Aerospace

21 pages, 2720 KB

Open AccessArticle

Adaptive Neural Barrier Function-Based Fast Terminal Sliding Mode Control for Bionic Aerial Manipulators in Canopy Sampling

by Xiaohu Chen, Li Ding, Wenfeng Wu and Hongtao Wu

Aerospace 2026, 13(4), 392; https://doi.org/10.3390/aerospace13040392 - 21 Apr 2026

Viewed by 233

Abstract

This paper proposes a novel adaptive sliding mode control strategy for bionic aerial manipulators performing canopy-sampling tasks. Specifically, an adaptive neural barrier function-based fast terminal sliding mode control (BFASMC-NN) scheme is developed to address the joint-space trajectory tracking problem by integrating fast continuous [...] Read more.

This paper proposes a novel adaptive sliding mode control strategy for bionic aerial manipulators performing canopy-sampling tasks. Specifically, an adaptive neural barrier function-based fast terminal sliding mode control (BFASMC-NN) scheme is developed to address the joint-space trajectory tracking problem by integrating fast continuous nonsingular terminal sliding mode control (FNTSMC), neural networks (NNs), and barrier functions (BFs). The aerial manipulator is modeled as a rootless system, and its kinematic and dynamic characteristics are analyzed separately. Radial basis function neural networks (RBF-NNs) are introduced to approximate lumped disturbances, while BFs are incorporated to mitigate the effects of joint input saturation. Meanwhile, FNTSMC is employed to guarantee finite-time convergence of the system states. The stability of the closed-loop system is rigorously proven based on Lyapunov stability theory. Two simulation studies are conducted to validate the proposed method, and the results demonstrate that it achieves stronger disturbance rejection capability, faster convergence, and higher tracking accuracy than existing approaches. Full article

(This article belongs to the Special Issue New Perspective on Flight Guidance, Control and Dynamics)

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32 pages, 12530 KB

Open AccessArticle

Effect of Compressor Root Slot Structure on Suppressing Corner Separation and Aerodynamic Parameter Deterioration Induced by Seal Cavity Leakage Flow

by Wenfeng Xu, Xinrui Du, Shilong Zou, Dan Sun and Guozhe Ren

Aerospace 2026, 13(4), 391; https://doi.org/10.3390/aerospace13040391 - 21 Apr 2026

Viewed by 304

Abstract

To alleviate the adverse effects of the flow-field structure caused by interstage sealing structures on the aerodynamic characteristics of compressor cascades, a blade-root through-slot structure was designed in this study. The structure links the pressure surface to the suction surface of the blade. [...] Read more.

To alleviate the adverse effects of the flow-field structure caused by interstage sealing structures on the aerodynamic characteristics of compressor cascades, a blade-root through-slot structure was designed in this study. The structure links the pressure surface to the suction surface of the blade. Numerical simulation techniques were utilized to investigate the process. In this process, the through-slot structure enhances corner separation across varying jet positions, jet heights, and jet widths. The results indicate that the high-speed fluid ejected by the through-slot configuration can suppress the accumulation of low-energy fluid at the suction root. It can also alleviate blockages in the cascade passage and reduce the range of separation vortices and recirculation zones on the suction side. Consequently, the flow loss due to separation is reduced. As the through-slot jet progresses from the blade leading edge to the trailing edge, its restraining impact on the low-energy fluid cluster gradually diminishes. This leads to a corresponding reduction in its effect on the total pressure loss. With an increase in the slot height, the restraining impact on corner separation and total pressure loss first rises and then falls. As the through-slot height increases, the suppressive effect on corner separation and loss initially intensifies and then weakens. As the through-slot width increases, the suppressive effect on corner separation and total pressure loss increases steadily. Compared to the original compressor cascade, the through-slot configuration attains peak performance at 25% chord length, with a height of 6% height and a width of 10 mm, reducing the total pressure loss coefficient by 19.22%. Furthermore, as the incoming flow incidence angle enlarges, the enhancement impact of the through-slot configuration on cascade performance initially intensifies and then diminishes. The peak enhancement impact occurs at a 0° incidence angle. At this angle, the configuration can reduce flow loss by 16.72% compared to the original, significantly improving the aerodynamic performance of the high-load compressor cascade. Full article

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23 pages, 3359 KB

Open AccessArticle

Development of Improved Empirical Landing Equations for Conceptual Design

by Timothy T. Takahashi

Aerospace 2026, 13(4), 390; https://doi.org/10.3390/aerospace13040390 - 21 Apr 2026

Viewed by 362

Abstract

This paper develops new empirical relationships to estimate FAA/EASA- and MIL-3013B-rules-compliant landing-field performance of multi-engine transport aircraft. Widely cited textbooks date from an era when inferior tire and braking capability limited aircraft performance. Today, the use of overly pessimistic conceptual design-level performance estimates [...] Read more.

This paper develops new empirical relationships to estimate FAA/EASA- and MIL-3013B-rules-compliant landing-field performance of multi-engine transport aircraft. Widely cited textbooks date from an era when inferior tire and braking capability limited aircraft performance. Today, the use of overly pessimistic conceptual design-level performance estimates may lead concept-design teams to advocate for unnecessary engineering solutions (for example, more complex flaps) to solve “problems” which do not actually exist. Moreover, today’s aircraft designer is likely to face customer-imposed wet and/or contaminated runway performance requirements, where the classic books only discussed dry-weather operations. Taken together, the design community needs a collection of revised empirical equations to estimate landing distances for dry and wet runways. The empirical relationships published here are based upon modern flight-manual data augmented by a calibrated physics-based numerical simulation applied to a wide range of possible vehicle configurations. They offer improved accuracy, compared to earlier methods. The new method, when applied to FAA rules for aircraft operating on dry runways, predicts the substantially shorter “real-world” certified landing distances attainable by modern aircraft. Full article

(This article belongs to the Section Aeronautics)

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20 pages, 7051 KB

Open AccessArticle

Potential Field-Based Topology Construction of Structured Grids Around an Aircraft

by Hai Zhu, Weiqiang Huang, Taohong Ye and Minming Zhu

Aerospace 2026, 13(4), 389; https://doi.org/10.3390/aerospace13040389 - 20 Apr 2026

Viewed by 419

Abstract

Multi-block structured mesh is widely used for high-precision aerodynamic simulation, but mesh blocking usually requires substantial manual intervention, which is time-consuming and demands a high level of user expertise. In this study, a potential field-based blocking algorithm for mesh generation around an aircraft [...] Read more.

