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Aerospace
Volume 13
Issue 7
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Aerospace, Volume 13, Issue 7 (July 2026) – 96 articles

Cover Story (view full-size image): Introducing air-launched uncrewed aerial systems (ALUAS), these small lightweight drones can be launched from a tube—whether from the ground or from the air—for extended range. The specific ALUAS at the center of this work is known as the Tailsitter. This aircraft has foldable wings to fit inside of a tube-launcher, and can operate as a vertical-takeoff-and-landing (VTOL) aircraft as well as a fixed-wing cruising aircraft, demonstrating its versatility. The present work explored the feasibility of such a concept through a rigorous non-linear flight dynamics modeling and simulation campaign. Simulations suggested that the Tailsitter ALUAS can perform a wide range of complex maneuvers, including transition between hover and cruise, as well as ground-launch and air-launch from a helicopter mothership. View this paper
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25 pages, 5020 KB  
Article
Design and Numerical Assessment of a Compact SWIR Optical Payload with Switchable Spectral Bands for a CubeSat
by Dulat Akzhigitov, Berik Zhumazhanov, Aigul Kulakayeva and Beksultan Zhumazhanov
Aerospace 2026, 13(7), 660; https://doi.org/10.3390/aerospace13070660 - 22 Jul 2026
Cited by 1 | Viewed by 459
Abstract
This paper presents the design and numerical assessment of a compact short-wave infrared (SWIR) optical payload for a CubeSat nanosatellite platform. The proposed payload is intended to provide sequential imaging in selected SWIR bands using a revolver filter wheel while accommodating a long-focal-length [...] Read more.
This paper presents the design and numerical assessment of a compact short-wave infrared (SWIR) optical payload for a CubeSat nanosatellite platform. The proposed payload is intended to provide sequential imaging in selected SWIR bands using a revolver filter wheel while accommodating a long-focal-length optical system within a limited 3U volume. The optical layout is based on a modified Maksutov configuration with an effective focal length of approximately 550 mm and an aperture of 84 mm. The system is designed to achieve a ground sampling distance (GSD) of ≤15 m at an orbital altitude of 500–550 km. For sequential imaging in different regions of the SWIR range, filters with central wavelengths of 1.24, 1.6, 1.9, and 2.1 μm are used together with an additional broadband window. The optical performance was evaluated using spot diagrams and modulation transfer function (MTF) analysis for the selected spectral bands. A preliminary thermo-optical sensitivity assessment was also performed over the temperature range from −20 °C to +40 °C by considering temperature-induced changes in axial distances between optical elements and surface curvatures caused by material expansion. The results indicate that the MTF at the detector Nyquist frequency of 33 lp/mm remains above the selected threshold of 0.1 for the considered spectral bands and uniform temperature states. The proposed configuration demonstrates the feasibility of implementing a compact long-focal-length SWIR payload with filter-wheel-based band selection for CubeSat missions, while maintaining the required calculated image quality within the considered design-stage assumptions. Full article
(This article belongs to the Section Astronautics & Space Science)
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18 pages, 2563 KB  
Article
Flow and Combustion Characteristics of a Novel Triple-Swirler Combustor Under Multiple Operating Conditions
by Chengji Wang, Ronghui Cheng, Wu Li, Qinghua Zeng, Yating Zhao and Wenjing Zuo
Aerospace 2026, 13(7), 659; https://doi.org/10.3390/aerospace13070659 - 22 Jul 2026
Viewed by 515
Abstract
A Realizable k−ε turbulence model and a finite-rate/eddy-dissipation combustion model, together with experimental validation, were used to investigate the flow and combustion characteristics of a novel triple-swirler combustor under multiple operating conditions. The results show that, compared with the conventional baseline configuration, the [...] Read more.
A Realizable k−ε turbulence model and a finite-rate/eddy-dissipation combustion model, together with experimental validation, were used to investigate the flow and combustion characteristics of a novel triple-swirler combustor under multiple operating conditions. The results show that, compared with the conventional baseline configuration, the ring-cooled radial structure induces a third-stage swirl through inclined cooling holes. This swirl regulates the recirculation structure formed by the first two axial swirlers, transforms the core reaction zone from a single large-scale recirculation vortex into multiple vortical structures, forms a low-temperature cooling coverage outside the main reaction zone, and weakens the near-wall entrainment and high-speed sweeping induced by the kidney-shaped vortex pair downstream of the primary holes. The peak temperature of the outer liner is reduced by 14.72%, and the wall-temperature uniformity is improved by 36.02%. The outlet temperature distribution factor (OTDF) decreases by 14.81% and 15.79% under high and medium operating conditions, respectively, indicating an improved outlet temperature field. This study provides engineering guidance for the design of high-performance combustors. Full article
(This article belongs to the Section Aeronautics)
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25 pages, 5325 KB  
Article
Analytical Methodology for Early-Stage Design and Stability Assessment of V-Tail Class-I UAVs
by Eleftherios Nikolaou, Spyridon Kilimtzidis, Vaios Lappas and Vassilis Kostopoulos
Aerospace 2026, 13(7), 658; https://doi.org/10.3390/aerospace13070658 - 21 Jul 2026
Viewed by 490
Abstract
Unmanned Air Vehicles (UAVs) are becoming increasingly popular and widely used in a variety of industries such as agriculture, construction, delivery, surveillance, rescue operations, mapping, wildlife tracking and many more. With the advancements in technology, UAVs are becoming more autonomous and able to [...] Read more.
Unmanned Air Vehicles (UAVs) are becoming increasingly popular and widely used in a variety of industries such as agriculture, construction, delivery, surveillance, rescue operations, mapping, wildlife tracking and many more. With the advancements in technology, UAVs are becoming more autonomous and able to perform tasks with minimal human intervention, rendering their use indispensable for military and law enforcement purposes. In terms of control surfaces, V-tail configurations are commonly used on UAVs due to their advantages in control and stability performance, as well as their ability to reduce drag and improve overall efficiency. However, research on V-tail design and sizing is limited, particularly for Class I mini-UAVs. The objective of this paper is to identify a methodology for the Conceptual and Preliminary sizing and design of a V-tail of a Class I Mini UAV (NATO classification). The methodology follows the design of a V-tail from the characteristics of the conventional tail of the UAV. Once the characteristics of the conventional tail are extracted, V-tail geometric characteristics are computed. The stability derivatives of the V-tail are then calculated. The methodology for the analytical aerodynamic characteristics and stability derivatives is a combination of two existing methodologies: one methodology for V-tail stability and control derivatives, which refers to the Preliminary or Detailed Design of an aircraft, and one methodology for a conventional tail design, which refers to the Conceptual and Preliminary design of an aircraft. With this combination, a V-tail Preliminary design methodology was achieved. Furthermore, the aerodynamic characteristics and stability derivatives of the designed V-tail were verified by Low Fidelity Aerodynamics simulation, and then by High Fidelity Aerodynamics by means of Computational Fluid Dynamics (CFD). Full article
(This article belongs to the Section Aeronautics)
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27 pages, 6151 KB  
Article
Dual-Boundary Mechanism of Shimmy over the Full Speed Range in Nose Landing Gear and Inerter-Based Shimmy Suppression Design
by Jian Wei, Hangming Liu, Jiahao Zhang, Shixing Zhu, Shuangbao Li and Hengjia Zhu
Aerospace 2026, 13(7), 657; https://doi.org/10.3390/aerospace13070657 - 21 Jul 2026
Viewed by 432
Abstract
To overcome the limitation of conventional nose landing gear shimmy damper design, which is mainly based on the critical damping for torsional shimmy while neglecting the high-damping-side instability boundary, this study establishes a nonlinear shimmy dynamic model of a nose landing gear equipped [...] Read more.
