Browse Topic: Aircraft structures

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Thermomechanical Fatigue Life Prediction of Grey Cast Iron Brake Rotors Using Advanced Material Models and Elastic-Plastic Fracture Mechanics2026-01-08169/14/2026
A unified thermomechanical fatigue (TMF) life-prediction methodology is presented for lamellar graphite (grey) cast iron brake rotors operating under the severe transient thermal loads that arise in brake dynamometer durability testing. The workflow links four ingredients within a single rotor-level framework: transient nonlinear finite-element analysis, temperature-dependent inelastic constitutive modeling, a mechanism-based short-crack TMF damage model, and an elastic-plastic (nonlinear) fracture-mechanics crack-growth simulation. Two constitutive descriptions are exercised for the structural analysis — the standard rate-dependent Chaboche viscoplastic model available in Abaqus, and a user material subroutine (UMAT) that couples Chaboche viscoplasticity with continuum damage in order to reproduce the tension–compression asymmetry of cast iron. The resulting stress, strain, and temperature histories drive a multiaxial thermomechanical fatigue Damage (DTMF) computation that estimates crack initiation and early extension, after which a nonlinear fracture-mechanics procedure simulates crack-front advance toward through-thickness failure. Both constitutive models correctly localize the crack-initiation site on the rotor inner diameter, consistent with the dynamometer observations; for the loading histories examined, the standard Chaboche model yields lives in closer agreement with test. The crack-growth simulation reproduces the rapid post-initiation propagation seen experimentally and resolves branch-wise differences in crack-front evolution through the rotor section.
Lee, Heewook, Garcia, Arnoldo, Liu, Yi, Hazime, Radwan, Boughanmi, Heni, Kassir, Abdallah
Study on Brake Efficiency Airworthiness Requirements and Verification of Transport Category Aircraft2026-99-14049/11/2026
Braking efficiency is one of the key indicators for evaluating the performance of braking systems on transport category aircraft. The value of braking efficiency is directly related to the safety of aircraft deceleration processes, especially during landing, and it is also critical for civil aircraft operators to improve operational efficiency on routes. This paper presents the airworthiness regulation requirements related to braking efficiency, requirements for aircraft wheels and tires, requirements for runway pavement types, major sources of contaminants, and specific requirements for simulating wet runway conditions using different contaminants. This paper analyzes effective methods for calculating braking efficiency, including the pressure method, torque method, and slip ratio method, and introduces the approaches for acquiring data of relevant parameters. Combining experience from braking efficiency verification work, the paper demonstrates the specific test procedures for the actual measurement of braking efficiency. Based on measured data such as braking pressure, wheel speed, and aircraft speed during braking, as well as the wheel dimensions and rotational inertia of wheels and brakes, the specific braking efficiency values under different calculation methods are derived. The paper compares the differences in braking efficiency values obtained by various calculation methods for similar braking processes, analyzes the causes of these differences, and demonstrates that the accuracy of braking efficiency calculated by different methods is acceptable. Additionally, the same calculation method is applied to compute the braking efficiency of multiple braking deceleration processes, which demonstrates that the method has good repeatability and can be stably used for braking efficiency calculation. This verification method provides a reference for the certification work to ensure that the braking efficiency of transport category aircraft complies with airworthiness and performance requirements.
Feng, Yibo
An Analysis Method for the Static Stability of Helicopter Rotor in Level Flight Based on Flight Test2026-99-14029/11/2026
To provide better data support for the aerodynamic design, flight control system design, and parameter optimization of helicopters, it is necessary to obtain the aerodynamic derivatives of the helicopter rotor based on flight test data and analyze the static stability of the helicopter rotor. This paper breaks through the limitations of aerodynamic testing of helicopter rotors and establishes a quantitative analysis method for the static stability of helicopter rotors in level flight based on flight test data. Based on the flight test data of the helicopter, this study establishes an aerodynamic model of the helicopter rotor and employs a genetic algorithm for parameter identification to obtain the aerodynamic derivatives of the rotor in level flight. The identified parameters are then used to quantitatively analyze the static stability of the helicopter rotor. The results show that the method developed in this study can accurately and effectively obtain the aerodynamic derivatives of the helicopter rotor from flight test data. Furthermore, this method can reliably evaluate the static stability of the helicopter rotor, demonstrating significant value for engineering applications.
Zhao, Jingchao
Design and Validation of Lightweight Composite Load-Bearing Structures for Aircraft Using Topology Optimization and Multiscale Verification2026-99-14089/11/2026
Composite materials have become widespread for use in aircraft load bearing structures due to their ability of reducing structural mass without compromising the required stiffness, strength and safety requirements in the face of aerodynamic, inertial and thermal service loads. This work has addressed with success the development and validation of such an integrated lightweight-design framework applied to a representative composite aircraft load-carrying structure. The workflow exploits SIMP topology optimization and parametric modelling as well as Kriging and support vector regression surrogate models, Latin hypercube sampling and a multi-island genetic algorithm, to screen the low mass design space subject to stress, deformation, buckling and manufacture ability constraints. The optimized FE model contained 2.15M elements. It predicts a max prinicpal stress of 263.4MPa,a stress margin of 4.18, and a tip deflection of 1.24 mm under the 2.0 mm limit, and the minimum buckling factor was 3.47. The prototype test recorded maximum stress at 257.6 MPa, and thermal deflection of 1.27 mm while deviation between simulations and testing remained below 6%. In general, the above results indicate that the surrogate model based optimization coupled by the manufacturing feedback will be able to relate the aircraft composite structure design, fabrication and validation, and can be used as a realistic benchmark for digital engineering analysis of light-weight aircraft structures.
He, Haoming
Research on the Application of Multi-Source Data in Bus Route Network Optimization2026-99-15669/11/2026
This research aims to optimize the bus route network in Shiyan City using bus Origin-Destination (OD) data. By integrating multi-source data, including GDP, population, and bus OD big data from 2018 to 2022, short-term and long-term indicators are forecasted by time-series methods. Shiyan city is divided into 77 Traffic Analysis Zones (TAZs) considering its mountainous terrain, population-industry distribution, and urban planning. A conventional four-stage traffic demand model is applied, calibrated with bus OD data in 2021. The investigation reveals peak-hour bus passenger travel demand of 29,700 short-term and 31,800 long-term person-trips in the city center and key corridors. Bus passenger travel forms a four-vertical and five-horizontal layout in the short term, evolving to a five-vertical, five-horizontal, and two wings pattern in the long term with eastward urban expansion. Accordingly, an optimized and upgraded bus route improvement strategy is devised. In the short term, there are seventy existing bus routes that are adjusted, creating a five-layer bus route network with diverse functions. Long-term plans involve optimizing twenty bus routes and adding eight new routes to align with urban development. This research not only aids an integrated bus route network optimization framework using bus OD data in a time-consuming way, but also provides a sample of bus route network adjustment for a typical mountainous city.
Ye, Qian, Chang, Sheng, Shen, Yucan, Li, Tanfeng, Tian, He, Tian, Shimo, Cen, Jian
Rolling Element Bearing No-Load Torque TestARP5483/1B (Current)9/9/2026
This test method outlines the recommended procedure for performing the no-load rotational starting torque test on airframe rolling bearings. Bearings covered by this test method shall be antifriction ball bearings and spherical roller bearings.
