Aerospace

26 pages, 55836 KiB

Open AccessArticle

Experimental Acoustic Investigation of Rotor Noise Directivity and Decay in Multiple Configurations

by Giovanni Fasulo, Giosuè Longobardo, Fabrizio De Gregorio and Mattia Barbarino

Aerospace 2025, 12(7), 647; https://doi.org/10.3390/aerospace12070647 - 21 Jul 2025

Viewed by 212

In the framework of the MATIM project, an acoustic test campaign was conducted on a platform derived from a commercial-class quadcopter within the CIRA semi-anechoic chamber. A dedicated rotor rig allowed systematic measurements of thrust, torque, and shaft speed together with near- and [...] Read more.

In the framework of the MATIM project, an acoustic test campaign was conducted on a platform derived from a commercial-class quadcopter within the CIRA semi-anechoic chamber. A dedicated rotor rig allowed systematic measurements of thrust, torque, and shaft speed together with near- and far-field noise using ten calibrated 1/2-inch precision microphones. Three configurations were examined: an isolated rotor, the same rotor mounted on an aluminium quadcopter plate, and the full four-rotor assembly. The resulting data set, acquired over 3000–8000 rpm, documents the azimuthal directivity and radial decay of tonal and broadband noise while separating motor, propeller, and installation contributions. Analysis shows that a nearby rigid plate scatters part of the sound field towards frontal and oblique observers and produces a shielding effect in the rotor plane. The combined operation of four rotors further redistributes energy and broadens blade-passing frequency harmonics. The database is intended as a benchmark for aeroacoustics codes and for the development of reduced-order models. Full article

(This article belongs to the Special Issue New Developments in Aeroacoustics Research: From Fundamentals to Applications)

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16 pages, 3620 KiB

Open AccessArticle

Wind Tunnel Experimental Study on Dynamic Coupling Characteristics of Flexible Refueling Hose–Drogue System

by Yinzhu Wang, Jiangtao Huang, Qisheng Chen, Enguang Shan and Yufeng Guo

Aerospace 2025, 12(7), 646; https://doi.org/10.3390/aerospace12070646 - 21 Jul 2025

Viewed by 145

Abstract

During the process of flexible aerial refueling, the flexible structure of the hose drogue assembly is affected by internal and external interference, such as docking maneuvering, deformation of the hose, attitude changes, and body vibrations, causing the hose to swing and the whipping [...] Read more.

During the process of flexible aerial refueling, the flexible structure of the hose drogue assembly is affected by internal and external interference, such as docking maneuvering, deformation of the hose, attitude changes, and body vibrations, causing the hose to swing and the whipping phenomenon, which greatly limits the success rate and safety of aerial refueling operations. Based on a 2.4 m transonic wind tunnel, high-speed wind tunnel test technology of a flexible aerial refueling hose–drogue system was established to carry out experimental research on the coupling characteristics of aerodynamics and multi-body dynamics. Based on the aid of Videogrammetry Model Deformation (VMD), high-speed photography, dynamic balance, and other wind tunnel test technologies, the dynamic characteristics of the hose–drogue system in a high-speed airflow and during the approach of the receiver are obtained. Adopting flexible multi-body dynamics, a dynamic system of the tanker, hose, drogue, and receiver is modeled. The cable/beam model is based on an arbitrary Lagrange–Euler method, and the absolute node coordinate method is used to describe the deformation, movement, and length variation in the hose during both winding and unwinding. The aerodynamic forces of the tanker, receiver, hose, and drogue are modeled, reflecting the coupling influence of movement of the tanker and receiver, the deformation of the hose and drogue, and the aerodynamic forces on each other. The tests show that during the approach of the receiver (distance from 1000 mm to 20 mm), the sinking amount of the drogue increases by 31 mm; due to the offset of the receiver probe, the drogue moves sideways from the symmetric plane of the receiver. Meanwhile, the oscillation magnitude of the drogue increases (from 33 to 48 and from 48 to 80 in spanwise and longitudinal directions, respectively). The simulation results show that the shear force induced by the oscillation of the hose and the propagation velocity of both the longitudinal and shear waves are affected by the hose stiffness and Mach number. The results presented in this work can be of great reference to further increase the safety of aerial refueling. Full article

(This article belongs to the Section Aeronautics)

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32 pages, 8923 KiB

Open AccessArticle

A Comparative Study of Unsupervised Deep Learning Methods for Anomaly Detection in Flight Data

by Sameer Kumar Jasra, Gianluca Valentino, Alan Muscat and Robert Camilleri

Aerospace 2025, 12(7), 645; https://doi.org/10.3390/aerospace12070645 - 21 Jul 2025

Viewed by 228

Abstract

This paper provides a comparative study of unsupervised Deep Learning (DL) methods for anomaly detection in Flight Data Monitoring (FDM). The paper applies Long Short-Term Memory (LSTM), Gated Recurrent Units (GRUs), Convolutional Neural Network (CNN), classic Transformer architecture, and LSTM combined with a [...] Read more.

This paper provides a comparative study of unsupervised Deep Learning (DL) methods for anomaly detection in Flight Data Monitoring (FDM). The paper applies Long Short-Term Memory (LSTM), Gated Recurrent Units (GRUs), Convolutional Neural Network (CNN), classic Transformer architecture, and LSTM combined with a self-attention mechanism to real-world flight data and compares the results to the current state-of-the-art flight data analysis techniques applied in the industry. The paper finds that LSTM, when integrated with a self-attention mechanism, offers notable benefits over other deep learning methods as it effectively handles lengthy time series like those present in flight data, establishes a generalized model applicable across various airports and facilitates the detection of trends across the entire fleet. The results were validated by industrial experts. The paper additionally investigates a range of methods for feeding flight data (lengthy time series) to a neural network. The innovation of this paper involves utilizing Transformer architecture and LSTM with self-attention mechanism for the first time in the realm of aviation data, exploring the optimal method for inputting flight data into a model and evaluating all deep learning techniques for anomaly detection against the ground truth determined by human experts. The paper puts forth a compelling case for shifting from the existing method, which relies on examining events through threshold exceedances, to a deep learning-based approach that offers a more proactive style of data analysis. This not only enhances the generalization of the FDM process but also has the potential to improve air transport safety and optimize aviation operations. Full article

(This article belongs to the Section Air Traffic and Transportation)

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23 pages, 2908 KiB

Open AccessArticle

A Gradient Enhanced Efficient Global Optimization-Driven Aerodynamic Shape Optimization Framework

by Niyazi Şenol, Hasan U. Akay and Şahin Yiğit

Aerospace 2025, 12(7), 644; https://doi.org/10.3390/aerospace12070644 - 21 Jul 2025

Viewed by 285

Abstract

The aerodynamic optimization of airfoil shapes remains a critical research area for enhancing aircraft performance under various flight conditions. In this study, the RAE 2822 airfoil was selected as a benchmark case to investigate and compare the effectiveness of surrogate-based methods under an [...] Read more.