Multi-block structured mesh is widely used for high-precision aerodynamic simulation, but mesh blocking usually requires substantial manual intervention, which is time-consuming and demands a high level of user expertise. In this study, a potential field-based blocking algorithm for mesh generation around an aircraft is proposed, and a corresponding multi-block grid generation workflow is established. First, the hyperbolic partial differential equation (PDE) method is used to march boundary layer grids from the body surface. Next, the potential field is solved on an unstructured background grid, and the grid topology is flexibly designed by adjusting boundary conditions. The gradient lines of the potential field are then determined and employed to partition the external domain into blocks. Finally, the elliptic PDE method is applied to generate structured grids within each sub-block. A low-aspect-ratio flying-wing configuration is adopted as the test case. Structured grids of both H-type and O-type topologies are generated and compared with the benchmark grid released by the China Aerodynamics Research and Development Center (CARDC). The grid quality analysis and aerodynamic calculation results demonstrate that the two generated grids possess good quality, and the computational results show satisfactory agreement with experimental data. The O-type mesh yields more accurate predictions for the lift coefficient and pitching moment coefficients. Furthermore, two test cases, namely a rocket sled and a V-tail aircraft, are presented to demonstrate that the proposed method can flexibly design either O-type or H-type topologies to accommodate different geometric characteristics. In summary, the proposed method enables efficient generation of high-quality multi-block structured grids for the configurations examined in this study. Full article

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28 pages, 10687 KB

Open AccessArticle

Investigation of Liquid Hydrogen Tank Structural Integration Concepts for Regional Aircraft

by Panagiotis Gyftos, Ioannis Sioutis and George Lampeas

Aerospace 2026, 13(4), 388; https://doi.org/10.3390/aerospace13040388 - 20 Apr 2026

Viewed by 441

Abstract

Liquid hydrogen (LH₂) as an energy source is viewed as a potential path to achieve carbon neutral commercial aviation, albeit accompanied by a plethora of structural, thermal and safety challenges that still need to be resolved. With respect to a LH [...] Read more.

Liquid hydrogen (LH₂) as an energy source is viewed as a potential path to achieve carbon neutral commercial aviation, albeit accompanied by a plethora of structural, thermal and safety challenges that still need to be resolved. With respect to a LH₂ tank’s structural integration aspect, static, damage tolerance and impact/crashworthiness responses need to be investigated. Ιn the present work, an efficient structural integration concept of LH₂ tanks into a Regional Commercial Aircraft fuselage is proposed, analyzed and preliminary designed, as part of the Clean Aviation project HERFUSE. The main purpose of the work is the feasibility assessment of introducing adhesively bonded solutions in the connection of LH₂ tanks to the aircraft fuselage. The initial design of the potential mounting system configuration was investigated via a finite element parametric simulation model that was developed for this purpose and used to analyze different variations in the proposed concept, under certification relevant load cases. Different variations in the mounting system were assessed, considering their effect on the stress concentrations developed in the fuselage and the tank structure, as well as induced deformations and potential joints debonding. The results indicated that the utilization of adhesive bonding elements in the design of an LH₂ tank integration system is conceptually efficient, although the specific configuration-related shortcomings that were identified need to be tackled. As far as the preliminary design study results are concerned, the minimum required number of joining elements were identified and an initial mass prediction of the mounting system was performed to be used as initial value in the entire hybrid–electric novel aircraft design loop. Future studies on the detailed design and sizing of the mounting system, as well as to incorporate dynamic crash analyses and implementation of energy absorbing elements are needed. Full article

(This article belongs to the Special Issue 15th EASN International Conference on Innovation in Aviation & Space Towards Sustainability Today and Tomorrow)

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31 pages, 6226 KB

Open AccessArticle

Vibration and Aerodynamic Characteristics of Dielectric Elastomer Membranes of Various Shapes

by Pratik Sarker, Bianca Fernandez and M. Shafiqur Rahman

Aerospace 2026, 13(4), 387; https://doi.org/10.3390/aerospace13040387 - 20 Apr 2026

Viewed by 376

Abstract

The dielectric elastomer is a category of electroactive polymer capable of having large deformation under electric excitation and vice versa. They show great potential for the proper maneuvering of small-scale aerial vehicles due to low density and fast actuation, and the successful design [...] Read more.

The dielectric elastomer is a category of electroactive polymer capable of having large deformation under electric excitation and vice versa. They show great potential for the proper maneuvering of small-scale aerial vehicles due to low density and fast actuation, and the successful design demands a proper prediction of their overall dynamic characteristics. However, these characteristics cannot be accurately predicted from lower-order material approximation and/or one specific elastomer shape under a specific flow velocity, pretension, and relaxation. In this research, a comprehensive modal and aerodynamic analysis for the VHB 4910 dielectric elastomer membrane of three different shapes is computationally investigated under different electric excitations, pretensions, and flow velocities using the higher-order Ogden model. A finite element model and a two-way, fully coupled fluid–structure interaction model are developed to obtain vibration and aerodynamic characteristics, respectively, for different membrane shapes. It is found that the variation in electric excitation, pretension, and air velocity is influential in altering the overall dynamics of the membrane and is unique to specific shapes. The rectangular membrane shows a higher vibration frequency for the fundamental mode, whereas the circular membrane provides higher frequencies in higher modes. Increased relaxation for a membrane prestretch higher than the moderate range of stretch ratio (

λ

= 3) demonstrates a slight increase in lift coefficient within a small range of angle of attack, followed by a decrease after exceeding that range. Both the rectangular and elliptical membranes show more flexibility to delay the stall compared to the circular membrane. The circular membrane is observed to have more potential for enhancing the aerodynamic performance and altering the flow field within a certain range of electric excitation and pretension. Computational results are compared with published experimental results to validate the corresponding models. Full article

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17 pages, 1612 KB

Open AccessArticle

A Flight Path Angle Reconstruction-Based Polynomial Guidance Law with Multiple Constraints

by Hong Liang, Zechen Zhang and Sijiang Chang

Aerospace 2026, 13(4), 386; https://doi.org/10.3390/aerospace13040386 - 20 Apr 2026

Viewed by 255

Abstract

A novel polynomial guidance law is proposed for flight vehicle terminal guidance, subject to multiple constraints including launch angle, impact angle, impact time, and zero terminal acceleration. This approach reconstructs the flight path angle profile into two components. One component satisfies the constraints. [...] Read more.

A novel polynomial guidance law is proposed for flight vehicle terminal guidance, subject to multiple constraints including launch angle, impact angle, impact time, and zero terminal acceleration. This approach reconstructs the flight path angle profile into two components. One component satisfies the constraints. The other ensures target interception. The constraint-oriented component is formulated as a polynomial function of the relative range-to-go. Based on this reconstruction framework, a new linearization approach is introduced to handle the nonlinear engagement kinematics. A closed-form guidance law is then derived to satisfy multiple constraints, and its convergence is analyzed theoretically. To optimize the control effort, a data-driven method is subsequently incorporated into the framework. Numerical simulation results show that the proposed guidance law achieves multiple constraints with high precision. Compared with existing methods, it also requires less control effort. Specifically, the impact angle error is within 0.02°, and the impact time error is within 0.05 s. Full article

(This article belongs to the Special Issue Flight Guidance and Control)

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4 pages, 647 KB

Open AccessEditorial

Special Issue “Advanced Aircraft Structural Design and Applications”

by Heyuan Huang, Liaojun Yao and Meiying Zhao

Aerospace 2026, 13(4), 385; https://doi.org/10.3390/aerospace13040385 - 19 Apr 2026

Viewed by 315

Abstract

Aircraft structural design is undergoing a profound transformation driven by increasingly demanding requirements in lightweight construction [...] Full article

(This article belongs to the Special Issue Advanced Aircraft Structural Design and Applications)

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17 pages, 2039 KB

Open AccessArticle

Airport Taxiway–Gate Joint Scheduling Problem: A Multi-Objective Optimization Approach Based on a Spatiotemporal Graph

by Jinghan Du, Hongwei Li, Weining Zhang, Weijun Pan and Jianan Yin

Aerospace 2026, 13(4), 384; https://doi.org/10.3390/aerospace13040384 - 18 Apr 2026

Viewed by 302

Abstract

The optimization of gate allocation and taxiway routing represents a critical challenge in enhancing airport ground operations performance. To simultaneously address these two closely coupled tasks, their interconnected processes are first modeled as flows in a spatiotemporal graph. On this basis, we develop [...] Read more.