ACBG Rolling Element Bearing Committee
Aerodynamic Load Calculation and Prediction Method for Folded Wing Mechanism2026-99-12899/4/2026
The folding wing mechanism is widely used in aircraft design. Whether the folding wing surface can unfold smoothly determines whether the aircraft can fly normally. Therefore, studying the aerodynamic loads and structural deformations during the unfolding process of folded wing surfaces is very important. The motion process of a folded wing mechanism is a typical fluid-structure interaction (FSI) process. During deployment, the wing surface moves under the combined action of the actuator’s pull and the aerodynamic loads from the incoming flow, while the large deformation of the wing surface during its movement, in turn, affects the aerodynamic loads on the mechanism from the flow field. Considering the FSI effects during the unfolded motion process of the folded wing, simulation was conducted using the ALE algorithm in LS-DYNA to obtain the kinematic and dynamic parameters in the unfolded motion process, and also to get the aerodynamic torque on the wing under different angles and angular velocities. In practical engineering applications, the actuation force of the deployment mechanism can vary due to factors such as the amount and performance of the pyrotechnic material. Consequently, the final velocity and the whole motion process of the wing mechanism will also change. For the calculation of aerodynamic external loads under multiple operating conditions, using the ALE algorithm will consume a large amount of computational time and cost. Given the high computational cost and long computation time of finite element simulations, a BP neural network was established to calculate the aerodynamic loads on the wing surface under different actuation forces. This allows for a rapid assessment of whether significant deformation or damage will occur to the folding mechanism or nearby components during the deployment process.
Wei, Ting, Li, Naitian, Tong, Zongkai
Detection of Pipe Surface Coatings on Ultrasonic Guided Wave Propagation2026-99-12159/4/2026
Coating the surface of pipelines is one of the most crucial and effective methods for inhibiting corrosion and prolonging the operational lifespan of pipelines. The coating acts as a protective shield that isolates the pipeline metal from external corrosive environments. However, once the coating begins to peel off or deteriorate due to aging, mechanical damage, or environmental factors, the exposed metal surface becomes highly susceptible to corrosion. Statistics indicate that over 50% of external corrosion failures in pipelines are directly associated with coating defects. Despite the critical importance of coating integrity, research on the interaction between surface coatings and nondestructive testing methods—particularly ultrasonic guided wave techniques—has remained relatively limited in recent years. In this study, the impact of surface coatings on the propagation behaviors of ultrasonic guided waves in pipeline systems was systematically investigated. Coal tar pitch, a commonly used and cost-effective coating material, was applied to steel pipeline specimens with varying coating lengths. The attenuation rate of the guided wave signal amplitude was measured under different coating conditions to analyze the relationship between coating parameters and acoustic energy loss. The experimental results reveal that the coating significantly affects guided wave propagation, especially in terms of signal attenuation and boundary reflection. Furthermore, the study reveals that ultrasonical guided waves possess strong sensitivity to coating discontinuities and can accurately locate coating boundaries. These findings confirm the potential of guided wave technology for early detection of coating defects and quantitative evaluation of coating adhesion. Moreover, the outcomes provide useful insight for other transportation and aerospace structures that employ multilayer coatings or protective films, such as aircraft pipelines and composite fuselage components, where similar material interfaces and inspection challenges exist. This research provides theoretical and experimental references for improving the reliability of pipeline health status detection.
Xiao, Tianyi, Li, Bing
Nonlinear Modeling and Parameter Identification of Air Rudder System2026-99-12129/4/2026
The modeling accuracy of the air rudder system directly affects the quality of aircraft attitude control. However, the commonly used simplified second-order model cannot accurately represent its nonlinear transfer characteristics. To this end, a dynamic model of the air rudder system considering three types of nonlinear factors, such as saturation, clearance, and dry friction, was established. On this basis, a stepwise identification test modeling method based on frequency characteristic data was proposed. By designing two different excitation levels of test conditions to excite or suppress the influence of some nonlinear factors, the stepwise identification of each unknown physical parameter was completed. The identification results show that the air rudder system model established in this paper can accurately characterize its nonlinear transfer characteristics, and the transfer characteristic curve of the identification results is in good agreement with the measured data.
Wang, Ding, Nangong, Zi-jun, Liu, Bo
Simulation Modeling and Analysis of Landing Gear Brake-Induced Buffeting2026-99-12489/4/2026
This paper establishes a joint simulation model for landing gear vibration problems. Based on the model, the influence laws of different braking control methods, different runway conditions, and different positions of the rear strut on the main landing gear vibration are compared and analyzed. The results show that the runway conditions have a certain influence on the landing gear braking performance and heading vibration; the rear strut landing gear has better vibration response, and the vibration displacement is reduced by 10–20% in all simulation conditions compared with the strut in front.
Huang, Linyu, Lyu, Ning, Chen, Jie
Dynamic Modeling and Robust Active Control of Graphene-Piezoelectric Composite Missile Wings with Elastic Boundary Constraints2026-99-12819/4/2026
To improve the stability and vibration suppression capability of missile wings under complex aerodynamic conditions, this study develops a dynamic model and explores the active control strategy for a graphene-reinforced piezoelectric composite missile wing subjected to elastic boundary constraints. An electromechanically coupled dynamic model with elastic boundary conditions is constructed by employing CLPT, the geometric nonlinearity following the von Karman assumptions, and piezoelectric coupling theory. The system is discretized and solved numerically using characteristic orthogonal polynomials and the Galerkin method. The influences of graphene distribution configurations, material properties, and boundary flexibility on the linear natural frequencies and nonlinear hardening characteristics are investigated. Results show that the X-type graphene distribution significantly enhances the equivalent stiffness and reduces nonlinearity. Boundary flexibility markedly modulates the vibration characteristics; in particular, increased structural flexibility strengthens geometric nonlinearity, leading to noticeable changes in frequency characteristics and hardening degree. A robust state-feedback controller together with a full-order observer is developed using the Linear Matrix Inequality (LMI) framework, and their performance is verified under different parameter disturbances and uncertainties. The control strategy effectively suppresses vibrations while maintaining good robustness, with the best performance achieved under X-type graphene reinforcement combined with thin piezoelectric layers. This study reveals the coupling mechanisms among material distribution, boundary flexibility, and robust control, providing a theoretical basis for the structural optimization and active control design of smart missile wings.
Qin, Shilong, Chen, Jie
Numerical Analysis of the Frequency Acceleration Effect on the Aerodynamic Efficiency of 3-DoFs Flapping Wing2026-99-12889/4/2026
This study examines how frequency acceleration affects the aerodynamic efficiency of a forward flying airfoil by establishing a kinematic model and conducting numerical simulations using the NACA0012 model. Since the aerodynamic force coefficients have been obtained in previous studies, this paper directly utilizes these coefficients to evaluate the effects of different frequency acceleration combinations on aerodynamic efficiency. It is concluded that under the condition of no pitch frequency acceleration, the combination of positive plunging frequency acceleration and sweep frequency acceleration significantly reduces the lift efficiency from 89.7% (under no frequency acceleration) to 18.1%, and can increase the propulsion efficiency from 44.1% (under no frequency acceleration) to 75.5%. Furthermore, under the AM-8 condition, the lift efficiency shows a decreasing trend as the acceleration factor increases. The analysis and investigation of frequency acceleration effect provide a theoretical foundation for enhancing the aerodynamic performance and optimizing the structural design of flapping wing drones.
