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Aerospace
Volume 12
Issue 9
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Aerospace, Volume 12, Issue 9 (September 2025) – 72 articles

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31 pages, 7404 KB  
Article
Multi-Stage Coordinated Azimuth Control for High-Precision Balloon-Borne Astronomical Platforms
by Yulang Cui, Jianghua Zhou, Yijian Li, Wanning Huang and Yongqi Liu
Aerospace 2025, 12(9), 821; https://doi.org/10.3390/aerospace12090821 - 11 Sep 2025
Abstract
This study investigates multi-level coupled dynamic issues in near-space balloon-borne astronomical observation platforms subjected to multi-source disturbances, proposing an integrated azimuth pointing control scheme combining unified modeling with composite control strategies. A nonlinear dynamic model is established to characterize inertial coupling effects between [...] Read more.
This study investigates multi-level coupled dynamic issues in near-space balloon-borne astronomical observation platforms subjected to multi-source disturbances, proposing an integrated azimuth pointing control scheme combining unified modeling with composite control strategies. A nonlinear dynamic model is established to characterize inertial coupling effects between the gondola system and secondary gimbal platform. The velocity-loop feedback mechanism utilizing fiber-optic gyroscopes achieves base disturbance decoupling, while an adaptive fuzzy PID controller enhances position-loop disturbance rejection capabilities. A gain adaptation strategy coordinates hierarchical control dynamics, complemented by anti-windup constraints safeguarding actuator operational boundaries. Simulation verifications confirm the exceptional high-precision pointing capability and robust stability under representative wind disturbances and sensor noise conditions. The system maintains a superior control performance across parameter perturbation scenarios, demonstrating consistent operational reliability. This study provides an innovative technical paradigm for precision observation missions in near space. Full article
(This article belongs to the Special Issue Design, Characterization and Operations of Lighter-than-Air Flying Vehicles)
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18 pages, 3270 KB  
Article
The Effect of Combustor Material for Micro-Propulsion Systems
by David M. Dias, Pedro R. Resende and Alexandre M. Afonso
Aerospace 2025, 12(9), 820; https://doi.org/10.3390/aerospace12090820 - 11 Sep 2025
Abstract
The increasing demand on combustion-based micro-power generation systems, mainly due to the high energy density of hydrocarbon fuels, created a great opportunity to develop portable power devices, which can be applied on micro unmanned aerial vehicles, micro-satellite thrusters, or micro chemical reactors and [...] Read more.
The increasing demand on combustion-based micro-power generation systems, mainly due to the high energy density of hydrocarbon fuels, created a great opportunity to develop portable power devices, which can be applied on micro unmanned aerial vehicles, micro-satellite thrusters, or micro chemical reactors and sensors. Also, the need for better and cheaper communications networks and control systems has led space companies to invest in micro and meso satellites, such as CubeSat. In this study, we conducted a comprehensive and meticulous study of micro-combustion within wavy channel micro-propulsion systems, which can be applied on micro unmanned aerial vehicles or CubeSat. The primary objective was to gain a deeper comprehension of the dynamics within these complex non-linear geometries and analyze the effect of different materials on the combustion dynamics and propulsion efficiency. Full article
(This article belongs to the Topic Theoretical, Numerical and Experimental Studies on Clean Energy and Combustion, 2nd Edition)
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46 pages, 8516 KB  
Review
A Review of Advancements in Inspection, Manufacturing and Repair, and Robots for On-Orbit Servicing, Assembly, and Manufacturing (OSAM) of Spacecraft
by Kayla Dremann, Motaz Hassan, Isabelle Davis, Ashton Vicente Orosa, Natasha Ninan, Ajay Mahajan, Xiaosheng Gao and Siamak Farhad
Aerospace 2025, 12(9), 819; https://doi.org/10.3390/aerospace12090819 - 11 Sep 2025
Abstract
Since the first successful on-orbit repair mission in 1984 to the Solar Maximum Mission (SMM) satellite, considerable progress has been made in the field of On-orbit Servicing, Assembly, and Manufacturing (OSAM) of spacecraft using either human-guided or autonomous robots. This article aims to [...] Read more.
Since the first successful on-orbit repair mission in 1984 to the Solar Maximum Mission (SMM) satellite, considerable progress has been made in the field of On-orbit Servicing, Assembly, and Manufacturing (OSAM) of spacecraft using either human-guided or autonomous robots. This article aims to provide a review of state-of-the-art efforts in this field and the necessary technologies to achieve the ultimate objective of autonomous spacecraft repairs while in orbit. The article covers the literature relevant to OSAM, including a brief overview of OSAM, inspection technologies, manufacturing and repair technologies, state-of-the-art robotic technologies capable of performing the required tasks, and intelligent path planning of robots. The article also highlights the research’s location, timeframe, and public versus private sector efforts, and outlines future directions in this field. This article aims to foster a community of researchers and public-private partnerships working towards the common objective of autonomous robotic inspection and repair of on-orbit spacecraft. Full article
(This article belongs to the Section Astronautics & Space Science)
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20 pages, 3507 KB  
Article
Aerodynamic Design Optimization for Flying Wing Gliders Based on the Combination of Artificial Neural Networks and Genetic Algorithms
by Dinh Thang Tran, Van Khiem Pham, Anh Tuan Nguyen and Duy-Trong Nguyen
Aerospace 2025, 12(9), 818; https://doi.org/10.3390/aerospace12090818 - 10 Sep 2025
Abstract
Gliders are engineless aircraft capable of maintaining altitude for extended periods and achieving long ranges. This paper presents an optimal aerodynamic design method for flying wing gliders, leveraging a combination of artificial neural networks (ANNs) as a surrogate model and genetic algorithms (GAs) [...] Read more.
Gliders are engineless aircraft capable of maintaining altitude for extended periods and achieving long ranges. This paper presents an optimal aerodynamic design method for flying wing gliders, leveraging a combination of artificial neural networks (ANNs) as a surrogate model and genetic algorithms (GAs) for optimization. Data for training the ANN is generated using the vortex-lattice method (VLM). The study identifies optimal aerodynamic shapes for two objectives: maximum flight endurance and maximum range. A key finding is the inherent conflict between aerodynamic performance and static stability in tailless designs. By introducing a stability constraint via a penalty function, we successfully generate stable and high-performance configurations. For instance, the stabilized RG15 airfoil design achieves a maximum glide ratio of 24.1 with a robust 5.1% static margin. This represents a calculated 11.5% performance reduction compared to its unstable theoretical optimum, quantitatively demonstrating the crucial trade-off between stability and performance. The methodology provides a computationally efficient path to designing practical, high-performance, and inherently stable flying wing gliders. Full article
(This article belongs to the Section Aeronautics)
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16 pages, 2410 KB  
Article
Constitutive Model Based on Stress Relaxation for Composite Modified Double-Base Propellants and Master Curve of Relaxation Modulus
by Yao Li, Jinsheng Xu, Changsheng Zhou, Xiong Chen and Xiumin Yang
Aerospace 2025, 12(9), 817; https://doi.org/10.3390/aerospace12090817 - 10 Sep 2025
Abstract
This study investigates the constitutive model and relaxation modulus master curve of composite modified double-base (CMDB) propellants through uniaxial constant-rate tensile tests and stress relaxation tests. The experimental observations demonstrate that CMDB propellants exhibit pronounced strain-rate dependence and temperature dependence. Specifically, the yield [...] Read more.