The optimization of gate allocation and taxiway routing represents a critical challenge in enhancing airport ground operations performance. To simultaneously address these two closely coupled tasks, their interconnected processes are first modeled as flows in a spatiotemporal graph. On this basis, we develop a multi-objective optimization approach that accounts for both temporal and spatial factors across different operational aspects, effectively balancing the diverse needs of travelers, carriers, and airport authorities. To mitigate differences in scale and preference among various optimization objectives, min-max normalization combined with the linear weighting method is employed to transform the multi-objective problem into a single-objective one, which is solved by binary integer linear programming. Based on the actual operational data of Terminal 1 at Shanghai Pudong International Airport, three typical scenarios of different complexity are constructed for validation purposes. Performance comparisons with the state-of-the-art methods demonstrate the superiority of the proposed model in terms of various operational costs and parameter sensitivity. The integrated scheduling solution offers airport operators a reliable and efficient decision-making tool with practical applicability. Full article

(This article belongs to the Special Issue Next-Generation Airport Operations and Management)

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19 pages, 535 KB

Open AccessArticle

Life Cycle Assessment of Innovative Propulsion Technologies for Regional Aviation Within the HERA Project

by Felicia Molinaro and Marco Fioriti

Aerospace 2026, 13(4), 383; https://doi.org/10.3390/aerospace13040383 - 17 Apr 2026

Viewed by 384

Abstract

Hybrid-electric propulsion and alternative energy carriers are being considered to mitigate the climate impact of short-range regional aviation. Within this framework, the HERA (Hybrid Electric Regional Architecture) project investigates advanced propulsion architectures for a next-generation 72 passenger regional platform. This work presents a [...] Read more.

Hybrid-electric propulsion and alternative energy carriers are being considered to mitigate the climate impact of short-range regional aviation. Within this framework, the HERA (Hybrid Electric Regional Architecture) project investigates advanced propulsion architectures for a next-generation 72 passenger regional platform. This work presents a cradle-to-grave Life Cycle Assessment of two HERA reference configurations and compares them with a conventional 70 passenger turboprop representative of current service aircraft. The analysis focuses on lithium–sulphur batteries, proton exchange membrane fuel cells, liquid hydrogen storage tanks, and electric motors. The assessment is implemented through a parametric LCA tool supported by a detailed Life Cycle Inventory based on Ecoinvent v3.8 and evaluated using ReCiPe 2016 midpoint indicators. The system boundary includes raw material extraction, manufacturing and assembly, operation under defined mission profiles, maintenance with component replacement, and End-of-Life (EoL) treatment. Results show that the operational phase remains the main driver of climate change impacts, exceeding 95% of total CO₂ equivalent emissions across configurations. The battery-based hybrid reduces fuel consumption but increases manufacturing and maintenance burdens. The fuel cell configuration shows a more balanced life cycle profile, with platinum identified as a critical hotspot. Full article

(This article belongs to the Special Issue 15th EASN International Conference on Innovation in Aviation & Space Towards Sustainability Today and Tomorrow)

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40 pages, 6612 KB

Open AccessArticle

A Method for Selecting Key Flight Parameters of Aircraft Based on Dual-Domain Rough Set and Three-Branch Decision

by Shengkai Yan, Qiang Wang, Jiayang Yu, Jiajin Li, Qiuhan Liu and Gaocheng Chen

Aerospace 2026, 13(4), 382; https://doi.org/10.3390/aerospace13040382 - 17 Apr 2026

Viewed by 230

Abstract

The precise selection of key flight parameters is fundamental to enhancing aircraft condition monitoring and risk warning capabilities. However, existing methods typically rely on a single source of information, i.e., either solely expert judgments or solely objective flight data, and lack effective mechanisms [...] Read more.

The precise selection of key flight parameters is fundamental to enhancing aircraft condition monitoring and risk warning capabilities. However, existing methods typically rely on a single source of information, i.e., either solely expert judgments or solely objective flight data, and lack effective mechanisms to reconcile conflicts between subjective opinions and objective data characteristics, which limits their applicability in complex aviation safety scenarios. To address this issue, a flight parameter selection method based on dual-domain rough sets and three-way decision theory is proposed in this paper. First, regret theory is introduced to quantify experts’ psychological preferences, and a subjective evaluation model integrating both psychological and absolute agreement is constructed. Second, a subjective–objective conflict information system is established within a dual-domain framework. Based on this system, bidirectional decision rules are designed to simultaneously consider positive-domain and negative-domain conditional probabilities, through which candidate sets of key flight parameters are generated. Finally, a new Bayesian minimum loss criterion is designed to determine the optimal parameter set. Experimental results demonstrate that the accuracy and robustness of flight parameter selection are improved by the proposed method while interpretability is maintained, offering reliable decision support for aviation safety analysis. Full article

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25 pages, 5519 KB

Open AccessArticle

An Attention-Augmented CNN–LSTM Framework for Reconstructing Transient Temperature Fields of Turbine Blades from Sparse Measurements

by Yingtao Chen, Langlang Liu, Dan Sun, Haida Liu and Junjie Yang

Aerospace 2026, 13(4), 381; https://doi.org/10.3390/aerospace13040381 - 17 Apr 2026

Viewed by 229

Abstract

Accurately predicting the temperature field of turbine blades is of great significance for evaluating the thermal reliability and service life of high-temperature components in aero-engines. However, due to the high computational cost of numerical simulations and the limitations imposed by complex geometric structures [...] Read more.

Accurately predicting the temperature field of turbine blades is of great significance for evaluating the thermal reliability and service life of high-temperature components in aero-engines. However, due to the high computational cost of numerical simulations and the limitations imposed by complex geometric structures and harsh operating environments, experimental measurements can usually only obtain sparse sensor data, making the acquisition of complete temperature distributions still challenging. Therefore, reconstructing the complete temperature field under sparse measurement conditions has become a key research issue in turbine thermal analysis. To address this problem, this paper proposes an attention-enhanced CNN–LSTM framework for reconstructing transient turbine blade temperature fields from sparse data. The model combines the spatial feature extraction capability of Convolutional Neural Networks (CNNs) with the time-series modeling capability of Long Short-Term Memory networks (LSTM). An SE channel attention module is introduced in the CNN feature extraction stage to achieve adaptive recalibration of channel features, and a temporal attention mechanism is incorporated after the LSTM layer to highlight key transient thermal features. A multi-condition temperature field dataset was constructed by conducting Computational Fluid Dynamics (CFD) simulations on low-pressure turbine guide vanes, and the model was experimentally validated through thermal shock tests. The results show that the proposed model can accurately reconstruct the spatial distribution and transient evolution of the turbine blade temperature field under sparse measurement conditions. Under different operating conditions, the predicted temperature fields are highly consistent with the CFD results, with the maximum Reconstruction error remaining below 19 °C. Error distribution analysis indicates that the model has stable Reconstruction performance and good generalization ability. Full article