To overcome the limitation of conventional nose landing gear shimmy damper design, which is mainly based on the critical damping for torsional shimmy while neglecting the high-damping-side instability boundary, this study establishes a nonlinear shimmy dynamic model of a nose landing gear equipped with a hydraulic damper and an inerter-based suppression system. Hopf bifurcation analysis, numerical continuation, and energy-evolution analysis are employed to investigate the effects of damper, structural, and inerter parameters on the zero-shimmy region over the full speed range. The results show that the zero-shimmy damping interval is not governed by a single torsional critical damping value but is jointly bounded by the tire-induced torsional shimmy boundary on the low-damping side and the lateral or structural torsional shimmy boundary on the high-damping side. Thus, increasing damper damping is not always beneficial. Among the structural parameters, trail determines the existence of the zero-shimmy region, strut torsional stiffness mainly regulates the high-damping-side boundary, and rake angle provides local correction. With proper inertance and tuning-stiffness matching, the inerter-based system raises the upper critical damping by about 210% and improves low-speed shimmy suppression by transferring vibration energy to the damping branch through inertial coupling. Full article
(This article belongs to the Section Aeronautics)
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22 pages, 2624 KB  
Article
A Parallel Solver on a Dynamically Adaptive Overset Grid for Compressible Flow Problems
by Mohamad El Hajj Ali Barada and Bayram Celik
Aerospace 2026, 13(7), 656; https://doi.org/10.3390/aerospace13070656 - 20 Jul 2026
Viewed by 474
Abstract
The overset grid adaptive method offers an efficient approach for the computational modeling of steady or transient three-dimensional compressible flow problems. When implementing this approach on parallel distributed memory computing systems, its scaling, load balancing, and partitioning must be addressed. In this study, [...] Read more.
The overset grid adaptive method offers an efficient approach for the computational modeling of steady or transient three-dimensional compressible flow problems. When implementing this approach on parallel distributed memory computing systems, its scaling, load balancing, and partitioning must be addressed. In this study, we present a parallel, three-dimensional, finite volume compressible Navier–Stokes solver with block-based adaptive mesh refinement capability. The overset grid system consists of an Octree forest governed adaptive Cartesian off-body grid and a pre-partitioned body-conforming grid. To create, manage, and efficiently handle the load balancing and partitioning of the off-body grid, the developed solver utilizes the open source library of p4est. The communication between the partitions of the p4est governed off-body grid and the body-conforming grid is established by using an efficient spatial query algorithm. The parallel performance of the developed solver is evaluated by solving two benchmark problems: steady supersonic flow over a semi-infinite blunt-nose cylinder and the transient interaction of an incident planar shock with a sphere in quiescent air. The results show that the solver accurately captures and tracks the resultant flow shock structures while exhibiting good scalable parallel performance. Full article
(This article belongs to the Section Aeronautics)
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24 pages, 27004 KB  
Article
Physics-Constrained Relative-State Prediction of Encounter Point and Encounter Time for Penetration Decision Support
by Zhichao Yu, Zhanpeng Gao and Wenjun Yi
Aerospace 2026, 13(7), 655; https://doi.org/10.3390/aerospace13070655 - 20 Jul 2026
Viewed by 301
Abstract
In the information-supported penetration scenario, the predicted encounter point and encounter time can provide the future spatial threat position and the time margin for avoidance maneuver, respectively, which are important prior information for dangerous-area judgment, avoidance triggering, and penetration decision making. However, the [...] Read more.
In the information-supported penetration scenario, the predicted encounter point and encounter time can provide the future spatial threat position and the time margin for avoidance maneuver, respectively, which are important prior information for dangerous-area judgment, avoidance triggering, and penetration decision making. However, the data-driven prediction method based on absolute coordinates is likely to depend on the fixed training airspace, resulting in insufficient cross-space generalization ability. Meanwhile, the unconstrained prediction space will lead to an excessively large sample size and an unbalanced sample distribution. Aiming at the above problems, this paper proposes a physics-constrained relative-state prediction framework for the rapid prediction of the encounter point and encounter time. Firstly, the relative-state input centered on the maneuvering vehicle is adopted to reduce the dependence of the model on the fixed global coordinate system. Secondly, a concentric double-layer spherical-shell detectable threat domain is constructed to limit the approximately unbounded prediction space to a finite region that satisfies the sensor detection condition and the maneuvering constraint of the maneuvering vehicle. Furthermore, a physical geometric stratified sampling strategy based on relative distance, azimuth angle, and pitch angle is designed, and a sample-weight correction mechanism is combined to improve the balance of sample coverage under different distance layers and incoming directions. Finally, a ResNet-MLP joint regression model is constructed and trained using offline numerical simulation samples, which is used as an online rapid predictor. The simulation results show that, on the stratified training subset, the mean absolute error of the proposed model for encounter time is 0.1775 s, and the three-dimensional Euclidean error of the encounter point is 129.89 m. The tests with spatial position variation and bounded measurement noise further verify the generalization ability and robustness of the model. The proposed method can provide rapid spatial threat information and time-margin information for dynamic penetration decision making and reduce the computational requirement of repeated online numerical propagation. Full article
(This article belongs to the Special Issue Advanced Navigation, Guidance, and Control for Aerospace Vehicles)
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30 pages, 9531 KB  
Article
Verification and Testing of a Resource-Constrained University CubeSat: On-Orbit Results and Lessons Learned from COSMIC
by Dohyeon Park, Youngho Eun and Sang-Young Park
Aerospace 2026, 13(7), 654; https://doi.org/10.3390/aerospace13070654 - 20 Jul 2026
Viewed by 402
Abstract
University CubeSat programs are often conducted under severe constraints in budget, personnel, schedule, and knowledge continuity, while still requiring sufficient verification to support mission success. This paper presents the verification, testing, on-orbit operation, and anomaly analysis of COSMIC, a 3U university CubeSat developed [...] Read more.
University CubeSat programs are often conducted under severe constraints in budget, personnel, schedule, and knowledge continuity, while still requiring sufficient verification to support mission success. This paper presents the verification, testing, on-orbit operation, and anomaly analysis of COSMIC, a 3U university CubeSat developed by Yonsei University in less than eleven months from project kickoff to launch. COSMIC adopted a protoflight model approach, prioritized commercial off-the-shelf components with flight heritage and prior laboratory experience, and concentrated limited resources on subsystem, FlatSat, system-level, environmental, communication, and scenario-based testing. The test program is reviewed against the subsequent on-orbit results to identify which verification activities contributed to anomaly prevention, fault isolation, and recovery. The results show that system-level integration testing, thermal vacuum cycle testing, and scenario testing were particularly effective in revealing interface, software, and deployment-related issues before launch and in supporting early orbit recovery. However, the mission also exposed limitations in recovery-logic verification, long-duration software testing, communication robustness, and independent reset paths. Based on these findings, practical recommendations are derived for resource-constrained university CubeSat teams seeking to tailor verification activities without simply reducing test rigor. Full article
(This article belongs to the Special Issue Small Satellite Missions (2nd Edition))
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27 pages, 3812 KB  
Article
Perceived Workload in Mixed IFR/VFR Terminal Operations: An Exploratory Pilot Simulator Study in Zagreb TMA
by Bruno Antulov-Fantulin, Karolina Krajček Nikolić, Petar Andraši and Antonio Živko
Aerospace 2026, 13(7), 653; https://doi.org/10.3390/aerospace13070653 - 19 Jul 2026
Viewed by 359
Abstract
Visual flight rules (VFR) traffic is routinely excluded from capacity models and workload assessments in terminal airspace, despite its potential to increase air traffic controller (ATCO) workload. This exploratory pilot study examined the association between a mixed instrument flight rules (IFR) and VFR [...] Read more.
