Aircraft Design Research Articles

Transonic Aerodynamic Performance Analysis of a CRM Joined-Wing Configuration

This study examines the aerodynamic performance of a joined-wing (JW) aircraft design based on the NASA Common Research Model (CRM), aiming to assess its potential for efficient commercial transport or cargo aircraft at transonic speed (Mach 0.85). The CRM wing, optimised for transonic flight, was transformed into a JW design featuring a high-aspect-ratio main wing. An initial parametric study using the vortex lattice minimum drag panel method identified viable designs. The selected JW configuration, comprising front and rear wings joined by a vertical fin, was analysed using ANSYS Fluent to understand flow interactions and aerodynamic performance. At an angle of attack (AoA) of −1°, the JW design achieved a peak lift-to-drag ratio (L/D) of 17.45, close to the CRM’s peak L/D of 19.64 at 2°, demonstrating competitive efficiency. The JW’s L/D exceeded the CRM’s between AoA −3° and 0.8°, but the CRM performed better above 0.8°, with differences decreasing at a higher AoA. Based on induced drag alone, the JW outperformed the CRM across AoA −3° to 8°, but flow complications restricted its L/D advantage to a small, low AoA range. A strong shock on the vertical fin’s inboard side due to high incoming flow speed delayed shock formation on the main wing near the joint. Optimising the vertical fin shape slightly improved L/D, suggesting potential for further enhancements or that other design factors significantly affect JW performance. This study provides insights into JW aerodynamics at transonic speeds, revealing its potential benefits and challenges compared to the CRM design.

Geometric description of a gliding grey-headed albatross (Thalassarche chrysostoma) for computer-aided design.

Albatrosses are increasingly drawing attention from the scientific community due to their remarkable flight capabilities. Recent studies suggest that grey-headed albatrosses may be the fastest and most energy-efficient of the albatross species, yet no attempts have been made to replicate their wing design. A key factor in aircraft design is the airfoil, which remains uncharacterized for the grey-headed albatross. Other critical aspects, such as wing twist and dihedral/anhedral, also remain unquantified for any albatross species. This study aimed to fill this gap in the current knowledge by extracting detailed morphological data from a grey-headed albatross wing to recreate digitally. A well-preserved dried grey-headed albatross wing was scanned in the presence of airflow in a wind tunnel, at conditions that represent a grey-headed albatross in gliding flight. Wing cross-sections were extracted and smoothed to produce a series of airfoils along the wing span. The 3D properties such as wing dihedral/anhedral, sweep and twist were also extracted and used to build a CAD model of the wing. Variations in airfoil shape were observed along the wing span, with thicker, more cambered airfoils near the wing base. The model wing's camber was slightly higher, particularly in the arm section, but overall matched flight photographs. The body, tail, and bill were modelled based on available photographs and known dimensions from literature and merged with the wing to form the final bill-body-wing-tail model. This model is based on real grey-headed albatross morphology under aerodynamic pressure, in gliding flight. Although geometric changes due to scanner interference remain a limitation of this method, the extracted geometric data still provide valuable insights into wing performance under varying conditions. The geometry can also be fully parameterized for complex simulations, aiding studies of grey-headed albatross aerodynamics and engineering design, such as in aircraft or wind turbines at similar Reynolds numbers.

Aerodynamic analysis of complex flapping motions based on free-flight biological data

The wings of birds contain complex morphing mechanisms that enable them to perform remarkable aerial maneuvers. Wing morphing is often described using five wingbeat motion parameters: flapping, bending, folding, sweeping, and twisting. However, the specific impact of these motions on the aerodynamic performance of wings throughout the wingbeat cycle, and their potential to inform engineering applications, remains insufficiently explored. To bridge this gap and better incorporate the properties of coupled motions into the design of biomimetic aircraft, we present a numerical investigation of four flapping-based coupled motions during different flight phases (i.e. take-off, level flight, and landing) using a pigeon-like airfoil model. The wingbeat motion data for these four coupled motions were based on real flying pigeons and divided into: flap-bending, flap-folding, flap-sweeping, and flap-twisting. We used computational fluid dynamic simulations to study the effects of these coupled motions on the flow field, generation of transient aerodynamic forces, and work done by different motions on flapping. It was found that, first, the flap-bending motion causes unstable changes in the effective angle of attack (AoA), which affects the attachment of the leading-edge vortex (LEV), thereby producing more lift at smaller bending angles. Next, the flap-folding motion causes the LEV to attach to the wing earlier and regulates the detachment of vortices. Significant changes in the folding angle are used to influence lift generation and the flap-sweeping motion has minimal effect on the flow field structure across the three flight phases. Finally, flap-twisting motion leads to notable changes in the effective AoA, allowing for dynamic adjustments to control aerodynamics at different stroke stages, resulting in less drag during take-off and more drag during landing. This study enhances the understanding of the aerodynamic performance of bird with coupled motions in different flight phases and provides theoretical guidance for the design of bionic flapping-wing aircraft with multi-degree-of-freedom wings.