(This article belongs to the Section Aeronautics)

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20 pages, 2926 KB

Open AccessArticle

Quasi-One-Dimensional Reacting-Flow Modeling for Rocket-Based Combined Cycle Engines

by Jung Jin Park, Sang Gon Lee, Sang Won Lim and Sang Hun Kang

Aerospace 2026, 13(4), 380; https://doi.org/10.3390/aerospace13040380 - 17 Apr 2026

Viewed by 352

Abstract

A rapid quasi-one-dimensional (quasi-1D) reacting-flow analysis code was developed for the preliminary assessment of rocket-based combined cycle engines over a broad flight envelope. The internal flow was modeled as steady and quasi-1D in a variable-area duct by solving the coupled conservation equations together [...] Read more.

A rapid quasi-one-dimensional (quasi-1D) reacting-flow analysis code was developed for the preliminary assessment of rocket-based combined cycle engines over a broad flight envelope. The internal flow was modeled as steady and quasi-1D in a variable-area duct by solving the coupled conservation equations together with species transport, and finite-rate chemical kinetics were included to represent combustion-induced heat release and composition change. To incorporate configuration-dependent mixing effects that affect RBCC heat release evolution and thermal choking tendencies, a streamwise mixing efficiency distribution was extracted from non-reacting 3D CFD and prescribed as an input to the quasi-1D formulation to represent the progressive availability of reactable fuel along the flowpath. A mode-dependent solution strategy was established by separating the computation into scramjet mode and ramjet mode procedures with a switching criterion based on whether a sonic condition occurs within the combustor, allowing thermal choking and mode transition behavior to be addressed within a single framework. The numerical solver was implemented in Python 3.12.2 and integrated using a stiff ordinary differential equation (ODE) scheme to ensure robust convergence in the presence of reaction-induced stiffness. Verification against previously published hydrogen-fueled scramjet results reproduced the overall streamwise trends of key quantities including Mach number, pressure, temperature, and density. The developed code was then applied to an RBCC configuration under operating conditions representative of ERJ and ESJ regimes, and the quasi-1D predictions were compared with cross-section-averaged 3D RANS CFD results, showing consistent mode identification and comparable axial behavior at a level suitable for preliminary analysis with substantially reduced computational cost. Full article

(This article belongs to the Special Issue High Speed Aircraft and Engine Design)

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39 pages, 2980 KB

Open AccessArticle

A Roadmap for Twin-Fuselage Aircraft Conceptual Design

by Álvaro Cobo-González and Cristina Cuerno-Rejado

Aerospace 2026, 13(4), 379; https://doi.org/10.3390/aerospace13040379 - 17 Apr 2026

Viewed by 510

Abstract

Unconventional aircraft configurations show significant potential to reduce aviation’s environmental footprint. Computerized conceptual design environments enable the design of unconventional aircraft concepts and the comparison of their performance and environmental impact against conventional Tube-And-Wing aircraft and other competing unconventional layouts. However, no environment [...] Read more.

Unconventional aircraft configurations show significant potential to reduce aviation’s environmental footprint. Computerized conceptual design environments enable the design of unconventional aircraft concepts and the comparison of their performance and environmental impact against conventional Tube-And-Wing aircraft and other competing unconventional layouts. However, no environment has yet been specifically developed to support the Twin-Fuselage configuration. This paper addresses this gap by analyzing the advantages of the Twin-Fuselage configuration, identifying a potentially relevant design space, and compiling the existing conceptual-level design methods applicable to this layout. Building on these results, a roadmap for the conception of computerized conceptual design environments supporting Twin-Fuselage aircraft is presented. A structured environment architecture is proposed considering current trends and limitations of state-of-the-art environments supporting other unconventional configurations. The proposed modules for each discipline are also outlined. Finally, the main research gaps in Twin-Fuselage aircraft conceptual design are identified, highlighting and prioritizing the developments needed to enable a fully operational Twin-Fuselage-supporting computerized conceptual design environment. Full article

(This article belongs to the Special Issue 15th EASN International Conference on Innovation in Aviation & Space Towards Sustainability Today and Tomorrow)

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24 pages, 17020 KB

Open AccessArticle

Operational Modal Analysis of Aeronautical Structures via Tangential Interpolation

by Gabriele Dessena, Marco Civera and Oscar E. Bonilla-Manrique

Aerospace 2026, 13(4), 378; https://doi.org/10.3390/aerospace13040378 - 16 Apr 2026

Viewed by 282

Abstract

Over the last decades, progress in modal analysis has enabled the increasingly routine use of modal parameters for applications such as structural health monitoring and finite element model updating. For output-only identification, or operational modal analysis (OMA), widely adopted approaches include stochastic subspace [...] Read more.

Over the last decades, progress in modal analysis has enabled the increasingly routine use of modal parameters for applications such as structural health monitoring and finite element model updating. For output-only identification, or operational modal analysis (OMA), widely adopted approaches include stochastic subspace identification (SSI) methods and the Natural Excitation Technique, combined with the Eigensystem Realization Algorithm (NExT-ERA). Nevertheless, SSI-based techniques may become cumbersome on large systems, while NExT-ERA fitting can struggle when measurements are contaminated by noise. To alleviate these, this work investigates an OMA frequency-domain formulation for aeronautical structures by coupling the Loewner Framework (LF) with NExT, yielding the proposed NExT-LF method. The method exploits the computational efficiency of LF, due to the effectiveness of tangential interpolation, together with the impulse response function retrieval enabled by NExT. NExT-LF is assessed on two experimental benchmarks: the eXperimental BeaRDS 2 high-aspect-ratio wing main spar and an Airbus Helicopters H135 bearingless main rotor blade. The identified modal parameters are compared against available experimental references and results obtained via SSI with a Canonical Variate Analysis and NExT-ERA. The results show that the modes identified by NExT-LF correlate well with benchmark data, particularly for high-amplitude tests and in the low-frequency range. Full article

(This article belongs to the Special Issue 15th EASN International Conference on Innovation in Aviation & Space Towards Sustainability Today and Tomorrow)

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24 pages, 5265 KB

Open AccessArticle

Experimental and Numerical Determination of Aerodynamic Characteristics of an Ogive with Canards

by Teodora Đilas, Dunja Ukšanović, Jelena Svorcan and Boško Rašuo

Aerospace 2026, 13(4), 377; https://doi.org/10.3390/aerospace13040377 - 16 Apr 2026

Viewed by 254

Abstract

This work presents an integrated experimental and numerical determination of the aerodynamic (lift) characteristics of an ogive forebody equipped with all moving canards. Experimental testing was conducted in the subsonic custom-made wind tunnel of the Vlatacom Institute at a nominal free stream velocity [...] Read more.