Visual flight rules (VFR) traffic is routinely excluded from capacity models and workload assessments in terminal airspace, despite its potential to increase air traffic controller (ATCO) workload. This exploratory pilot study examined the association between a mixed instrument flight rules (IFR) and VFR terminal scenario and perceived approach-control workload in the simulated Zagreb Terminal Manoeuvring Area (TMA). Nine ATCO trainees completed three within-subject simulator exercises in a fixed order: a mixed IFR/VFR scenario (EXP1), an operationally comparable IFR-only baseline (EXP2), and a higher-density IFR-only scenario (EXP3). Workload was measured using the NASA Task Load Index (NASA-TLX). The mixed scenario was associated with a 9.26-point higher mean weighted NASA-TLX score than the IFR-only baseline (Cohen’s dz=0.67; 95% CI −1.33 to 19.85; two-sided p=0.079); an exploratory directional analysis, specified before data collection, yielded one-sided p=0.039. The omnibus analysis was not significant (F(2,16)=2.56, p=0.109). Frustration and Effort were the only subscales with Holm-adjusted p-values below 0.05; these results are interpreted as exploratory. The two IFR-only scenarios showed little observed difference. The fixed scenario order, small trainee sample, and scripted degraded communication preclude causal inference, motivating a larger counterbalanced confirmatory study with operational controllers. Full article
(This article belongs to the Collection Air Transportation—Operations and Management)
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32 pages, 5647 KB  
Article
An Adaptive Cylindrical-Pruning Decision Tree Method for Conflict Detection During Low-Altitude Multi-UAV Operations
by Xijun Liu, Zelin Chen, Zhaoyang Li and Dongcheng Luo
Aerospace 2026, 13(7), 652; https://doi.org/10.3390/aerospace13070652 - 18 Jul 2026
Viewed by 374
Abstract
Dense low-altitude multi-UAV operations require conflict detection methods that can rapidly identify potential conflicts while preserving detection reliability under realistic motion constraints. This paper proposes an Adaptive Cylindrical-Pruning Decision Tree Method (AC-DTPM) for short-term conflict detection in dense low-altitude UAV traffic. A realistic [...] Read more.
Dense low-altitude multi-UAV operations require conflict detection methods that can rapidly identify potential conflicts while preserving detection reliability under realistic motion constraints. This paper proposes an Adaptive Cylindrical-Pruning Decision Tree Method (AC-DTPM) for short-term conflict detection in dense low-altitude UAV traffic. A realistic UAV motion model is first constructed by considering speed limits, acceleration constraints, climb/descent limits, response delay, positioning error, and wind disturbance. Based on this model, a double-layer cylindrical protection zone is established, including a core conflict zone and an outer warning zone. The proposed AC-DTPM improves the basic Decision Tree Pruning Method through two mechanisms: adaptive time segmentation, which adjusts trajectory-segment length according to UAV speed and local traffic density, and cylindrical warning-zone lower-bound pruning, which eliminates impossible conflict candidates by separately evaluating horizontal and vertical distance lower bounds during tree search. Simulation experiments were conducted for 100–800 UAVs under locally dense and crossing-route scenarios. At 800 UAVs, AC-DTPM reduced the number of evaluated candidate pairs from 601.0 with the basic DTPM to 178.8, corresponding to a 70.3% reduction and a candidate compression ratio of 5.59×10−4. Compared with the basic DTPM, AC-DTPM reduced total detection time by 32.5% and memory cost by approximately 17.0%, while maintaining a missed-detection rate of zero. These results indicate that AC-DTPM provides an interpretable and resource-efficient front-end conflict detection method for scalable low-altitude UAV traffic management. Full article
(This article belongs to the Section Aeronautics)
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23 pages, 18135 KB  
Article
Film Cooling Performance of the Moving Pintle in a Thrust-Controlled Solid Rocket Motor
by Bo-Lun Zhang and Jun Xia
Aerospace 2026, 13(7), 651; https://doi.org/10.3390/aerospace13070651 - 17 Jul 2026
Cited by 3 | Viewed by 345
Abstract
To push the specific impulse and power output of the thrust-controlled solid rocket motor (TCSRM) even higher, the solid-propellant flame temperature is driven to 3000–3600 K. That level of thermal assault subjects the pintle to extreme heat flux and aggressive erosion, a combination [...] Read more.
To push the specific impulse and power output of the thrust-controlled solid rocket motor (TCSRM) even higher, the solid-propellant flame temperature is driven to 3000–3600 K. That level of thermal assault subjects the pintle to extreme heat flux and aggressive erosion, a combination that directly undercuts motor reliability. An effective cooling strategy for the pintle is therefore mandatory. Here, a film-cooling scheme is deployed for thermal protection of the pintle, and a comprehensive study on the transient aero-thermal characteristics of pintle film cooling is carried out to demonstrate how it outperforms the uncooled baseline in extending pintle survival and to reveal the effects of the blowing ratio and pintle moving speed on the performance. The results indicate that the film cooling contributes to improving the pintle cooling performance. As pintle velocity increases, the absolute velocity component of the coolant jet parallel to the mainstream velocity decreases. This causes the relative angle between the coolant jet and mainstream to increase, leading to a stronger interaction between the coolant jet and mainstream. Accordingly, except under low-blowing-ratio conditions, the time-averaged film-cooling effectiveness declines as the pintle velocity increases. Moreover, there is an optimum blowing ratio to achieve the highest time-averaged film-cooling effectiveness. Full article
(This article belongs to the Section Astronautics & Space Science)
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35 pages, 6767 KB  
Article
Study on Longitudinal Dynamic Stability of a Swift-Inspired Idealized Model Considering Body Periodic Vibrations
by Yating Gao and Dong Xue
Aerospace 2026, 13(7), 650; https://doi.org/10.3390/aerospace13070650 - 17 Jul 2026
Cited by 1 | Viewed by 391
Abstract
This study focuses on the longitudinal dynamic stability of swifts in cruising forward flight, which is critical for their high maneuverability but remains insufficiently investigated. Understanding longitudinal dynamic stability is the essential prerequisite for revealing the physical mechanism underlying their maneuverability: it is [...] Read more.
This study focuses on the longitudinal dynamic stability of swifts in cruising forward flight, which is critical for their high maneuverability but remains insufficiently investigated. Understanding longitudinal dynamic stability is the essential prerequisite for revealing the physical mechanism underlying their maneuverability: it is the dynamic stability characteristics that determine how the flight state responds to disturbances and control inputs, thereby laying a foundation for subsequent flight control during agile maneuvers. Conventional studies mostly adopt steady or quasi-steady assumptions, which cannot accurately reflect the influence of periodic body vibration. This study combines CFD numerical simulation and dynamic modeling to systematically analyze the unsteady dynamic stability of swifts. A bio-inspired dynamic model is established using the BE3357B airfoil with a 5° sweep angle, and the flapping-wing motion is decomposed into three degrees of freedom: sweeping, pitching, and flapping. Numerical reliability is assessed through grid independence and time-step independence verification. Aerodynamic force and moment trimming are performed on fixed-DOF and free-DOF models, where the latter considers coupled heaving–pitching motion and adjusted trim parameters. Stability analysis is conducted using three aerodynamic derivative methods: fixed velocity, forced oscillation, and Floquet. By solving small perturbation equations, eigenvalues and eigenmodes are obtained. All three methods identify two stable modes: a short-period mode with damping coefficient 0.1236–0.1870 and oscillation period 0.1121 s–0.1380 s, and a long-period mode with damping coefficient 0.2456–0.6203 and damping half-life 3.5803 s–4.8890 s, verifying stability under periodic vibration and unsteady aerodynamic coupling. Flow field results show clear distinct dynamic pressure and drag fluctuation characteristics between the downstroke and the upstroke. The unsteady stability framework provides a theoretical reference for analyzing the longitudinal stability of biomimetic flapping-wing aircraft and offers useful insight for future bird-inspired flight dynamics studies. Full article
(This article belongs to the Section Aeronautics)
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24 pages, 8639 KB  
Article
Design and Development of a SWIR Optical-Electronic Payload for Earth Remote Sensing Applications
by Ainur Zhetpisbayeva, Samal Kaliyeva, Berik Zhumazhanov, Almira Mukhamejanova, Ainur Satpayeva and Aliya Kargulova
Aerospace 2026, 13(7), 649; https://doi.org/10.3390/aerospace13070649 - 17 Jul 2026
Viewed by 435
Abstract
Wildfires are significant ecological and environmental disasters, impacting forests, ecosystems, climate stability and human life. The visible-spectrum imagery-based traditional wildfire monitoring system can fail to perform well in the presence of smoke, haze and low lighting. A number of machine learning and deep [...] Read more.
