces on the wing were calculated using Peters' aerodynamics with an assumed inflow coupled with blade element theory. A multiobjective optimization approach was taken to find the best planform designs for three objectives: wing area, peak power input, and an aerodynamic force based on the kinematic configuration – lift for hovering and thrust for forward flight. A gradient-based optimizer and the ε-constraint method were used to find the Pareto front of optimal designs with the aerodynamic force as the primary objective function. The choice of primary and secondary objective functions is important in determining the optimal planform. The Pareto optimal planforms for the case when only area is considered as a secondary objective function drastically differ from the optimal planforms when only power is taken as a secondary objective function. As the secondary objective ε values change over the design space, so do the optimal planform shapes.

Aerodynamic shape optimisation, wind tunnel measurements and CFD analysis of a MAV wing

AbstractThe aerodynamic shape optimisation of a micro air vehicle (MAV) wing is performed to obtain the basic wing geometrical characteristics which produce the maximum range and endurance requirements. Multhopp’s method based on Prandtl’s classical lifting line theory is used for the determination of the spanwise load distribution required during the optimisation process. The obtained lift and drag characteristics are used for the derivation of the range and endurance equations of an electrically driven micro air vehicle. The optimisation process is based on the modified feasible directions gradient based optimisation algorithm. Results are validated using wind tunnel measurements showing very good agreement. Results are also compared with solutions to the Navier-Stokes equations obtained with ANSYS-CFX finite elements using different turbulence models. These include the k-ε and the shear stress transport (SST) models as well as the Reynolds stress model.