This study investigates the constitutive model and relaxation modulus master curve of composite modified double-base (CMDB) propellants through uniaxial constant-rate tensile tests and stress relaxation tests. The experimental observations demonstrate that CMDB propellants exhibit pronounced strain-rate dependence and temperature dependence. Specifically, the yield stress and fracture strength of the propellant increase with increasing strain rate and decrease with increasing temperature. Conversely, the fracture strain increases with increasing temperature. The stress–strain curves of CMDB propellants display marked nonlinearity, attributed to progressive damage accumulation. The relaxation modulus increases significantly with decreasing temperature. Utilizing the time-temperature superposition principle, we constructed a master curve model for the relaxation modulus of CMDB propellants across varying temperatures. Furthermore, based on the observed stress relaxation behavior, a nonlinear constitutive model for CMDB propellants was developed. Theoretical predictions derived from this model show good agreement with experimental data. This model effectively captures the characteristic stress softening and damage evolution in CMDB propellants, thereby providing a theoretical foundation for assessing its mechanical performance and predicting its service life. Full article
(This article belongs to the Section Astronautics & Space Science)
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32 pages, 7175 KB  
Article
Learning Aircraft Spin Dynamics from Measurement Data Using Hankel DMDc with Error in Variables
by Balakumaran Swaminathan and Joel George Manathara
Aerospace 2025, 12(9), 816; https://doi.org/10.3390/aerospace12090816 - 10 Sep 2025
Abstract
Aircraft spin, a nonlinear phenomenon dominated by unsteady aerodynamics, is difficult to predict. This article proposes a novel approach using Hankel Dynamic Mode Decomposition with Control (HDMDc) to identify an aircraft plant model for spin motion directly from measurement data. A key challenge [...] Read more.
Aircraft spin, a nonlinear phenomenon dominated by unsteady aerodynamics, is difficult to predict. This article proposes a novel approach using Hankel Dynamic Mode Decomposition with Control (HDMDc) to identify an aircraft plant model for spin motion directly from measurement data. A key challenge in real-world data-driven modeling is addressing noise in both input and output measurements, often termed errors in variables (EIV). The standard HDMDc does not account for the distinct noise characteristics of different sensors. To overcome this, modifications are proposed to the standard HDMDc algorithm using EIV approaches: total least squares and bias-eliminating least squares. The proposed algorithms are validated first with a simple nonlinear dynamical system exhibiting limit cycle oscillation. Further, the methodology is applied to the simulated steady spin of the T-2 aircraft and the oscillatory spin motion of the F-18 aircraft. It is demonstrated that models identified using HDMDc with the EIV approach predicted spin trajectories with high goodness-of-fit values, even for unseen control inputs and initial conditions that differed from the training data. Specifically, the predicted trajectories had a FIT% close to 90% in most cases, with the worst-case FIT% being 38%. In contrast, the standard HDMDc algorithm’s predicted trajectory was not even visually close to the actual system trajectory, highlighting the significant improvement of the modified approach. Full article
(This article belongs to the Section Aeronautics)
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23 pages, 2424 KB  
Article
The Impacts of Climate Change on Aircraft Noise near European Airports
by Jonny Williams, Paul D. Williams, Marco Venturini, Anil Padhra, Guy Gratton and Spyridon Rapsomanikis
Aerospace 2025, 12(9), 815; https://doi.org/10.3390/aerospace12090815 - 10 Sep 2025
Abstract
The warmer air resulting from climate change reduces the lift force on a departing aircraft, potentially reducing its climb angle and causing more engine noise near the airport. Here, we study this phenomenon at a selection of 30 European airports in northern hemisphere [...] Read more.
The warmer air resulting from climate change reduces the lift force on a departing aircraft, potentially reducing its climb angle and causing more engine noise near the airport. Here, we study this phenomenon at a selection of 30 European airports in northern hemisphere summer (June–July–August). We first formulate and verify a low-complexity model of noise propagation around airports, although we emphasise that our high-level results do not explicitly depend on this agreement. The model includes anisotropic noise propagation, atmospheric absorption, and the ability to model the noise emissions from multiple engines. We study the Airbus A320, but the method could be straightforwardly generalised to other aircraft. We refer to the model as an emulator since (using Latin hypercube parameter sampling) it mimics a more comprehensive model against which it is verified. The model is used to calculate the area enclosed by the 50 dB SPL (sound pressure level) contour, A50, which agrees well with a similar metric (using the day–evening–night sound level, Lden) from the verification target, A. Using temperature and pressure data from IPCC simulations of future climate, and using a straightforward relation between climb angle and air density, we assess how climate change could affect climb angles by mid-century (2035–2064). The value of A50 is obtained by efficiently covarying (1) the engine noise at 10 m from the engines and (2) the climb angle under ‘historical’ conditions (1985–2014). The median values (across 10 climate models) of climb angle reduction in the future warmer climate are around 1–3% (depending on the airport and climate model used), but individual days can show values as high as 7.5% for the most extreme warming scenarios. By considering the variation in the absorption coefficient of the air with frequency, we find that the number of people affected by noise pollution could increase by up to 4%—as much as 2500 people for the most highly populated areas—by mid-century and that these changes are maximised for the most damaging and psychologically ‘annoying’ (low) frequencies. Full article
(This article belongs to the Section Air Traffic and Transportation)
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22 pages, 5146 KB  
Article
Improving Control Performance of Tilt-Rotor VTOL UAV with Model-Based Reward and Multi-Agent Reinforcement Learning
by Muammer Ugur and Aydin Yesildirek
Aerospace 2025, 12(9), 814; https://doi.org/10.3390/aerospace12090814 - 9 Sep 2025
Abstract
Tilt-rotor Vertical Takeoff and Landing Unmanned Aerial Vehicles (TR-VTOL UAVs) combine fixed-wing and rotary-wing configurations, offering optimized flight planning but presenting challenges due to their complex dynamics and uncertainties. This study investigates a multi-agent reinforcement learning (RL) control system utilizing Soft Actor-Critic (SAC) [...] Read more.