Research on Optimization Design of Intelligent Aircraft

Demand analysis and concept research of intelligent deform-able aircraft, overall and subsystem design technology of intelligent deform-able aircraft. From the perspective of basic scientific problems and bottleneck technologies, the main problems lie in two aspects, namely: aerodynamics, flight mechanics and flight control of deform-able aircraft, deform-able structure, drive and deformation control. The connotation of intelligent deform-able aircraft, deform-able technical indicators, deform-able materials and structures, and cost-effectiveness analysis. Technical difficulties for each performance indicator mentioned above, some novel technologies and methods are used to improve the performance of cross-medium aircraft, which are mainly divided into variable wing technology, variable blade technology, variable density technology and structural buffer technology.

Design and Aerodynamic Analysis of a Flapping Mechanism for Foldable Biomimetic Aircraft.

This study investigates the unsteady aerodynamic mechanisms underlying the efficient flight of birds and proposes a biomimetic flapping-wing aircraft design utilizing a double-crank double-rocker mechanism. Building upon a detailed analysis of avian flight dynamics, a two-stage foldable flapping mechanism was developed, integrating an optimized double-crank double-rocker structure with a secondary linkage system. This design enables synchronized wing flapping and spanwise folding, significantly enhancing aerodynamic efficiency and dynamic performance. The system's planar symmetric layout and high-ratio reduction gear configuration ensure movement synchronicity and stability while reducing mechanical wear and energy consumption. Through precise modeling, the motion trajectories of the inner and outer wing segments were derived, providing a robust mathematical foundation for motion control and optimization. Computational simulations based on trajectory equations successfully demonstrated the characteristic figure-eight wingtip motion. Using 3D simulations and CFD analysis, key parameters-including initial angle of attack, aspect ratio, flapping frequency, and flapping speed-were optimized. The results indicate that optimal aerodynamic performance is achieved at an initial angle of attack of 9°, an aspect ratio of 5.1, and a flapping frequency and speed of 4-5 Hz and 4-5 m/s, respectively. These findings underscore the potential of biomimetic flapping-wing aircraft in applications such as UAVs and military technology, providing a solid theoretical foundation for future advancements in this field.

History and Future Development of Morphing-Wing Aircrafts

Morphing-wing aircraft can alter the shape of their wings to achieve different flight performances. Such changes are made to achieve the optimum aerodynamic profile for the current flight environment. The morphing wings greatly improve the flight efficiency and reduces the energy loss in different environments. Morphing designs can be categorized into three distinct types based on their fundamental mechanisms: rotation of specific segments or the entire wing, telescoping, and inflation of particular components or the entire wing. With the continuous technological innovation and practical applications, many famous type of morphing-wing aircrafts have left marks in humans aviation history. Although morphing-wing aircrafts have been shown to be mostly withdrawn from service, the research on morphing-wing aircraft has promoted the development of aviation technology and provided valuable reference for the design of modern fighter aircraft. In order to speculate on the future development of morphing-wing aircraft design, this article overviews the history of morphing-wing aircraft, analyses the reasons for the abandonment of morphing-wing design, and finally discusses the potential trend of morphing-wing aircraft. This article may offer a reference for the design of aircraft.

Effect of ultra-high aspect ratio wings and distributed propulsion on the viability of fully electric regional aircraft