The aerodynamic optimization of airfoil shapes remains a critical research area for enhancing aircraft performance under various flight conditions. In this study, the RAE 2822 airfoil was selected as a benchmark case to investigate and compare the effectiveness of surrogate-based methods under an Efficient Global Optimization (EGO) framework and an adjoint-based approach in both single-point and multi-point optimization settings. Prior to optimization, the computational fluid dynamics (CFD) model was validated against experimental data to ensure accuracy. For the surrogate-based methods, Kriging (KRG), Kriging with Partial Least Squares (KPLS), Gradient-Enhanced Kriging (GEK), and Gradient-Enhanced Kriging with Partial Least Squares (GEKPLS) were employed. In the single-point optimization, the GEK method achieved the highest drag reduction, outperforming other approaches, while in the multi-point case, GEKPLS provided the best overall improvement. Detailed comparisons were made against existing literature results, with the proposed methods showing competitive and superior performance, particularly in viscous, transonic conditions. The results underline the importance of incorporating gradient information into surrogate models for achieving high-fidelity aerodynamic optimizations. The study demonstrates that surrogate-based methods, especially those enriched with gradient information, can effectively match or exceed the performance of gradient-based adjoint methods within reasonable computational costs. Full article

(This article belongs to the Section Aeronautics)

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32 pages, 1444 KiB

Open AccessArticle

Enhancing Airport Resource Efficiency Through Statistical Modeling of Heavy-Tailed Service Durations: A Case Study on Potable Water Trucks

by Changcheng Li, Minghua Hu, Yuxin Hu, Zheng Zhao and Yanjun Wang

Aerospace 2025, 12(7), 643; https://doi.org/10.3390/aerospace12070643 - 21 Jul 2025

Viewed by 228

Abstract

In airport operations management, accurately estimating the service durations of ground support equipment such as Potable Water Trucks (PWTs) is essential for improving resource allocation efficiency and ensuring timely aircraft turnaround. Traditional estimation methods often use fixed averages or assume normal distributions, failing [...] Read more.

In airport operations management, accurately estimating the service durations of ground support equipment such as Potable Water Trucks (PWTs) is essential for improving resource allocation efficiency and ensuring timely aircraft turnaround. Traditional estimation methods often use fixed averages or assume normal distributions, failing to capture real-world variability and extreme scenarios effectively. To address these limitations, this study performs a comprehensive statistical analysis of PWT service durations using operational data from Beijing Daxing International Airport (ZBAD) and Shanghai Pudong International Airport (ZSPD). Employing chi-square goodness-of-fit tests, twenty probability distributions—including several heavy-tailed candidates—were rigorously evaluated under segmented scenarios, such as peak versus non-peak periods, varying temperature conditions, and different aircraft sizes. Results reveal that heavy-tailed distributions offer context-dependent advantages: the stable distribution exhibits superior modeling performance during peak operational periods, whereas the Burr distribution excels under non-peak conditions. Interestingly, contrary to existing operational assumptions, service durations at extremely high and low temperatures showed no significant statistical differences, prompting a reconsideration of temperature-dependent planning practices. Additionally, analysis by aircraft category showed that the Burr distribution best described service durations for large aircraft, while stable and log-logistic distributions were optimal for medium-sized aircraft. Numerical simulations confirmed these findings, demonstrating that the proposed heavy-tailed probabilistic models significantly improved resource prediction accuracy, reducing estimation errors by 13% to 25% compared to conventional methods. This research uniquely demonstrates the practical effectiveness of employing context-sensitive heavy-tailed distributions, substantially enhancing resource efficiency and operational reliability in airport ground handling management. Full article

(This article belongs to the Section Air Traffic and Transportation)

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25 pages, 4682 KiB

Open AccessArticle

Visual Active SLAM Method Considering Measurement and State Uncertainty for Space Exploration

by Yao Zhao, Zhi Xiong, Jingqi Wang, Lin Zhang and Pascual Campoy

Aerospace 2025, 12(7), 642; https://doi.org/10.3390/aerospace12070642 - 20 Jul 2025

Viewed by 277

Abstract

This paper presents a visual active SLAM method considering measurement and state uncertainty for space exploration in urban search and rescue environments. An uncertainty evaluation method based on the Fisher Information Matrix (FIM) is studied from the perspective of evaluating the localization uncertainty [...] Read more.

This paper presents a visual active SLAM method considering measurement and state uncertainty for space exploration in urban search and rescue environments. An uncertainty evaluation method based on the Fisher Information Matrix (FIM) is studied from the perspective of evaluating the localization uncertainty of SLAM systems. With the aid of the Fisher Information Matrix, the Cramér–Rao Lower Bound (CRLB) of the pose uncertainty in the stereo visual SLAM system is derived to describe the boundary of the pose uncertainty. Optimality criteria are introduced to quantitatively evaluate the localization uncertainty. The odometry information selection method and the local bundle adjustment information selection method based on Fisher Information are proposed to find out the measurements with low uncertainty for localization and mapping in the search and rescue process. By adopting the method above, the computing efficiency of the system is improved while the localization accuracy is equivalent to the classical ORB-SLAM2. Moreover, by the quantified uncertainty of local poses and map points, the generalized unary node and generalized unary edge are defined to improve the computational efficiency in computing local state uncertainty. In addition, an active loop closing planner considering local state uncertainty is proposed to make use of uncertainty in assisting the space exploration and decision-making of MAV, which is beneficial to the improvement of MAV localization performance in search and rescue environments. Simulations and field tests in different challenging scenarios are conducted to verify the effectiveness of the proposed method. Full article

(This article belongs to the Section Aeronautics)

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30 pages, 15434 KiB

Open AccessArticle

A DSP–FPGA Heterogeneous Accelerator for On-Board Pose Estimation of Non-Cooperative Targets

by Qiuyu Song, Kai Liu, Shangrong Li, Mengyuan Wang and Junyi Wang

Aerospace 2025, 12(7), 641; https://doi.org/10.3390/aerospace12070641 - 19 Jul 2025

Viewed by 299

Abstract

The increasing presence of non-cooperative targets poses significant challenges to the space environment and threatens the sustainability of aerospace operations. Accurate on-orbit perception of such targets, particularly those without cooperative markers, requires advanced algorithms and efficient system architectures. This study presents a hardware–software [...] Read more.