Kong, Fanwei, Qu, Ligang, Li, Zhandong, Li, Jing, Lao, Yile
Shimmy Dynamics Analysis of a Dual-Wheel Main Landing Gear Considering Side Stay Angular Coupling01-19-02-00078/31/2026
Main landing gear shimmy is jointly affected by tire forces, structural elasticity, damping, and geometric coupling. To investigate the influence of side stay angular coupling on shimmy stability, this article establishes a shimmy dynamic model of a dual-wheel main landing gear considering side stay angular coupling. Numerical continuation bifurcation analysis, Hopf bifurcation frequency mapping, and local sensitivity analysis are then employed to study its influence mechanism on stability boundaries, dominant modes, and multistable behavior. The results show that the horizontal inclination angle of the side stay introduces additional structural coupling between strut torsion and longitudinal bending, causing the longitudinal motion to evolve from a passive response into an important mode participating in shimmy instability. A small horizontal inclination angle can induce the coexistence of multiple stable periodic responses, whereas a larger inclination angle changes the connectivity of Hopf bifurcation curves and forms a new instability branch involving longitudinal motion. Further analysis indicates that adjusting the orientation angle to make the local horizontal inclination angle approach zero can weaken the direct structural coupling between torsion and longitudinal motion and reduce the sensitivity of the longitudinal response to variations in the horizontal inclination angle. These results indicate that the angular design of the side stay should comprehensively consider the coupling effect between the horizontal inclination angle and the orientation angle, so as to avoid multistability and mode transition induced by the side stay angular arrangement.
Wei, Jian, He, Jipeng, Zhang, Jiahao, Zhu, Shixing, Li, Shuangbao, Zhu, Hengjia
Bi-Directional Evolutionary Topology Optimization Design for Rib Structures2026-99-03148/14/2026
The performance of modern high-speed aircraft is intrinsically linked to structural mass. As a key component that generates lift, the shape and lightweight of the wing are crucial for improving aircraft performance. This study employs the bi-directional evolutionary structural optimization (BESO) method to perform topology optimization on the wingrib structure of a modern high-speed fighter aircraft. Minimize the overall strain energy as the objective and use the wing rib volume fraction as the constraint to perform topology optimization design on the wing ribs. Based on element stress/strain energy density criteria, the method iteratively adds or removes material to efficiently construct optimal load-transfer paths within the rib configuration. Following the redesign according to the optimized topology, the structural mass was reduced by 39.236% while satisfying strength and stiffness constraints. Results demonstrate that the BESO methodology effectively generates high-efficiency load-bearing configurations for wing ribs, significantly improving material utilization efficiency and structural performance while substantially reducing wing mass. This research provides an effective approach for lightweight design and performance enhancement of critical load-bearing structures in modern high-speed aircraft.
Zhou, Lei, Wang, Wei, Gong, Quanwei, Zhou, Jingchao, Guan, Shenxiaoge
Design Study of the Landing Gear Door Assembly Unit for the Aircraft2026-99-03408/14/2026
Against the backdrop of the rapidly developing aviation manufacturing industry, there is an increasingly urgent demand for the high-volume and high-quality delivery of aircraft landing gear doors, which are critical components for ensuring flight safety. Traditional assembly methods face numerous bottlenecks, making it difficult to meet the industry’s evolving requirements. Consequently, a design study has been conducted on the assembly units for aircraft landing gear. By analyzing the structural characteristics and assembly process flow of the landing gear doors, the assembly procedures were optimized and reorganized. A pulsatile assembly unit incorporating dual-attitude modular assembly devices, an automatic transportation system, curing devices with heating, and module storage facilities was designed. Digital simulation technology was employed to perform a simulation analysis of the assembly process, verifying the feasibility of the proposed scheme. This production addressed issues such as long curing cycles for liquid gaskets, low efficiency in layered hole-making, and difficulties in transporting modular fixtures. It achieved semi-automation and intelligence in the assembly, curing, and transportation processes of landing gear doors. Compared to the production mode during the development phase, the production cycle for individual products was reduced by 50%, and annual delivery capacity increased by 100%. The research findings provide effective technical support for achieving efficient and high-quality assembly of aircraft landing gear doors.
Bo, Donghai, Gao, Chunlin, Zhou, Houchao, Chen, Yilong
Review of Semi-Active Shock Absorption Mechanisms in Landing Systems01-19-02-00068/13/2026
Effective shock absorption is essential for maintaining stability during landing events. Aerospace systems traditionally rely on oleo-pneumatic struts, while robotic platforms utilize lightweight compliant joints for impact mitigation. Recent advances have shifted attention toward adaptive solutions, including magnetorheological and electrorheological dampers, which can adjust their damping characteristics in real time through sensor feedback and control algorithms. By integrating established mechanical design principles with advanced materials and intelligent control strategies, modern landing systems can achieve improved energy dissipation and enhanced performance under variable and unpredictable conditions. This work evaluates the transition from passive to adaptive shock absorption technologies by examining landing dynamics, the mechanical architectures of conventional and semi-active systems, and the control strategies that enable adaptive damping. The findings indicate that, although passive systems offer reliability and simplicity, they lack the adaptability required for highly variable environments, while semi-active systems provide enhanced performance through real-time modulation enabled by advanced control algorithms. However, challenges related to power requirements, system complexity, material durability, and long-term reliability continue to limit widespread implementation of adaptive technologies. Overall, this review highlights the limitations of passive designs, evaluates the tradeoffs between MR and ER damping technologies, examines the evolution of semi-active control strategies, and identifies the key technical barriers that must be addressed before adaptive shock absorption systems achieve broader operational adoption.
Shah, Rajesh, Patel, Parth, Mittal, Vikram
Airplane Design and Test Considerations for Tire Spray SuppressionARP1904 (Current)8/10/2026
This SAE Aerospace Recommended Practice (ARP) relates considerations and recommendations for design test procedures and test data evaluation for qualification of tire spray deflection devices.
A-5 Aerospace Landing Gear Systems Committee
Experimental and Mechanistic Study on Current Carrying Friction of Sliding Ring Slide in Shaft-Type Oil Distributor under Different Oil Environments2026-99-10058/7/2026
The issue of current-carrying friction wear in the sliding ring slider of a controllable pitch propeller (CPP) oil distributor under shaft current conditions was addressed through the development of a specialized wear test device. Comparative tests were carried out with and without the application of electrical current in order to assess lubrication performance in bio-oil, mineral oil, and gear oil. Under conditions of low electrical current, the device exhibited significant signs of current-induced friction wear, in addition to substantial oil oxidation and the accumulation of deposits within the bio-oil. Conversely, the level of wear experienced was minimal in both mineral oil and gear oil conditions. These results imply that CPP systems utilising bio-oil encounter a considerable risk of wear under current-carrying circumstances. Quantitative analysis revealed that the wear depth of the friction pair in bio-oil under energized conditions reached 0.02 mm, accompanied by the formation of a phase-transformed layer up to 11.2 μm thick, which was approximately twice that observed in mineral or gear oils. Metallographic evidence confirmed severe arc erosion as the dominant wear mechanism, which was significantly exacerbated by the inferior oxidation stability and higher electrical conductivity of the bio-oil. In engineering practice, the utilisation of alternative lubricants is to be given precedence, and the shaft-type oil distributor is to be electrically insulated.