Tilt-rotor Vertical Takeoff and Landing Unmanned Aerial Vehicles (TR-VTOL UAVs) combine fixed-wing and rotary-wing configurations, offering optimized flight planning but presenting challenges due to their complex dynamics and uncertainties. This study investigates a multi-agent reinforcement learning (RL) control system utilizing Soft Actor-Critic (SAC) modules, which are designed to independently control each input with a tailored reward mechanism. By implementing a novel reward structure based on a dynamic reference response region, the multi-agent design improves learning efficiency by minimizing data redundancy. Compared to other control methods such as Actor-Critic Neural Networks (AC NN), Proximal Policy Optimization (PPO), Nonsingular Terminal Sliding Mode Control (NTSMC), and PID controllers, the proposed system shows at least a 30% improvement in transient performance metrics—including RMSE, rise time, settling time, and maximum overshoot—under both no wind and constant 20 m/s wind conditions, representing an extreme scenario to evaluate controller robustness. This approach has also reduced training time by 80% compared to single-agent systems, lowering energy consumption and environmental impact. Full article
(This article belongs to the Special Issue Advances in UAVs: Design Methods, Performance Enhancement Techniques and Technologies)
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24 pages, 4545 KB  
Article
Enhanced Test Data Management in Spacecraft Ground Testing: A Practical Approach for Centralized Storage and Automated Processing
by Jooho Park, Young-Joo Song and Donghun Lee
Aerospace 2025, 12(9), 813; https://doi.org/10.3390/aerospace12090813 - 9 Sep 2025
Abstract
In recent years, spacecraft have been developed to support higher data-rate communication systems and accommodate a wider range of payloads. These advancements have led to the generation of large volumes of data and increased system complexity. In particular, during the ground-testing phase, the [...] Read more.
In recent years, spacecraft have been developed to support higher data-rate communication systems and accommodate a wider range of payloads. These advancements have led to the generation of large volumes of data and increased system complexity. In particular, during the ground-testing phase, the need for an effective test data management strategy has become increasingly important to improve test efficiency and reduce costs, as sorting, distributing, and analyzing extensive test data is both time consuming and resource intensive. To address these challenges, this study introduces a practical and implementation-oriented autonomous system for centralized test data handling, which has been successfully applied and verified during actual spacecraft development and ground testing operations. The system enables the rapid transfer of test data to centralized storage without waiting for test completion or requiring human intervention by utilizing an event-triggered architecture. In addition, it automatically provides the transferred test data in multiple formats tailored to each engineering team, facilitating effective data comparison and analysis. It also performs automated test data validation without manual input. The performance of the enhanced test data management was evaluated through big-data analysis of logs generated during automated test data transfer and post-processing in actual spacecraft ground tests. Full article
(This article belongs to the Section Astronautics & Space Science)
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32 pages, 10218 KB  
Article
A Study of the Collision Characteristics of Colloidal Particles in Fuel Servo Valves
by Jin Zhang, Ranheng Du, Jie Ni, Wenlong Yin, Geng Cao, Ying Li and Huan Wang
Aerospace 2025, 12(9), 812; https://doi.org/10.3390/aerospace12090812 - 8 Sep 2025
Abstract
The fuel electro-hydraulic servo valve is a core component of the aero-engine fuel control system, playing a crucial role in engine performance. Due to the operational characteristics of the aviation fuel supply and injection system, fuel is directly sprayed through the nozzle for [...] Read more.
The fuel electro-hydraulic servo valve is a core component of the aero-engine fuel control system, playing a crucial role in engine performance. Due to the operational characteristics of the aviation fuel supply and injection system, fuel is directly sprayed through the nozzle for combustion after passing through the pipeline. The working environment and medium are subject to a wide temperature range, and the medium lacks a circulating filtration process, making it difficult to effectively remove impurities. As a result, the fuel contains a high concentration of contaminant particles. Under high-temperature conditions, colloidal particles precipitated from the fuel medium collide and adhere to metallic and other contaminant particles carried by the fuel, subsequently attaching to the internal surfaces of the fuel servo valve, causing valve sticking. This study aims to establish an adhesion criterion suitable for colloidal particles in fuel systems based on a traditional particle collision model. The adhesion criterion incorporates the viscoelastic and surface energy characteristics of colloidal particles, providing a more accurate description of their deposition behavior under the conditions studied. A particle–particle and particle–wall collision test apparatus was designed, and experiments were conducted. A comparison between experimental results and theoretical calculations shows that the overall error for collisions between colloidal particles and walls is controlled within 10%, validating the feasibility of the adhesion criterion. The Young’s modulus, Poisson’s ratio, and surface free energy of the colloidal particles were measured as 688 MPa, 0.39, and 77 mJ/m2, respectively. These results provide theoretical and experimental foundations for particle migration and deposition processes in fuel systems. The analytical method clarifies the key mechanism of adhesion caused by colloidal particles, providing guidance for improving the reliability, safety, and maintenance of fuel servo valves in aero-engine applications. Full article
(This article belongs to the Section Aeronautics)
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30 pages, 9157 KB  
Article
ST-GTNet: A Spatio-Temporal Graph Attention Network for Dynamic Airport Capacity Prediction
by Pinzheng Qian, Jian Zhang, Haiyan Zhang, Xunhao Li and Jie Ouyang
Aerospace 2025, 12(9), 811; https://doi.org/10.3390/aerospace12090811 - 8 Sep 2025
Abstract
Dynamic evaluation of airport terminal capacity is critical for efficient operations, yet it remains challenging due to the complex interplay of spatial and temporal factors. Existing approaches often handle spatial connectivity and temporal fluctuations separately, limiting their predictive power under rapidly changing conditions. [...] Read more.
Dynamic evaluation of airport terminal capacity is critical for efficient operations, yet it remains challenging due to the complex interplay of spatial and temporal factors. Existing approaches often handle spatial connectivity and temporal fluctuations separately, limiting their predictive power under rapidly changing conditions. Here the ST-GTNet (Spatio-Temporal Graph Transformer Network) is presented, a novel deep learning model that integrates Graph Convolutional Networks (GCNs) with a Transformer architecture to simultaneously capture spatial interdependencies among airport gates and temporal patterns in operational data. To ensure interpretability and efficiency, a feature selection mechanism guided by XGBoost and SHAP (Shapley Additive Explanations) is incorporated to identify the most influential features. This unified spatio-temporal framework overcomes the limitations of conventional methods by learning spatial and temporal dynamics jointly, thereby enhancing the accuracy of dynamic capacity predictions. In a case study at a large international airport with a U-shaped corridor terminal, the ST-GTNet delivered robust and reliable capacity forecasts, validating its effectiveness in a complex real-world scenario. These findings highlight the potential of the ST-GTNet as a powerful tool for dynamic airport capacity evaluation and management. Full article
(This article belongs to the Section Air Traffic and Transportation)
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22 pages, 1725 KB  
Article
Stochastic Model Predictive Control for Parafoil System via Markov-Based Multi-Scenario Optimization
by Qi Feng, Qingbin Zhang, Zhiwei Feng, Jianquan Ge, Qingquan Chen, Linhong Li and Yujiao Huang
Aerospace 2025, 12(9), 810; https://doi.org/10.3390/aerospace12090810 - 8 Sep 2025
Abstract
As an essential technology for precision airdrop missions, parafoil systems have gained widespread adoption in military and civilian applications due to their superior glide performance and maneuverability compared to conventional parachutes. Addressing the trajectory-tracking control challenges of the parafoil system under significant wind [...] Read more.
