Aircraft Design Research Articles

Composite Materials in Advancing Electric Aircraft Technologies

The transition towards electric aviation represents a significant stride in addressing the environmental impact of transportation, particularly concerning gas emissions. With the aviation sector identified as a substantial contributor to carbon emissions, the development of electric aircraft emerges as a crucial innovation towards achieving sustainable air travel. This paper explores the role of composite materials in the advancement of electric aircraft, focusing on their application in airframe construction, electrical systems integration, and the enhancement of propulsion systems. Composite materials, including carbon fiber-reinforced polymer (CFRP), glass fiber-reinforced polymer (GFRP), aramid fiber composite, and hybrid composites, offer superior strength, reduced weight, and high durability, making them ideal for electric aircraft design. Despite their advantages, challenges such as high manufacturing costs and recycling complexities persist. Through a comprehensive analysis, this study examines the potential of advanced manufacturing techniques and sustainable organic materials in overcoming these hurdles, paving the way for the widespread adoption of electric aircraft. The paper highlights the transformative impact of composite materials on electric aviation, addressing both the performance enhancements they facilitate and the obstacles to their broader application.

Early concurrent engineering in the aerospace industry supported by a Digital Thread framework

The traditional sequential aircraft design process is reaching its limits in an increasingly complex environment. Therefore, it has become an industrial necessity to implement radical change in working methods. This paper focuses on the conceptual design phase, where concurrent engineering offers the greatest potential to improve the costs, quality, and development time of a new aircraft. It pays particular attention to the knowledge management and modeling activities used to provide global perspectives that are inherently lacking in early phases. A digital thread framework is presented linking model-based systems engineering artifacts from product and manufacturing systems, coupled with knowledge capture methods. This framework aims to enable early trade-of analysis to support concurrent engineering during the conceptual design phase.

Multi-Objective Bayesian Optimization Design of Elliptical Double Serpentine Nozzle

The use of traditional optimization methods in engineering design problems, specifically in aerodynamic and infrared stealth optimization for engine nozzles, requires a large number of objective function evaluations, therefore introducing a considerable challenge in terms of time constraints. In this paper, this limitation is addressed by using a sample-efficient multi-objective Bayesian optimization that takes Kriging as a surrogate model and Expected Hypervolume Improvement as the infill criterion. Using this approach, the probabilistic model is continuously established and updated, and the approximate Pareto front is obtained at a relatively small computational budget. The objective of this work is to evaluate the applicability of employing a multi-objective Bayesian optimization framework for the aerodynamic-infrared shape optimization of an elliptical double serpentine nozzle at 6 km flight condition, where the objective functions are evaluated by means of high-fidelity computational fluid dynamics and reversed Monte Carlo ray tracing simulations. We achieve good results in both infrared radiation signature reduction and aerodynamic performance improvement with a reasonable number of evaluations, indicating that the proposed method is effective and efficient for tackling the computationally intensive optimization challenges in the aircraft design.

Suitability of different machine learning methods for high-speed flow modeling issues

In the present study, machine learning algorithms are applied for modeling transport coefficients in strongly nonequilibrium reacting gas flows. As a model case, the problem of a hypersonic flow of a five-component air mixture around a sphere is considered. Various approaches for an application of machine learning methods, such as linear regression, k-nearest neighbors, support vector machine, regression tree, random forest, gradient boosting, and neural network (multilayer perceptron) are investigated. For the transport coefficients regression modeling the combination of machine learning methods with the finite volume method is constructed. The machine learning regressors are trained on the accurate numerical data given by one-temperature approach of the kinetic theory. The results of trained models are compared with approximate formulae of Blottner-Eucken-Wilke model. The results of different machine learning methods are analyzed in terms of the relationship between the obtained accuracy of calculations and the overall speed of calculations. The overall time of dataset formation and model training is estimated. The design of the constructed multilayer perceptron is discussed. The machine learning methods considered in the article can be used for the engineering problem such as design of high-speed aircraft, as well as for modeling of flows around complex shape bodies.