PurposeRevolutionary advances in aircraft technology and performance are needed for fuel-efficient and sustainable next-generation air transportation. This study aims to explore the influence of integrating distributed propulsion with ultra-high aspect ratio (AR) wings (UHARW) on the realization of fully electric regional aviation.Design/methodology/approachThe strut-braced wing (SBW) configuration is advantageous for UHARW due to its additional support. A conceptual design and analysis framework for UHARW aircraft with SBW and distributed propulsion configurations is developed by enhancing and integrating several methods and tools. Based on the mission profile and top-level requirements, a fully electric regional SBW aircraft with distributed propulsion is designed and analyzed.FindingsIntegrating distributed propulsion with a high AR SBW configuration in a fully electric regional aircraft results in notable energy efficiencies. The design achieves a 2.85% increase in the lift-to-drag ratio and a 2.62% reduction in drag during cruise. Sensitivity analysis indicates optimal performance with an AR up to 22, beyond which structural weight penalties diminish benefits. The aircraft’s energy efficiency improves by 9.9% during climb and 6% during cruise, highlighting the importance of propulsion integration.Practical implicationsThis research provides a viable framework for designing fully electric regional aircraft by integrating distributed propulsion with high AR SBW configurations. The findings provide practical guidance for enhancing energy efficiency and reducing structural weight, supporting the development of more sustainable and efficient aircraft designs.Social implicationsThe findings support the development of sustainable aviation technologies, potentially reducing the environmental footprint of regional air travel and contributing to global efforts toward greener transportation solutions.Originality/valueThis study presents a comprehensive methodology for designing and analyzing UHARW aircraft with SBW and distributed propulsion, contributing to the feasibility assessment of fully electric regional aviation.

Credibility-Based Multidisciplinary Design Optimization of Hybrid and Fully Electric Aircraft

Aircraft designs for future electric aircraft often have large discrepancies in the underlying assumptions for highly influential design parameters. More optimistic assumptions on these parameters could result in better aircraft performance but include higher risks in the realization of the design in the defined timeline. In this work, the novel concept of design credibility is introduced to be used for quantifying the effect of assumptions on the underlying technologies on the design performance and the risks. For a range of highly important parameters, probability curves have been created that can predict a range of assumed future performance by 2035. A credibility-based multidisciplinary design optimization framework is created, which evaluates the maximum achievable mission ranges for hybrid electric aircraft under credibility constraints. The optimizations are performed using a surrogate-based global optimization routine, the efficient global optimization. With the full framework, the multiple aircraft designs are optimized under a range of credibility limits to create range-credibility Pareto curves. The results show that battery gravimetric energy density is the most dominant factor for the optimization. Motor and airframe parameters have a smaller effect on the achievable range. Their influence on the optimal design depends on the desired credibility level. For high credibilities, the motor is found to be more relevant. For low credibilities, airframe technology improvements are dominant. The shape of the underlying credibility distributions of secondary parameters has a strong effect on their relevance for the optimal configuration.

Zonal Safety and Particular Risk Analysis for Early Aircraft Design

Safety is paramount in aircraft design, and increasing aircraft complexity necessitates safety assessments early in design. For unconventional aircraft with novel propulsion or system technologies, it becomes even more critical to investigate safety as early as possible to avoid unfeasible configurations. In this context, the particular risk analysis (PRA) and the zonal safety analysis (ZSA) are essential to assess early, as they impact the aircraft configuration. These analyses require a three-dimensional (3D) aircraft model and substantial manual effort, limiting the ability to perform rapid iterations required to support design space exploration and multidisciplinary design optimization (MDO). To analyze many aircraft configurations and system architectures, the 3D parametric model and the PRA and ZSA require automation. This paper reviews methodologies for performing the ZSA and PRA from a systems point of view and proposes parametric zone definition, identification of risk zones, and a conceptual-level analysis of the component placement strategy. The effectiveness of the proposed approach is demonstrated with an aft equipment bay of a business aircraft for varying geometrical granularity and system electrification. Overall, the presented method is a step toward integrating system safety analysis into MDO environments, thus increasing conceptual design maturity and reducing development time.

Open-Source Framework for Sizing Hybrid and Electric General Aviation Aircraft

This paper presents FAST-OAD-CS23-HE, an open-source framework that has been developed as an extension of the existing FAST-OAD-GA framework to allow for medium fidelity sizing of hybrid and electric aircraft using component models dependent on operating conditions and sizing criteria. It inherits Overall Aircraft Design methodologies from the original framework and adds a library of models to represent physical components for hybrid powertrains. It also adds a generic methodology that enables the extension to multiphysic simulation for the powertrain and the consideration of synergistic interactions and supports the addition of new components. A graph-based description of the powertrain was chosen to easily describe complex powertrains that could be considered in innovative architectures as well as ease the future interfacing with external tools. In addition to that, the graph-based approach allows the automation of the construction of the design problem, which removes the need for users to handle complex scripts. It has been developed after a comparison of existing methodologies and open-source framework in an effort to bridge the gap in terms of preliminary design of electric aircraft. With the models implemented with the default delivery of the code, two aircraft were studied to serve as a reference to showcase the capabilities of this framework.