As an essential technology for precision airdrop missions, parafoil systems have gained widespread adoption in military and civilian applications due to their superior glide performance and maneuverability compared to conventional parachutes. Addressing the trajectory-tracking control challenges of the parafoil system under significant wind disturbances, characterized by wind uncertainty and system underactuation, this paper proposes a stochastic model predictive control (SMPC) framework based on Markov-based multi-scenario optimization. Traditional deterministic model predictive control (MPC) methods often exhibit excessive conservatism due to reliance on worst-case assumptions and fail to capture the time-varying nature of real-world wind fields. To address these limitations, a high-fidelity dynamic model is developed to accurately characterize aerodynamic coupling effects, overcoming the oversimplifications of conventional three-degree-of-freedom point-mass models. Leveraging Markov state transitions, multiple wind-disturbance scenarios are dynamically generated, effectively overcoming the limitations of independent and identically distributed hypotheses in modeling realistic wind variations. A probabilistic constraint-reconstruction strategy combined with a rolling time-domain covariance update mechanism mitigates uncertainties and enables cooperative optimization of inner-loop attitude stabilization and outer-loop trajectory tracking. The simulation results demonstrate that the SMPC framework achieves superior comprehensive performance compared to deterministic MPC, evidenced by significant reductions in maximum position error, average position error, and control effort variation rate, along with a 94% tracking success rate. By balancing robustness, tracking precision, and computational efficiency, the method provides a theoretical foundation and a promising simulation-validated solution for airdrop missions. Full article
(This article belongs to the Special Issue Advances in Landing Systems Engineering)
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29 pages, 5672 KB  
Article
An Attack–Defense Non-Cooperative Game Model from the Perspective of Safety and Security Synergistically for Aircraft Avionics Systems
by He Sui, Yinuo Zhang, Zhaojun Gu and Monowar Bhuyan
Aerospace 2025, 12(9), 809; https://doi.org/10.3390/aerospace12090809 - 8 Sep 2025
Viewed by 61
Abstract
The interconnectivity of avionics systems supports the need to incorporate functional safety and information security into airworthiness validation and maintenance protocols, which is critical. This necessity arises from the demanding operational environments and the limitations on defense resource allocation. This study proposes an [...] Read more.
The interconnectivity of avionics systems supports the need to incorporate functional safety and information security into airworthiness validation and maintenance protocols, which is critical. This necessity arises from the demanding operational environments and the limitations on defense resource allocation. This study proposes an optimization model for the strategic deployment of defense mechanisms, leveraging the dynamic interplay between attack and defense modeled by non-cooperative game theory and aligning with the maintenance schedules of civil aircraft. By developing an Attack–Defense Tree and conducting a non-cooperative game analysis, this paper outlines strategies from both the attacker’s and defender’s perspectives, assessing the impact of focused defense improvements on the system’s security integrity. The results reveal that the broad expansion of defense measures reduces their effectiveness, whereas targeted deployment significantly enhances protection. Monte Carlo simulations are employed to approximate equilibrium solutions across the strategy space, reducing computational complexity while retaining robustness in capturing equilibrium trends. This approach supports efficient allocation of defense resources, strengthens overall system security, and provides a practical foundation for integrating security analysis into avionics maintenance and certification processes. Full article
(This article belongs to the Section Aeronautics)
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31 pages, 6396 KB  
Article
Performance and Stall Margin Evaluation of Axial Slot Casing Treatment in a Transonic Multistage Compressor
by Pedro Seiti Endo, Jesuino Takachi Tomita, Cleverson Bringhenti, Franco Jefferds dos Santos Silva and Ruben Bruno Diaz
Aerospace 2025, 12(9), 808; https://doi.org/10.3390/aerospace12090808 - 8 Sep 2025
Viewed by 129
Abstract
Adverse pressure gradients are intrinsic to compressor flow behavior and are further intensified by secondary effects associated with rotor tip clearance flow interactions. Tip clearance generates leakage flow, which leads to the formation of tip leakage vortices, a major contributor to aerodynamic losses [...] Read more.
Adverse pressure gradients are intrinsic to compressor flow behavior and are further intensified by secondary effects associated with rotor tip clearance flow interactions. Tip clearance generates leakage flow, which leads to the formation of tip leakage vortices, a major contributor to aerodynamic losses in axial compressors. These vortices significantly influence both compressor performance and operational stability. Extensive prior research has demonstrated that passive casing treatments, particularly axial slots, can substantially improve the stall margin in axial compressors. In this work, the performance of a new casing treatment geometry is investigated using the concept of recirculating flow within semi-circular axial slots. The proposed casing treatment geometry builds upon recent experimental findings involving single-rotor configurations. It was applied to the first rotor row of a three-and-a-half-stage (3.5-stage) axial compressor comprising an inlet guide vane followed by three rotor–stator stages. The numerical model incorporates axial slots with a novel periodic interface approach implemented in a multistage compressor simulation. Three-dimensional steady-state RANS (Reynolds Average Navier-Stokes) simulations were performed to investigate the aerodynamic effects of the casing treatment across various rotational speeds. The results for the casing treatment configuration were compared with those of a baseline smooth casing. The introduction of the new casing treatment produced noticeable modifications to the internal flow structure, particularly in the tip region, resulting in improved overall compressor stability within the operating range of 85 to 100% of design speed. Full article
(This article belongs to the Section Aeronautics)
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24 pages, 13649 KB  
Article
Research on the Influence of Cracked Control Surface on the Gust Response of High-Aspect-Ratio Flying Wing
by Mingdong Wang, Xiangmian He, Yuguang Bai and Sheng Zhang
Aerospace 2025, 12(9), 807; https://doi.org/10.3390/aerospace12090807 - 8 Sep 2025
Viewed by 291
Abstract
Flying-wing aircraft based on high-aspect-ratio wings are a popular configuration for many aerospace engineering applications. Cracked (or cross) control surface structures can adjust the aerodynamic characteristics of flying-wing aircraft. Deep investigations into the effects of such a control surface can provide a helpful [...] Read more.