Stress Distribution Analysis using ANSYS of the Nose Landing Gear of STOL Aircrafts Considering Runway Gradient: A Simulation Study

Landing gear failures are a major cause of aircraft failures because they are an integral part of the aircraft's development. According to the Federal Aviation Administration (FAA), 50% of all aircraft failures occur during take-offs and landing. The landing gear of a short take-offs and landing (STOL) aircraft has had its static and dynamic forces analyzed analytically and numerically. SOLIWORKS is used to model the landing gear, and ANSYS is used to perform the numerical simulation results. Following it, the model is examined for stress and deformation with the boundary conditions and computed loads into account. This study uses structural finite element analysis (FEA) to analyze the nose gear's stress behavior and displacement during landing, as well as to assess the effect of the runway gradient. Utilizing a comprehensive numerical simulation, the landing gear of a real material Twin-Otter STOL aircraft has been demonstrated to be subjected to a dynamic force of 3653.26N, a pneumatic pressure of 1.59MPa, a bead pressure of 7.97MPa, and a vertical force of 1672.31lbs on level runways, or runways with no gradient. These findings will increase the level of confidence of aircraft manufacturers to make necessary appropriate design of STOL aircraft’s landing gear. It may can decrease the aircraft accidents and increase human life safety ultimately saving valuable time and resources too.

Manufaktur Dan Pemasangan Komponen Avionik Pada UAV Skywalker 1900 Dengan Material Komposit Berpenguat Fiber Carbon

This research is a collaboration between STTKD Yogyakata and Frogs Indonesia, a startup that manufactures flying vehicles, with the aim of making the UAV Skywalker 1900 flying vehicle with Carbon Fiber reinforced composite materials to produce a structure that is stronger than the material commonly used, namely Styrofoam. The initial stage of making the UAV was to work on the Skywalker 1900 UAV design drawings and printed them with 3D printing using PLA Filament, the 3D printing results were then molded using Epoxy resin. From the resulting molding, the structure of the aircraft parts will be made with fiber glass reinforced composite materials using the Vacuum Bagging method. After the structure of the aircraft parts is completed, the electrical and avionic components are installed. The flight test results of the Skywalker 1900 UAV aircraft have a speed of around 15 m/s to 20 m/s, the weakness of this aircraft design is that it is still difficult to control, from the existing analysis this is caused by the aerofoil on the horizontal stabilizer causing lift in the tail of the aircraft of 1 newtons.

An aerodynamic optimization method based on virtual Nash equilibrium for global and local parameter decoupling

The parameterization of aerodynamic shape in the aircraft design optimization usually includes both global and local configuration features. The global parameters determine the wing span, aspect ratio, angle of attack, twist angle, and sweep angle. Meanwhile, the local parameters define the geometric shape of the wing section, including thickness and camber, etc. The changes in different types of parameters during the optimization process will lead to perturbations in the corresponding wavelength of the geometric shape, which in turn will cause different spatial frequency responses in the flow field. Generally, local parameter changes will generate high-frequency perturbations in the flow field and propagate only near the disturbance source; While global parameter changes will cause low-frequency perturbations in the flow field and propagate throughout the entire flow field. If these two different types of parameters are optimized at all once, it will lead to significant mutual interference, thereby reducing optimization efficiency. Therefore, this paper proposes an efficient optimization algorithm NashGL based on the concept of virtual Nash equilibrium. It decouples global and local variables and optimizes them simultaneously on different populations, effectively isolating interference between these two types of design variables. On the other hand, due to the small number of global variables, their rapid convergence can guide local variables towards the optimal solution. Through two aerodynamic optimization cases of NACA0012 airfoil and wing body aircraft, it is shown that compared with the method of simultaneously optimizing global and local parameters, the NashGL algorithm in this paper has the highest optimization efficiency, with an improvement of about 30% and 60%, respectively.