Xia, Miao, Li, Jiyue, Chang, Long, Wu, Rongjia
Research on the Operating Characteristics of a Micro Turbine-Based Emergency Device2026-99-09128/7/2026
To meet the power and electricity supply demands in special scenarios such as fire safety rescue, mine refuge chambers, and explosion-proof and dust-proof environments, a portable emergency rescue device powered by compressed air and driven by a two-stage axial-flow micro-pneumatic turbine is proposed. The pressure and velocity fields of the pneumatic turbine were analyzed using a combination of numerical analysis and experiments. The effects of nozzle number and inlet pressure on the operational characteristics of the turbine and the emergency device were compared. The results show that the maximum ratio of the output torque of rotor 2 to rotor 1 is 12%. The output power of rotor 2 is less than that of rotor 1, with the maximum output power of rotor 2 being 16.5% of rotor 1. The two-stage rotor structure helps to reduce residual speed loss. At the same rotational speed, increasing the inlet pressure of the turbine can enhance its output power. At an inlet pressure of 300 kPa and a rotational speed of 30, 000 rpm, the aerodynamic turbine torque is 13.8 N·m, and the turbine reaches an output power of 42 W. The emergency device, operating in a triple-nozzle mode, shows higher power and efficiency compared to the two-nozzle mode, demonstrating a higher power and efficiency than that observed in a two-nozzle mode. The maximum power output is 28.1 W, with the highest efficiency reaching 24.87%.
Liu, Jiang, Wu, Xi, Gao, Zhiwei, Chen, Bin, Ma, Renjun
683 Guidance for Electronic Shop Reports in Aviation MaintenanceARINC683 (Current)8/4/2026
The purpose of this standard is to provide guidance for the content, format and two-way electronic exchange of data between a Service Provider and the Customer. The standard is focused on the production of an electronic Shop Findings Report by the Service Provider, and to promote automated electronic data exchange.
Aviation Maintenance Committee
Design and Optimization of an External Rotor Permanent Magnet Motor with a Three-Segment Non-Uniform Halbach Array2026-99-01537/31/2026
To further enhance the performance of the drive unit motor, a novel three-segment non-uniform Halbach array magnetic pole structure is proposed, which is applied to an external rotor permanent magnet motor with magnetic pole optimization. First, the overall motor design is carried out according to the requirements, determining the fundamental parameters of the motor. Then, four common magnetic pole structures—conventional arc-shaped, three-segment, Halbach array, and three-segment non-uniform Halbach array—are analyzed. A finite element analysis model of the motor is established for electromagnetic analysis, comparing the air-gap flux density, torque, and torque ripple of the four magnetic pole structures. Finally, optimized parameters for the stator and rotor tooth shapes are determined, and an optimization model is established. The NSGA-II algorithm is employed to optimize the stator and rotor tooth shapes. After optimization, the motor maintains its torque output while reducing torque ripple by 50%, effectively improving its performance.
Zhao, Changle, Yang, Liu
Multi-Objective Topology Optimization of Wing Rib Structures for Additive Manufacturing2026-99-02287/31/2026
With the advance of high-end manufacturing and the rise of green design, lightweight structures have become a central concern in aerospace. Topology optimization offers a principled route to shed mass while preserving performance, yet most additive manufacturing (AM) studies still emphasize process tuning and new materials rather than structural layouts constrained by AM realities. This work targets a representative wing rib from a specific unmanned aerial vehicle (UAV) and formulates a multi-objective topology optimization that explicitly embeds AM constraints. Using the Solid Isotropic Material with Penalization (SIMP) variable-density framework, we couple static stiffness and strength measures with modal objectives so that the optimized rib not only resists deformation and limits stress but also improves the first three natural frequencies, thereby mitigating adverse vibration interactions at the wing level. A compromise-programming strategy balances these competing objectives under volume and manufacturability requirements, including AM-driven minimum feature scales and related geometric restrictions. Finite-element analyses are used throughout the loop to evaluate displacement, von Mises stress, and eigenfrequencies, ensuring that the emerging material distribution is both efficient and physically meaningful. The resulting topology exhibits clearer load paths and smoother stress flow, reduces peak displacements, and delivers a marked rise in the first three natural frequencies. Overall mass is lowered by approximately 55% while meeting all imposed constraints, achieving the dual aims of structural optimization and lightweighting. The study demonstrates that integrating AM constraints directly into the optimization stage yields designs that are performance-robust and fabrication-ready, and it provides a reusable workflow for thin-walled aerospace components such as wing ribs where stiffness, strength, and vibration behavior must be jointly considered.
Zhao, Fei, Zhang, Heran, Li, Xiaoting, Shi, Bowen, Kong, Xiangwei
Study on Energy-related Mechanisms of Aeroelastic Instability of Ultra-Long Flexible Wind Turbine Blades Under Various Working Conditions2026-99-01347/31/2026
With the continuous increase in wind turbine power capacity, ultra-long flexible blades face intensified aeroelastic instability risks due to reduced structural stiffness, enhanced modal coupling, and aerodynamic nonlinearity. In addition to the analysis of basic vibration characteristics, this study focuses on energy-related mechanisms of aeroelastic instability under various working conditions. Using a numerical model integrating Dynamic Blade Element Momentum Theory (DBEMT) and Geometrically Exact Beam Theory (GEBT), over 400 time-domain simulations were conducted to characterize instability onset and development. Results reveal four distinct aeroelastic instability regions, each dominated by specific modes. In Region A, flutter dominated by the 2nd flapwise mode is observed. In Region B, flutter dominated by the 1st edgewise mode is observed. In Region C, flutter dominated by the 2nd edgewise mode is observed. While in Region D, where the medial angle of attack (AoA) of the blade has exceeded the stall angle, stall-induced vibration dominated by the 1st flapwise mode is observed. Energy analysis shows aerodynamic work concentration near the blade tip drives instability, with diverse energy exchange patterns across regions. Except for some operating conditions in region C, where instability is dominated by edgewise energy absorption, most aeroelastic instability conditions are dominated by flapwise energy absorption. Torsional degree of freedom contributes minimally to aerodynamic work, but the torsional vibration exerts a notable influence on the AoA. This, in turn, changes the comprehensive aerodynamic forces impacting the blade as well as the general aeroelastic stability. This study clarifies the relationship between operating conditions and energy-driven instability, offering some reference values for the design work and safety assurance of ultra-long flexible blades of the wind turbine.
Wang, Su, Chen, Jiajia, Zhou, Le, Shen, Xin, Li, Chun, Du, Zhaohui
Implementation Strategies of Requirements Engineering in Commercial Aircraft Airframe Forward Design2026-99-01837/31/2026
Focusing on the requirements engineering activities, this study analyzed the problems in the implementation process of the forward design practice of commercial aircraft airframe, introduced the breakthrough methods, including the convergence and integration with the traditional design process, the supporting work organization model, process optimization, and specification, and proposed the airframe stakeholder need capture model based on the theory of systems engineering. Practice has shown that the requirements engineering implementation strategy introduced in this paper can effectively resolve conflicts and redundancies between the requirements system and the original top-level document system requirements. It ensures clear requirements sources, sufficient basis, reasonable allocation, controllable changes, adequate change assessments, clear design status, and controllable design risks. It effectively overcomes human resource bottlenecks during the early stage of requirements engineering implementation while cultivating talent reserves for systems engineering implementation, saving approximately 23.5 person-years in labor costs. It significantly optimizes non-value-added processes, reducing approximately 100 reports. It unifies the team’s understanding of requirements work, improves coordination efficiency, and significantly improves the requirements validation rate between aircraft-level and system-level requirements by an average of approximately 46%. It assists stakeholders and engineers in systematically and scientifically capturing product requirements during the design phase, with original product design specifications covering approximately 70% of subsystem specifications on average. Given its generality across the airframe forward design domain, the airframe requirement management paradigm established by this implementation strategy holds significant importance for the comprehensive and in-depth application of systems engineering methods in commercial aircraft development.