Flying-wing aircraft based on high-aspect-ratio wings are a popular configuration for many aerospace engineering applications. Cracked (or cross) control surface structures can adjust the aerodynamic characteristics of flying-wing aircraft. Deep investigations into the effects of such a control surface can provide a helpful design foundation. This paper investigates the mass distribution influences of cracked control surfaces on gust responses of high-aspect-ratio flying wings. Validated finite element modelling, revised by detailed ground vibration test (GVT) with a frequency error of less than 10%, reveals that root boundary conditions significantly affect the natural modes and frequencies of present wings with cracked control surfaces. Changes in control surface (CS) mass have a critical impact on gust response: a 150 g increase in CS mass results in a 15–22% increase in peak response acceleration and a 25–30% increase in response duration, while redistributing mass to the outboard CS reduces the peak response by 18–26% while keeping the total mass consistent. The results can provide an effective suppression strategy for the gust responses of flying-wing configurations without redesigning the main structure. Full article
(This article belongs to the Special Issue Advances in Thermal Fluid, Dynamics and Control)
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15 pages, 2594 KB  
Opinion
On Space Debris Removal by Lasers: Can Spatially and Temporally Shaped Laser Pulses Be Advantageous for Propulsion?
by Nadezhda M. Bulgakova
Aerospace 2025, 12(9), 806; https://doi.org/10.3390/aerospace12090806 - 8 Sep 2025
Viewed by 390
Abstract
For exploration of space, in particular in attempts to find new extra-terrestrial resources, human society has encountered the problem of space pollution with human-made debris, which represents high risks for space missions. This prompted extensive activities for cleaning the space using various techniques, [...] Read more.
For exploration of space, in particular in attempts to find new extra-terrestrial resources, human society has encountered the problem of space pollution with human-made debris, which represents high risks for space missions. This prompted extensive activities for cleaning the space using various techniques, which are briefly overviewed here. But the main focus of this paper is on using lasers for space debris removal. The attention is drawn to laser beam shaping techniques, which are discussed as potential technologies for deorbiting space debris, providing more energetically favorable laser propulsion compared to conventional laser beams. Full article
(This article belongs to the Special Issue Laser Propulsion Science and Technology (2nd Edition))
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24 pages, 4642 KB  
Article
Multi-Objective Design Optimization of Solid Rocket Motors via Surrogate Modeling
by Xinping Fan, Ran Wei, Yumeng He, Weihua Hui, Weijie Zhao, Futing Bao, Xiao Hou and Lin Sun
Aerospace 2025, 12(9), 805; https://doi.org/10.3390/aerospace12090805 - 7 Sep 2025
Viewed by 383
Abstract
To reduce the high computational cost and lengthy design cycles of traditional solid rocket motor (SRM) development, this paper proposes an efficient surrogate-assisted multi-objective optimization approach. A comprehensive performance model was first established, integrating internal ballistics, grain structural integrity, and cost estimation, to [...] Read more.
To reduce the high computational cost and lengthy design cycles of traditional solid rocket motor (SRM) development, this paper proposes an efficient surrogate-assisted multi-objective optimization approach. A comprehensive performance model was first established, integrating internal ballistics, grain structural integrity, and cost estimation, to enable holistic assessment of the coupled effects of key motor components. A parametric analysis framework was then developed to automate the model, facilitating seamless data exchange and coordination among sub-models through chain coupling. Leveraging this framework, a large-scale, high-fidelity dataset was generated via uniform sampling of the design space. The Kriging surrogate model with the highest global fitting accuracy was subsequently employed to replicate the integrated model’s complex responses and reveal underlying design principles. Finally, an enhanced NSGA-III algorithm incorporating a phased hybrid crossover operator was applied to improve global search performance and guide solution evolution along the Pareto front. Applied to a specific SRM, the proposed method achieved a 4.72% increase in total impulse and a 6.73% reduction in cost compared with the initial design, while satisfying all constraints. Full article
(This article belongs to the Section Astronautics & Space Science)
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21 pages, 6093 KB  
Article
Ensemble Modeling Method for Aero-Engines Based on Automatic Neural Network Architecture Search Under Sparse Data
by Guanghuan Xiong, Xiangmin Tan, Guanzhen Cao, Xingkui Hong, Xingen Lu and Junqiang Zhu
Aerospace 2025, 12(9), 804; https://doi.org/10.3390/aerospace12090804 - 5 Sep 2025
Viewed by 207
Abstract
In this paper, the problem of aero-engines ensemble modeling under sparse data is addressed. Firstly, the Makima method is used to interpolate and complement the sparse data by analyzing the experimental data of a specific real aero-engine. In this way, the data sparsity [...] Read more.
In this paper, the problem of aero-engines ensemble modeling under sparse data is addressed. Firstly, the Makima method is used to interpolate and complement the sparse data by analyzing the experimental data of a specific real aero-engine. In this way, the data sparsity problem due to sampling or transmission is solved equally well. Secondly, the Nonlinear Auto-Regressive with Exogenous Inputs (NARX) neural network is brought in as the computational structure of the model. Based on the Automatic Neural Network Architecture Search (ANAS) method, the hyperparameters of the model can be searched efficiently, and the performance is improved. Third, a novel ensemble modeling method based on the Makima method, the NARX model, and the ANAS method is proposed to realize high-precision modeling throughout the entire operation process of the aero-engine from the idle state to the full throttle state. Finally, the proposed method is validated by simulations and experiments, and the results illustrate the innovation and correctness. Full article
(This article belongs to the Section Aeronautics)
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27 pages, 2936 KB  
Article
Dynamic Event-Triggered Multi-Aircraft Collision Avoidance: A Reference Correction Method Based on APF-CBF
by Yadong Tang, Jiong Li, Jikun Ye, Xiangwei Bu and Changxin Luo
Aerospace 2025, 12(9), 803; https://doi.org/10.3390/aerospace12090803 - 5 Sep 2025
Viewed by 179
Abstract
To address the key issues in cooperative collision avoidance of multiple aircraft, such as unknown dynamics, external disturbances, and limited communication resources, this paper proposes a reference correction method based on the Artificial Potential Field-Control Barrier Function (APF-CBF) and combines it with a [...] Read more.