On the aerodynamic performance of redundant propellers for multi-rotor eVTOL in cruise

As multi-rotor and convertible configurations gain compelling popularity in Advanced Air Mobility designs, the handling of redundant propellers during cruise flight regimes becomes a new challenge. This paper presents a systematic study of the aerodynamic performance of feathered and windmilling redundant propellers on a simplified multi-rotor, multi-wing configuration. High-fidelity CFD simulations were performed with a systematic test matrix including the blade feathering angle, azimuth shift, coning angle, and windmilling pitch angle and RPM. For the feathered blades, the feathering angle had a strong impact on the aerodynamic performance. The feathered blades could substantially reduce the overall lift and increase the overall drag at high feathering angles (up to 25% lift reduction and 70% drag increase). This is correlated with changes in the sectional wing inflow angles induced by the upstream feathered blades. Windmilling propellers, in ideal cases, were found capable of considerable wind energy extraction (50% of required cruise power) and could create slowed inflows for downstream thrusting propellers, at the cost of excessive drag (up to 90% more). Comparisons of vehicle performance with feathered and windmilling blades, showed similar aerodynamic forces and energy consumption. This shows that windmilling could be a feasible option for redundant propellers, given careful balancing of the drag and energy conversions. The presented results provide valuable guidance for the handling of redundant blades, for future multi-rotor aircraft designs for sustainable aviation.

Concurrent Value-Driven Decision-Making Process for the Aircraft, Supply Chain and Manufacturing Systems Design

The integration of product design and supply-chain management can lead to an increase in the profitability and efficiency of companies. However, considering manufacturing, supply chain, and aircraft criteria in the early design phase increases the size of the solutions’ trade space and, thus, the complexity of performing the decision-making process. This paper demonstrates how to leverage value-model theory to simplify the decision-making process when multiple criteria related to multiple systems are considered at the same time. The proposed concurrent approach is formalized from a systems-engineering perspective, considering the interactions between the lifecycle stages of the System of Interest, i.e., the aircraft, and Enabling Systems like the supply chain and manufacturing. A value-based interactive dashboard, called VALORISE, is developed to automatize the process, support decision-makers in modeling their expectations, analyze real-time strategic scenarios, and easily explore the value-driven trade space for best-solution identification. An aeronautical application case highlights the advantages of leveraging the proposed concurrent approach to overcome the limits of traditional approaches, in which decisions about supply chain and manufacturing are addressed once the aircraft configuration is decided.

Control moment coefficient methodology validation for eVTOL sizing

This paper presents a novel approach for the preliminary design of electric Vertical Takeoff and Landing (eVTOL) aircraft that utilizes the new Control Moment Coefficient (CMC) to size electric motors and to determine the rotor location and incidence angle. The CMC is determined for both thrust and arm length in eVTOL aircraft design, and is used to measure the moment produced by the rotors in the roll, pitch, and yaw axes. Analyzing its dimensionless value thus allows insights into an eVTOL aircraft's controllability. To test our methodology, two eVTOL aircraft were used in flight tests, one of which had up to 126% higher CMC values than the other. The results of the flight tests showed that a higher CMC value yielded many benefits, including an increased margin of safety between the rotors and the saturation level, reduced tracking error, and reduced control effort (or energy consumption).Furthermore, the 126% increase in the dimensionless CMC related to the pitch resulted in a 30% increase in the Pulse-Width Modulation - PWM margin of safety of the rotors at the saturated level while still maintaining a reasonable tracking error and a 97% decrease in the pitch control effort. Our research suggests that incorporating higher CMCs into the preliminary design of an eVTOL aircraft can significantly improve its safety and controllability. We hope that our findings will encourage further exploration of this promising approach in future.

Closed-Loop Control and Plant Co-Design of a Hybrid Electric Unmanned Air Vehicle

Abstract Novel conceptual aircraft designs have been enabled by more electrified aircraft components providing enhanced capability and versatility. Through the advancement of multidisciplinary design optimization, control co-design methods have become a popular approach for system design conceptualization wherein the plant and control actions are designed simultaneously to account for the coupling between vehicle subsystems and power management systems. Many prior efforts have focused on open-loop control co-design that can later be adapted for a more realistic operating case. This work focuses on the development and scalability of closed-loop control co-design that would result in a physically realizable plant and closed-loop control law. The theoretical approach is demonstrated practically through the design of a hybrid electric unmanned air vehicle and two feedback controllers that operate the hybrid power split and propulsion system. The system is designed to complete a dynamic seven phase mission consisting of multiple cruise, dash, engage, dive, and climb segments as quickly as possible. Given the scale of the dynamic design problem, a convergence study is introduced that facilitates accurate and computationally tractable design optimization studies. The study is conducted for independent, sequential, and simultaneous design approaches. The results indicate high-speed motors, high voltage batteries, and responsive control gains result in a fast vehicle with high thrust-to-weight ratio. The simultaneous design solution had the best closed-loop performance, outclassing a baseline system design by over 30%.

