Aircraft Design Research Articles

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.

Differences in large aircraft design between military and civil perspectives

Military transport aircrafts and civil aircrafts are important parts of the aviation field. With the development of aviation technology and the specificity of aircraft functions, the design of military transport aircraft and civil aircraft gradually differs according to application scenarios. However, in the aircraft design, military transport aircrafts and civil aircrafts still have a lot of mutual references. Analyzing the differences between them and the reasons for the differences may contribute to the design and development of military transport aircraft and civil aircraft in the future, and provide reference suggestions for the design of civil aircraft in the context of the civil-military integration. In this article, the application scenarios and functions of military transport aircraft and civil aircraft are analyzed, as well as the special situation of civil aircraft research and development. This article may offer a reference for the future research and development of military transport aircraft and civil aircraft.

Study on development of aircraft design theory

Nowadays, the aircraft has become a very important part of human life. The invention of the aircraft is a shining point in human civilization. During the development of aircraft, there have been significant changes in aircrafts appearance, power systems, design theories, and applications. In order to provide a clearer understanding of the development process of aircraft and lay the groundwork for future development of the aircraft, this article reviews the three important stages in the development of aircraft and elaborates on the development of aircraft from the perspectives of structural changes, theoretical updates, and applications. While introducing the development process, this article emphasizes the difficulties at each stage and the measures to solve them. In a hundred years of development, human beings have evolved from relying solely on the experience and imitation of birds in the early stages to developing and applying aerodynamics and then combining theory and practice to design.

Evaluation of feasibility of commercial supersonic flight based on aeroacoustics

The drive to attain ever higher speeds, to be able to travel ever faster fuels the research and development for a commercial supersonic aircraft. This has previously led to the Concorde which travelled at more than twice the speed of sound. Now, in addition to business considerations about economic viability, supersonic aircraft must be quieter and emit less emissions. Considering the 20 years that have elapsed since Concordes retirement, this study aims to reevaluate the current challenges and limitations to achieving commercial supersonic flight again, in the context of noise. Identifying sonic booms and jet exhaust noise as two main challenges, it reviews current shape optimization methods, plasma as a sonic boom mitigator, sonic boom circumvention, chevron nozzles, variable cycle engines, engine positioning, and their corresponding limitations. Some of the methods have been refined for use and application in final stage design and manufacture of certain supersonic aircraft which indicates a certain feasibility.

Control-Oriented Modeling for Flexible Aircraft

Flexible aircraft designs with high-aspect-ratio wings and lightweight structures are increasingly adopted to achieve improved fuel efficiency. To design a controller for a flexible aircraft, a low-order model of its dynamics that captures the aeroelastic behavior is needed. One approach to establishing such a low-order model is to extend the six-degree-of-freedom rigid aircraft model with additional elastic states. However, most of the existing models along these lines are based on simplified aerodynamics models (e.g., experimentally corrected aerodynamic coefficients), which limits the applicability of such low-order models in early design stages. In this work, a semi-analytical model of flexible aircraft is established through the combination of the dynamics of elastic body and the numerical linearization of high-order structure and aerodynamics models. The proposed model is derived in the body-fixed axes formulation, represents full flight dynamics (both longitudinal and lateral), and preserves the physical meanings for the states and all the derived terms. Static residualization is also adopted to enhance the model’s accuracy with a limited number of elastic states. Using the proposed approach, low-order semi-analytical models are exemplified for different complexity aircraft representations and verified against the corresponding nonlinear high-order models.

On ecologically-safe high-speed vehicles: Conceptual design study of the next generation supersonic transport

Space-age technology makes it possible to travel faster than the speed of sound from one continent to another one or even to make suborbital flight as a space tourism. The existing technology challenge is to bring this innovative way of travel without damaging the environment to ensure human safety and to preserve environment balance. The sonic boom issue is one of the concerns when flying faster than sound. The issue must be taking into account at the stage of developing environmentally friendly high-speed vehicle. The next generation supersonic transport is fundamentally different from subsonic medium- and long-range aircraft in a breakthrough feature: it ensures a long-term supersonic cruise flight in the range of Mach numbers 1.6–1.8. For a successful implementation of the civil supersonic project at a new stage of technology development, it is necessary to solve a number of scientific and technical problems. In the present paper some of them are under discussion. In particular, the addressed issues are as follows: how to achieve a high level of aerodynamic efficiency at supersonic cruise along with low sonic boom; how to fit into low noise requirements at take-off and landing modes of supersonic aircraft with a moderate-bypass-ratio engine; how to implement a wing with high load factor and fuselage with long nose part to fit into required airframe structural stiffness, etc. Also, new technology approaches in multidisciplinary optimization task to achieve aircraft design goals of low drag, low boom and low noise characteristics are discussed. A few examples of optimal supersonic aircraft configurations along with passenger cabin are given. The paper was presented at the X-th IAA Symposium “Space Flight Safety” in St.-Petersburg on June 2023.