To address the key issues in cooperative collision avoidance of multiple aircraft, such as unknown dynamics, external disturbances, and limited communication resources, this paper proposes a reference correction method based on the Artificial Potential Field-Control Barrier Function (APF-CBF) and combines it with a dynamic event-triggered mechanism to achieve efficient cooperative control. This paper adopts a Fuzzy Wavelet Neural Network (FWNN) to design a finite-time disturbance observer. By leveraging the advantages of FWNN, which integrates fuzzy logic reasoning and the time-frequency locality of wavelet basis functions, this observer can synchronously estimate system states and unknown disturbances, to ensure the finite-time uniformly ultimate boundedness of errors and break through the limitation of insufficient robustness in traditional observers. Meanwhile, the APF is embedded in the CBF framework. On the one hand, APF is utilized to intuitively describe spatial interaction relationships, thereby reducing reliance on prior knowledge of obstacles; on the other hand, CBF is used to strictly construct safety constraints to overcome the local minimum problem existing in APF. Additionally, the reference correction mechanism is combined to optimize trajectory tracking performance. In addition, this paper introduces a dynamic event-triggered mechanism, which adjusts the triggering threshold by real-time adaptation to error trends and mission phases, realizing “communication on demand”. This mechanism can reduce communication resource consumption by 49.8% to 69.8% while avoiding Zeno behavior. Theoretical analysis and simulation experiments show that the proposed method can ensure the uniformly ultimate boundedness of system states and effectively achieve safe collision avoidance and efficient formation tracking of multiple aircraft. Full article
(This article belongs to the Special Issue Formation Flight of Fixed-Wing Aircraft)
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27 pages, 6795 KB  
Article
Dynamic Analysis of Variable-Stiffness Laminated Composite Plates with an Arbitrary Damaged Area in Supersonic Airflow
by Pingan Zou, Dong Shao, Ningze Sun and Weige Liang
Aerospace 2025, 12(9), 802; https://doi.org/10.3390/aerospace12090802 - 5 Sep 2025
Viewed by 160
Abstract
In response to the urgent need for performance predictions of damaged aerospace structures, this study undertakes a comprehensive investigation into the flutter characteristics of damaged variable-stiffness composite laminate (VSCL) plates. The governing boundary value problem for the dynamics of damaged VSCL plates is [...] Read more.
In response to the urgent need for performance predictions of damaged aerospace structures, this study undertakes a comprehensive investigation into the flutter characteristics of damaged variable-stiffness composite laminate (VSCL) plates. The governing boundary value problem for the dynamics of damaged VSCL plates is formulated using first-order shear deformation theory (FSDT). Additionally, the first-order piston theory is utilized to model the aerodynamic pressure in supersonic airflow. A novel coupling methodology is developed through the integration of penalty function methods and irregular mapping techniques, which effectively establishes the interaction between damaged and undamaged plate elements. The vibration characteristics and aeroelastic responses are systematically analyzed using the Chebyshev differential quadrature method (CDQM). The validity of the proposed model is thoroughly demonstrated through comparative analyses with the existing literature and finite element simulations, confirming its computational accuracy and broad applicability. A notable characteristic of this research is its ability to accommodate arbitrary geometric configurations within damaged regions. The numerical results unequivocally demonstrate that accurately predicting the flutter characteristics of damaged VSCL plates constitutes an effective strategy for mitigating structural stability degradation. This approach provides valuable insights for aerospace structural design and maintenance. Full article
(This article belongs to the Section Aeronautics)
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2 pages, 233 KB  
Correction
Correction: Schnell, R.; Mennicken, M. Unified Assessment of Open and Ducted Propulsors. Aerospace 2024, 11, 1002
by Rainer Schnell and Maximilian Mennicken
Aerospace 2025, 12(9), 801; https://doi.org/10.3390/aerospace12090801 - 5 Sep 2025
Viewed by 115
Abstract
In the original publication [...] Full article
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29 pages, 529 KB  
Article
Fuzzy Multi-Criteria Decision Framework for Asteroid Selection in Boulder Capture Missions
by Nelson Ramírez, Juan Miguel Sánchez-Lozano and Eloy Peña-Asensio
Aerospace 2025, 12(9), 800; https://doi.org/10.3390/aerospace12090800 - 4 Sep 2025
Viewed by 165
Abstract
A systematic fuzzy multi-criteria decision making (MCDM) framework is proposed to prioritize near-Earth asteroids (NEAs) for a boulder capture mission, addressing the requirement for rigorous prioritization of asteroid candidates under conditions of data uncertainty. Twenty-eight NEA candidates were first selected through filtering based [...] Read more.
A systematic fuzzy multi-criteria decision making (MCDM) framework is proposed to prioritize near-Earth asteroids (NEAs) for a boulder capture mission, addressing the requirement for rigorous prioritization of asteroid candidates under conditions of data uncertainty. Twenty-eight NEA candidates were first selected through filtering based on physical and orbital properties. Then, objective fuzzy weighting MCDM methods (statistical variance, CRITIC, and MEREC) were applied to determine the importance of criteria such as capture cost, synodic period, rotation rate, orbit determination accuracy, and similarity to other candidates. Subsequent fuzzy ranking MCDM techniques (WASPAS, TOPSIS, MARCOS) generated nine prioritization schemes whose coherence was assessed via correlation analysis. An innovative sensitivity analysis employing Dirichlet-distributed random sampling around reference weights quantified ranking robustness. All methodologies combinations consistently identified the same top four asteroids, with 2013 NJ ranked first in every scenario, and stability metrics confirmed resilience to plausible weight variations. The modular MCDM methodology proposed provides mission planners with a reliable, adaptable decision support tool for asteroid selection, demonstrably narrowing broad candidate pools to robust targets while accommodating future data updates. Full article
(This article belongs to the Special Issue Fuzzy Multi-Criteria Decision Making Methods for Aerospace Science and Technology)
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26 pages, 2586 KB  
Article
Assessment of Extending Flight Endurance Through Engine Dynamic Clearance Control via Fuel Heat Sink Utilization
by Shiyu Yang, Weilong Gou, Yuanfang Lin, Xianghua Xu, Xingang Liang and Bo Shi
Aerospace 2025, 12(9), 799; https://doi.org/10.3390/aerospace12090799 - 4 Sep 2025
Viewed by 254
Abstract
Active clearance control (ACC) is an effective means of reducing engine fuel consumption. Recently, an innovative fuel-cooled ACC (FCACC) scheme has been developed to improve engine performance by utilizing fuel from the aircraft fuel thermal management system (AFTMS) to precool bleed air, creating [...] Read more.