The increasing presence of non-cooperative targets poses significant challenges to the space environment and threatens the sustainability of aerospace operations. Accurate on-orbit perception of such targets, particularly those without cooperative markers, requires advanced algorithms and efficient system architectures. This study presents a hardware–software co-design framework for the pose estimation of non-cooperative targets. Firstly, a two-stage architecture is proposed, comprising object detection and pose estimation. YOLOv5s is modified with a Focus module to enhance feature extraction, and URSONet adopts global average pooling to reduce the computational burden. Optimization techniques, including batch normalization fusion, ReLU integration, and linear quantization, are applied to improve inference efficiency. Secondly, a customized FPGA-based accelerator is developed with an instruction scheduler, memory slicing mechanism, and computation array. Instruction-level control supports model generalization, while a weight concatenation strategy improves resource utilization during convolution. Finally, a heterogeneous DSP–FPGA system is implemented, where the DSP manages data pre-processing and result integration, and the FPGA performs core inference. The system is deployed on a Xilinx X7K325T FPGA operating at 200 MHz. Experimental results show that the optimized model achieves a peak throughput of 399.16 GOP/s with less than 1% accuracy loss. The proposed design reaches 0.461 and 0.447 GOP/s/DSP48E1 for two model variants, achieving a 2× to 3× improvement over comparable designs. Full article

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

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17 pages, 33742 KiB

Open AccessArticle

Experimental Study of Aerodynamic and Bird Exclusion Characteristics of a Branched Turboprop Inlet Under Ground Suction Conditions

by Ge Zhou, Zhenlong Wu and Huijun Tan

Aerospace 2025, 12(7), 640; https://doi.org/10.3390/aerospace12070640 - 19 Jul 2025

Viewed by 187

Abstract

A turboprop aircraft is exposed to the risk of bird strikes during flight, which may have a serious impact on flight safety once the bird is sucked into the engine. In this study, the aerodynamic and bird exclusion characteristics of a branched turboprop [...] Read more.

A turboprop aircraft is exposed to the risk of bird strikes during flight, which may have a serious impact on flight safety once the bird is sucked into the engine. In this study, the aerodynamic and bird exclusion characteristics of a branched turboprop inlet were tested on a branched turboprop inlet–bird striking experiment system under ground suction conditions. The ingestion processes of the bird were captured by a high-speed camera system. The static pressure at the inner wall of the inlet during the ingestion process was measured. The results indicate that when a low-speed bird at a large incident angle impacts on the wall of the inlet near the lower lip under ground suction conditions, the bird is easily sucked into the core duct. Conversely, it is more likely to be excluded by the bypass duct. Moreover, when the bird moves into the inlet, the static pressure on the wall of the area where it passes through increases significantly. Full article

(This article belongs to the Special Issue Environmental Influences on Aircraft Aerodynamics)

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36 pages, 11687 KiB

Open AccessArticle

Macroscopic-Level Collaborative Optimization Framework for IADS: Multiple-Route Terminal Maneuvering Area Scheduling Problem

by Chaoyu Xia, Minghua Hu, Xiuying Zhu, Yi Wen, Junqing Wu and Changbo Hou

Aerospace 2025, 12(7), 639; https://doi.org/10.3390/aerospace12070639 - 18 Jul 2025

Viewed by 153

Abstract

The terminal maneuvering area (TMA) serves as a critical transition zone between upper enroute airways and airports, representing one of the most complex regions for managing high volumes of arrival and departure traffic. This paper presents the multi-route TMA scheduling problem as an [...] Read more.

The terminal maneuvering area (TMA) serves as a critical transition zone between upper enroute airways and airports, representing one of the most complex regions for managing high volumes of arrival and departure traffic. This paper presents the multi-route TMA scheduling problem as an optimization challenge aimed at optimizing TMA interventions, such as rerouting, speed control, time-based metering, dynamic minimum time separation, and holding procedures; the objective function minimizes schedule deviations and the accumulated holding time. Furthermore, the problem is formulated as a mixed-integer linear program (MILP) to facilitate finding solutions. A rolling horizon control (RHC) dynamic optimization framework is also introduced to decompose the large-scale problem into manageable subproblems for iterative resolution. To demonstrate the applicability and effectiveness of the proposed scheduling models, a hub airport—Chengdu Tianfu International Airport (ICAO code: ZUTF) in the Cheng-Yu Metroplex—is selected for validation. Numerical analyses confirm the superiority of the proposed models, which are expected to reduce aircraft delays, shorten airborne and holding times, and improve airspace resource utilization. This study provides intelligent decision support and engineering design ideas for the macroscopic-level collaborative optimization framework of the Integrated Arrival–Departure and Surface (IADS) system. Full article

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

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25 pages, 7778 KiB

Open AccessArticle

Pressure Characteristics Analysis of the Deflector Jet Pilot Stage Under Dynamic Skewed Velocity Distribution

by Zhilin Cheng, Wenjun Yang, Liangcai Zeng and Lin Wu

Aerospace 2025, 12(7), 638; https://doi.org/10.3390/aerospace12070638 - 17 Jul 2025

Viewed by 201

Abstract

The velocity distribution at the deflector jet outlet significantly influences the pressure characteristics of the pilot stage, thereby affecting the dynamic performance of the servo valve. Conventional mathematical models fail to account for the influence of dynamic velocity distribution on pilot stage pressure [...] Read more.

The velocity distribution at the deflector jet outlet significantly influences the pressure characteristics of the pilot stage, thereby affecting the dynamic performance of the servo valve. Conventional mathematical models fail to account for the influence of dynamic velocity distribution on pilot stage pressure characteristics, resulting in significant deviations from actual situations. As the deflector shifts, the secondary jet velocity distribution transitions from a symmetric to an asymmetric dynamic profile, altering the pressure within the receiving chambers. To address this, a dynamic skewed velocity distribution model is proposed to more accurately capture the pressure characteristics. The relationship between the skewness coefficient and deflector displacement is established, and the pressure calculation method for the receiving chambers is refined accordingly. A comparative analysis shows that the proposed model aligns most closely with computational fluid dynamics results, achieving a 98% match in velocity distribution and a maximum pressure error of 1.43%. This represents an improvement of 84.98% over the normal model and 82.35% over the uniform model, confirming the superior accuracy of the dynamic skewed model in pilot stage pressure calculation. Full article

(This article belongs to the Special Issue Aerospace Vehicles and Complex Fluid Flow Modelling)

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20 pages, 4974 KiB

Open AccessArticle

A Novel Shape Memory Alloy Actuated Bearing Active Preload System (SMA-BAPS) for Space Spindles

by Yuhang Zhang, Jun Jiang, Qiang Zhang, Yuanzi Zhou, Xiaoyong Zhang and Ruijie Sun

Aerospace 2025, 12(7), 637; https://doi.org/10.3390/aerospace12070637 - 17 Jul 2025

Viewed by 225

Abstract

In this study, a novel shape memory alloy actuated bearing active preload system (SMA-BAPS) was proposed and experimentally demonstrated. SMA actuators placed in a single or antagonistic configuration were employed to drive the screw pair and thus fulfill one-way or bidirectional preload adjustment. [...] Read more.