This work presents an integrated experimental and numerical determination of the aerodynamic (lift) characteristics of an ogive forebody equipped with all moving canards. Experimental testing was conducted in the subsonic custom-made wind tunnel of the Vlatacom Institute at a nominal free stream velocity of 32 m/s (and Mach number M = 0.09). Aerodynamic loads on the canards were measured using a custom one-component force balance, while free stream flow properties were obtained via a calibrated Pitot–Prandtl probe on the full-scale geometry model. On the numerical side, RANS simulations were performed in ANSYS Fluent using the k-ω SST turbulence model. Two geometric representations were considered: (a) a high-fidelity configuration explicitly resolving the physical gap between the canard and ogive, and (b) a simplified configuration with the gap removed. Boundary conditions, Reynolds number, and operating parameters were matched to the wind tunnel conditions to enable a strict one-to-one comparison. Particular emphasis was placed on examining the effect of geometric simplification on the predicted lift characteristics. The gap-resolved configuration reproduces the experimentally measured lift curve within approximately 10% across the investigated angle-of-attack range, satisfying conventional aerodynamic validation criteria. The results confirm both the robustness of the applied RANS approach for highly three-dimensional separated flows often found in engineering applications, as well as the reliability of the experimental measurement system. Full article

(This article belongs to the Special Issue Recent Advances in Applied Aerodynamics (2nd Edition))

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25 pages, 1514 KB

Open AccessArticle

Reliability Allocation Method for Aircraft Mechanical Systems Involving Motion Performance and Failure Correlation

by Linjie Shen, Lu Wang, Feng Xiao and Jiawei Du

Aerospace 2026, 13(4), 376; https://doi.org/10.3390/aerospace13040376 - 16 Apr 2026

Viewed by 254

Abstract

One of the most important design requirements for aircraft mechanical systems is to ensure that their motion functions can be executed smoothly. In this paper, an unconstrained reliability allocation method is proposed, taking into account the characteristics of aircraft mechanical systems. A decomposition [...] Read more.

One of the most important design requirements for aircraft mechanical systems is to ensure that their motion functions can be executed smoothly. In this paper, an unconstrained reliability allocation method is proposed, taking into account the characteristics of aircraft mechanical systems. A decomposition principle for assessing the motion performance of aircraft mechanical systems has been proposed, and the contribution of each subsystem is analyzed. Weighting factors for system allocation are proposed and refined, and a failure correlation index is proposed to account for the influence of the interaction between subsystems on the potential failure rate. Furthermore, non-destructive failure events that could have a significant impact on motion performance have been taken into account in the potential improvement of subsystems. Subsequently, reliability prediction models of the systems are established using the Copula function, and a calculation method is introduced to distinguish and quantify the correlation between different subsystems. Finally, the applicability and validity of the proposed method are demonstrated through an engineering case. The results indicate that when failure correlation is considered, the reliability allocated to subsystems is significantly lower than that obtained using traditional methods, providing theoretical guidance for the reliability design of aircraft mechanical systems. Full article

(This article belongs to the Special Issue Aircraft Structural Design Materials, Modeling, and Optimization)

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22 pages, 4648 KB

Open AccessArticle

Digital Twin-Driven TLE Error Correction for Precise LEO Satellite Orbit Prediction

by Xinchen Xu, Hong Wen, Wenjing Hou, Liang Chen, Yingwei Zhao and Tian Liu

Aerospace 2026, 13(4), 375; https://doi.org/10.3390/aerospace13040375 - 16 Apr 2026

Viewed by 348

Abstract

Low earth orbit (LEO) satellite orbit prediction is one of the key measures to compensate for position errors and ensure position accuracy, which plays an important role in the aerospace communication network for undertaking functions such as routing relay, real-time communication, and signal [...] Read more.

Low earth orbit (LEO) satellite orbit prediction is one of the key measures to compensate for position errors and ensure position accuracy, which plays an important role in the aerospace communication network for undertaking functions such as routing relay, real-time communication, and signal forwarding. However, existing learning-based satellite orbit prediction models that are recognized as the best measurement inevitably face the problem of distribution bias. Orbit predictions can lead to a decrease in model performance due to different types of satellites (LEO and SSO) and different time scales. In this article, a new method is explored to overcome these shortcomings. Unlike previous methods that explore the temporal correlation of orbit data, this novel orbit prediction method converts satellite orbit data into the frequency domain via Fourier transformation, using a third-order Fourier-derivative convolution framework. Specifically, the proposed Fourier dilation convolution (FDC) model demonstrates better generalization ability across different types of satellites and different time scales by combining frequency domain analysis and dilated convolution. Two real datasets are applied for experimental validation, and the results show the effectiveness of our proposed FDC model. Meanwhile, the proposed FDC model shows a decrease in mean absolute error (MAE) values compared to the temporal convolutional network based seasonal and trend decomposition using a Loess (STL-TCN) model. Quantitative comparisons demonstrate that compared to the STL-TCN model, the FDC model reduces the mean absolute error (MAE) by approximately 10% to 85% across different orbital dimensions. Finally, we conducted further analysis of the interpretability of the model. Full article

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29 pages, 3415 KB

Open AccessArticle

Neural Network-Based Optimization of Hybrid Rocket Design for Modular Multistage Launch Vehicle

by Paolo Maria Zolla, Alessandro Zavoli, Mario Tindaro Migliorino and Daniele Bianchi

Aerospace 2026, 13(4), 374; https://doi.org/10.3390/aerospace13040374 - 16 Apr 2026

Viewed by 502

Abstract

In this paper, an integrated optimization is carried out to find the optimal hybrid rocket engine design for a modular multistage launch vehicle targeting a 500 km polar circular orbit. A single hybrid rocket engine unit is reused across the whole launch vehicle, [...] Read more.

In this paper, an integrated optimization is carried out to find the optimal hybrid rocket engine design for a modular multistage launch vehicle targeting a 500 km polar circular orbit. A single hybrid rocket engine unit is reused across the whole launch vehicle, with each stage constituted by a cluster of a specified number of units. Only the nozzle exit diameter of the units is allowed to change across each stage. This clustering approach is aimed at reducing the costs of the launch vehicle and at simplifying the optimization procedure. After a brief mission analysis based on Tsiolkovsky’s equation, a three-stage configuration is chosen for the launch vehicle, employing 16, 4, and 1 engine units for, respectively, the first, second, and third stage. A neural network-based surrogate model is employed to approximate the complex hybrid rocket internal ballistics, with the aim to reduce the computational cost of the optimization process. The surrogate model is trained to map a reduced number of design parameters to the performance and mass budget of a single engine unit using data from a 0-D hybrid rocket engine model. The accuracy of the trained network in predicting crucial features is then assessed. Finally, the trained network is integrated into a multidisciplinary optimization process. The aim is to identify the optimal rocket engine design and launch vehicle ascent trajectory that maximize the payload capacity to the target orbit. Full article

(This article belongs to the Special Issue Green Propulsion: Present Solutions and Perspectives for Powering Environmentally Friendly Space Missions (2nd Edition))

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54 pages, 2588 KB

Open AccessArticle

Hypersonic Impact Method for Aerodynamics and Convective Heating (HI-Mach) with Sensitivities

by Jeremiah Goates, Logan Freeman, Nathan Hoch and Douglas Hunsaker

Aerospace 2026, 13(4), 373; https://doi.org/10.3390/aerospace13040373 - 15 Apr 2026

Viewed by 316

Abstract

The purpose of this paper is to present the development of an engineering level code for calculating hypersonic aerodynamics and convective heating, HI-Mach. Novel to this paper are the use of analytic methods for streamline tracing and the direct differentiation of geometric sensitivities [...] Read more.