Sun, Luyan, Chang, Liang
The Influence of Stator Vane Lean on the Rotor Blade Forced Response of an Axial Turbine2026-99-02107/31/2026
Forced response resulting from rotor-stator interaction is a primary cause of high-cycle fatigue (HCF) failure in axial turbine blades. To investigate the mitigating effect of stator vane lean on the forced response of a downstream rotor blade, this paper conducts a numerical analysis based on a fluid-structure interaction (FSI) method, comparing a baseline radial vane with a leaned vane configuration in a single-stage axial turbine. Unsteady computational fluid dynamics (CFD) was used to analyze the unsteady flow field and aerodynamic excitation, and the resulting harmonic pressures were applied to a finite element (FE) model for harmonic response analysis. The results show that, compared to the radial vane, the leaned vane design effectively weakens the potential field and wake interactions by introducing a spanwise phase difference, which significantly reduces the amplitude of the unsteady pressure fluctuations. The harmonic response analysis further validates the effectiveness of this approach, demonstrating that under the first harmonic excitation, the leaned vane configuration reduces the maximum dynamic stress on the rotor blades by 37.7%. This study confirms that stator vane lean is an effective aerodynamic detuning strategy that mitigates the excitation at its source, leading to a substantial reduction in the rotor’s dynamic stress and thus offering a valuable method for improving turbine blade reliability.
Huang, Zhi, Zhang, Ying, Xiong, Zhonggang
Research on Integrated Design and Optimization Method of High Speed Shuttle UUV Rudder and Propeller2026-99-08647/30/2026
Along with the advancement of the maritime power strategy, the research, development, and application of deep-sea space stations are becoming increasingly important. However, since deep-sea space stations mainly rely on acoustic communication, they cannot exchange information with ground stations quickly and accurately. To improve data transmission efficiency, this paper proposes using a high-speed shuttle UUV instead of acoustic communication. In this context, an efficient propulsion system is critical as it enables the UUV to achieve high speed and maintain stability. A propeller meeting the 110.9 N thrust requirement is designed using the chart design method, and the 110BL230-630 brushless DC motor is selected based on motor–propeller matching. This motor has a rated speed of 3000 rpm, rated power of 3000 W, and torque of 9.6 Nm. The performance curve of the NACA0012 airfoil is analyzed to select an appropriate rudder surface. The rudder area (4067 mm^2) is designed in accordance with DNV rules, with the following parameters: tip chord length 40 mm, root chord length 40 mm, and half-span 70 mm. CFD analysis is conducted on the designed propeller and the UUV equipped with the integrated propulsion system. The predicted performance of the P4119 propeller (hydrodynamic parameter deviation ≤ 1%) and the SUBOFF hull (resistance relative error ≤ 3.04%) confirms the accuracy of the CFD method for calculating propeller open-water performance and UUV drag. Through comparative analysis, the optimal rudder–propeller spacing is determined to be 60 mm, as this spacing yields the highest propulsion efficiency.
Wei, Jiaguang, Feng, Xiaowei, Zhao, Fuchen, Wang, Xingke, Xu, Shanzhi, He, Wenxuan
Analysis of the Hot Forming Behavior of AZ91 Magnesium Alloy2026-99-08387/30/2026
This study systematically discussed the high-temperature flow behavior of the Mg-Al-Zn based AZ91 alloy, which has significant application potential in modern aviation and automotive industries. The study was carried out in the temperature range of 250°C-450°C and the strain rate range of 0.001 s^−1 -0.1 s^−1, which met the typical industrial hot processing environment. The analysis of high-temperature flow behavior shows that the flow stress is inversely proportional to the deformation temperature and is proportional to the strain rate. An important finding is that the constitutive model parameters are significantly sensitive to strain, so the strain-compensated Arrhenius constitutive model is developed. The model shows high accuracy in predicting the thermal flow stress of AZ91, and provides a valuable calculation tool for the simulation and optimization of forming processes in aerospace parts manufacturing. The results show that the extruded original microstructure presents slender fine grains, while the deformed sample shows a temperature dependent transformation: the low-temperature bimodal structure evolves into uniform fine grains at intermediate temperature, and the grains begin to coarsen at high temperature. At constant high temperature, low strain rate promotes grain growth and twin formation, while high strain rate refines grains and inhibits twins, and dislocation slip is the dominant deformation mechanism. These findings provide vital guidance and support for optimizing hot working parameters of AZ91, and are particularly important for manufacturing lightweight components in aircraft structures and automotive systems. The established process performance relationship is helpful to develop energy-saving manufacturing strategies for transportation equipment, and supports the goal of reducing weight and improving performance in the industrial field.
Li, Jusen, Chang, Ming, Zhu, Wenyu, Sun, Haoran, Chen, Kaida, Yang, Xiaoyin, Zheng, Zhenhao, Zhao, Shengdun
Research on the Design Technology of Anti-Roll Attachment for Seaplanes2026-99-08037/30/2026
This paper takes a seaplane as the research object, based on the roll damping commonly used in the field of ships, to carry out the applicability analysis and design technology research of the roll damping for the seaplane. A T-tail configuration was selected as the attachment. The design process involved sequentially selecting the horizontal stabilizer airfoil, designing the aspect ratio parameters, and determining the strut airfoil. Consequently, two T-tail design schemes with aspect ratios of 0.76 and 1.53 were proposed. Through the hydrodynamic performance analysis of the T-tail design installed on the seaplane, the advantages and disadvantages of the two T-tail designs in the wave environment are studied. The results demonstrate that the aspect ratio of the T-tail’s horizontal stabilizer directly affects the seaplane’s wave-induced motion response. The proposed design with a larger aspect ratio of 1.53 significantly reduces wave resistance and motion response across various conditions. In the case of a relatively small aspect ratio, the maximum pitching motion is reduced by 38.4%, and the maximum heave is reduced by 59%.
Jiang, Ting, Pi, Xufeng, He, Chao, Wen, Changqing, Li, Xu
A Standardized Mid-Fidelity Aerodynamic Comparison of Four Tiltrotor eVTOL Configurations Using SUAVE and VSPAero2026-99-08397/30/2026
This study compares 4 representative tiltrotor platforms: Joby S4, Archer Midnight, Vertical Aerospace VX4, and Uber eCRM-001 in a typical UAM mission profile under standardized rotor and wing assumptions using an integrated OpenVSP-SUAVE-VSPAero framework. This work aims to isolate the influence of eVTOL configuration from proprietary optimizations on thrust generation and aerodynamic interaction by using standard wing airfoils and a consistent rotor design tool. Vehicle geometries were modeled in OpenVSP. Rotor Operating conditions were obtained from the SUAVE conceptual design platform. Mid-fidelity aerodynamic analysis was done using VSPAero. SUAVE results show a decrease in thrust requirements as the tilt angle decreases, with the most complexity occurring in the transition phase where lift shifts from rotors to wing. Archer Midnight and Vertical Aerospace VX4 show higher hover thrust requirements due to their high takeoff weights. They display localized thrust increase near mid transition due to numerical adjustments made to achieve solver convergence. Joby S4 and Uber eCRM-001 display a smoother thrust requirement trend. VSPAero simulations also show a gradual decrease in thrust from hover to cruise. Joby S4’s continuously active rotor configuration maintained more stable performance than the hybrid configurations, which deactivate lift-only rotors after takeoff. A comparative flight feasibility analysis was conducted, defined as the difference between VSPAero-predicted thrust and SUAVE-required thrust. This analysis reveals that Joby S4 maintains a positive margin across most flight phases. Archer Midnight and Vertical Aerospace VX4 show a marginal deficit in near-cruise phases. Uber eCRM-001 showed negative margins throughout the mission, indicating limited aerodynamic robustness under standardized assumptions. Rotor-wing interactions enhances rotor thrust across all mission segments, while creating periodic pressure oscillations on the wings. Rotor-rotor interactions provide limited near-field benefits that dissipate in forward flight. The findings of this study highlight the significance of eVTOL configuration in determining performance and aerodynamic efficiency.