In this study, a novel shape memory alloy actuated bearing active preload system (SMA-BAPS) was proposed and experimentally demonstrated. SMA actuators placed in a single or antagonistic configuration were employed to drive the screw pair and thus fulfill one-way or bidirectional preload adjustment. Moreover, the self-locking screw pair was used to maintain the bearing preload without external energy input. To determine the parameters of screw pair and SMA actuators, a detailed design process was conducted based on analytical models of the proposed system. Finally, a screw pair with a lead of 3 mm and SMA actuators with a diameter of 0.5 mm and a length of 130 mm were adopted. Prototype tests were conducted to validate and evaluate the performance of the preload adjustment with the SMA-BAPS. The resistive torque and the natural frequency of spindles were recorded to represent the preload level of the bearing. Through the performance tests, the SMA-BAPS induced a maximum 47% variation in the resistive torque and a 20% variation in the spindle’s natural frequency. The response time of the SMA-BAPS was less than 5 s when the heating current of 5 A was applied on the SMA actuator. This design highlighted the compact size, quick response, as well as the bidirectional preload adjustment, representing its potential use in aerospace mechanisms and advanced motors. Full article

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

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15 pages, 3857 KiB

Open AccessArticle

Numerical and Experimental Investigation of Damage and Failure Analysis of Aero-Engine Electronic Controllers Under Thermal Shock

by Fang Wen, Jinshan Wen and Jie Jin

Aerospace 2025, 12(7), 636; https://doi.org/10.3390/aerospace12070636 - 16 Jul 2025

Viewed by 211

Abstract

The Engine Electronic Controller (EEC), as the core component of an aircraft engine control system, is vulnerable to rapid failure when exposed to thermal shock during engine fire incidents, potentially leading to catastrophic aviation accidents. To address this issue, this study conducts both [...] Read more.

The Engine Electronic Controller (EEC), as the core component of an aircraft engine control system, is vulnerable to rapid failure when exposed to thermal shock during engine fire incidents, potentially leading to catastrophic aviation accidents. To address this issue, this study conducts both numerical simulations and experimental investigations to evaluate the thermal performance of the EEC under thermal shock conditions, exploring the weaknesses of the EEC chassis under high-temperature thermal shock and the damage to important internal electronic components. A three-dimensional finite element model of the EEC was established to simulate its behavior under a thermal shock of 1100 °C. Simulation results reveal that the aluminum alloy chassis wall cannot withstand the extreme thermal load, resulting in failure of the internal electronic components within the first 5 min of exposure, thereby rendering the EEC inoperative. In contrast, when the chassis wall is made of stainless steel, all components and internal electronics remain functional throughout the initial 5 min thermal shock period. Experimental results show that the temperature evolution and component failure patterns under both scenarios align well with the simulation outcomes, thus validating the model’s accuracy. Full article

(This article belongs to the Section Aeronautics)

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32 pages, 5465 KiB

Open AccessArticle

DETEAMSK: A Model-Based Reinforcement Learning Approach to Intelligent Top-Level Planning and Decisions for Multi-Drone Ad Hoc Teamwork by Decoupling the Identification of Teammate and Task

by Penghui Xu, Yu Zhang, Le Hao and Qilin Yan

Aerospace 2025, 12(7), 635; https://doi.org/10.3390/aerospace12070635 - 16 Jul 2025

Viewed by 189

Abstract

The ability to collaborate with new teammates, adapt to unfamiliar environments, and engage in effective planning is essential for multi-drone agents within unmanned combat systems. This paper introduces DETEAMSK (Model-based Reinforcement Learning by Decoupling the Identification of Teammates and Tasks), a model-based reinforcement [...] Read more.

The ability to collaborate with new teammates, adapt to unfamiliar environments, and engage in effective planning is essential for multi-drone agents within unmanned combat systems. This paper introduces DETEAMSK (Model-based Reinforcement Learning by Decoupling the Identification of Teammates and Tasks), a model-based reinforcement learning method in intelligent top-level planning and decisions designed for ad hoc teamwork among multi-drone agents. It specifically addresses integrated reconnaissance and strike missions in urban combat scenarios under varying conditions. DETEAMSK’s performance is evaluated through comprehensive, multidimensional experiments and compared with other baseline models. The results demonstrate that DETEAMSK exhibits superior effectiveness, robustness, and generalization capabilities across a range of task domains. Moreover, the model-based reinforcement learning approach offers distinct advantages over traditional models, such as the PLASTIC-Model, and model-free approaches, like the PLASTIC-Policy, due to its unique “dynamic decoupling identification” feature. This study provides valuable insights for advancing both theoretical and applied research in model-based reinforcement learning methods for multi-drone systems. Full article

(This article belongs to the Special Issue Innovations in Unmanned Aerial Vehicle: Design and Development)

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16 pages, 2272 KiB

Open AccessArticle

A Rapid Method for Heat Transfer Coefficient Prediction on the Icing Surfaces of Aircraft Wings Based on a Partitioned Boundary Layer Integral Model

by Liu Wang, Dexin Zhang, Zikang Cheng, Jiaxin Feng, Bo Sun, Jianye Chen and Junlong Xie

Aerospace 2025, 12(7), 634; https://doi.org/10.3390/aerospace12070634 - 16 Jul 2025

Viewed by 241

Abstract

Aircraft wing surface icing compromises flight safety, where accurate calculation of heat transfer coefficient on airfoil surfaces serves as a prerequisite for designing thermal anti-icing systems. However, during icing conditions, ice morphology changes wall roughness and transition properties, making it difficult to accurately [...] Read more.

Aircraft wing surface icing compromises flight safety, where accurate calculation of heat transfer coefficient on airfoil surfaces serves as a prerequisite for designing thermal anti-icing systems. However, during icing conditions, ice morphology changes wall roughness and transition properties, making it difficult to accurately determine the heat transfer coefficient. The current study develops a partitioned rough-wall boundary layer integral methodology in order to overcome this issue, extending the conventional boundary layer integral method. The technique generates a convective heat transfer coefficient formulation for aircraft icing surfaces while accounting for roughness differences brought on by water droplet shape. The results show that the partitioned rough-wall boundary layer integral method divides the wing surface into three distinct zones based on water droplet dynamics—a smooth zone, rough zone, and runback zone—each associated with specific roughness values. The NACA0012 airfoil was used for numerical validation, which showed that computational and experimental data concur well. Additionally, the suggested approach predicts transition locations with a high degree of agreement with experimental results. Full article

(This article belongs to the Section Aeronautics)

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17 pages, 2117 KiB

Open AccessArticle

On-Orbit Life Prediction and Analysis of Triple-Junction Gallium Arsenide Solar Arrays for MEO Satellites

by Huan Liu, Chenjie Kong, Yuan Shen, Baojun Lin, Xueliang Wang and Qiang Zhang

Aerospace 2025, 12(7), 633; https://doi.org/10.3390/aerospace12070633 - 16 Jul 2025

Viewed by 245

Abstract

This paper focuses on the triple-junction gallium arsenide solar array of a MEO (Medium Earth Orbit) satellite that has been in orbit for 7 years. Through a combination of theoretical and data-driven methods, it conducts research on anti-radiation design verification and life prediction. [...] Read more.