The purpose of this paper is to present the development of an engineering level code for calculating hypersonic aerodynamics and convective heating, HI-Mach. Novel to this paper are the use of analytic methods for streamline tracing and the direct differentiation of geometric sensitivities for both forces and heat load. Independent panel inclination methods calculate the pressure distribution on the surface of a hypersonic vehicle. Normal shock relations provide the thermodynamic state on each panel. Streamlines are integrated using closed-form streamline equations. Flat plate formulas corrected for compressibility calculate the skin friction coefficient and acreage heat flux on each panel. Formulas for heating on stagnation points and lines, including effects of ellipticity and sweep, are used to calculate stagnation region heating. A method for obtaining the sensitivities of a quantity of interest with respect to the geometry in a hypersonic panel code is described. These are obtained using direct analytical derivatives. The approach is precise and has been thoroughly tested against finite differencing. HI-Mach provides results orders of magnitude faster than would be obtained by CFD. Results from HI-Mach are analyzed and compared to experimental results for the HL-20 lifting body geometry. For the aerodynamic characteristics, HI-Mach predicted force coefficients within 12% of experimental results at

M \infty = 4.5

and 21% at

M_{\infty} = 1.6

. Heating results for the HL-20 match experimental and CFD results to within 20% over a wide range of operating conditions. Full article

(This article belongs to the Special Issue Aircraft Conceptual Design: Tools, Processes and Examples)

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24 pages, 3723 KB

Open AccessArticle

Power-Law Truncation Correction for the Relative Orbital Element State Transition Matrix in Active Debris Removal

by Shengfu Xia and Jizhang Sang

Aerospace 2026, 13(4), 372; https://doi.org/10.3390/aerospace13040372 - 15 Apr 2026

Viewed by 300

Abstract

In active debris removal missions in low Earth orbit, the semi-major axis difference between a service platform and its target can be large. Analytical relative dynamics models used in formation-flying applications typically retain only the first-order expansion in the orbital element differences; at [...] Read more.

In active debris removal missions in low Earth orbit, the semi-major axis difference between a service platform and its target can be large. Analytical relative dynamics models used in formation-flying applications typically retain only the first-order expansion in the orbital element differences; at large separations, the discarded higher-order terms—particularly the power-law dependence on the semi-major axis—introduce systematic along-track drift that degrades the propagation accuracy. This paper derives the power-law truncation correction, a closed-form additive vector that exactly compensates the truncated semi-major-axis power-law remainder, together with a consistent Jacobian correction for the extended Kalman filter covariance prediction. The state dimension and state transition matrix structure remain unchanged. Propagation tests over semi-major axis differences of 36–146 km yield ten-revolution terminal position errors of 0.008–0.065 km for the corrected models, compared with tens to hundreds of kilometers for the uncorrected first-order models and 0.1–8 km for the second-order state transition tensor. In 500-run Monte Carlo angles-only filtering experiments, the corrected filter reduces the median terminal position error by one to nearly three orders of magnitude relative to the uncorrected model. A process noise sensitivity study confirms robustness to calibration uncertainty across two orders of magnitude at a lower computational cost and with simpler implementation than higher-order tensor methods. Full article

(This article belongs to the Special Issue Guidance, Navigation and Control Algorithms for Satellite Formation Flying (2nd Edition))

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23 pages, 464 KB

Open AccessReview

A Review of Intelligent Trajectory Planning and Optimization for Aerospace Vehicles

by Guanjie Hu, Linxin Li, Yingmin Yi, Lecheng Liang, Zongyi Guo, Jianguo Guo and Jing Chang

Aerospace 2026, 13(4), 371; https://doi.org/10.3390/aerospace13040371 - 15 Apr 2026

Viewed by 481

Abstract

Aerospace vehicles operate across a wide flight envelope, traversing dense atmospheric layers from near-space to low Earth orbit. Trajectory planning and optimization in a large spatial domain and wide speed range present severe challenges to traditional methods, including computational efficiency, model accuracy, and [...] Read more.

Aerospace vehicles operate across a wide flight envelope, traversing dense atmospheric layers from near-space to low Earth orbit. Trajectory planning and optimization in a large spatial domain and wide speed range present severe challenges to traditional methods, including computational efficiency, model accuracy, and constraint adaptability. Artificial intelligence provides an effective pathway to overcome these limitations and has become a key driver for advancing trajectory planning and optimization of aerospace vehicles. This paper presents a systematic review of the core characteristics of aerospace trajectory planning, including environment coupling, multi-constraint compliance, propulsion integration, and aerodynamic nonlinearity, as well as the limitations of traditional methods. The study focuses on the application of intelligent algorithms in both the ascent and reentry phases. For the ascent phase, three key issues are addressed: multistage hybrid optimization with continuous and discrete variables, propulsion multimodal–trajectory coupling, and trajectory reconfiguration under engine failure. For the reentry phase, discussions are focused on such technical difficulties as multi-constraint trajectory generation, no-fly zone avoidance, and multi-mission requirement optimization. Finally, future research directions in intelligent trajectory planning and optimization are discussed, providing theoretical support and methodological guidance for the autonomous and intelligent development of aerospace vehicle trajectory planning. Full article

(This article belongs to the Special Issue Guidance and Control Systems of Aerospace Vehicles)

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26 pages, 6253 KB

Open AccessArticle

Optimization of Low-Altitude Vertiport Network Topology Resilience

by Hua Xie, Ziyuan Zhu, Jianan Yin, Yuhang Wu, Long Zhou and Qingchun Wu

Aerospace 2026, 13(4), 370; https://doi.org/10.3390/aerospace13040370 - 15 Apr 2026

Viewed by 334

Abstract

This study investigates the construction of a topological network for resilient low-altitude vertiports. Addressing the issue of excessive network redundancy often caused by maximizing algebraic connectivity in traditional topology optimization problems, we employ algebraic connectivity—a key spectral metric—as a measure of network topology [...] Read more.

This study investigates the construction of a topological network for resilient low-altitude vertiports. Addressing the issue of excessive network redundancy often caused by maximizing algebraic connectivity in traditional topology optimization problems, we employ algebraic connectivity—a key spectral metric—as a measure of network topology resilience. The objective function employs normalized algebraic connectivity that simultaneously considers total network distance, achieving an effective trade-off between global fault tolerance and construction costs at the model level. To address this challenging combinatorial optimization problem, the Gray Wolf Optimizer (GWO) algorithm is mechanistically enhanced. Experiments demonstrate that the proposed method achieves superior performance in key metrics such as objective function value and total network distance, significantly enhancing network resilience while controlling construction costs. For the optimized network topology solutions, simulations of six failure modes for nodes and edges analyze the response characteristics of the vertiport network’s maximum connected subgraph proportion and global efficiency during the gradual removal of nodes and edges. Results demonstrate that the designed vertiport topology network exhibits robust resilience. It maintains high connectivity and global efficiency under both random attacks and degree-based targeted node attacks, showcasing strong engineering applicability. Full article

(This article belongs to the Collection Air Transportation—Operations and Management)

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31 pages, 2324 KB

Open AccessArticle

A Large-Scale Urban Drone Delivery System: An Environmental, Economic, and Temporal Assessment

by Danwen Bao, Jing Tian, Ziqian Zhang, Jiajun Chu, Yu Yan and Yuhan Li

Aerospace 2026, 13(4), 369; https://doi.org/10.3390/aerospace13040369 - 15 Apr 2026

Viewed by 294

Abstract

Drone logistics is emerging as a key trend in future delivery systems due to its efficiency. However, current benefit assessments are often one-dimensional, focusing on single-node modes and overlooking load variations and charging processes in continuous multi-node delivery. To address this gap, this [...] Read more.