Sawron, Md Sadat Shahrier
Systematic Assessment of State-of-the-Art Approaches Available for Variable Camber Morphing01-19-01-00057/29/2026
Aerodynamicists around the globe are developing mechanisms and structures inspired by nature that enable variable camber morphing (VCM) for aerodynamic surfaces. The implementation of the VCM mechanism in an airplane wing enhances the performance and stability during various flight segments. The present review article is focused mainly on the up-to-date VCM methods in a qualitative as well as quantitative approach that are specific to Aircraft/unmanned aerial vehicle (UAV) wing configurations. Initial literature discussions are confined to the conventional mechanisms that enable VCM in different aircraft configurations and the added aerodynamic advantages such as lift enhancement, drag reduction, boundary layer separation, and flow control. However, those designs need either external shape optimization or internal structural refinements to ensure the factor of safety (FoS). The modern aviation industry is also focused on bioinspired technology because of the adaptive flying capabilities and stall-delay characteristics. Therefore, a review of bioinspired VCM methods that are assessed based on the aerodynamic potentials is sequentially organized in the article. Additionally, considerations are motivated by the application of various compliant structural patterns for VCM in the aircraft industry. The discussion indicates the prospective benefits of morphing toward the future of the Green Aviation industry.
Manjunath, S. V., Jini Raj, R.
Landing Gear Structural Health MonitoringAIR6168A (Current)7/27/2026
This SAE Aerospace Information Report (AIR) discusses past and present approaches for monitoring the landing gear structure and shock absorber (servicing), opportunities for corrosion detection, methods for transient overload detection, techniques for measuring the forces seen by the landing gear structure, and methods for determining the fatigue state of the landing gear structure. Landing gear tire condition and tire pressure monitoring are detailed in ARP6225, AIR4830, and ARP6137, respectively. Aircraft Brake Temperature Monitoring Systems (BTMS) are detailed in AS1145.
A-5 Aerospace Landing Gear Systems Committee
Research and Application of Flush Adjustment for Multi-Link Retractable Hatch2026-99-16207/24/2026
The adjustment process for multi-link retractable hatches has long relied on personal experience, making it difficult to achieve precise and quantitative length adjustments. This limitation has consistently constrained the efficiency of the adjustment process. This paper aims to analyze the risks and shortcomings in the existing flush adjustment process, simplify the flush adjustment process into a mathematical model, and calculate the required adjustment amount of the actuator length. By simplifying the flush adjustment process and steps, the risk associated with the adjustment process can be reduced, and the efficiency of door step difference adjustment can be improved.
Deng, Qinwen, Shen, Yingdong, Wang, Zhihai, Li, Yixiao, Wei, Xingxu, Gao, Haosen
Numerical Study of Structures for a Next-Generation Supersonic Transport2026-99-16267/24/2026
Because of the increasing requirement for frequent international traveling, developing a new generation of supersonic transport is critical for commercial aviation. The typical features of supersonic transport are a large swept-back wing and thin airfoil, potentially causing excessive tip deflection and triggering aeroelastic divergence. Hence, conducting evaluation, analysis, and optimization of the structures of an SST is essential. This study applied the finite element method to investigate the wing and fuselage structures under aerodynamic loads during cruise for a next-generation supersonic transport aircraft. Deformations and stress contributions were analyzed, showing the feasibility of the structure design and the stress concentration zones requiring reinforcement in the detailed design. Structural optimizations were also conducted, yielding significant weight reduction.
Ding, Menglong, Xu, Zhaoyang, Wang, Yongqiang, Meng, Li, Tan, Jiaxin, Xuan, Jinting, Bie, Dawei, Shao, Lintao
Study on the Aerodynamic Characteristics of Canard Configuration Missile Influenced by Aileron2026-99-16107/24/2026
The canard configuration has been widely adopted in short-range missiles. However, its main drawbacks include difficulties in roll control and a limited angle-of-attack (AoA) range. Compared to conventional canard missiles, the addition of a pair of control surfaces (referred to as “aileron”) behind the canard control surfaces achieves decoupling between the roll channel and pitch-yaw channel. To investigate the influence of ailerons on the aerodynamic characteristics of canard configuration missiles, numerical simulations were conducted for two typical flow conditions: subsonic (Mach 0.5) and supersonic (Mach2.0). The results show that the introduction of ailerons increases the normal force of missiles, causes the center of pressure to shift forward, and reduces the static stability of missiles, thus enhancing their maneuverability. When the ailerons control the roll channel, the effectiveness of the rolling moment remains consistent over the entire AoA range without adverse effects. However, when the canards control the pitch channel, the interference caused by the deflection of the canards on the ailerons leads to increased lift and generates additional nose-up pitching moments, which reduces the pitching moment effectiveness of the missile.
Zhang, Zilun, Xu, Jiasheng, Mei, Zhiwei
Research on the Application of Eddy Current Retarders in Aircraft Arresting Systems2026-99-16217/24/2026
At present, the aircraft arresting system in our country is the fixed water turbine type. This kind of equipment cannot achieve the arrestment of multiple aircraft types, and the arresting distance cannot be adjusted. According to these problems of the aircraft arresting system in our country, the eddy current retarding device is added, based on the water turbine braking device of the aircraft arresting system. It derives the differential equation for an aircraft arresting system with a water turbine brake and eddy current retarder using mathematical modeling. Four types of aircraft parameters are selected, and MATLAB is used as a simulation tool to verify the reliability of the arresting system after installing the eddy current retarder. This research can improve the arresting support ability and make the arresting device meet the arresting requirements of different types of aircraft.
Wei, Yan, Feng, Chunchun, Wang, Jianwu, Li, Binghong, Yang, Yang
Integrated Guidance and Control Design Based on Sliding Mode Control Theory2026-99-16337/24/2026
In order to meet the demand for missile miniaturization and simplify the system complexity, this paper designs a guidance control integration method according to sliding mode control based on the longitudinal plane motion model, which is combined with the theory of sliding mode control. The design realizes tracing of attack angle to line-of-sight angle through sliding mode control of the outer loop, and the tracking of the control volume rudder deflection angle to the virtual control volume angle of attack through the sliding mode control of the inner loop. The stability of the guidance law is also verified by the Lyapunov function. The simulation results show that the guidance law can hit the target successfully, which verifies the feasibility and effectiveness of the design method.
Bai, Jiajun, Ming, Chao, An, Zhichao, Niu, Zhaoqi, Wen, Guangbao
Load Analysis of Flap and Slat Actuators in Aircraft High-Lift Systems2026-99-18027/17/2026
This study develops an end-to-end load analysis scheme for flap and slat actuators, which comprise the aircraft’s high-lift system, and the analysis results are directly integrated into hardware optimization. Because they shoulder heavy responsibilities during the takeoff and landing phases, whether they can remain rock-solid under complex aerodynamic conditions or even remain unmoved in emergencies is directly related to their overall safety performance. This work process is closely linked and includes three major links. First of all, according to the CCAR-25.301 standard, the load envelope under normal working conditions is sorted out, and the limit cases of abnormal faults are exhausted. Subsequently, ANSYS Workbench pulled silk and peeled off the cocoons to capture the peak stress at the engagement between the output shaft and the gear. In the end, the closed-loop verification of the customized test bench made the theoretical calculations and the hardware-measured data exactly the same. The entire package provides designers with hardcore data support, and always uses airworthiness, not convenience, as the criterion when improving actuator performance.