Analysis Leading to the Design of a Hybrid Gas-Electric Multi-Engine Testbed

Given the increase in air traffic, the main challenges in aircraft design are in-flight emissions and noise heard by the community. These problems have thus far been solved by incremental improvements in aerodynamics, engine technology and operation. To dramatically reduce aviation’s carbon footprint towards an environmentally friendly air transport system, alternative propulsion concepts are one of the promising areas of research and first applications. In this context, the goal of integrating a hybrid-electric powertrain with a suitable airframe is to increase efficiency while reducing in-flight emissions, reduce noise for the community, drive down direct operating costs and increase reliability. This article presents an inexpensive approach to testing small, manned aircraft with a hybrid fuel–electric propulsion system. First, the design assumptions of the research flying platform are presented. Next, modifications of the existing two-seater glider are analyzed. These modifications are necessary to fit the fuel–electric hybrid propulsion system. The analysis allows us to select the elements of an appropriate hybrid electric system. It also shows that this type of small experimental propulsion system can be mounted on a two-seater aerobatic glider without significant structural modifications and still comply with the most important points of the Certification Standard-22. Finally, the design of the ground test stand for the propulsion system is described. It is believed that a thorough examination of the propulsion system on the ground will reveal both the advantages and disadvantages of the system. This should facilitate the successful installation of the system under study on a flying aircraft.

An easy-to-produce HIS-based MIMO radio altimeter antenna design for aircraft

Purpose The purpose of this study is to design a radio altimeter antenna whose production process is facilitated and can work with multiple-input multiple-output (MIMO) properties to provide space gain on the aircraft. Design/methodology/approach To create an easy-to-produce MIMO, a two-storied structure consisting of a reflector and a top antenna was designed. The dimensions of the reflector were prevented to get smaller to supply easy production. The unit cell nearly with the same dimensions of a lower frequency was protected through the original cell design. The co-planar structure with the use of a via connection was modified and a structure was achieved with no need to via for easy production, too. Finally, the antennas were placed side by side and the distance between them was optimized to achieve a MIMO operation. Findings As a result, an easy-to-produce, compact and successful radio altimeter antenna was obtained with high antenna parameters such as 10.14 dBi gain and 10.55 dBi directivity, and the conical pattern along with proper MIMO features, through original reflector surface and top antenna system. Originality/value Since radio altimeter antennas require high radiation properties, the microstrip antenna structure is generally used in literature. This paper contributes by presenting the radio altimeter application with antenna-reflective structure participation. The technical solutions were developed during the design, focusing on an easy manufacturing process for both the reflective surface and the upper antenna. Also, the combination of International Telecommunication Union’s recommended features that require high antenna properties was achieved, which is challenging to reach. In addition, by operating the antenna as a successful MIMO, two goals of easy production and space gain on aircraft have been attained at the same time.

The Critical Threshold of The Relationship Between Take-Off Load And Powertrain Load of the Aircraft

The critical threshold of the relationship between take-off load and powertrain load of the aircraft has long intrigued researchers and posed significant challenges. Delving into this subject, extensive research has been conducted to comprehend the intricate dynamics between these two variables. This thesis aims to contribute to this ongoing investigation by analyzing and drawing conclusions based on observed load variations and their impact on power system functionality. The study encompasses a comprehensive examination of various aircraft types, ranging from ultralight aircraft to wide-bodied aircraft and Unmanned Aerial Vehicles (UAVs). Each aircraft category presents unique characteristics and demands distinct engine requirements, further complicating understanding the take-off load to powertrain load relationship. By meticulously studying the changes in loads during the crucial take-off phase, this research aims to uncover valuable insights into the essentiality of an efficient power system. The findings of this study have the potential to enhance aircraft design and operations, ultimately leading to safer and more optimized flight experiences.