Drone logistics is emerging as a key trend in future delivery systems due to its efficiency. However, current benefit assessments are often one-dimensional, focusing on single-node modes and overlooking load variations and charging processes in continuous multi-node delivery. To address this gap, this paper develops an integrated assessment framework across three dimensions: environment, economy, and time. Based on lifecycle emissions and total cost of ownership, a structured time-performance indicator, time value, is introduced. By incorporating an energy consumption model that accounts for dynamic loads and a charging model that considers charging behavior, an improved genetic algorithm is designed to optimize large-scale urban drone dispatch. Furthermore, a comparative sensitivity analysis with electric trucks quantifies the effects of market demand, charging strategy and technological progress. Results show that, under the modeled scenarios and parameter assumptions, electric trucks remain preferable in the short term, while drones demonstrate stronger long-term potential. Enterprises should align drone and truck deployment with demand and manage charging dynamically, while governments should combine initial subsidies with long-term guidance and systemic support to enable large-scale drone logistics adoption. Full article

(This article belongs to the Special Issue Low-Altitude Technology and Engineering)

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27 pages, 7296 KB

Open AccessArticle

Design of Hollow Spiral Lattice Architectures for Integrated Thermal and Mechanical Performance in Additive Manufacturing

by Shaoying Li, Qidong Sun, Yu Pang, Yongli Zhang, Guangzhi Nan, Yingchao Ma, Jiawen Chen, Bin Sun and Jiang Li

Aerospace 2026, 13(4), 368; https://doi.org/10.3390/aerospace13040368 - 15 Apr 2026

Viewed by 493

Abstract

This study proposes a novel parameterized hollow spiral lattice (HSL) structure designed for additive manufacturing (AM). The structure is composed of two right-handed and two left-handed spiral members. Its unit cell is formed by sweeping a circular ring cross-section along a cylindrical helical [...] Read more.

This study proposes a novel parameterized hollow spiral lattice (HSL) structure designed for additive manufacturing (AM). The structure is composed of two right-handed and two left-handed spiral members. Its unit cell is formed by sweeping a circular ring cross-section along a cylindrical helical path, creating a porous topology that integrates continuous flow channels with structural load-bearing capability. An analytical model correlating key design parameters, including spiral radius, helix angle, and tube inner/outer diameters, with the structural relative density is established. Considering the manufacturability constraints of Laser Powder Bed Fusion (LPBF), an adaptive parametric design framework is developed to simultaneously optimize the geometry, relative density, and process feasibility. Ti6Al4V HSL samples were fabricated using LPBF. Their thermo–mechanical performance was systematically characterized through Computational Fluid Dynamics (CFD) simulations, Finite Element Analysis (FEA), and quasi-static compression experiments. Thermal analysis under internal and internal–external flow conditions reveals that the centrifugal force induced by the spiral geometry generates Dean vortices. This enhances momentum exchange between the central mainstream and near-wall fluid, significantly improving radial mixing, promoting temperature uniformity, and effectively suppressing local hot spots. Mechanically, the HSL exhibits significantly superior specific strength and stiffness compared to traditional body-centered cubic (BCC) and diamond lattices, approaching the performance of cubic topology, thus demonstrating outstanding lightweight load-bearing potential. The developed HSL structure presents a promising innovative design strategy for next-generation applications requiring integrated thermal management and structural load-bearing functions. Full article

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19 pages, 4785 KB

Open AccessArticle

A Design Method for Elliptical Orbit Constellations Targeting Discontinuous Regional Coverage in Environmental Monitoring

by Yi Wei and Zhanxia Zhu

Aerospace 2026, 13(4), 367; https://doi.org/10.3390/aerospace13040367 - 14 Apr 2026

Viewed by 386

Abstract

Satellite constellations are increasingly employed in regional remote sensing applications such as environmental monitoring and disaster management. However, achieving efficient and timely coverage for discontinuous regions with high revisit frequency remains a significant challenge. This study first compares low Earth circular and elliptical [...] Read more.

Satellite constellations are increasingly employed in regional remote sensing applications such as environmental monitoring and disaster management. However, achieving efficient and timely coverage for discontinuous regions with high revisit frequency remains a significant challenge. This study first compares low Earth circular and elliptical orbit constellations in terms of coverage performance, economic efficiency, and orbital lifetime. Based on this comparison, a dedicated design methodology for elliptical orbit constellations aimed at discontinuous regional coverage is developed. A critical Sun-synchronous repeating elliptical orbit is selected as the baseline configuration, and its key orbital parameters including the semi-major axis, eccentricity, and argument of perigee are analytically derived. Furthermore, a flexible constellation configuration model is proposed, introducing a modified Walker-inspired

k n / k n / k

pattern. This model establishes direct mathematical relationships between the constellation’s repetition factor, phasing parameters, and temporal coverage metrics to systematically guide the overall design process. A case study on wildfire monitoring in China’s Qinling Mountains demonstrates the feasibility and effectiveness of the proposed approach, achieving a one-hour revisit time over the target region with a 24-satellite constellation. The results indicate that the proposed methodology provides a cost-effective and adaptable framework for satellite constellation design in remote sensing applications, particularly suited to dynamic environmental monitoring and emergency response missions. Full article

(This article belongs to the Section Astronautics & Space Science)

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24 pages, 8255 KB

Open AccessArticle

Further Development of a Low-Energy Arc-Ignition System for Nytrox/ABS Hybrid Propulsion Systems

by Stephen A. Whitmore, Jared S. Coen and Ryan J. Thibaudeau

Aerospace 2026, 13(4), 366; https://doi.org/10.3390/aerospace13040366 - 14 Apr 2026

Viewed by 329

Abstract

Utah State University has developed a high-performance “green” hybrid propulsion technology based on the unique electrical breakdown properties of 3D-printed acrylonitrile butadiene styrene. Using 3D-printed ABS as fuel, typical startup sequences require approximately 5–15 joules and, once started, the system can be sequentially [...] Read more.