Aerodynamic Evaluation of Static and Dynamic Stability Characteristics of Double-Delta Wings

Vortex interactions and breakdown play a critical role in determining the static and dynamic stability of aircraft, particularly at high angles of attack. This study investigates the relationship between vortex interactions and aircraft stability characteristics, focusing on how chord ratio, angle of attack, and sideslip angle influence stability metrics. Utilizing force and moment measurements along with pressure-sensitive paint (PSP) for surface pressure distributions, the results show the effects of varying double-delta wing chord ratios at a target Mach number of 0.15. The stability metrics derived from force and moment measurements demonstrate directional stability improvements with increasing sideslip angle due to larger vortex-induced differential drag induced by advanced windward wing vortex breakdown. This asymmetric vortex breakdown was confirmed through PSP-measured surface pressure distributions. The study metrics revealed trend reversals in lateral stability due to the varying state of vortex systems on different models, and higher reduced frequencies, pitch rates, and chord ratios correlated with greater dynamic instability and sensitivity. This is attributed to the more rapid and extensive vortex breakdown associated with these higher parameters. These findings provide deeper insights into the flow physics governing high-alpha maneuvers, offering a foundation for future research, enhancing the design and performance of next-generation aircraft.

A research of the discrete digital brake valve matching design and control for large aircraft

A research of the discrete digital brake valve matching design and control for large aircraft

Damping orifice design of a civil aircraft's tail bumper

Damping orifice design of a civil aircraft's tail bumper

Simultaneous Design and Trajectory Optimization Strategies for Computationally Expensive Models

Simultaneous design and trajectory optimization aims to find the best possible design of a dynamic engineering system, such as an aircraft, by considering the coupling between a physical system design and its trajectory. Multidisciplinary design optimization (MDO) fully considers this coupling and corresponding design trade-offs. This article discusses the computational efficiency of MDO formulations for design-trajectory optimization. Numerical studies are performed to compare two monolithic MDO architectures and two design-trajectory coupling strategies on aircraft design test problems. The test problems concurrently optimize a climb trajectory, wing design based on a low-fidelity aerostructural analysis, and aircraft sizing variables. The results indicate that surrogate-based coupling is more efficient than direct coupling when there are only a few variables coupling the trajectory and disciplinary models, whereas direct coupling is preferable otherwise. The simultaneous analysis and design (SAND) architecture outperforms the multidisciplinary feasible (MDF) architecture when using direct coupling, whereas the costs of SAND and MDF are comparable with surrogate-based coupling. The results and discussion in this paper provide general guidelines for selecting a computationally efficient approach for simultaneous design and trajectory optimization.

Ducted Fan Design for VTOL Aircraft Flight Mission Based on Bayesian Optimization

Vertical takeoff and landing (VTOL) aircraft have great potential in both military and civil applications. Due to the high power and energy requirements of VTOL and its potential widespread use in the future, it is important to improve the overall efficiency of VTOL aircraft, where one promising way is using the ducted fan concept because of the potentially higher aerodynamic performance and noise shielding effects. The goal of this paper is to adopt an approach that can efficiently include both continuous and discrete ducted fan design variables and further to design and to optimize the ducted fan for conceptual VTOL aircraft design study. Firstly, the open-source Ducted Fan Design Code (DFDC) tool is employed for fast and efficient ducted fan analysis. Then, we formulate the ducted fan design and optimization problem as mixed integer nonlinear programming to include both class-shape-transformation-based parameters and intuitive ducted fan parameters. The performance of the ducted fan was optimized for hovering, cruising, and the overall flight mission based on the Bayesian optimization approach. The results showed that optimization considering only hovering or cruising can enhance the performance of the ducted fan at the corresponding phase, but the overall aircraft performance might not be improved. As such, the whole aircraft flight mission performance was set as the design objective while carrying out the ducted fan optimization, which in the end led to the reduction of fuel consumption from the original 828.41 kg to 713.46 kg, i.e., about 15.9% fuel saving for the selected flight mission.