Xu, Yuanze
Flight Test Methodology for Verification of Precipitation Static Protection in Civil Aircraft Radio Navigation Systems2026-99-18097/17/2026
The verification of Precipitation static (P-static) protection for the radio navigation system of civil aircraft is a critical test item for airworthiness certification. However, determining the presence of P-Static on the aircraft fuselage and assessing whether its discharge interferes with the radio navigation system remains challenging, with testing methods still under exploration. By analyzing airworthiness certification test provisions, the necessity of conducting flight tests for P-static protection verification of the radio navigation system was clarified. Based on existing conditions for civil aircraft flight tests, a comprehensive flight test method was proposed to verify the P-satic protection capability of the radio navigation system. This method includes determining external meteorological conditions, measuring electrostatic parameters, and designing aircraft maneuvers and states. The test plan was validated on a test aircraft. Discharge current data measured on a discharger indicates that during the flight of a civil aircraft through cirrus clouds, negative charge accumulated on the aircraft's surface, leading to electrostatic discharge. The maximum peak discharge current recorded was 330 μA. P-satic radiation field data were obtained near the Automatic Direction Finder (ADF) antenna; the radiation energy is primarily concentrated within the 200 MHz range, with some energy distribution still observed between 200 MHz and 500 MHz. Within the 200 MHz range, the signal amplitude exceeds the background noise, and stable peaks appear at multiple frequency points, with the maximum amplitude reaching up to 50 dBm.confirming the presence of a P-Static environment. This achieved the objective of evaluating the functional performance of the radio navigation system in an electrostatic environment, providing technical support for P-Static protection verification flight tests and offering a reference for the practical application of electrostatic protection design.
Han, Chunyong, Wang, Fusheng
Flight Test Analysis Method for Aerodynamic Characteristics of Helicopter Rotor in Level Flight2026-99-18217/17/2026
To analyze flight test failures, ensure flight safety, and provide data support for the aerodynamic design of helicopters, it is necessary to conduct aerodynamic characteristic analysis of helicopter rotors based on flight test data. This article establishes a helicopter rotor aerodynamic model and an aerodynamic parameter identification method in level flight. In this article, we take the flight test data of a helicopter’s level flight performance as an example, and use the genetic algorithm and Particle Swarm Optimization for parameter identification calculation. We obtain aerodynamic parameters such as rotor angle of attack and rotor lift-to-drag ratio in the helicopter’s level flight state, and so on, and analyze the aerodynamic characteristics of the helicopter’s rotor. The results show that the method established in this paper can accurately and effectively obtain the aerodynamic parameters of the helicopter rotor through flight tests. It can also evaluate the aerodynamic characteristics of the helicopter rotor and meet the requirements of the American standard ADS40 for obtaining the aerodynamic characteristics of the helicopter through flight tests. Thus, it has great engineering application value.
Zhao, Jingchao
Key Technologies of Aircraft Flight Test Based on Structural Control2026-99-18257/17/2026
A comprehensive solution integrating advanced sensor technology, structural dynamics models, and intelligent control algorithms is proposed to address the shortcomings of traditional flight testing techniques in monitoring and controlling aircraft structures under complex flight conditions. By establishing precise aircraft structural dynamic equations through fiber optic sensors, an accurate description of the dynamic characteristics of the aircraft structure can be achieved. A distributed structural monitoring system is constructed through FBG to monitor the physical quantities, such as strain and temperature, of key parts of the aircraft in real time during flight testing. Based on the real-time monitoring data, the structural state of the aircraft can be predicted, and the structural response can be actively adjusted by controlling the actuator. The experimental results show that this technology system effectively improves the accuracy of structural monitoring and the effectiveness of control during aircraft flight testing, providing strong guarantees for the safety and reliability of aircraft flight testing, and laying a solid foundation for aircraft structural design optimization and flight performance improvement.
Gao, Sheng
Machine Learning-Based Prediction of Landing Dynamic Response for Bogie Landing Gear2026-99-18297/17/2026
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Zhang, Hong, Fang, Wei, Zhao, Junfeng
Research on Explicit Topology Construction and Shape Optimization via Hole Deformation2026-99-18367/17/2026
Topology optimization provides innovative solutions for lightweight structural design by rationally arranging material distribution. It enhances structural performance while reducing material consumption and structural weight, thereby significantly lowering production and operational costs and generating enormous economic benefits. In the development of topology optimization, the density-based method has gained widespread adoption due to its easy-to-understand principles. However, this method still faces the following challenges when applied to engineering applications. First, the geometric models generated by topology optimization lack explicit parameter descriptions, leading to data interaction barriers with Computer Aided Design (CAD) systems. Second, due to element discretization and density penalty mechanisms, structural boundaries exhibit rough and blurred characteristics. These problems severely constrain the iterative efficiency of structural design and manufacturing feasibility. To address these issues, this paper proposes a strategy for geometric reconstruction and shape optimization of topology optimization results. The reconstruction process begins with extracting isolines from the density field as a set of contour points. These points are subsequently interpolated with B-spline curves to explicitly represent the geometric boundaries. Shape optimization is then carried out by adjusting the positions of the B-spline control points. Compared to post-processing methods based on graphics techniques for topology optimization, which ignore the volume constraint and performance loss, the structures reconstructed in this paper exhibits the following advantages: structural boundaries are smoothed and characterized with explicit parameters, reducing performance loss caused by geometric reconstruction while satisfying volume constraints. This paper successfully establishes compatibility between topology optimization and CAD systems, facilitating the transition from conceptual design to manufacturing.
Tang, Yuting, Li, Yu, Luo, Jiaxiang, Chen, Junwei, Zhou, Weien, Yao, Wen
The Impact of Powerplant on Stall Characteristics of Propeller Aircraft2026-99-18377/17/2026
This study focuses on a compact-layout propeller aircraft, investigating how its powerplant influences stall characteristics via combined theoretical analysis of aerodynamic principles and validation with flight test data. Special attention is paid to the effects of propeller slipstream, appropriate evaluation criteria are selected to assess the aircraft’s high-angle-of-attack performance and stall behavior, and the Weissman chart criteria are further adopted to analyze its lateral-directional departure tendencies. A theoretical analysis of the stall characteristics of compact-layout propeller aircraft is conducted. Through flight test data analysis, the stall characteristics of compact-layout propeller aircraft are studied, with an emphasis on understanding how slipstream effects influence their longitudinal and lateral-directional stall characteristics.
Fang, Shengyou, Yang, Xiaoli, Jiang, Tianjun, Fu, Yi
Dynamic Characteristics Study of the Deployment Process of Aircraft Folding Wing2026-99-18607/17/2026
Folding wing mechanisms are widely applied in aircraft structural design. This design reduces the size of the aircraft, making it easier to store and transport. Whether the foldable wing can successfully deploy determines the completion of the flight mission. Therefore, it is crucial to study the kinematic and dynamic parameters of the mechanism during the deployment process. The deployment of the folding wing typically occurs within milliseconds. The flow field imposes aerodynamic loads on the mechanism, causing it to move, while the large deformation motion of the mechanism, in turn, affects the aerodynamic loads from the flow field. This is a typical fluid-structure interaction (FSI) process. Traditional CFD methods for solving the deployment process in a decoupled manner often result in large errors and cumbersome procedures. To investigate the aerodynamic loads and deformation of the folding wing mechanism during deployment, the ALE algorithm in LS-DYNA was selected to directly solve the kinematic and dynamic parameters of the mechanism in unsteady flow fields, guiding the design of foldable wing mechanisms.