Utah State University has developed a high-performance “green” hybrid propulsion technology based on the unique electrical breakdown properties of 3D-printed acrylonitrile butadiene styrene. Using 3D-printed ABS as fuel, typical startup sequences require approximately 5–15 joules and, once started, the system can be sequentially fired with no additional energy inputs required. The number of possible ignitions is limited only by the amount of fuel. The most technologically mature version uses gaseous oxygen (GOX) as oxidizer and 3D-printed ABS as fuel. While GOX is mass-efficient, it lacks volumetric efficiency unless highly pressurized. Nytrox, a blend of GOX and nitrous oxide, improves propellant density and volumetric efficiency, while maintaining acceptable levels of mass efficiency (specific impulse). Nytrox can safely self-pressurize, eliminating the need for a separate oxidizer pressurization system and reducing overall complexity. However, employing Nytrox as a direct substitute for GOX results in reduced ignition reliability and considerably increases cold-start ignition latency. This paper quantifies the latency, explores its sources, and analyzes expected behaviors. Solutions include raising combustion and storage pressures to boost oxygen content in Nitrox’s liquid phase and increasing combustion chamber pressure to reduce ignition delays. Full article

(This article belongs to the Special Issue Propulsion Solutions for Enhancing the Small Launchers’ Competitiveness)

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32 pages, 12012 KB

Open AccessArticle

Multi-Agent Reinforcement Learning-Based Intelligent Game Guidance with Complex Constraint

by Fucong Liu, Yang Guo, Shaobo Wang, Jin Wang and Zhengquan Liu

Aerospace 2026, 13(4), 365; https://doi.org/10.3390/aerospace13040365 - 14 Apr 2026

Viewed by 376

Abstract

For the complex problems of multi-aircraft cooperative game guidance with No-Fly Zone (NFZ) avoidance and cross-task constraint propagation, a deep deterministic policy gradient algorithm with temporal awareness and priority cooperative optimization (TP-MADDPG) is proposed. Based on the three-body cooperative guidance, a new coupled [...] Read more.

For the complex problems of multi-aircraft cooperative game guidance with No-Fly Zone (NFZ) avoidance and cross-task constraint propagation, a deep deterministic policy gradient algorithm with temporal awareness and priority cooperative optimization (TP-MADDPG) is proposed. Based on the three-body cooperative guidance, a new coupled guidance task is formed by adding the NFZ avoidance constraint. At the same time, considering the constraint compatibility problem in dynamic task switching, the cooperative aircraft are modeled as independent agents with differentiated policy networks. First, a nonlinear kinematic model of the three-body game constructed by Evader–Pursuer–Defender is established. And four complex constraint conditions, namely homing guidance, NFZ avoidance, collision avoidance, and cooperative guidance, are modeled separately. Secondly, the Long Short-Term Memory-based (LSTM) Actor–Critic framework is proposed to dynamically capture the evolution patterns of adversarial scenarios by mining hidden correlations in historical state-action sequences. This enables smooth policy transitions between the cooperative guidance phase and subsequent homing guidance phase, effectively addressing the challenges of environmental non-stationarity and temporal task dependencies. Then, a priority-driven adaptive sampling mechanism is proposed along with a heterogeneous roles cooperative reward function to specifically address credit assignment imbalance and sparse reward problems, respectively. The sampling mechanism capitalizes on the efficient retrieval properties of SumTree data structures while integrating bias correction techniques to expedite policy gradient convergence. The reward function utilizes the reward shaping method to formulate cooperative reward components that explicitly capture behavioral correlations among agents. Finally, simulations show that the proposed method significantly outperforms multi-agent reinforcement learning baselines, effectively improving the performance of cooperative game guidance under complex constraints. Full article

(This article belongs to the Special Issue Flight Guidance and Control)

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19 pages, 6134 KB

Open AccessArticle

Modular and Highly Reliable COTS-Based Power Conditioning and Distribution Unit for Small Satellites

by Cristian Torres Vergara, José Manuel Blanes Martínez, Ausiàs Garrigós Sirvent, David Marroquí Sempere, Pablo Casado Pérez and José Luis Lizan Mas

Aerospace 2026, 13(4), 364; https://doi.org/10.3390/aerospace13040364 - 14 Apr 2026

Viewed by 378

Abstract

This paper presents a modular Power Conditioning and Distribution Unit (PCDU) designed for small satellites. The proposed system features a highly adaptable architecture capable of managing a total power throughput of up to 100 W, with specific limits defined by mission-dependent thermal and [...] Read more.

This paper presents a modular Power Conditioning and Distribution Unit (PCDU) designed for small satellites. The proposed system features a highly adaptable architecture capable of managing a total power throughput of up to 100 W, with specific limits defined by mission-dependent thermal and redundancy configurations. Aligned with the New Space paradigm, the implementation relies on Commercial Off-The-Shelf (COTS) components, a strategy that drastically reduces development and manufacturing costs without compromising reliability. The system has been optimized for operation in harsh environments, including high vacuum, ionizing radiation, and extreme thermal gradients. The design incorporates strict redundancy and fault-tolerance criteria to provide a robust solution for critical subsystems. Comprehensive validation was performed through functional testing, Total Ionizing Dose (TID) radiation campaigns, and Thermal Vacuum (TVAC) cycles. Experimental results demonstrate that the PCDU withstands high-vacuum thermal cycling and cumulative radiation doses exceeding 75 kRad. These findings confirm that the developed unit is a cost-effective, high-reliability solution suitable for both Low Earth Orbit (LEO) and deep-space missions. Full article

(This article belongs to the Special Issue Space Power and Electronic Systems)

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19 pages, 4951 KB

Open AccessArticle

Estimating Active Space Noise Extent from Two Aircraft Weight Classes over the Great Smoky Mountains National Park

by Bijan Gurung, Davyd H. Betchkal, J. Adam Beeco, Brian A. Peterson, Tyra A. Olstad, Sharolyn Anderson, Shawn Hutchinson, Sarah Jackson and Damon Joyce

Aerospace 2026, 13(4), 363; https://doi.org/10.3390/aerospace13040363 - 14 Apr 2026

Viewed by 364

Abstract

The natural and cultural components of the acoustic environment are a resource intrinsic to parks and protected areas and are critical to wildlife and the visitor experience. However, noise degrades the natural acoustic environment, and aircraft introduce spatially extensive noise into such environments. [...] Read more.

The natural and cultural components of the acoustic environment are a resource intrinsic to parks and protected areas and are critical to wildlife and the visitor experience. However, noise degrades the natural acoustic environment, and aircraft introduce spatially extensive noise into such environments. This study examined aircraft noise events at Great Smoky Mountains National Park, U.S., for different jet aircraft types categorized as “Light” (<20,000 pounds) and “Heavy” (>20,000 pounds). Detection distances were determined for these aircraft types by examining the active space of each aircraft’s noise events. The results of this study determined mean detection distances of 15.2 km for “Light” aircraft and 18.3 km for “Heavy” aircraft to the active space boundaries. Increased thrust or jet velocity from the higher mean altitude resulted in a larger active space. From a practical management perspective, to minimize noise impacts on the park’s natural and cultural resources, efforts should focus on “Heavy” aircraft because they produce greater thrust and frequently operate above GRSM. Using detection distances, managers could work with these aircraft operators or airports to reduce thrust and velocity when flying above protected areas and to discuss routing around noise-sensitive areas, especially with low-level overflights. Full article

(This article belongs to the Special Issue Aircraft Noise Mitigation—Concepts, Assessment, and Implementation)

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