This paper focuses on the triple-junction gallium arsenide solar array of a MEO (Medium Earth Orbit) satellite that has been in orbit for 7 years. Through a combination of theoretical and data-driven methods, it conducts research on anti-radiation design verification and life prediction. This study integrates the Long Short-Term Memory (LSTM) algorithm into the full life cycle management of MEO satellite solar arrays, providing a solution that combines theory and engineering for the design of high-reliability energy systems. Based on semiconductor physics theory, this paper establishes an output current calculation model. By combining radiation attenuation factors obtained from ground experiments, it derives the theoretical current values for the initial orbit insertion and the end of life. Aiming at the limitations of traditional physical models in addressing solar performance degradation under complex radiation environments, this paper introduces an LSTM algorithm to deeply mine the high-density current telemetry data (approximately 30 min per point) accumulated over 7 years in orbit. By comparing the prediction accuracy of LSTM with traditional models such as Recurrent Neural Network (RNN) and Feedforward Neural Network (FNN), the significant advantage of LSTM in capturing the long-term attenuation trend of solar arrays is verified. This study integrates deep learning technology into the full life cycle management of solar arrays, constructs a closed-loop verification system of “theoretical modeling–data-driven intelligent prediction”, and provides a solution for the long-life and high-reliability operation of the energy system of MEO orbit satellites. Full article

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27 pages, 8289 KiB

Open AccessArticle

A High-Efficient Modeling Method for Aerodynamic Loads of an Airfoil with Active Leading Edge Based on RFA and CFD

by Shengyong Fang, Sheng Zhang, Jinlong Zhou and Weidong Yang

Aerospace 2025, 12(7), 632; https://doi.org/10.3390/aerospace12070632 - 15 Jul 2025

Viewed by 279

Abstract

For the airfoil in freestream, the pressure difference between the upper and lower surfaces and the variations in pressure gradients are significant at its leading edge area. Under reasonable deflections, the active leading edge can effectively change airfoil aerodynamic loads, which helps to [...] Read more.

For the airfoil in freestream, the pressure difference between the upper and lower surfaces and the variations in pressure gradients are significant at its leading edge area. Under reasonable deflections, the active leading edge can effectively change airfoil aerodynamic loads, which helps to improve the rotor aerodynamic performance. In this paper, a modeling method for an airfoil with an active leading edge was developed to calculate its aerodynamic loads. The pitch motion of the rotor blade and the leading edge deflections were taken into account. Firstly, simulations of steady and unsteady flow for the airfoil with an active leading edge were conducted under different boundary conditions and with different leading edge deflection movement. Secondly, the rational function approximation (RFA) was employed to establish the relationship between aerodynamic loads and airfoil/active leading edge deflections. Then, coefficient matrices of the RFA approach were identified based on a limited number of high-fidelity computational fluid dynamics (CFD) results. Finally, an aerodynamic model of the airfoil with an active leading edge was developed, and its accuracy was validated by comparing it to the high-fidelity CFD results. Comparative results reveal that the developed model can calculate the aerodynamic loads of an airfoil with an active leading edge accurately and efficiently when applied appropriately. The modeling method can be used in aerodynamic load calculations and the aeroelastic coupling analysis of a rotor with active control devices. Full article

(This article belongs to the Section Aeronautics)

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15 pages, 1617 KiB

Open AccessArticle

A Stochastic Optimization Model for Multi-Airport Flight Cooperative Scheduling Considering CvaR of Both Travel and Departure Time

by Wei Cong, Zheng Zhao, Ming Wei and Huan Liu

Aerospace 2025, 12(7), 631; https://doi.org/10.3390/aerospace12070631 - 14 Jul 2025

Viewed by 188

Abstract

By assuming that both travel and departure time are normally distributed variables, a multi-objective stochastic optimization model for the multi-airport flight cooperative scheduling problem (MAFCSP) with CvaR of travel and departure time is firstly proposed. Herein, conflicts of flights from different airports at [...] Read more.

By assuming that both travel and departure time are normally distributed variables, a multi-objective stochastic optimization model for the multi-airport flight cooperative scheduling problem (MAFCSP) with CvaR of travel and departure time is firstly proposed. Herein, conflicts of flights from different airports at the same waypoint can be avoided by simultaneously assigning an optimal route to each flight between the airport and waypoint and determining its practical departure time. Furthermore, several real-world constraints, including the safe interval between any two aircraft at the same waypoint and the maximum allowable delay for each flight, have been incorporated into the proposed model. The primary objective is minimization of both total carbon emissions and delay times for all flights across all airports. A feasible set of non-dominated solutions were obtained using a two-stage heuristic approach-based NSGA-II. Finally, we present a case study of four airports and three waypoints in the Beijing–Tianjin–Hebei region of China to test our study. Full article

(This article belongs to the Special Issue Flight Performance and Planning for Sustainable Aviation)

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23 pages, 4015 KiB

Open AccessArticle

Predicting Electromagnetic Performance Under Wrinkling in Thin-Film Phased Arrays

by Xiaotao Zhou, Jianfei Yang, Lei Zhang, Huanxiao Li, Xin Jin, Yesen Fan, Yan Xu and Xiaofei Ma

Aerospace 2025, 12(7), 630; https://doi.org/10.3390/aerospace12070630 - 14 Jul 2025

Viewed by 237

Abstract

Deployable thin-film antennas deliver large aperture gains and high stowage efficiency for spaceborne phased arrays but suffer wrinkling-induced planarity loss and radiation distortion. To bridge the lack of electromechanical coupling models for tensioned thin-film patch antennas, we present a unified framework combining structural [...] Read more.

Deployable thin-film antennas deliver large aperture gains and high stowage efficiency for spaceborne phased arrays but suffer wrinkling-induced planarity loss and radiation distortion. To bridge the lack of electromechanical coupling models for tensioned thin-film patch antennas, we present a unified framework combining structural deformation and electromagnetic simulation. We derive a coupling model capturing the increased bending stiffness of stepped-thickness membranes, formulate a wrinkling analysis algorithm to compute tension-induced displacements, and fit representative unit-cell deformations to a dual-domain displacement model. Parametric studies across stiffness ratios confirm the framework’s ability to predict shifts in pattern, gain, and impedance due to wrinkling. This tool supports the optimized design of wrinkle-resistant thin-film phased arrays for reliable, high-performance space communications. Full article

(This article belongs to the Special Issue Space Mechanisms and Robots)

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16 pages, 2144 KiB

Open AccessArticle

Inter-Frequency Aided Acquisition for BeiDou DFMC Receivers: Dual-Frequency Cooperation and Extended Integration

by Zhenyang Ma, Xupeng Zhang, Zhaobin Duan and Yicheng Li

Aerospace 2025, 12(7), 629; https://doi.org/10.3390/aerospace12070629 - 12 Jul 2025

Viewed by 188

Abstract

With the advancement of the third-generation BeiDou Navigation Satellite System (BDS-3), BeiDou dual-frequency multi-constellation (DFMC) receivers exhibit distinct advantages in accuracy and reliability due to their dual-frequency capabilities. However, the integration time imposes constraints on further improvements in sensitivity. To address this limitation, [...] Read more.