Wildfires are significant ecological and environmental disasters, impacting forests, ecosystems, climate stability and human life. The visible-spectrum imagery-based traditional wildfire monitoring system can fail to perform well in the presence of smoke, haze and low lighting. A number of machine learning and deep learning techniques have been proposed, but most of the studies do not provide an integrated Short-Wave Infrared (SWIR) optical-electronic payload framework along with an intelligent optimization technique. The objective of this research is to design an intelligent SWIR-based optical-electronic payload architecture for accurate detection and remote sensing of wildfire and Earth applications via deep learning and optimization techniques. The proposed framework is based on Sentinel-2 SWIR satellite data layers with wildfire and non-wildfire samples. To enhance the quality of the images and the representation of their spectral domain, the following preprocessing operations are carried out: resizing, image normalization, SWIR band extraction, and data augmentation. The following spectral feature extraction techniques are then used: burn area analysis, vegetation stress analysis, and thermal anomaly detection. The framework also incorporates SWIR optical payload design, electronic subsystem development and SWIR InGaAs sensor modeling. Finally, a Hybrid Convolutional Neural Network (CNN)–Residual Network 50 (ResNet50) model optimized by Grey Wolf Optimization (GWO) is used for wildfire classification and hyperparameter tuning. The proposed framework achieved an accuracy of 91.03%, precision of 91.27%, recall of 91.03%, and F1-score of 91.01%. The wildfire detection capability, classification robustness, and convergence performance were enhanced through the integration of SWIR spectral analysis, hybrid deep learning and GWO. The proposed framework offers an effective and trustworthy solution for intelligent wildfire monitoring and Earth remote sensing applications with enhanced spectral sensing and classification performance. Full article
(This article belongs to the Special Issue Spacecraft Close-Proximity Operations)
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29 pages, 5426 KB  
Article
Design, Dynamic Verification, and Multi-Objective Optimization of a Passive Multi-Link Deployable Support Mechanism for Lunar Surface Solar-Concentrating Systems
by Deqiu He, Ping Ruan, Youjin Xie, Wei Hao, Wei Song, Kai Cui, Yiming Dong, Zhize Du and Meilin Xie
Aerospace 2026, 13(7), 648; https://doi.org/10.3390/aerospace13070648 - 16 Jul 2026
Viewed by 435
Abstract
Lunar in situ resource utilization requires solar concentrating systems that can be launched in a compact configuration and deployed reliably on the lunar surface. This paper presents a multi-link coupled deployable support mechanism for a reflector-Fresnel concentrating system. The mechanism adopts a shape-memory-alloy [...] Read more.
Lunar in situ resource utilization requires solar concentrating systems that can be launched in a compact configuration and deployed reliably on the lunar surface. This paper presents a multi-link coupled deployable support mechanism for a reflector-Fresnel concentrating system. The mechanism adopts a shape-memory-alloy rigid release for the stowed state and passive spring hinges for autonomous deployment, aiming to reduce drive complexity while maintaining a high deployment ratio. To avoid interference caused by coupled link motion, a motion-envelope model is established for joint trajectory planning. The deployment process is then analyzed through vector-based kinematic modeling, D’Alembert force analysis, and Lagrange dynamic equations. The analytical predictions are corroborated through high-fidelity multibody dynamic simulations: the predicted driving torque of Link 3 is 0–0.68 N⋅m, close to the simulated range of 0–0.70 N⋅m, with a relative peak-value error of 2.8%; the maximum angular acceleration is 0.08 rad/s2. Finite-element modal analysis gives a first locked-state natural frequency of 54.969 Hz. NSGA-II optimization further reduces the maximum driving torque by 10.9%, reduces torque fluctuation by 9.7%, and increases the maximum deployment ratio from 5.6 to 7.2. The results provide a quantified design and simulation basis for passive deployable concentrating mechanisms intended for lunar surface concentrating systems. Full article
(This article belongs to the Section Astronautics & Space Science)
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26 pages, 679 KB  
Article
Selection of Launch Sites: An Ensemble of MCDM Methods with Discrete Single-Valued Neutrosophic Number Evaluation
by Napat Harnpornchai and Tatcha Sudtasan
Aerospace 2026, 13(7), 647; https://doi.org/10.3390/aerospace13070647 - 16 Jul 2026
Viewed by 419
Abstract
Space economy involves all activities and resource allocations that generate additional economic and societal benefits through space exploitation. The development of space infrastructure enables a wider range of economic activities. Regarding economic sustainability and national security, the possession of the launch site within [...] Read more.
Space economy involves all activities and resource allocations that generate additional economic and societal benefits through space exploitation. The development of space infrastructure enables a wider range of economic activities. Regarding economic sustainability and national security, the possession of the launch site within national territory is of utmost importance. This paper presents a methodology for selecting launch sites based on linguistic term evaluation using a Discrete Single-Valued Neutrosophic Number (DSVNN) representation. The existence of support makes the DSVNN interpretable, which is not possible in the case of Single-Valued Neutrosophic Number (SVNN) with only specific values of truth, indeterminacy, and falsity degrees. An ensemble of five widely well-known MCDM methods, namely TOPSIS, CODAS, COPRAS, EDAS, and MOORA, are used in the decision-making process. The whole procedure is then applied to the launch site selection in Thailand. All MCDM methods result in the same top priority location, U-Tapao Rayong–Pattaya International Airport, Chonburi. The weight sensitivity analysis and the method cross-validation are applied to test the robustness of the result. Full article
(This article belongs to the Special Issue Decision-Making Strategies for Aerospace Mission Design and Planning)
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22 pages, 7675 KB  
Article
Fast Estimation of the Diffractive Loads on a Quadrotor UAV Following an Explosive Blast
by Nicholas P. Kakavitsas, Andrew Willis, Dipankar Maity and Artur Wolek
Aerospace 2026, 13(7), 646; https://doi.org/10.3390/aerospace13070646 - 16 Jul 2026
Viewed by 386
Abstract
This work develops a tool to efficiently estimate the diffractive loads on a quadrotor uncrewed aerial vehicle (UAV) immediately following a nearby explosion. Existing models in the literature that predict the time history of wind velocity and the overpressure at a single distance [...] Read more.