Meshless Large-Eddy Simulation of Propeller–Wing Interactions with Reformulated Vortex Particle Method

The vortex particle method (VPM) has gained popularity in recent years due to a growing need to predict complex aerodynamic interactions during the preliminary design of electric multirotor aircraft. However, VPM is known to be numerically unstable when vortical structures break down close to the turbulent regime. In recent work, the VPM has been reformulated as a large-eddy simulation (LES) in a scheme that is both meshless and numerically stable without increasing its computational cost. In this study, we build upon this meshless LES scheme to create a solver for interactional aerodynamics. Propeller blades are introduced through an actuator line model following well-established practices for LES. A novel, vorticity-based actuator surface model (ASM) is developed for wings, which is suitable for propeller–wing interactions when a wake impinges on the surface of a wing. This ASM imposes the no-flow-through condition at the airfoil centerline by calculating the circulation that meets this condition and by immersing the associated vorticity in the LES following a pressure-like distribution. Extensive validation of propeller–wing interactions is presented by simulating a tailplane with tip-mounted propellers and a blown wing with propellers mounted midspan.

Damage tolerance allowable calculation for the aircraft design with static ultimate load

Accounting for damage tolerance (DT) is crucial during the design process of aerospace composite structures. Typically, a DT design allowable limits the permitted strain level. Calculating this design allowable requires an assessment of the expected damage, the damage detectability, and the residual strength. Current state-of-the-art methods rely on empirical data, offering little flexibility and constraining the design space for a structural optimization. For a tailored calculation of the design allowable for arbitrary laminates and materials, we present an analytical analysis chain, composed from existing methods for the assessment of accidental damage (impact), the damage detectability, and the residual strength. We employ the assembled process in three steps. The determination of a DT design point for a given laminate, the calculation of a laminate-specific allowable, and the obtainment of a ply-share specific and general design allowables through minimization procedures. The highest allowables are achieved by stacking [−45,90,45]n-blocks in the outermost plies while moving the 0∘-plies to the laminate center. Compared to a standard legacy quad configuration, an allowable increase between approx. 30% and 50% was identified. Applied in a structural optimization procedure for a composite wing, this corresponds a mass reduction of up to 5%.

METHOD OF ESTIMATING THE DANGEROUS RANGE OF TRANSONIC NUMBERS M OF THE FLIGHT OF SUPERSONIC AIRCRAFT AND AEROSPACE SYSTEMS

Ensuring flight safety of supersonic aircraft and aerospace systems in the transonic range of flight M numbers still remains an ac- tual scientific and applied problem. This is due to the occurrence of various dangerous aeroelasticity phenomena in these flight modes. Such phenomena include transonic flutter, the occurrence of which has repeatedly resulted in the destruction of aircraft structural elements and, first of all, of aerodynamic control surface structural elements. Many publications are devoted to the theoretical and experimental research of this phenomenon, in which various approaches are proposed to substantiate the causes of intense oscillations of the aerodynamic control surfaces of modern supersonic aircraft in these flight modes, the conditions of their occurrence, the influence of various factors on the level of oscillations. It is noted that there are still no reliable theoretical methods for estimating the non-stationary forces of aerodynamic control surfaces that oscillate in a transonic flow, so the use of linear mathematical similarity models does not always allow transferring the results of blowing models in wind tunnels to full-scale aircraft designs. The paper proposes a method for estimating the dangerous range of M numbers in which transonic flutter of the aerodynamic control surfaces of supersonic aircraft and aerospace systems is possible. The method is based on the analysis of regularities of the adiabatic expansion of the local supersonic air flow on the surface of the airfoil in the range of transonic numbers M. Calculations have proven that for typical aerodynamic surfaces of modern supersonic aircraft, the occurrence of transonic flutter is possible in a narrow range of numbers M = 0.9…0.94. The obtained results can be used to substantiate the safe flight modes of supersonic aircraft both at the stage of flight tests and at the stage of operation. Further studies of this problem should be devoted to the analysis of methods for reducing the level of oscillations of aerodynamic control surfaces when transonic flutter occurs.