Wei, Ting, Tong, Zongkai, Li, Naitian
Analysis of the Nonlinear Behavior of the Composite Helicopter Horizontal Centralwing Skin2026-99-18327/17/2026
Test results of the composite helicopter horizontal central-wing under symmetric and unsymmetric loads showed that the strain value of the lower skin would turn from negative to positive, showing a nonlinear behavior. FEM results of the linear and nonlinear analytical approach showed a great difference. The strain value of the lower skin remains negative and decreases linearly when using a linear FEM analysis. The strain value of the lower skin would turn from negative to positive when a nonlinear FEM analysis is applied, and this result agrees well with the test results. Besides, the results of the FEM buckling analysis showed that the buckling load of the lower skin is considerably higher than the value at which the skin would show a nonlinear behavior. Therefore, the specific behavior is a result of the nonlinear property of the structure, not buckling.
Wang, Zhe, Zhang, Tiesong, Li, Mengjia, Chen, Puhui, Huang, Zhiwen, Wang, Binwen
Attitude Control of a Variant Flying Wing UAV Based on L1 Adaptive and Fuzzy Clustering2026-99-18587/17/2026
This study presents a full-envelope attitude-stabilisation and trajectory-tracking strategy for morphing flying-wing UAVs operating in highly nonlinear and strongly coupled conditions. The approach integrates fuzzy C-means (FCM) envelope partitioning with L1 adaptive control. Small-disturbance linear models are first generated at multiple altitude–Mach trim points; the FCM algorithm then performs unsupervised clustering in the state space, yielding representative subintervals that capture local flight-dynamic characteristics. The optimal cluster number and fuzziness exponent are selected using the partition coefficient, partition index, partition entropy, and Xie–Beni indices. For each sub-interval, an LQR baseline controller is designed and augmented by an L1 adaptive compensator, where a low-pass filter decouples adaptation from robustness to guarantee specified transient-performance bounds under matched/unmatched uncertainties, actuator saturation, and external disturbances. A feed-forward pre-filter realises online decoupling of the multi-input multi-output channels, thereby enhancing adaptability to variable sweep angles and large aerodynamic variations. Simulations covering low-speed/small-sweep and high-speed/large-sweep scenarios demonstrate that the proposed method sustains robust stability across the clustered envelope, outperforming conventional control schemes and confirming its engineering applicability.
Tang, Longhao, Sun, Xiaoxu, Liu, Changlin
Numerical Investigation of Inverted Airfoils in Ground Effect for Motorsport Applications01-19-01-00047/15/2026
Ground effect plays a critical role in enhancing the aerodynamic performance of race cars by increasing downforce without a proportional rise in drag. Despite its importance, the influence of airfoil geometry on inverted airfoils operating in ground proximity remains underexplored in open literature. This study addresses this gap through a detailed numerical investigation of chord-dominated ground effect using two-dimensional Reynolds-Averaged Navier–Stokes (RANS) simulations. A range of NACA four-digit airfoils is systematically analyzed to isolate the effects of camber, thickness, and camber location on aerodynamic performance in ground proximity. Results show that increased camber enhances downforce and efficiency both in and out of ground effect; thinner airfoils yield higher downforce and efficiency in ground effect; and forward camber locations outperform rearward ones in maximizing downforce contrary to out-of-ground-effect trends. Detailed pressure distribution and flow separation analyses explain the underlying mechanisms, offering actionable guidelines for optimizing ground effect airfoil design in motorsport.
Chowdhury, Rohan, Shukla, Dhwanil
Study on the Effect of Flap Parameters on Hydrodynamic Characteristics of Marine Flap Rudder2026-99-05267/10/2026
By tweaking the flap’s deflection angle, the flap rudder significantly enhances the hydrodynamic performance. This study investigates the influence of the location of the flap rotation axis and the size of the flap’s deflection affect how well the rudder performs in the water, using computer simulations to obtain high-resolution flow-field data. The results demonstrate that the flap rudder consistently generates more lift than your standard rudder. Prior to stall, pushing the flap rotation axis further back results in less lift, but also less drag. For maximum lift at small or moderate angles of attack, a rotation axis located at 0.75 c provides the highest lift coefficient, whereas the 0.85 c configuration combined with δ = 25° offers the best compromise between postponed stall and maintained lift-to-drag ratio. Put the pivot at 85% chord and set the flap deflection to 25 degrees, and an optimal configuration is achieved in terms of lift and drag. The configuration yields a stall angle pushed out to 16 degrees and a maximum lift coefficient that jumps to 3.86. That’s a significant increase of 15.77 % over what you’d get with 15° flap deflection. Ultimately, this research lays the groundwork for designing better flap rudders and gives us some serious pointers on how to increase the performance of ship rudders in the real world.
Liu, Zirong, Wang, Jianming
Helicopter Engine-Rotor System CompatibilityARP704A (Current)7/2/2026
This SAE Aerospace Recommended Practice (ARP) recommends a methodology to be used for the design, analysis and test evaluation of modern helicopter gas turbine propulsion system stability and transient response characteristics. This methodology utilizes the computational power of modern digital computers to more thoroughly analyze, simulate and bench-test the helicopter engine/rotor system speed control loop over the flight envelope. This up-front work results in significantly less effort expended during flight test and delivers a more effective system into service. The methodology presented herein is recommended for modern digital electronic propulsion control systems and also for traditional analog and hydromechanical systems.
S-12 Powered Lift Propulsion Committee
Integrated DC Boost Charger in Post-800V Architecture with Open-End Winding Machine – Magnetic-Domain Modelling and Torque Analysis2026-01-07397/1/2026
Next-generation powertrain architectures proposed within EU Horizon projects adopt operating voltages above 800 V, providing improvements in efficiency as well as reductions in copper usage and system weight. However, post-800 V vehicles must remain backward compatible with existing 400 V and 800 V charging infrastructure, which requires the installation of an additional onboard DC boost charging unit on the vehicle. This paper proposes an integrated DC boost charging solution that reutilizes the open-end winding electric machine and the traction inverter of the electric powertrain, enabling backward compatibility while further reducing system cost and weight. In charging mode, the electric machine is repurposed as a passive inductive component, imposing a strict requirement of stationary operation with zero torque generation, which fundamentally differs from the driving mode characterized by rotor rotation and electromagnetic torque production. Consequently, conventional electric machine modeling approaches based on the rotor-oriented reference frame are not applicable to charging operation due to the unsymmetrical and unbalanced three-phase currents in the machine windings. To evaluate the machine behavior and develop charging control strategy, this paper introduces a magnetic-domain model based on physical model using phase self- and mutual-inductance parameters, from which the electromagnetic torque is directly derived based on the interaction between magnetic flux and phase currents. The simulations compare the charging current ripple and electromagnetic torque generation of a stationary open-end winding machine under two charging configurations: open-winding charging and neutral-point charging. The results show that the open-winding charging configuration exhibits lower current ripple than the neutral-point charging configuration due to higher inductance utilization. However, a non-zero charging torque is generated in the open-winding charging configuration and is strongly dependent on rotor position. The specific rotor positions corresponding to zero torque are identified and used to optimize the charging process.
Wang, Haoran, Kallur-Krishnamoorthy, Rajesh, Neuhaus, Christoph, Andert, Jakob
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