With the advancement of the third-generation BeiDou Navigation Satellite System (BDS-3), BeiDou dual-frequency multi-constellation (DFMC) receivers exhibit distinct advantages in accuracy and reliability due to their dual-frequency capabilities. However, the integration time imposes constraints on further improvements in sensitivity. To address this limitation, this study proposes a dual-frequency cooperative acquisition strategy targeting the B1C and B2a signals, with the objective of enhancing acquisition performance in weak signal environments. A dual-channel acquisition architecture was designed, incorporating an inter-frequency Doppler assistance technique to improve acquisition efficiency. Simulation results demonstrate that, compared to conventional fixed short integration time architectures, the proposed cooperative acquisition approach increases the receiver’s acquisition sensitivity by 5.7 dB. Real-world experiments further confirm the effectiveness of this strategy, achieving successful acquisition of the PRN28 signal with 5 ms of coherent integration, thereby highlighting its practical utility. This research offers an innovative solution for high-sensitivity signal acquisition in challenging environments for BeiDou DFMC receivers and provides valuable insights for the advancement of high-precision BeiDou applications. Full article

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

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21 pages, 29238 KiB

Open AccessArticle

Distributed Impulsive Multi-Spacecraft Approach Trajectory Optimization Based on Cooperative Game Negotiation

by Shuhui Fan, Xiang Zhang and Wenhe Liao

Aerospace 2025, 12(7), 628; https://doi.org/10.3390/aerospace12070628 - 12 Jul 2025

Viewed by 219

Abstract

A cooperative game negotiation strategy considering multiple constraints is proposed for distributed impulsive multi-spacecraft approach missions in the presence of defending spacecraft. It is a dual-stage decision-making method that includes offline trajectory planning and online distributed negotiation. In the trajectory planning stage, a [...] Read more.

A cooperative game negotiation strategy considering multiple constraints is proposed for distributed impulsive multi-spacecraft approach missions in the presence of defending spacecraft. It is a dual-stage decision-making method that includes offline trajectory planning and online distributed negotiation. In the trajectory planning stage, a relative orbital dynamics model is first established based on the Clohessy–Wiltshire (CW) equations, and the state transition equations for impulsive maneuvers are derived. Subsequently, a multi-objective optimization model is formulated based on the NSGA-II algorithm, utilizing a constraint dominance principle (CDP) to address various constraints and generate Pareto front solutions for each spacecraft. In the distributed negotiation stage, the negotiation strategy among spacecraft is modeled as a cooperative game. A potential function is constructed to further analyze the existence and global convergence of Nash equilibrium. Additionally, a simulated annealing negotiation strategy is developed to iteratively select the optimal comprehensive approach strategy from the Pareto fronts. Simulation results demonstrate that the proposed method effectively optimizes approach trajectories for multi-spacecraft under complex constraints. By leveraging inter-satellite iterative negotiation, the method converges to a Nash equilibrium. Additionally, the simulated annealing negotiation strategy enhances global search performance, avoiding entrapment in local optima. Finally, the effectiveness and robustness of the dual-stage decision-making method were further demonstrated through Monte Carlo simulations. Full article

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

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22 pages, 6645 KiB

Open AccessArticle

Visual Detection on Aircraft Wing Icing Process Using a Lightweight Deep Learning Model

by Yang Yan, Chao Tang, Jirong Huang, Zhixiong Cen and Zonghong Xie

Aerospace 2025, 12(7), 627; https://doi.org/10.3390/aerospace12070627 - 12 Jul 2025

Viewed by 182

Abstract

Aircraft wing icing significantly threatens aviation safety, causing substantial losses to the aviation industry each year. High transparency and blurred edges of icing areas in wing images pose challenges to wing icing detection by machine vision. To address these challenges, this study proposes [...] Read more.

Aircraft wing icing significantly threatens aviation safety, causing substantial losses to the aviation industry each year. High transparency and blurred edges of icing areas in wing images pose challenges to wing icing detection by machine vision. To address these challenges, this study proposes a detection model, Wing Icing Detection DeeplabV3+ (WID-DeeplabV3+), for efficient and precise aircraft wing leading edge icing detection under natural lighting conditions. WID-DeeplabV3+ adopts the lightweight MobileNetV3 as its backbone network to enhance the extraction of edge features in icing areas. Ghost Convolution and Atrous Spatial Pyramid Pooling modules are incorporated to reduce model parameters and computational complexity. The model is optimized using the transfer learning method, where pre-trained weights are utilized to accelerate convergence and enhance performance. Experimental results show WID-DeepLabV3+ segments the icing edge at 1920 × 1080 within 0.03 s. The model achieves the accuracy of 97.15%, an IOU of 94.16%, a precision of 97%, and a recall of 96.96%, representing respective improvements of 1.83%, 3.55%, 1.79%, and 2.04% over DeeplabV3+. The number of parameters and computational complexity are reduced by 92% and 76%, respectively. With high accuracy, superior IOU, and fast inference speed, WID-DeeplabV3+ provides an effective solution for wing-icing detection. Full article

(This article belongs to the Section Aeronautics)

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21 pages, 2304 KiB

Open AccessReview

Quantifying Pilot Performance and Mental Workload in Modern Aviation Systems: A Scoping Literature Review

by Ainsley R. Kyle, Brock Rouser, Ryan C. Paul and Katherina A. Jurewicz

Aerospace 2025, 12(7), 626; https://doi.org/10.3390/aerospace12070626 - 12 Jul 2025

Viewed by 513

Abstract

Flight deck automation changes the nature of traditional piloting tasks, ultimately changing the cognitive requirements of the pilot. It is unclear how pilot performance should be measured as automation increases. The objective of this work is to understand the variability in experimental methodology [...] Read more.

Flight deck automation changes the nature of traditional piloting tasks, ultimately changing the cognitive requirements of the pilot. It is unclear how pilot performance should be measured as automation increases. The objective of this work is to understand the variability in experimental methodology regarding how pilot performance is measured since the introduction of flight deck automation. There were 90 articles included in this scoping literature review. Less than half of the articles investigated pilot performance (~40%), about half of the articles investigated mental workload (~45%), and almost 70% of the articles collected psychophysiological data; however, only 20% of the articles investigated human–automation interaction despite automation increasing in the flight deck. Design of resilient systems that support the needs of the pilot require consideration of human-system dynamics. As aircraft systems become more autonomous, performance metrics are increasingly derived from the human operator, reflecting a shift towards human-centered evaluation. Thus, it becomes more important to understand and model the relationship between performance, mental workload, and psychophysiological data when humans work with automation. Full article

(This article belongs to the Section Air Traffic and Transportation)

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15 pages, 1974 KiB

Open AccessArticle

A Study on the Conceptual Design of a 50-Seat Supersonic Transport

by Taichi Kawanabe and Zhong Lei

Aerospace 2025, 12(7), 625; https://doi.org/10.3390/aerospace12070625 - 11 Jul 2025

Viewed by 205

Abstract

The research and development of the next generation of supersonic transports (SSTs) meets economic and environmental problems. An SST encounters critical challenges, including the need for low fuel consumption, low noise, and low gas emissions. Currently, the feasibility of developing SSTs is increasing [...] Read more.