On the use of filament-based free wake panel methods for preliminary design of propeller-wing configurations

With distributed propulsion and electric vertical take-off and landing aircraft on the rise, fast and accurate methods to simulate propeller slipstreams and their interaction with aircraft components are needed. In this work, we compare results obtained with a filament-based free wake panel method to experimental and previously validated numerical data. In particular, we study a propeller-wing configuration at zero angle of attack and the aerodynamics of the blade-resolved slipstream interaction with the wing. We use a prescribed wake on the wing and a free wake on the propeller, which greatly accelerate the computations. Results indicate that, while forces are overpredicted due to the inviscid nature of the panel method, the free wake is able to capture the slipstream deformation and shearing with remarkable success. We find that a filament-based free wake panel method can be a useful tool for propeller-wing interaction in preliminary aircraft design.

Mechanical characteristics determination of aircraft wing carbon plastic panel

The paper presents the method of calculating the mechanical characteristics of multilayer composite panels. The optimal sequence of laying out monolayers was selected. The mechanical behavior of the composition is determined by the ratio of the properties of the reinforcing elements and the matrix, as well as the strength of the connection between them. Among the most important requirements for the designs of modern aircraft, we can mention the minimum weight, the maximum stiffness and strength of the nodes, the maximum service life of the structures in operational conditions, and high reliability. With the help of the developed methodology, the elastic properties of the composite material with different angles of laying layers were determined. Calculations of the mechanical characteristics of carbon-plastic panels made of carbon tape and carbon fabric are given.

Investigation of viscous supersonic laminar flows around F-16 airfoil: experimental, numerical, and analytical approaches

Abstract This research paper primarily focuses on the behavior of viscous supersonic laminar flows around the F-16’s NACA 64A-204 airfoil, while also extending its scope to Shock-Wave/Boundary-Layer Interactions. The aim is to evaluate and compare methodologies for accurately characterizing these crucial aerodynamic phenomena. A unique experimental setup was developed, featuring mock-ups of F-16 airfoil equipped with pressure taps, and tested in the Supersonic Burst Wind Tunnel AF300. Computational Fluid Dynamics simulations were conducted using Ansys Fluent 2022 R2 and were supplemented by our previously established analytical model was adapted to our specific airfoil case, following calculations of the wing section equation. Key aerodynamic parameters such as lift coefficient, drag coefficient, Local Mach numbers, and the characteristics of the shock waves formed around the airfoil were examined. The study validates the NACA 64A-204 mock-up, with average errors for key parameters and 1st and 2nd Pressure Taps between the three adopted approaches remaining below 2.5%. The findings contribute valuable insights into the fundamental physics of viscous supersonic laminar flows, offering immediate applications to the design of high-speed aircraft and other advanced aerospace technologies. Additionally, the validated mock-up enhances the research capabilities of the Supersonic Burst Wind Tunnel AF300. Ultimately, this study serves as a foundational reference for optimizing aerodynamic surfaces, thereby facilitating advancements in key vehicle performance metrics such as manoeuvrability and fuel efficiency.

A Value-driven Concurrent Approach for Aircraft Design-Manufacturing-Supply Chain

ABSTRACT The research activity proposed in this paper is framed within the context of the concurrent engineering applied to the complex aeronautical system development. The main objective is to extend the aircraft design parameters with those of manufacturing and supply chain including, among others, logistics aspects, quality management, risk production, resources and materials availability. This surely complicates the design problem due to an enlargement of the alternatives populating the solutions tradespace. However, it provides a great opportunity to gain agility, variety and competitive advantages in the nowadays global market. The formulation and implementation of the new value-driven methodology, here-proposed, offers advantageous benefits to the decision-maker, as also highlighted by the aeronautical application case addressed in this paper.

Airfoils optimization based on deep reinforcement learning to improve the aerodynamic performance of rotors