This work develops a tool to efficiently estimate the diffractive loads on a quadrotor uncrewed aerial vehicle (UAV) immediately following a nearby explosion. Existing models in the literature that predict the time history of wind velocity and the overpressure at a single distance from the blast are extended to model a moving blast wave that passes over the vehicle. The time-varying diffractive loads (i.e., due to the blast-induced pressure differential) are first modeled for a single sphere in a blast wave and then for a quadrotor approximated as a series of spheres connected by rods—one sphere for each of the four motors and one sphere for the central body. The overpressure and wind velocity models are compared with computational fluid dynamics (CFD) data. To illustrate the computational approach, a representative quadrotor model is perturbed by a blast from an initial hover flight condition in simulation. The rigid body dynamics are simulated over a short duration (ninety milliseconds) to determine the UAV’s state immediately after the explosion has concluded. The vehicle state history is predicted under the assumption of diffractive loads with a quadratic drag model and constant hover thrust. Full article
(This article belongs to the Special Issue Flight Dynamics, Control & Simulation (3rd Edition))
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25 pages, 1913 KB  
Article
Spin-Modulated Thermoelastic Response of a Flexible Spacecraft Appendage Under Attitude-Dependent Solar Radiation
by Ou Li, Xue Zhong, Yaze Liu, Peixing Li and Hexi Baoyin
Aerospace 2026, 13(7), 645; https://doi.org/10.3390/aerospace13070645 - 16 Jul 2026
Viewed by 460
Abstract
Solar radiation can induce circumferential temperature gradients and thermoelastic bending moments in lightweight spacecraft appendages. For spinning spacecraft, this thermal excitation is periodically modulated by spin motion and may amplify flexible response when the modulation frequency approaches a structural frequency. This study investigates [...] Read more.
Solar radiation can induce circumferential temperature gradients and thermoelastic bending moments in lightweight spacecraft appendages. For spinning spacecraft, this thermal excitation is periodically modulated by spin motion and may amplify flexible response when the modulation frequency approaches a structural frequency. This study investigates the spin-modulated thermoelastic response of a spacecraft with a circular thin-walled flexible appendage under attitude-dependent solar radiation. A reduced-order rigid-flexible-thermal model is formulated by coupling rigid-body attitude motion, assumed-mode appendage deformation, first-harmonic circumferential temperature perturbations, and the resulting generalised thermoelastic bending moment. Long-time simulations, spin-period response sampling, degraded-model comparisons and modal energy/work diagnostics are used to identify the dominant response mechanism. The results show that the post-transient flexible response is governed mainly by spin rate, while the initial solar-incidence angle modifies the local response classification in the sampled high-spin region. Representative high-spin loss-of-admissibility cases lie near the first bending-frequency region, where the retained structural energy and positive thermoelastic work input are concentrated mainly in the first bending mode. Removing deformation-dependent solar-incidence feedback does not eliminate these cases, whereas suppressing thermoelastic bending does. Thus, spin-modulated thermoelastic bending is the essential pathway by which attitude-dependent solar radiation amplifies appendage response. Full article
(This article belongs to the Section Astronautics & Space Science)
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42 pages, 7382 KB  
Article
Glide Trajectory Optimization of Guided Projectiles Using an Improved Grey Wolf Optimizer and hp-Adaptive Radau Pseudospectral Method
by Chen Zhao, Yuhao Wu and Jun Guan
Aerospace 2026, 13(7), 644; https://doi.org/10.3390/aerospace13070644 - 15 Jul 2026
Viewed by 383
Abstract
This study proposes an NSL-GWO-hpRPM framework for constrained glide trajectory optimization of guided projectiles. The method combines an improved Grey Wolf Optimizer with the hp-adaptive Radau pseudospectral method to reduce the dependence of hpRPM on initial guesses and improve global search performance. In [...] Read more.
This study proposes an NSL-GWO-hpRPM framework for constrained glide trajectory optimization of guided projectiles. The method combines an improved Grey Wolf Optimizer with the hp-adaptive Radau pseudospectral method to reduce the dependence of hpRPM on initial guesses and improve global search performance. In the improved GWO, Sobol low-discrepancy sequence initialization is used to enhance population diversity, a nonlinear convergence strategy is introduced to balance exploration and exploitation, and Levy flight is adopted to improve the ability to escape local optima. The optimized solution obtained by NSL-GWO is then used as the initial guess for hpRPM to achieve high-precision local refinement. Simulation results show that the proposed NSL-GWO-hpRPM achieves a feasible range of 71,211.514 m, improving the range by 4.53% over hpRPM and 1.48% over GWO-hpRPM. Statistical results from 35 independent runs further demonstrate that the proposed method obtains the best mean range, Friedman mean rank, and significant Wilcoxon test results with p<0.001. The optimized trajectory reaches a maximum range of approximately 71.2 km with an optimal launch angle of 62.4∘ while satisfying all flight constraints, indicating that the proposed framework is effective for complex constrained glide trajectory optimization. Full article
(This article belongs to the Special Issue Advanced Navigation, Guidance, and Control for Aerospace Vehicles)
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15 pages, 38264 KB  
Article
A Novel Strong-Form Zonal Free Element Method Based on Lagrange Interpolation for Vibro-Acoustic Coupling Analysis
by Liang Jin, Yi Yang, Kaimin Liu, Fengrong Zhao, Jun Lv, Xiaowei Gao and Huayu Liu
Aerospace 2026, 13(7), 643; https://doi.org/10.3390/aerospace13070643 - 15 Jul 2026
Viewed by 363
Abstract
A novel strong-form meshless method based on Lagrange interpolation is proposed for vibro-acoustic coupling analysis. The governing equations of acoustic and structural domains, together with the coupling interface conditions, are discretized directly in differential form without relying on predefined meshes, thereby improving geometric [...] Read more.
A novel strong-form meshless method based on Lagrange interpolation is proposed for vibro-acoustic coupling analysis. The governing equations of acoustic and structural domains, together with the coupling interface conditions, are discretized directly in differential form without relying on predefined meshes, thereby improving geometric flexibility. The computational domain is partitioned into local subdomains, within which Lagrange interpolation is employed to construct approximation functions from nodal distributions. In this manner, the proposed framework combines the flexibility of meshless formulations with a zonal parameterization strategy similar to that used in isogeometric analysis. Moreover, spatial derivatives and system matrices are directly evaluated and assembled at nodal points, avoiding numerical integration and simplifying the implementation procedure. Owing to the Kronecker delta property of Lagrange polynomials, boundary conditions can be imposed accurately and conveniently. For transient analysis, the Newmark-β scheme is adopted to integrate both first- and second-order temporal terms, ensuring stable and accurate time integration. Finally, numerical examples, including comparisons with commercial software, demonstrate the accuracy and effectiveness of the proposed method for complex vibro-acoustic problems. Full article
(This article belongs to the Special Issue Aircraft Structural Dynamics)
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25 pages, 3510 KB  
Article
Co-Optimization of Air Refueling Airspace Planning and Mission Scheduling with Continuous Refueling Zones
by Xu Ma, Fuping Yu and Di Shen
Aerospace 2026, 13(7), 642; https://doi.org/10.3390/aerospace13070642 - 15 Jul 2026
Viewed by 658
Abstract
Air refueling extends aircraft range and endurance, but its operational value hinges on where the refueling airspace is placed and how tanker missions are sequenced. This paper addresses the joint optimization of refueling airspace planning and tanker scheduling, in which each receiver selects [...] Read more.