Design of a new sweptback wing for a future supersonic aircraftResearch on lift drag characteristics and aerodynamic analysis

In recent years, with the gradual development of the aviation industry, how to make supersonic aircraft truly used in military air defense has become a global problem. In this paper, the wing design of supersonic aircraft is studied, a swept back symmetrical wing suitable for supersonic reconnaissance aircraft is designed with reasonable aspect ratio, span length, sweep angle, thrust weight ratio and wing load. On the basis of the aerodynamic characteristics of the aircraft analyzed, the inboard electron, outboard electron, flasheron, leading edge flap and all moving tip are designed to ensure the controllability in the flight line and to maintain the balance and stability of the aircraft. The qualitative analysis of the flight performance of the wing is also performed. This paper provides a possibility for the design of supersonic aircraft in the future.

АНАЛІЗ МЕТОДІВ ПРОЕКТУВАННЯ ТА ВИРОБНИЦТВА ЛІТАКІВ З ЕЛЕКТРИЧНИМ ВЕРТИКАЛЬНИМ ЗЛЬОТОМ І ПОСАДКОЮ

Recent advances in electric vertical take-off and landing (eVTOL) technology make these vehicles attractive for mass production in the aerospace industry. The subject of the study is a review of advances in the field of eVTOL aircraft design using modern modeling and computational tools. The goal is to analyze the current common concepts and design features of eVTOL aircraft in terms of power supply, power plant capacity, rotor designs, and the use of advanced lightweight composites. The method used is the study and analysis of open publications on the subject under investigation. Modern design methodologies are reviewed, comparison of tools used to analyze and optimize key parameters, such as total take-off weight, wingspan, rotor radius, battery performance, flight controllability, etc. An important stage is the test. The use of various methods of digital modeling increases the efficiency of this stage, as well as shortens the terms of production and modernization. A large place is devoted to the review of the problems of safe operation of eVTOL aircraft. Modeling eVTOL aircraft in a visually realistic environment allows you to get better results in less time. Conclusions: Research in the field of eVTOL & vehicle test design is of great practical importance in the world. The considered methodologies demonstrate the powerful dynamics of the industry. The use of modern information technologies allows at the stage of design and testing to model elements and processes more qualitatively, which gives such researchers a competitive advantage. The review carried out in the article allows you to use it as a basis for research in the field of eVTOL design, as well as research in the development of methods of autonomous intelligent control of eVTOL.

Probabilistic aeroelastic analysis of high-fidelity composite aircraft wing with manufacturing variability

Safety margins of aerospace structures can be improved through altering the laminate parameters of composite materials to increase flutter and divergence velocities. Existing work demonstrates the impact of material uncertainties on low-fidelity structural models that are not sufficient to represent realistic aircraft designs. A gap exists in quantifying laminate parameter uncertainties on aeroelasticity for high-fidelity three-dimensional composite structures in realistic tailored designs. This paper puts forward an efficient methodology for uncertainty quantification on the aeroelastic characteristics of three-dimensional composite structures using FE-based parametric composite models and advanced Kriging surrogate models. The methodology is tested on both low and high fidelity case studies to represent the composite wing structure. Similarities between the case studies are observed in the coefficient of variance of all hard flutter modes being within 0.15-1.4% of each other. The difference was found for divergence and soft flutter velocities where the coefficient of variance could be over ten times higher in the high fidelity case. Global sensitivity results revealed similar physical behavior cases can be produced from both studies at early design stages.