Active clearance control (ACC) is an effective means of reducing engine fuel consumption. Recently, an innovative fuel-cooled ACC (FCACC) scheme has been developed to improve engine performance by utilizing fuel from the aircraft fuel thermal management system (AFTMS) to precool bleed air, creating a trade-off between fuel supply and thermal management capabilities. To maximize flight endurance through FCACC, this paper firstly elucidates its mechanism for conserving both fuel and fuel heat sink when the thermal management flow path (TMFP) operates in the full recirculation state (FRS), benefiting from the configuration of the recirculation fuel supply branch (RFSB). Calculation results indicate that flight endurance can be extended by 2.28% and 11.62% under the standard condition and extreme mission, respectively. Then, the impact of further utilizing fuel heat sink on flight endurance at the critical transition from FRS to partial recirculation state (PRS) is investigated. In this case, thermal failure, rather than fuel depletion, dominates and shortens flight endurance. Based on this, a novel dynamic regulation strategy for fuel/bleed air heat exchange is established, which is applicable across various operating conditions. Finally, a common mission demonstrates that FCACC can reduce takeoff weight by 20.33 kg, enabling the aircraft to carry additional devices. Full article
(This article belongs to the Special Issue Aircraft Thermal Management Technologies)
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24 pages, 5678 KB  
Article
An Emergency Rescue Reconnaissance UAV Nest Site Selection Method Considering Regional Differentiated Coverage and Rescue Satisfaction
by Xiwei Zeng, Xinlan Chu, Rundong Yao, Jiayi Liu, Yuezhou Yang and Weili Zeng
Aerospace 2025, 12(9), 798; https://doi.org/10.3390/aerospace12090798 - 4 Sep 2025
Viewed by 245
Abstract
Traditional emergency reconnaissance UAV nest deployment methods face limitations such as blind coverage, delayed response, single coverage targets, and undifferentiated regional priorities. This paper proposes an optimized deployment approach that maximizes response satisfaction and regional coverage, achieving comprehensive coverage while avoiding resource waste [...] Read more.
Traditional emergency reconnaissance UAV nest deployment methods face limitations such as blind coverage, delayed response, single coverage targets, and undifferentiated regional priorities. This paper proposes an optimized deployment approach that maximizes response satisfaction and regional coverage, achieving comprehensive coverage while avoiding resource waste and blind zones. UAV nest location needs to consider several factors, including UAV nest coverage, distribution of mandatory coverage areas, scope of critical areas, and various constraints. Mandatory coverage areas are disaster-prone zones identified from historical data, requiring focused reconnaissance. Critical areas are regions with high population density and critical infrastructure concentration. Constraints contain the nest coverage radius constraints, surplus coverage constraints, economic cost constraints, nest distance constraints, nest synergy constraints, and regional boundary constraints. We developed an improved multi-dimensional ant colony optimization algorithm tailored to the problem characteristics, which incorporates multi-dimensional pheromones representing coverage potential, cost efficiency, and spatial constraints, along with adaptive updating and dynamic selection mechanisms for effective problem-solving. This paper takes Nanjing, Jiangsu Province as an analysis case. And the solution achieved 100% regional coverage, redundant coverage of critical zones, and seamless inter-nest collaboration. Sensitivity analysis confirmed the model’s robustness and effectiveness under varying coverage radius and budget conditions. Full article
(This article belongs to the Section Aeronautics)
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21 pages, 8653 KB  
Article
Startup Characteristics and Thermal Instability of a Visual Loop Heat Pipe Under Acceleration Force
by Lijun Chen, Yongqi Xie, Longzhu Han, Huifeng Kang and Hongwei Wu
Aerospace 2025, 12(9), 797; https://doi.org/10.3390/aerospace12090797 - 4 Sep 2025
Viewed by 270
Abstract
Loop heat pipes are efficiently two-phase heat transfer devices in the field of aircraft thermal management. To investigate the startup behavior and thermal instability of loop heat pipes under acceleration force, this study designed a novel loop heat pipe featuring two visual compensation [...] Read more.
Loop heat pipes are efficiently two-phase heat transfer devices in the field of aircraft thermal management. To investigate the startup behavior and thermal instability of loop heat pipes under acceleration force, this study designed a novel loop heat pipe featuring two visual compensation chambers and a visual condenser. Elevated acceleration experiments were conducted across four different heat loads, acceleration magnitudes, and directions. The heat load ranged from 30 W to 150 W, while the acceleration magnitude varied from 1 g to 15 g, with four acceleration directions (A, B, C, and D). The startup behavior, thermal instability, internal flow pattern, and phase distribution were analyzed systematically. The experimental results reveal the following: (i) The startup behaviors vary across the four acceleration directions. In direction A, startup is more difficult due to additional resistance induced by the acceleration force. In direction C, startup time generally decreases with increasing heat load and acceleration up to 7 g. The longest startup time observed is 372 s at 30 W and 11 g. (ii) At high heat load, periodic temperature fluctuations are observed, particularly in directions B and C. Simultaneously, the vapor–liquid phase interface in the condenser exhibits periodic back-and-forth movement. (iii) The visual DCCLHP exhibits a loss of temperature control under the combined influence of high heat loads and acceleration force, often accompanied by working fluid reverse flow, periodic temperature fluctuations, or wick dry-out. Full article
(This article belongs to the Special Issue Aircraft Thermal Management Technologies)
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19 pages, 12279 KB  
Article
Numerical Study on Self-Pulsation Phenomenon in Liquid-Centered Swirl Coaxial Injector with Recess
by Jiwon Lee, Hadong Jung and Kyubok Ahn
Aerospace 2025, 12(9), 796; https://doi.org/10.3390/aerospace12090796 - 3 Sep 2025
Viewed by 242
Abstract
This study investigates self-pulsation phenomena in a liquid-centered swirl coaxial injector with a recess length of 4 mm, under varying liquid flow conditions, using numerical simulations. The simulations focused on analyzing spray patterns, pressure oscillations, and dominant frequency characteristics, and the results were [...] Read more.
This study investigates self-pulsation phenomena in a liquid-centered swirl coaxial injector with a recess length of 4 mm, under varying liquid flow conditions, using numerical simulations. The simulations focused on analyzing spray patterns, pressure oscillations, and dominant frequency characteristics, and the results were compared with previous experimental data. Self-pulsation, observed at liquid flow rates of 60%, 90%, and 100% of nominal values, generated distinctive periodic oscillations in the spray pattern, forming “neck” and “shoulder” breakup structures that resemble a Christmas tree. Surface waves induced by Kelvin-Helmholtz and Rayleigh-Taylor instabilities were identified at the gas-liquid interface, contributing to enhanced atomization and reduced spray breakup length. FFT analysis of the pressure oscillations highlighted a match in trends between simulation and experimental data, although variations in dominant frequency magnitudes arose due to the absence of manifold space in simulations, confining oscillations and slightly elevating dominant frequencies. Regional analysis revealed that interactions between the high-speed gas and liquid film in the recess region drive self-pulsation, leading to amplified pressure oscillations throughout the injector’s internal regions, including the gas annular passage, tangential hole, and gas core. These findings provide insights into the internal flow dynamics of swirl coaxial injectors and inform design optimizations to control instabilities in liquid rocket engines. Full article
(This article belongs to the Section Astronautics & Space Science)
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20 pages, 2760 KB  
Article
A Rapid Prediction Model of Three-Dimensional Ice Accretion on Rotorcraft in Hover Flight
by Weibin Li, Fan Liu, Dazhi Zhao, Xingda Cui, Zhongyun Xiao and Kaicheng Li
Aerospace 2025, 12(9), 795; https://doi.org/10.3390/aerospace12090795 - 3 Sep 2025
Viewed by 270
Abstract
Helicopters often operate at altitudes where cloud activity is prevalent, making them susceptible to icing hazards. Accurate and rapid prediction of ice accretion on rotors is crucial for expanding helicopter flight capabilities and enhancing flight safety. In this paper, we first introduce an [...] Read more.