Air refueling extends aircraft range and endurance, but its operational value hinges on where the refueling airspace is placed and how tanker missions are sequenced. This paper addresses the joint optimization of refueling airspace planning and tanker scheduling, in which each receiver selects a refueling point from a continuous feasible interval along a fixed route. The upper level determines refueling point locations (continuous variables), while the lower level schedules multiple heterogeneous tankers (discrete combinatorial variables); the two levels are tightly coupled through spatiotemporal constraints and fuel propagation. We propose a bottleneck-driven decoupled update (BDDU) strategy built on the Whale Optimization Algorithm (WOA). BDDU extracts bottleneck states from lower-level scheduling feedback and applies per-dimension step-size control to damp the coupling amplification effect inherent in bi-level optimization. Across three scenarios of varying coupling intensities and scales, BDDU-WOA raises the feasibility rate from 50% (WOA baseline) to 90% (+40 percentage points; p<0.05, Fisher’s exact test). The gain stems from a bottleneck-aware, dimension-wise step-size control mechanism with an adaptive, parameter-free classification threshold and only two tunable parameters, adding roughly 10% computational overhead. The method is intended for pre-mission planning of large-scale air refueling operations. Full article
(This article belongs to the Section Air Traffic and Transportation)
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18 pages, 3355 KB  
Article
Energy Management Strategy Under Fuel Constraints for Battery–Fuel Cell-Powered All-Electric Aircraft
by Ayesha R. E. Wise, Sharmila Sumsurooah, Serhiy Bozhko and Seang Yeoh
Aerospace 2026, 13(7), 641; https://doi.org/10.3390/aerospace13070641 - 15 Jul 2026
Viewed by 440
Abstract
Sustainable aviation is an ever-growing field, with feasibility, safety, and longevity being key areas of concern. Future electric aircraft will rely on multiple energy sources. Batteries can provide a fast response to changes in power demands, and fuel cells offer high energy density [...] Read more.
Sustainable aviation is an ever-growing field, with feasibility, safety, and longevity being key areas of concern. Future electric aircraft will rely on multiple energy sources. Batteries can provide a fast response to changes in power demands, and fuel cells offer high energy density for prolonged operation. This work has developed an energy management strategy (EMS) aimed to minimise the overall energy consumption from these sources. The EMS is further designed to respect the operational limits of each component. It investigates three EM approaches to account for the hydrogen consumption restriction, namely the unconstrained method, the fixed-limit method, and a novel depletion-aware method. The unconstrained method assumes there is an unlimited amount of hydrogen, meaning it uses 14.81% more hydrogen than is available, whereas the fixed-limit approach applies the maximum amount of hydrogen available within the fuel tank. However, when there is no hydrogen available, the fuel cell shuts down immediately. This work introduces a novel depletion-aware approach which is conscious of reaching the hydrogen supply minimum limit and, hence, allows for greater use of the battery energy during this period. This allows for better coordination between the battery and fuel cell. The three EMSs are simulated and verified in MATLAB/SIMULINK. The simulation results are then validated using software-in-the-loop in dSPACE. The work demonstrates that the depletion-aware approach has distinct benefits compared to the other two methods as it constrains the fuel consumption and allows a smoother transition between energy storage devices and provides a scalable energy management strategy applicable to a range of all-electric and hybrid-electric aircraft. Full article
(This article belongs to the Special Issue Power Management for Hybrid Electric Aircraft)
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28 pages, 3309 KB  
Article
A Research Method for Dynamic Coupling Modeling and Analysis of Space Robots with Multi-Flexibility Cooperative Structural Deformation
by Fuli Zhang and Na Liang
Aerospace 2026, 13(7), 640; https://doi.org/10.3390/aerospace13070640 - 14 Jul 2026
Viewed by 354
Abstract
Space robots must be designed with a large operating radius and lightweight components (flexible joints and flexible links). The integration of flexible components inevitably affects the control accuracy of the robot. When modeling the link deformation of the space robot, the idealized description [...] Read more.
Space robots must be designed with a large operating radius and lightweight components (flexible joints and flexible links). The integration of flexible components inevitably affects the control accuracy of the robot. When modeling the link deformation of the space robot, the idealized description method has the problem of incomplete accuracy in link deformation due to the coupling effects of the non-fixed base, flexible joints, and changes in control parameters. To address this challenge and improve the accuracy of robot modeling, this study proposes a dynamic coupling analysis method for the link deformation of space robots based on time-domain response. The double finite difference method is adopted to calculate the time-domain response of link deformation. On this basis, using the local linear operator method, the modal information of the deformed links is extracted. This method systematically quantifies the individual and interactive effects of the robot’s base motion, joint flexibility, and control parameters on link deformation. This work not only lays a theoretical foundation for the accurate dynamic modeling of space robots but also provides practical insights for optimizing their structural design. Ultimately, it contributes to the development of more reliable and high-performance space robot systems. Full article
(This article belongs to the Section Astronautics & Space Science)
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23 pages, 1969 KB  
Article
Hybrid Rocket Motor Performance Dispersion and Its Mitigation Through Real-Time State Estimation and Feedback Control
by Albertus Stephanus Louw, Marco Rotondi, Landon Kamps and Toru Shimada
Aerospace 2026, 13(7), 639; https://doi.org/10.3390/aerospace13070639 - 14 Jul 2026
Viewed by 593
Abstract
Hybrid rocket motors are an attractive option for the upper-stages of low-cost small launchers, but are susceptible to variability in performance both in time and between firings. Moreover, key contributors to hybrid motors’ performance such as oxidizer-to-fuel ratio (O/F) [...] Read more.
Hybrid rocket motors are an attractive option for the upper-stages of low-cost small launchers, but are susceptible to variability in performance both in time and between firings. Moreover, key contributors to hybrid motors’ performance such as oxidizer-to-fuel ratio (O/F) are difficult to estimate, and by extension, to control. Four approaches were evaluated for the estimation and control of O/F under system uncertainty, including through on-line estimation by an Unscented Kalman Filter (UKF). A Monte Carlo analysis was conducted of a simulated hybrid kick motor, where key sources of system uncertainty such as the characteristic velocity efficiency (ηc*), fuel regression coefficients, and oxidizer flow characteristics were allowed to be variable. Feedback control of O/F informed by the UKF obtained 6.8% smaller control error than the best alternative approach. Yet the Monte Carlo analysis showed that among uncertainty sources considered, ηc* was the primary driver of performance variability, while O/F regulation had a small influence. This was because the total and specific impulses were relatively insensitive to O/F for the considered motor configuration and ranges of O/F observed during the simulated burns—highlighting the importance of system uncertainty quantification when formulating performance-regulating interventions. Further, the proposed UKF observer provided data-informed estimates of combustion efficiency and propellant residuals in time, which are valuable for the planning and execution of accurate orbital insertions in a kick motor susceptible to performance uncertainty. The developed uncertainty quantification and control modeling framework can be used also during the design and assessment of other control interventions under system uncertainty. Full article
(This article belongs to the Special Issue Propulsion Solutions for Enhancing the Small Launchers’ Competitiveness)
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23 pages, 5710 KB  
Article
Cooperative Guidance Law for Targets Maneuvering in 3D with Multiple Constraints
by Yekun Liu and Xiaoyu Zhang
Aerospace 2026, 13(7), 638; https://doi.org/10.3390/aerospace13070638 - 14 Jul 2026
Viewed by 316
Abstract
This study focuses on the situation where multiple vehicles simultaneously intercept a maneuvering target with desired line-of-sight (LOS) angles and impact time in a three-dimensional environment. A predefined-time cooperative guidance law is proposed, which adapts to the switching communication topologies among the vehicles. [...] Read more.
