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Aerospace
Volume 12
Issue 6
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Aerospace, Volume 12, Issue 6 (June 2025) – 113 articles

Cover Story (view full-size image): Aviation is key to global interconnectivity. To maintain its benefits while reducing emissions, future aircraft will require radical redesigns and novel technologies. Hydrogen aircraft offer a promising path to emissions reduction, with entry into service targeted for 2035. Achieving this goal demands rapid certification despite immature designs and unestablished processes. Accelerating progress requires early regulatory analysis and definition of technology and operational options. The CONCERTO project addressed this by analysing and weighting these elements, resulting in a Generic Concept at CRL1. This paper outline major system changes, integration challenges, and operational shifts needed to enable this concept’s flight. View this paper
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26 pages, 17358 KiB  
Article
Direct Numerical Simulation of Flow and Heat Transfer in a Compressor Blade Passage Across a Range of Reynolds Numbers
by Yang Liu, Chenchen Zhao, Lei Zhou, Duo Wang and Hongyi Xu
Aerospace 2025, 12(6), 563; https://doi.org/10.3390/aerospace12060563 - 19 Jun 2025
Viewed by 746
Abstract
This study employs Direct Numerical Simulation (DNS) to investigate the flow and heat transfer characteristics in a compressor blade passage at five Reynolds numbers (Re=1.091×105, 1.229×105, 1.367×105, [...] Read more.
This study employs Direct Numerical Simulation (DNS) to investigate the flow and heat transfer characteristics in a compressor blade passage at five Reynolds numbers (Re=1.091×105, 1.229×105, 1.367×105, 1.506×105, and 1.645×105). A recent method based on local inviscid velocity reconstruction is applied to define and calculate boundary layer parameters, whereas the Rortex vortex identification method is used to analyze turbulent vortical structures. Results indicate that Re significantly affects separation bubble size, transition location, and reattachment behavior, thereby altering wall heat transfer characteristics. On the pressure surface, separation and early transition are observed at higher Re, with the Nusselt number (Nu) remaining high after transition. On the suction surfaces, separation occurs such that large-scale separation at low Re reduces Nu, while reattachment combined with turbulent mixing at high Re significantly increases Nu. Turbulent vortical structures enhance near-wall fluid mixing through induced ejection and sweep events, thereby promoting momentum and heat transport. As Re increases, the vortical structures become denser with reduced scales and the peaks in heat flux move closer to the wall, thus improving convective heat transfer efficiency. Full article
(This article belongs to the Special Issue Vortex Flow Phenomena and Physics of Aerospace Engineering Applications (2nd Edition))
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28 pages, 11218 KiB  
Article
Transient Temperature Evaluation and Thermal Management Optimization Strategy for Aero-Engine Across the Entire Flight Envelope
by Weilong Gou, Shiyu Yang, Kehan Liu, Yuanfang Lin, Xingang Liang and Bo Shi
Aerospace 2025, 12(6), 562; https://doi.org/10.3390/aerospace12060562 - 19 Jun 2025
Viewed by 520
Abstract
With the enhancement of thermodynamic cycle parameters and heat dissipation constraints in aero-engines, effective thermal management has become a critical challenge to ensure safe and stable engine operation. This study developed a transient temperature evaluation model applicable to the entire flight envelope, considering [...] Read more.
With the enhancement of thermodynamic cycle parameters and heat dissipation constraints in aero-engines, effective thermal management has become a critical challenge to ensure safe and stable engine operation. This study developed a transient temperature evaluation model applicable to the entire flight envelope, considering fluid–solid coupling heat transfer on both the main flow path and fuel systems. Firstly, the impact of heat transfer on the acceleration and deceleration performance of a low-bypass-ratio turbofan engine was analyzed. The results indicate that, compared to the conventional adiabatic model, the improved model predicts metal components absorb 4.5% of the total combustor energy during cold-state acceleration, leading to a maximum reduction of 1.42 kN in net thrust and an increase in specific fuel consumption by 1.18 g/(kN·s). Subsequently, a systematic evaluation of engine thermal management performance throughout the complete flight mission was conducted, revealing the limitations of the existing thermal management design and proposing targeted optimization strategies, including employing Cooled Cooling Air technology to improve high-pressure turbine blade cooling efficiency, dynamically adjusting low-pressure turbine bleed air to minimize unnecessary losses, optimizing fuel heat sink utilization for enhanced cooling performance, and replacing mechanical pumps with motor pumps for precise fuel supply control. Full article
(This article belongs to the Special Issue Aircraft Thermal Management Technologies)
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24 pages, 5570 KiB  
Article
Study on Propellant Management Device for Small-Scale Supersonic Flight Experiment Vehicle
by Ryoji Imai and Takuya Wada
Aerospace 2025, 12(6), 561; https://doi.org/10.3390/aerospace12060561 - 19 Jun 2025
Viewed by 305
Abstract
To commercialize supersonic and hypersonic passenger aircraft and reusable spaceplanes, we are developing a small-scale supersonic flight experiment vehicle as a flying testbed for technical demonstrations in high-speed flight environments. This experiment vehicle is equipped with a fuel tank and an oxidizer tank, [...] Read more.