The research and development of the next generation of supersonic transports (SSTs) meets economic and environmental problems. An SST encounters critical challenges, including the need for low fuel consumption, low noise, and low gas emissions. Currently, the feasibility of developing SSTs is increasing through the application of cutting-edge technologies, such as composite materials, advanced electric systems, sustainable aviation fuel, and innovative design methodologies. The object of this study was to perform the conceptual design of a 50-seat supersonic transport utilizing general conceptual design methods. In estimating weight and flight performance, statistical formulae were correlated with data from civil supersonic and subsonic jet transports. For wing sizing, carpet plots were created to explore the optimal combination of wing aspect ratio and wing loading. The results suggested that by utilizing advanced technologies, such as the use of a composite material for the structure, the maximum takeoff weight can potentially be reduced while still meeting design requirements. The constraint of climb gradient largely affects the maximum takeoff weight, and it is anticipated that flight performance at low speeds will be improved. Full article

(This article belongs to the Special Issue Research and Development of Supersonic Aircraft)

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19 pages, 1841 KiB

Open AccessArticle

Analysis of Liquid Xenon Tank Filling Process in Different Gravity Environments

by Zong-Yu Wu, Chao Jiang, Yong Chen, Kai Li, Yiyong Huang and Yun Cheng

Aerospace 2025, 12(7), 624; https://doi.org/10.3390/aerospace12070624 - 11 Jul 2025

Viewed by 235

Abstract

With the advancement in deep-space exploration, the injection technology using xenon as a working fluid in electric propulsion systems has emerged as a key area of interest. To delve into the gas-liquid dynamics of the liquid xenon injection process and the influence of [...] Read more.

With the advancement in deep-space exploration, the injection technology using xenon as a working fluid in electric propulsion systems has emerged as a key area of interest. To delve into the gas-liquid dynamics of the liquid xenon injection process and the influence of gravity on this mechanism, this investigation employs a VOF two-phase flow model coupled with the Lee model to elucidate the characteristics of the two-phase flow during microgravity conditions. The findings uncover that in the absence of gravitational forces, gas-liquid stratification does not occur during the filling process. Consequently, this leads to an even distribution of gas and liquid within the tank, which in turn prolongs the filling duration in orbiting scenarios. Full article

(This article belongs to the Special Issue Numerical Simulations in Electric Propulsion)

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16 pages, 3138 KiB

Open AccessArticle

Analysis of Vibration Characteristics of Angular Contact Ball Bearings in Aviation Engines Under Changing Conditions

by Yanfang Dong, Zibo Yan, Jianyong Sun, Wei Yu, Hai Zhang, Wenbo Zhou and Jihao Jin

Aerospace 2025, 12(7), 623; https://doi.org/10.3390/aerospace12070623 - 11 Jul 2025

Viewed by 281

Abstract

This paper addresses the vibration characteristics of angular contact ball bearings in aircraft engines under variable load conditions. Based on multibody dynamics theory, a dynamic model of the bearing was established. Vibration data under actual operating conditions were obtained using an experimental test [...] Read more.

This paper addresses the vibration characteristics of angular contact ball bearings in aircraft engines under variable load conditions. Based on multibody dynamics theory, a dynamic model of the bearing was established. Vibration data under actual operating conditions were obtained using an experimental test platform. This study systematically investigated the influence of rotational speed, axial load, and radial load on the vibration acceleration level of the bearing outer ring. Through a comparison of simulation and experimental data (with an error rate below 10%), the reliability of the model was validated. The results indicate that the bearing vibration acceleration level exhibits a nonlinear increasing relationship with rotational speed. An increase in radial load significantly amplifies the amplitude of acceleration-level fluctuations, while appropriately increasing axial load can reduce bearing vibration intensity. Under variable load coupling conditions, the dynamic interaction between axial and radial forces results in complex nonlinear vibration responses, with a 2 s acceleration time achieving the optimal balance between vibration suppression and efficiency (steady-state average of 70.4 dB). Additionally, the morphological characteristics of the cage center-of-gravity trajectory (such as trajectory disorder and poor smoothness) are closely related to vibration characteristics, revealing the critical role of dynamic load changes in bearing stability. The research results provide a theoretical basis for optimizing the operating conditions, vibration control, and reliability design of aircraft engine bearings. Full article

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10 pages, 1102 KiB

Open AccessArticle

Prediction of Propellant Electrostatic Sensitivity Based on Small-Sample Machine Learning Models

by Fei Wang, Kai Cui, Jinxiang Liu, Wenhai He, Qiuyu Zhang, Weihai Zhang and Tianshuai Wang

Aerospace 2025, 12(7), 622; https://doi.org/10.3390/aerospace12070622 - 11 Jul 2025

Viewed by 263

Abstract

Hydroxyl-terminated-polybutadiene (HTPB)-based composite solid propellants are extensively used in aerospace and defense applications due to their high energy density, thermal stability, and processability. However, the presence of highly sensitive energetic components in their formulations leads to a significant risk of accidental ignition under [...] Read more.

Hydroxyl-terminated-polybutadiene (HTPB)-based composite solid propellants are extensively used in aerospace and defense applications due to their high energy density, thermal stability, and processability. However, the presence of highly sensitive energetic components in their formulations leads to a significant risk of accidental ignition under electrostatic discharge, posing serious safety concerns during storage, transportation, and handling. To address this issue, this study explores the prediction of electrostatic sensitivity in HTPB propellants using machine learning techniques. A dataset comprising 18 experimental formulations was employed to train and evaluate six machine learning models. Among them, the Random Forest (RF) model achieved the highest predictive accuracy (R² = 0.9681), demonstrating a strong generalization capability through leave-one-out cross-validation. Feature importance analysis using SHAP and Gini index methods revealed that aluminum, catalyst, and ammonium perchlorate were the most influential factors. These findings provide a data-driven approach for accurately predicting electrostatic sensitivity and offer valuable guidance for the rational design and safety optimization of HTPB-based propellant formulations. Full article

(This article belongs to the Special Issue Artificial Intelligence in the Design of Solid Propellants for Aerospace Applications)

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27 pages, 5964 KiB

Open AccessArticle

Investigation of Improved Labyrinth Seal Stability Accounting for Radial Deformation

by Guozhe Ren, Hongyuan Tang, Dan Sun, Wenfeng Xu and Yu Li

Aerospace 2025, 12(7), 621; https://doi.org/10.3390/aerospace12070621 - 10 Jul 2025

Viewed by 242

Abstract

This study examines the labyrinth seal disc of an aero-engine, specifically analysing the radial deformation caused by centrifugal force and heat stress during operation. This distortion may lead to discrepancies in the performance attributes of the labyrinth seal and could potentially result in [...] Read more.