This study focuses on the situation where multiple vehicles simultaneously intercept a maneuvering target with desired line-of-sight (LOS) angles and impact time in a three-dimensional environment. A predefined-time cooperative guidance law is proposed, which adapts to the switching communication topologies among the vehicles. To accomplish the task of adjusting the impact time by leveraging the multi-agent consensus principle, a novel adaptive predefined-time consensus protocol is designed in the LOS direction, which allows multiple vehicles to intercept the target at the desired impact time, while ensuring that the impact times of all vehicles converge within a predefined time. In the LOS normal direction, based on the error transformation function, a novel predefined-time non-singular fast terminal sliding mode guidance law is proposed to guarantee the convergence of the LOS angular rate within the predefined time, achieving the simultaneous interception of the target by multiple vehicles at different terminal angles and eliminating singularities. At the same time, the tracking error satisfies the prescribed performance constraint. In particular, for scenarios where the target acceleration is unknown, a predefined-time external state observer is employed to estimate disturbances and compensate within the guidance law. The simulation results validate the effectiveness and robustness of the proposed method. Full article
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24 pages, 10883 KB  
Article
Reduced-Order Modelling of Wall Heat Flux in Rotating Detonation Rocket Combustors with One-Dimensional Coolant Coupling
by Victor Petri Milo, Wolfgang Armbruster, Michael Börner and Justin S. Hardi
Aerospace 2026, 13(7), 637; https://doi.org/10.3390/aerospace13070637 - 14 Jul 2026
Viewed by 572
Abstract
Rotating detonation engines combine compact geometry with the potential for higher specific impulse compared to deflagration-based propulsion, enabled by pressure-gain combustion. However, their increased thermal loads present a major challenge. In the current literature, thermal characterisation of rotating detonation hardware relies either on [...] Read more.
Rotating detonation engines combine compact geometry with the potential for higher specific impulse compared to deflagration-based propulsion, enabled by pressure-gain combustion. However, their increased thermal loads present a major challenge. In the current literature, thermal characterisation of rotating detonation hardware relies either on experimental reconstructions or on high-fidelity simulations. A predictive and coolant-coupled low-order heat transfer model for rotating detonation rocket engines is not yet available in the open literature. This paper introduces such a reduced-order predictive tool for rotating detonation combustors, capable of estimating both cycle-averaged wall heat flux and coolant thermal behaviour. Implemented in Python, the tool supports any propellant available in NASA’s Chemical Equilibrium with Applications and CoolProp, handles single-phase thermodynamic regimes, and spans geometric and operating ranges from laboratory-scale test rigs to engine-relevant conditions. With computation times below one second, it enables rapid trade studies, model-based screening, and sensitivity analyses. Benchmarking was performed against experimental test cases covering H2/O2, CH4/O2 and C2H4/O2 mixtures, as well as multiple injector geometries and chamber configurations. The approach complements existing high-fidelity tools by offering a low-order alternative grounded in transparent assumptions and benchmarked against multiple datasets. Full article
(This article belongs to the Section Aeronautics)
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27 pages, 7124 KB  
Article
Executable Reference Trajectory Construction and Conflict-Aware Residual Reinforcement Learning for Urban Multi-UAV Navigation
by Xiangzhi Zhou, Siqin Li, Qianjin Xia and Shanmei Li
Aerospace 2026, 13(7), 636; https://doi.org/10.3390/aerospace13070636 - 13 Jul 2026
Viewed by 499
Abstract
Urban multi-UAV navigation in dense building environments requires not only collision-free geometric paths but also executable flight processes under motion constraints and inter-UAV safety requirements. A static path that is feasible in a geometric map may still fail during closed-loop execution because of [...] Read more.
Urban multi-UAV navigation in dense building environments requires not only collision-free geometric paths but also executable flight processes under motion constraints and inter-UAV safety requirements. A static path that is feasible in a geometric map may still fail during closed-loop execution because of velocity limits, acceleration constraints, local path-association errors, and coupled multi-UAV interactions. Meanwhile, end-to-end reinforcement learning often suffers from unstable training, weak geometric interpretability, poor early-stage safety, and high sample complexity. To address these issues, this paper proposes a hierarchical planning-and-learning framework that connects static reference path generation, executable reference tracking, successful demonstration distillation, and conflict-aware residual reinforcement learning. First, three-dimensional reference paths are generated offline in an OpenStreetMap-based urban scene represented by cuboid buildings. Second, a damped reference-tracking mechanism transforms these static paths into closed-loop executable reference processes through local path association, monotonic progress updating, path recapture, look-ahead guidance, and bounded action construction. Third, successful pure-reference executions are distilled for behavior-cloning initialization. Finally, a bounded residual TD3 module is introduced as a local conflict-correction mechanism around the verified executable reference baseline. Experiments in an urban scene containing 754 buildings show that simplified tracking strategies fail to execute the static paths reliably, whereas the proposed full-damped reference-tracking controller achieves a 91.67% all-success rate and eliminates building collision episodes in the tracking-ablation test. Speed-sensitivity experiments at 10, 15, and 20 m/s show the same 91.67% all-success rate, indicating that the conclusion is not dependent on a single speed setting. In constructed conflict-stress tests, the conflict-aware residual TD3 module increases the all-success rate from 33.33% to 80.09%, reduces inter-UAV collision episodes from 66.67% to 11.57%, and improves the hard-safety satisfaction rate from 33.33% to 87.04%. These results show that the main contribution of the proposed framework lies in converting static geometric paths into executable reference trajectories and further enabling bounded residual correction under inter-UAV conflict conditions. Full article
(This article belongs to the Topic Unmanned Vehicles Technology and Embodied Intelligence Systems for Intelligent Transportation)
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25 pages, 14560 KB  
Article
Three-Dimensional Prescribed-Time Hierarchical Cooperative Guidance Law for Head-On Interception
by Shengli Xu, Kechen Xiang, Hongyang Xu, Yonghua Fan and Haoyu Cheng
Aerospace 2026, 13(7), 635; https://doi.org/10.3390/aerospace13070635 - 13 Jul 2026
Viewed by 277
Abstract
This paper proposes a three-dimensional prescribed-time hierarchical cooperative guidance law (3-D PTHCGL) for rapid and reliable head-on encirclement in cooperative interception of high-speed targets under incomplete directed communication topology, target maneuvers, and limited terminal engagement time. The proposed method consists of a distributed [...] Read more.
This paper proposes a three-dimensional prescribed-time hierarchical cooperative guidance law (3-D PTHCGL) for rapid and reliable head-on encirclement in cooperative interception of high-speed targets under incomplete directed communication topology, target maneuvers, and limited terminal engagement time. The proposed method consists of a distributed estimator layer (DEL) and a local controller layer (LCL), addressing three key issues in head-on encirclement formation: information acquisition, rapid convergence, and geometric configuration. In the DEL, a distributed prescribed-time estimator (DPTE) is developed to enable followers without direct communication with the leader to estimate the leader’s states from neighborhood information within a prescribed time. In the LCL, a prescribed-time extended state observer (PTESO) and a three-dimensional prescribed-time cooperative guidance law (3-D PTCGL) are designed to estimate target-maneuver-induced disturbances and unknown states, and to guarantee prescribed-time convergence of estimation and cooperative tracking errors. Furthermore, virtual line-of-sight (LOS) angles are introduced based on a three-dimensional head-on interception kinematic model to characterize the head-on encirclement configuration, and range-to-go together with radial relative velocity are adopted instead of time-to-go to reduce sensitivity to time-estimation errors. Simulation results demonstrate the effectiveness and robustness of the proposed method in achieving prescribed-time head-on encirclement and simultaneous attack without a speed advantage. Full article
(This article belongs to the Section Aeronautics)
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27 pages, 2134 KB  
Article
Random Vibration Analysis of Linear/Nonlinear Systems with Fractional Derivatives Subjected to Colored Noise
by Wenkai Sun, Jinsheng Guo and Xianren Kong
Aerospace 2026, 13(7), 634; https://doi.org/10.3390/aerospace13070634 - 13 Jul 2026
Viewed by 356
Abstract
In this paper, the stochastic responses of multi-degree-of-freedom (MDOF) linear/nonlinear systems with rational-order fractional derivatives excited by colored noise are investigated. A closed-form expression for the PSDs of MDOF linear systems with fractional derivatives under exponential colored noise is derived by combining the [...] Read more.