Crested ibis algorithm and its application in human-powered aircraft design

Crested ibis algorithm and its application in human-powered aircraft design

Analysis of Structural Characteristics of the HALE Joined‐Wing Configuration UAV

This study focuses on a high‐altitude long‐endurance (HALE) joined‐wing configuration UAV and completes a preliminary structural design based on aircraft design indices and the fundamental principles of aircraft structure design. Based on the preliminary structural design scheme and aerodynamic shape, a structural finite element model and a vortex lattice aerodynamic analysis model of the UAV are established, and the aerodynamic loads in typical states are obtained. The aerodynamic loads of the UAV are applied to a finite element model using the multipoint row method, and the structural static characteristics are obtained. The study further explores typical structural dynamic characteristics, including natural mode, static aeroelastic, flutter, and gust response characteristics. A comparison with the structural characteristics of a conventional configuration UAV with the same structural weight reveals that the HALE joined‐wing configuration UAV exhibits significant advantages in structural stiffness, mode characteristics, flutter characteristics, and static aeroelastic characteristics, whereas the gust response characteristics are essentially equivalent to those of the conventional configuration. This superiority can be attributed to the reduced wingspan while providing the same lift and effective support effect of the rear wing on the front (Frt) wings, which enhances the structural stiffness of high‐aspect‐ratio HALE UAVs. This configuration is particularly suitable for deployment in high‐subsonic HALE configurations that require close coordination with conventional tactical aircraft. By comparing with the structural characteristics of the conventional configuration UAV with equal structural weight, the paper comprehensively analyzes the structural characteristics of the HALE joined‐wing configuration and obtains the advantages and disadvantages of applying the joined‐wing configuration in HALE aircraft and defines the design direction, which lays a solid foundation for the engineering application in the next stage.

Numerical investigation on energy absorption characteristics and damage modes of biomimetic thin-walled structures in aircraft

The crashworthiness of aircraft is essential for both airlines and passengers. Creating lightweight protective structures that achieve a balance between weight and impact resistance while also providing excellent cushioning and energy absorption presents a significant challenge for aircraft designers. The desert beetle's exoskeleton demonstrates remarkable strength and toughness, effectively shielding its body from external threats. This study examines the desert beetle's exoskeleton by developing bio-inspired thin-walled models with three distinct bottom structures based on its cross-section. Numerical simulations were used for calculations and model optimization. The research systematically investigates how various design parameters, such as impact angle, number of support plates, and wall thickness, affect energy absorption performance. The findings indicate that increasing the inclination angle notably decreases the energy absorption capacity of the protective structure, while adding more partitions can significantly enhance this capacity. Additionally, changes in wall thickness directly influence the structure's compressive performance. Furthermore, a comparative analysis of the optimized structure's energy absorption characteristics under various conditions is provided. Ultimately, this paper highlights the significance of design optimization for protective structures in micro aerial vehicles and outlines future research directions to better balance performance and practicality.

Contact electric conductivity of carbon fibers tows and anisotropic conductivity of 3D braided carbon fiber / epoxy composite materials

Carbon fiber composites have been widely used for aircraft and vehicle design, while the carbon fiber composites are electric conductive, and the conductivity depends on carbon fibers themselves and contacts among fibers. Among the conductive mechanisms, contact-based electrical conduction plays a pivotal role in determining the overall conductivity of carbon fiber composites. Understanding how to isolate contact conduction from the overall electrical behavior of composite is essential for optimizing composite design for electrical applications. Here we developed a micro-contact model to investigate the longitudinal and transverse electrical conductivity of 3D braided carbon fiber/epoxy resin composites. An analytical model based on the electrical tunneling effect was proposed to calculate the contact resistance between carbon fiber tows. Statistical methods were employed to determine the fiber contact ratio and the effective contact area between carbon fiber tows. Additionally, the electrical resistances of various contact configurations among carbon fiber tows were calculated based on the braided preform structure. To further analyze the conductivity, finite element analysis (FEA) models were constructed, both with and without yarn contacts, to evaluate longitudinal and transverse electrical conductivity. The results revealed that longitudinal conductivity is predominantly governed by continuous carbon fiber tows, whereas transverse conductivity is influenced by through-transverse carbon fiber tows and fiber-to-fiber contacts.

Aerofoil optimization using SLSQP and validation using numerical and analytical methods

Aircraft design optimization is one among the research enriched topic in the aerospace industry, with enhancing aircraft performance, safety, and efficiency numerous being the prime focus areas. The work done demonstrates the application of the Sequential Least Squares Programming (SLSQP) technique over a symmetrical aerofoil “NACA 0012” to improve its aerodynamic performance. The optimized aerofoil is validated using Design and Analysis Tools for Composite Aircraft (DATCOM) and Computational Fluid Dynamics (CFD) methods. The study focuses on optimizing the performance of a symmetric aerofoil, where drag minimization is crucial, subject to list constraints, such as in the design of fuel-efficient aircraft. The results reveal, the optimized aerofoil has a significant reduction in drag coefficient of closer to 11 % between 8° and 10° compared to the initial design. The validation using DATCOM and CFD methods confirms the accuracy and usefulness of the optimization results. Validation error values are found to be negligible when compared to the optimization data, coming in at 5.7% and 6.5% for DATCOM and CFD, respectively. The paper highlights that the SLSQP technique is efficient and reliable optimization method for designing high-performance aerofoils.