This study examines the labyrinth seal disc of an aero-engine, specifically analysing the radial deformation caused by centrifugal force and heat stress during operation. This distortion may lead to discrepancies in the performance attributes of the labyrinth seal and could potentially result in contact between the labyrinth seal tip and neighbouring components. A numerical analytical model incorporating the rotor and stator cavities, along with the labyrinth seal disc structure, has been established. The sealing integrity of a standard labyrinth seal disc’s flow channel is evaluated and studied at different clearances utilising the fluid–solid-thermal coupling method. The findings demonstrate that, after considering radial deformation, a cold gap of 0.5 mm in the conventional labyrinth structure leads to stabilisation of the final hot gap and flow rate, with no occurrence of tooth tip rubbing; however, both the gap value and flow rate show considerable variation relative to the cold state. When the cold gap is 0.3 mm, the labyrinth plate makes contact with the stator wall. To resolve the problem of tooth tip abrasion in the conventional design with a 0.3 mm cold gap, two improved configurations are proposed, and a stability study for each configuration is performed independently. The leakage and temperature rise attributes of the two upgraded configurations are markedly inferior to those of the classic configuration at a cold gap of 0.5 mm. At a cold gap of 0.3 mm, the two improved designs demonstrate no instances of tooth tip rubbing. Full article

(This article belongs to the Section Aeronautics)

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19 pages, 1293 KiB

Open AccessArticle

Open-Source Real-Time SDR Platform for Rapid Prototyping of LANS AFS Receiver

by Rion Sobukawa and Takuji Ebinuma

Aerospace 2025, 12(7), 620; https://doi.org/10.3390/aerospace12070620 - 10 Jul 2025

Viewed by 499

Abstract

The Lunar Augmented Navigation Service (LANS) is the lunar equivalent of GNSS for future lunar explorations. It offers users accurate position, navigation, and timing (PNT) capabilities on and around the Moon. The Augmented Forward Signal (AFS) is a standardized signal structure for LANS, [...] Read more.

The Lunar Augmented Navigation Service (LANS) is the lunar equivalent of GNSS for future lunar explorations. It offers users accurate position, navigation, and timing (PNT) capabilities on and around the Moon. The Augmented Forward Signal (AFS) is a standardized signal structure for LANS, and its recommended standard was published online on 7 February 2025. This work presents software-defined radio (SDR) implementations of the LANS AFS simulator and receiver, which were rapidly developed within a month of the signal specification release. Based on open-source GNSS software, including GPS-SDR-SIM and Pocket SDR, our system provides a valuable platform for future algorithm research and hardware-in-the-loop testing. The receiver can operate on embedded platforms, such as the Raspberry Pi 5, in real-time. This feature makes it suitable for lunar surface applications, where conventional PC-based SDR systems are impractical due to their size, weight, and power requirements. Our approach demonstrates how open-source SDR frameworks can be rapidly applied to emerging satellite navigation signals, even for extraterrestrial PNT applications. Full article

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

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18 pages, 3683 KiB

Open AccessArticle

Influence of Aerodynamic Modeling Errors on the Dynamic Characteristics of a Missile

by Qiang Li, Xiaming Yuan and Jihong Zhu

Aerospace 2025, 12(7), 619; https://doi.org/10.3390/aerospace12070619 - 10 Jul 2025

Viewed by 322

Abstract

Flight mechanics/dynamics models are essential for analyzing aircraft flight performance, where aerodynamic data play a critical role. This paper establishes a missile flight dynamics model and investigates the influence of aerodynamic modeling errors based on wind tunnel test data. Common aerodynamic modeling methods [...] Read more.

Flight mechanics/dynamics models are essential for analyzing aircraft flight performance, where aerodynamic data play a critical role. This paper establishes a missile flight dynamics model and investigates the influence of aerodynamic modeling errors based on wind tunnel test data. Common aerodynamic modeling methods are compared, the effects of longitudinal coefficient deviations on the linearized missile model are analyzed using a deviation test approach, and the results are validated through simulations. The results show that interpolation-based aerodynamic modeling may lead to overfitting; segmented or denser Mach number testing is recommended to improve accuracy. Although aerodynamic error models based on derivatives and coefficients are applicable only within limited flight envelopes, they offer faster simulation and convenient uncertainty introduction. The missile’s longitudinal eigenvalue distribution is affected only by

C_{L α}

,

C_{m C L}

, and

C_{m \bar{q}}

. The frequency domain differences between lift and pitch control surface effects determine the system’s non-minimum phase behavior. Furthermore, aerodynamic uncertainties may increase overshoot risk in a closed-loop control system, highlighting the need for robust control design. Full article

(This article belongs to the Section Aeronautics)

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25 pages, 1717 KiB

Open AccessArticle

Optimal Midcourse Guidance with Terminal Relaxation and Range Convex Optimization

by Jiong Li, Jinlin Zhang, Jikun Ye, Lei Shao and Xiangwei Bu

Aerospace 2025, 12(7), 618; https://doi.org/10.3390/aerospace12070618 - 9 Jul 2025

Viewed by 226

Abstract

In midcourse guidance, strong constraints and dual-channel control coupling pose major challenges for trajectory optimization. To address this, this paper proposes an optimal guidance method based on terminal relaxation and range convex programming. The study first derived a range-domain dynamics model with the [...] Read more.

In midcourse guidance, strong constraints and dual-channel control coupling pose major challenges for trajectory optimization. To address this, this paper proposes an optimal guidance method based on terminal relaxation and range convex programming. The study first derived a range-domain dynamics model with the angle of attack and bank angle as dual control inputs, augmented with path constraints including heat flux limitations, to formulate the midcourse guidance optimization problem. A terminal relaxation strategy was then proposed to mitigate numerical infeasibility induced by rigid terminal constraints, thereby guaranteeing the solvability of successive subproblems. Through the integration of affine variable transformations and successive linearization techniques, the original nonconvex problem was systematically converted into a second-order cone programming (SOCP) formulation, with theoretical equivalence between the relaxed and original problems established under well-justified assumptions. Furthermore, a heuristic initial trajectory generation scheme was devised, and the solution was obtained via a sequential convex programming (SCP) algorithm. Numerical simulation results demonstrated that the proposed method effectively satisfies strict path constraints, successfully generates feasible midcourse guidance trajectories, and exhibits strong computational efficiency and robustness. Additionally, a systematic comparison was conducted to evaluate the impact of different interpolation methods and discretization point quantities on algorithm performance. Full article

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

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Aerospace, Volume 12, Issue 7 (July 2025) – 84 articles

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