In this paper, the stochastic responses of multi-degree-of-freedom (MDOF) linear/nonlinear systems with rational-order fractional derivatives excited by colored noise are investigated. A closed-form expression for the PSDs of MDOF linear systems with fractional derivatives under exponential colored noise is derived by combining the eigenvector expansion method (EEM) and the pole-residue representation of the transfer function. The equivalent linearization method (ELM) is developed to determine the stochastic responses of fractional-order nonlinear systems. This is achieved by replacing the original system with an equivalent fractional-order linear system whose parameters are determined by minimizing the mean-square difference. The EEM is incorporated into the linearization framework to solve the linear fractional-order equations during the iterative process for the equivalent coefficients. Two widely adopted linearization criteria, the energy-based criterion and the equation-based criterion, are examined in detail. Numerical examples, including two linear systems and three nonlinear fractional-order systems with various types of nonlinearity under colored noise, are presented to verify the accuracy and applicability of the proposed method. Compared with Monte Carlo (MC) simulations, both criteria provide satisfactory accuracy. In addition, the results from the energy-based linearization criterion are more accurate than those from the equation-based criterion for single-degree-of-freedom (SDOF) systems, whereas for MDOF systems, the equation-based criterion yields slightly more accurate results than the energy-based criterion. The effects of nonlinear intensity and the order of the fractional derivative on the response statistics are also investigated. Full article
(This article belongs to the Section Astronautics & Space Science)
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18 pages, 4999 KB  
Article
Flutter Analysis of Telescopic Wing Structures Based on Non-Matching Grid Contact Equivalence
by Yilin Li, Rui Zhu, Xiaochen Hang, Qiang Chen and Qingguo Fei
Aerospace 2026, 13(7), 633; https://doi.org/10.3390/aerospace13070633 - 13 Jul 2026
Viewed by 387
Abstract
The frequency-domain flutter analysis method requires a linear model as input; however, when a telescopic actuator is applied to morphing aircraft, traditional frequency-domain flutter analysis methods face challenges in addressing issues involving contact nonlinearity. To enable classical frequency-domain methods to handle this type [...] Read more.
The frequency-domain flutter analysis method requires a linear model as input; however, when a telescopic actuator is applied to morphing aircraft, traditional frequency-domain flutter analysis methods face challenges in addressing issues involving contact nonlinearity. To enable classical frequency-domain methods to handle this type of nonlinearity, this paper presents an equivalent linearization modeling method for morphing aircraft wing structures. The proposed modeling method uses rod elements as the equivalent linearization elements and avoids the need to handle node correspondence issues. The model is parameterized by the rod element’s elastic modulus, contact surface distance, and element length coefficient. Upon completion of the equivalent modeling, flutter analysis can be performed by the PK method. The proposed modeling method increases modeling efficiency while maintaining the accuracy of the model. A simulation study of a typical hypersonic telescopic wing structure is conducted. The effects of angle of attack and altitude on flutter characteristics are analyzed. The proposed modeling method effectively captures both the static and dynamic characteristics of the original structure. The flutter Mach number decreases with increasing extension length, and it increases with altitude and angle of attack. The flutter frequency decreases with increasing extension length, angle of attack, and altitude. Full article
(This article belongs to the Section Aeronautics)
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27 pages, 8833 KB  
Article
Dynamics Modeling of a Rigid–Flexible Coupled Flapping-Wing Robot and Diffeomorphism-Based Disturbance Rejection Attitude-Constrained Control
by Guang Rong, Jingyuan Yang, Jinbao Chen, Jian Wang and Jianyuan Wang
Aerospace 2026, 13(7), 632; https://doi.org/10.3390/aerospace13070632 - 12 Jul 2026
Viewed by 303
Abstract
Lightweight flapping-wing robots are affected by structural flexibility, wind disturbances, and static friction in basal passive joints during perching and attitude-holding tasks. These coupled effects can make conventional PID and sliding mode control (SMC) produce error amplification, torque fluctuation, flexible-response excitation, and attitude-boundary [...] Read more.
Lightweight flapping-wing robots are affected by structural flexibility, wind disturbances, and static friction in basal passive joints during perching and attitude-holding tasks. These coupled effects can make conventional PID and sliding mode control (SMC) produce error amplification, torque fluctuation, flexible-response excitation, and attitude-boundary violation. This study establishes an ADAMS–Simulink co-simulation platform for a rigid–flexible coupled flapping-wing robot and proposes a diffeomorphism-based attitude-constrained controller. The inverse hyperbolic tangent mapping transforms bounded physical errors into unbounded virtual errors, allowing smooth small-error regulation and stronger constraint enforcement near safety boundaries. Wind-free tracking, compound wind rejection, pulse wind scanning, mapping-parameter sensitivity, and a CBF-QP safety-filtered baseline are evaluated. In manuscript parameter-synchronized ADAMS 2024 reruns under a 2 m/s steady wind with a 1 m/s pulse, PID and SMC show runaway angular excursions of 1602.56° and 381,330.03°, whereas the proposed method remains bounded at 23.58° with an RMSE of 2.943° and no boundary violation. The CBF-QP baseline still violates the boundary at 1394°. The results show improved tracking accuracy, boundary protection, measured-channel flexible-excitation attenuation, and stable disturbance recovery. Full article
(This article belongs to the Special Issue Space Robotics and Embodied Intelligence: Advancing Autonomous Exploration)
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20 pages, 28557 KB  
Article
Unsteady Buzz Characteristics of a Dorsal Supersonic Bump Inlet Based on Wind-Tunnel Tests and Numerical Simulations
by Meng Cao, Ce Zhang, Hexiang Wang, Dawei Liu, Jie Chen and Yang Tao
Aerospace 2026, 13(7), 631; https://doi.org/10.3390/aerospace13070631 - 11 Jul 2026
Viewed by 391
Abstract
The unsteady buzz characteristics of a dorsal supersonic bump inlet for a flying-wing configuration are investigated using wind-tunnel tests and three-dimensional unsteady numerical simulations. This study focuses on off-design operation at a freestream Mach number of 1.8, with particular attention to the effects [...] Read more.
The unsteady buzz characteristics of a dorsal supersonic bump inlet for a flying-wing configuration are investigated using wind-tunnel tests and three-dimensional unsteady numerical simulations. This study focuses on off-design operation at a freestream Mach number of 1.8, with particular attention to the effects of angle of attack and downstream throttling on shock motion, pressure oscillation, and inlet stability. Wind-tunnel measurements show that the onset and development of buzz are highly sensitive to angle of attack. At high angles of attack, pressure oscillations first appear near the inlet compression surface and subsequently develop into large-amplitude fluctuations at the aerodynamic interface plane. The dominant experimental buzz frequency is approximately 60–70 Hz, and the numerical prediction of 71 Hz agrees well with the measured dominant frequency of 66 Hz. The simulations further reveal a strongly three-dimensional buzz cycle in which asymmetric separation over the bump, spanwise accumulation and discharge of low-energy flow, and alternating inlet blockage and recovery govern the large-amplitude shock excursion. The oscillatory flow field is dominated by shock–system expulsion and ingestion on the spanwise side with stronger back-pressure tolerance, accompanied by the formation of strong and weak shear layers during different stages of the cycle. These results provide insight into the buzz mechanism of dorsal bump inlets and support the assessment of starting performance and stable operating limits for supersonic inlets integrated with flying-wing configurations. Full article
(This article belongs to the Section Aeronautics)
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