Helicopters often operate at altitudes where cloud activity is prevalent, making them susceptible to icing hazards. Accurate and rapid prediction of ice accretion on rotors is crucial for expanding helicopter flight capabilities and enhancing flight safety. In this paper, we first introduce an improved 3-D ice accretion simulation method that accurately models runback water characteristics by considering factors such as control volume size, runback water speed, and direction. This method precisely calculates the ice accretion mass and runback water distribution. Building upon this foundation, we then present a rapid ice accretion prediction model, designed to overcome the time-consuming nature of traditional CFD frameworks. In the experimental section, our simulation methodology is applied to a hovering UH-1H rotor. A comparative analysis with experimental results reveals that the maximum absolute ice thickness error remains below 3 mm, demonstrating satisfactory computational accuracy of the proposed approach. Moreover, we demonstrate the model’s rapid prediction capabilities (achieving within a computational time of 2.66 s and a maximum ice thickness error of 7.2 mm) and implement multi-parameter predictions. Full article
(This article belongs to the Section Aeronautics)
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17 pages, 1827 KB  
Review
A Review of Polymer Composites and Adhesives for Aircraft Landing Gear Applications
by Hasan Caglar, David Ayre, Andrew Mills, Yigeng Xu and Martin Skote
Aerospace 2025, 12(9), 794; https://doi.org/10.3390/aerospace12090794 - 2 Sep 2025
Viewed by 431
Abstract
This review paper explores the transformative potential of polymer composites and adhesives in reducing the weight of aircraft landing gear, thereby improving fuel efficiency and lowering emissions. The replacement of conventional metallic materials and mechanical fastenings with advanced thermoset/thermoplastic composites and adhesives can [...] Read more.
This review paper explores the transformative potential of polymer composites and adhesives in reducing the weight of aircraft landing gear, thereby improving fuel efficiency and lowering emissions. The replacement of conventional metallic materials and mechanical fastenings with advanced thermoset/thermoplastic composites and adhesives can significantly enhance durability and performance in demanding operational environments. Unlike traditional fastening methods, the structural adhesives eliminate the weight penalties associated with mechanical fasteners, offering a lighter and more reliable solution that meets the rigorous demands of modern aerospace engineering. Furthermore, the review highlights a variety of manufacturing techniques and innovative materials, including bio-based polymers, self-healing materials, noobed composites, helicoid composites, and hybrid composites. The use of thermosets and vitrimers in adhesive bonding are presented, illustrating their ability to create robust and durable joints that enhance the structural integrity of landing gear systems. The paper also addresses current challenges, including recycling limitations and high material costs. Sustainability considerations, including the integration of self-healing materials, structural health monitoring systems, and circular economy principles, are discussed as essential for aligning the aerospace sector with global climate goals. Full article
(This article belongs to the Section Aeronautics)
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28 pages, 3659 KB  
Article
Research on ATFM Delay Optimization Method Based on Dynamic Priority Ranking
by Zheng Zhao, Yanchun Li, Xiaocheng Liu, Jie Zhu and Siqi Zhao
Aerospace 2025, 12(9), 793; https://doi.org/10.3390/aerospace12090793 - 2 Sep 2025
Viewed by 284
Abstract
Air Traffic Flow Management (ATFM) delay refers to the difference between a flight’s Target Take-Off Time (TTOT) and its Calculated Take-Off Time (CTOT), reflecting congestion levels in the air traffic network. ATFM delays are assigned to balance demand and capacity at key points [...] Read more.
Air Traffic Flow Management (ATFM) delay refers to the difference between a flight’s Target Take-Off Time (TTOT) and its Calculated Take-Off Time (CTOT), reflecting congestion levels in the air traffic network. ATFM delays are assigned to balance demand and capacity at key points in the network. The traditional First-Come, First-Served (FCFS) approach allocates delays strictly in the order flights are ready to depart, which is simple but inflexible. This study proposes a dynamic priority-based aircraft sequencing method at critical waypoints under multi-resource scenarios, aiming to reduce ATFM delays. An improved Constrained Position Shifting (CPS) constraint is introduced into the optimization model to enhance the influence of flight priority during decision-making. Additionally, three different priority strategies are designed to compare their respective impacts on ATFM delay. Finally, a dynamic priority-based ATFM delay optimization model is developed to address the identified challenges. Experimental results demonstrate that, compared with the FCFS scheme, the three priority strategies achieve maximum ATFM delay reductions of 30.5%, 44.1%, and 19.9%, respectively. The proposed model effectively allocates shorter delays to critical flights, optimizing resource utilization and improving the operational efficiency of the air route network. The research provides a reference framework for air traffic managers in allocating spatiotemporal resources across multiple congestion hotspots. By aligning priorities with network-wide efficiency goals, it overcomes traditional model limitations, avoids local optima, and supports globally optimal ATFM policy and practice. Full article
(This article belongs to the Section Air Traffic and Transportation)
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9 pages, 1471 KB  
Communication
Numerical Study of the Induction Length Effect on Oblique Detonation Waves
by Shilong Sun, Yu Liu and Gaoxiang Xiang
Aerospace 2025, 12(9), 792; https://doi.org/10.3390/aerospace12090792 - 1 Sep 2025
Viewed by 275
Abstract
The typical structure of an oblique detonation wave (ODW) consists of a leading shock wave followed by a coupled shock-flame complex. The distance from the leading shock’s originating point to the ignition onset is referred to as the induction length. This work numerically [...] Read more.
The typical structure of an oblique detonation wave (ODW) consists of a leading shock wave followed by a coupled shock-flame complex. The distance from the leading shock’s originating point to the ignition onset is referred to as the induction length. This work numerically studies the induction length effect using a two-step induction-reaction kinetic model. Results reveal that the induction length governs the transition pattern of ODWs. By testing four distinct induction lengths, four ODW regimes are identified, including a prompt ODW, a delayed smooth ODW, a delayed abrupt ODW, and a delayed abrupt ODW with an upstream triple point in oscillatory motion. The mechanisms behind these regimes are analyzed in detail. Additionally, hysteresis is observed when the induction length decreases from a larger value, demonstrating that this phenomenon can be influenced by the kinetic process. Full article
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