Airfoil optimization is the key to improving the aerodynamic performance of a rotor. However, conventional optimization approaches cannot modify the airfoil shape intelligently in the way that an aircraft designer would. Because the optimization process is largely uninterpretable and ungeneralizable, the optimization knowledge and experience cannot be extracted and applied to similar optimization tasks. To address these issues, we propose an optimization framework for rotor airfoils based on deep reinforcement learning (DRL). Our DRL-based framework is capable of learning an interpretable and generalizable optimization strategy for alleviating the dynamic stall of a rotor airfoil. First, to enhance the efficiency of airfoil dynamic stall optimization, a deep neural network is trained to predict the dynamic stall hysteresis loops of rotor airfoils as a surrogate model. The asynchronous advantage actor–critic reinforcement learning algorithm is employed to train and learn the optimization strategy for alleviating the dynamic stall of the rotor airfoil. Next, the OA212 rotor airfoil is optimized using the well-trained optimization strategy. The results show that the dynamic stall characteristics of the airfoil are improved after optimization. The lift coefficients of the optimized airfoil are significantly enhanced, and the drag and moment coefficients peaks are reduced by 46.3% and 73.8%, respectively, compared with the baseline airfoil. Then, 20 airfoils are optimized using the well-trained optimization strategy to evaluate the generalizability of the dynamic stall optimization strategy. The results demonstrate that the optimization strategy learned by DRL for the rotor airfoil optimization is generalizable. Finally, the numerical simulation results comparing a rotor with baseline airfoils to one with optimized airfoils demonstrate that the aerodynamic performance of the optimized rotor is superior to that of the baseline rotor.

Analysis of the Pneumatics principles of several aircrafts

In recent years, the advancement of science and technology, particularly the development of flight control technology, has driven the progress of aircraft technology, which facilitates the rapid development of many kinds of aircraft. Pneumatics, the mechanics of gas flow, is used to study aerodynamics. In the design and manufacturing of aircraft, gas flow has a significant impact on the movement, control, attitude, stability, and other aspects of the aircraft. This paper describes the basic Pneumatics principles in aircraft design: aerodynamics is the discipline that studies the interaction between airflow and aircraft, it is the core foundation of aircraft external shape design, a pivotal discipline in overall design, and a prerequisite for conducting design analyses in fields, it plays a crucial role in aircraft design and force analysis for the aircraft, and this paper also introduces the aerodynamic layout design and aerodynamic characteristics of tilt-rotor Unmanned Aerial Vehicle (UAV), multi-rotor aircraft and bionic flapping wing aircraft, so as to offer some references for future study of air vehicles.

A New Range Equation for Hybrid Aircraft Design

A new Range Equation for a hybrid-electric propeller-driven aircraft was formulated by an original derivation based on the comparison of Virtual Electrical Aircraft (VEA) and Virtual Thermal Aircraft (VTA) range equations. The new formulation makes it possible to study the range of a hybrid aircraft with pre-established values of electric motor usage rate. The fuel and battery mass are defined "a priori", and do not depend on the power split, so even the aircraft’s total mass is constant. The comparison with the typical range formulas available for hybrid aircraft was made on the basis of a reference composite VLA category aircraft manufactured by the CFM Air company. The analysis carried out shows that there is an optimum hybridization level as a function of the pre-set specific energy of the batteries system.

Head Flail Corridors From Sled Impact Acceleration Tests for Use in Occupant-Centric Vehicle Design.

In aircraft crashes, injuries to the head and upper torso are frequently reported, with head injury reported most frequently of all body regions. Because preventing flail of the head and body is of utmost importance for occupant survival, the Aircraft Crash Survival Design Guide (ACSDG), the guide to crashworthy aircraft design, published flail envelopes. However, the ACSDG flail envelopes are based on a single test with an anthropomorphic test device subjected to a frontal acceleration. In this article, human research volunteer (HRV) response data are used to calculate head flail corridors and evaluate the ACSDG flail envelopes. Data from HRV sled tests were obtained from the historical Naval Biodynamics Laboratory collection of the Biodynamics Data Resource. Digitized high-speed film for each test was tracked and processed to represent the head flail response in a format amenable to corridor development. Time-based and position-based head flail corridors were developed for groups of exposure-matched tests and then compared to the ACSDG flail envelopes. A collection of 714 HRV sled tests conducted in six different impact directions ranging from 3 to 15 g was used to develop time-based and position-based head flail corridors for 39 match groups. The ACSDG vertical limit and anteroposterior limit and curve were not exceeded by the flail corridors, but the lateral limit and curve were exceeded by 4.6 cm to 15.8 cm. The flail corridors provide a useful baseline for representing the well-restrained occupant response at lower, non-injurious exposure levels and across multiple impact directions. Under these conditions, the ACSDG lateral limit and curve are not adequate. At higher exposure levels or with modified restraints, seating, or equipment, the ACSDG vertical limit and anteroposterior limit and curves may also be inadequate.