On impact loading of Voronoi functional graded porous structure

In the realm of developing novel lightweight forms with enhanced mechanical properties, structural innovation introduces a fresh perspective, with a key focus on porous structures that must be addressed. Different from previous gradient control methods, this paper focuses on porosity (relative density) control criteria and establishes porous structures with different porosity gradients. This paper aims to evaluate the potential application of Voronoi functional graded porous structures (FGPS). The study employs Poisson-Voronoi tessellation to generate FGPS models, creating four Voronoi porous structures with diverse porosity gradients. Model verification involves comparing results with the Gibson-Ashby porous structure theory. Subsequent analyses rely on numerical modeling and finite element analysis (FEA) using Abaqus. The research explores the impact of varying impact velocities and directions as parameters for analysis. Parametric studies reveal that the most influential factor affecting the deformation behavior of Voronoi FGPS is the impact velocity. As impact velocity increases, the influence of gradient magnitude and direction becomes relatively less pronounced. Notably, the stress-strain relationship on the impact side shows greater sensitivity to impact velocity compared to the fixed end. Furthermore, the energy absorption of Voronoi FGPS demonstrates varying advantageous ranges under different operational conditions, including impact velocity and final strain levels. In summary, the size, direction, and impact velocity of the porosity gradient in Voronoi FGPS distinctly influence deformation behavior, stress-strain relationships, densification strain, plateau stress, and energy absorption at different strain levels. The future of FGPS lies in the development of advanced materials with increasingly sophisticated gradients, allowing for superior performance optimization in demanding applications, such as the lightweight and crashworthiness design of vehicles and aircrafts, biomimetic porosity designs and protective layers for civil engineering. These findings provide valuable insights for the practical design of porosity-controlled FGPS.

Global–local multidisciplinary optimisation for the evaluation of local constraints on finer meshes in preliminary aircraft design

Multidisciplinary design optimisation (MDO) is a methodology increasingly being used in the preliminary design of aircraft. To limit the computational cost of the procedure, it is generally based on coarse models, which do not accurately capture the internal deformation of details with a complex geometry. Therefore, it is not possible to apply constraints in these areas and designers are limited to a conservative pre-sizing of these parts, which are then kept fixed during the optimisation. In this paper we expose the limitations of this approach and present a novel methodology for the preliminary sizing of aircraft, based on global–local MDO. The commonly used coarse model is used together with finer local models, for the parts where additional accuracy is needed. The global–local analysis solves the internal deformation field with sufficient accuracy for the evaluation of local constraints. Furthermore, thanks to the formulation we introduce to compute the coupled sensitivities, the optimiser successfully finds a locally feasible design.

Impact of Figures of Merit Selection on Hybrid–Electric Regional Aircraft Design and Performance Analysis

The adoption of hybrid–electric propulsion, allowing us to partially replace fuel with batteries and to reduce aircraft in-flight emissions, represents one of the main investigated solutions to mitigate the aviation climate impact. Despite its environmental potential being appealing for a practical application, two main drawbacks limit the actual implementation of this technology: first, the low gravimetric energy density of the batteries restricts hybrid–electric aircraft payload and range capabilities; second, the production of electricity is currently not entirely based on renewable energy sources, hence a non-direct emissions budget may limit the benefit in terms of overall decarbonization. When designing hybrid–electric aircraft, even projecting its actual entry into service in the next decades, it is necessary to take these limitations into account depending on both the more reliable technological forecasts on the development of electric components and on the estimates of electricity production. A proper analysis of the figure of merits related to the operation of such an aircraft, therefore, becomes crucial in assessing the impact related to its introduction into service. In this context, trade-offs between different performance metrics may be needed to efficiently exploit the environmental benefits of such an advanced concept, while limiting the possible drawbacks coming from its utilisation. This paper provides a performance analysis of hybrid–electric aircraft through an assessment of the relevant figures of merit characterizing its operations. In particular, direct and non-direct emissions, climate impact, ground pollution, operating costs, fuel consumption, weight, and a combination of these figures of merit allow us to define a proper development perimeter in which a possible (future) hybrid–electric aircraft can express its maximum potential towards all the aspects of its utilisation. The trade-off analyses provided in this paper allow us to identify more effective paths for the actual development of hybrid–electric aircraft, highlighting the impact of the selected design variables on the performance metrics, and bringing to light also the possible related limitations.