To commercialize supersonic and hypersonic passenger aircraft and reusable spaceplanes, we are developing a small-scale supersonic flight experiment vehicle as a flying testbed for technical demonstrations in high-speed flight environments. This experiment vehicle is equipped with a fuel tank and an oxidizer tank, and the propellants inside the tanks slosh due to changes in acceleration during flight. In this situation, there is a risk of gas entrainment during liquid discharge, which could potentially cause an engine malfunction. To avoid such a situation, we considered installing a propellant management device (PMD) inside the tank to suppress the gas entrainment. In this study, a capillary type PMD with a screen channel structure, commonly used in satellites featuring no moving parts, was adopted due to its applicability to a wide acceleration range. The PMD was designed with a structure featuring cylindrical mesh screen nozzles installed at the top and bottom of a cylindrical tank. A one-dimensional flow analysis model was developed taking into account factors such as the pressure loss across the mesh screens and the flow loss within the mesh screen nozzles, which enabled the identification of conditions under which gas entrainment occurred. In this analytical model, separate formulations were developed using Hartwig’s and Ingmanson’s formulas for evaluating the flow losses through the mesh screens. Furthermore, by applying the flow analysis model, the specifications of the mesh screens as key parameters of the PMD, together with the nozzle diameter and nozzle length, were selected. Moreover, we fabricated prototype PMDs with each nozzle and conducted visualization tests using a transparent tank. The tests were conducted under static conditions, where a gravitational acceleration acted downward, and the effects of the cylindrical mesh screen length and discharge flow rate on the free surface height at which gas entrainment occurred were investigated. This experiment demonstrated the effectiveness of the propellant acquisition mechanism of the present PMD. The height of the free surface was also compared with the experimental and analytical results, and it was shown that the results obtained by using Ingmanson’s formula for pressure loss through the screen mesh were closer to the experimental results. These findings demonstrated the validity of the one-dimensional flow analysis model. Full article
(This article belongs to the Section Aeronautics)
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15 pages, 6013 KiB  
Article
Urban Air Mobility Vertiport’s Capacity Simulation and Analysis
by Antoni Kopyt and Sebastian Dylicki
Aerospace 2025, 12(6), 560; https://doi.org/10.3390/aerospace12060560 - 19 Jun 2025
Viewed by 543
Abstract
This study shows a comprehensive simulation to assess and enhance the throughput capacity of unmanned air system vertiports, one of the most essential elements of urban air mobility ecosystems. The framework integrates dynamic grid-based spatial management, probabilistic mission duration algorithms, and EASA-compliant operational [...] Read more.
This study shows a comprehensive simulation to assess and enhance the throughput capacity of unmanned air system vertiports, one of the most essential elements of urban air mobility ecosystems. The framework integrates dynamic grid-based spatial management, probabilistic mission duration algorithms, and EASA-compliant operational protocols to address the infrastructural and logistical demands of high-density UAS operations. It was focused on two use cases—high-frequency food delivery utilizing small UASs and extended-range package logistics with larger UASs—and the model incorporates adaptive vertiport zoning strategies, segregating operations into dedicated sectors for battery charging, swapping, and cargo handling to enable parallel processing and mitigate congestion. The simulation evaluates critical variables such as vertiport dimensions, UAS fleet composition, and mission duration ranges while emphasizing scalability, safety, and compliance with evolving regulatory standards. By examining the interplay between infrastructure design, operational workflows, and resource allocation, the research provides a versatile tool for urban planners and policymakers to optimize vertiport layouts and traffic management protocols. Its modular architecture supports future extensions. This work underscores the necessity of adaptive, data-driven planning to harmonize vertiport functionality with the dynamic demands of urban air mobility, ensuring interoperability, safety, and long-term scalability. Full article
(This article belongs to the Special Issue Operational Requirements for Urban Air Traffic Management)
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35 pages, 6969 KiB  
Article
Building Credible VTOL Flight Models for Handling Quality Certification by Simulation
by Lorenzo Favaro, Agata Rylko and Giuseppe Quaranta
Aerospace 2025, 12(6), 559; https://doi.org/10.3390/aerospace12060559 - 19 Jun 2025
Viewed by 390
Abstract
Certifying novel VTOL aircraft handling qualities (HQs) may be challenging, relying on costly and high-risk flight testing. This paper presents a methodology to establish the credibility of flight simulation models for certification by simulation, aiming to bridge the gap between the model input [...] Read more.
Certifying novel VTOL aircraft handling qualities (HQs) may be challenging, relying on costly and high-risk flight testing. This paper presents a methodology to establish the credibility of flight simulation models for certification by simulation, aiming to bridge the gap between the model input uncertainty and certification confidence. The core objective is to assess if a model, despite its inherent uncertainties, can reliably predict the handling quality compliance for specific flight tasks. This is achieved by quantifying the impact of input parameter uncertainties on predicted handling qualities and, crucially, by evaluating the envelope of the resulting uncertain aircraft transfer functions—scaled by a confidence ratio—against established maximum unnoticeable added dynamics boundaries. Applied to a lift + cruise VTOL model performing a deceleration-to-hover manoeuvre, the study demonstrates that while longitudinal control dynamics largely remained within MUAD limits, indicating the model’s credibility for those aspects, vertical axis dynamics coupled with longitudinal inputs for some uncertain configurations exceeded these limits, correlating with observed flight test performance variability. Readers will find a structured, quantitative approach to model validation for HQ certification by simulation, leveraging MUAD to determine if a nominal model is sufficiently representative for certification, thereby supporting safer and more efficient VTOL development. Full article
(This article belongs to the Section Aeronautics)
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20 pages, 3653 KiB  
Article
Nonlinear Model and Ballistic Impact of Body Aerodynamics for Canard Dual-Spin Aircraft
by Xinxin Zhao, Jinguang Shi, Huajie Ren and Zhongyuan Wang
Aerospace 2025, 12(6), 558; https://doi.org/10.3390/aerospace12060558 - 18 Jun 2025
Viewed by 275
Abstract
Targeting the nonlinear issues of the canard dual-spin aircraft, which relies on the high-speed rotation of the afterbody for flight stability and achieves trajectory correction by adjusting the roll angle of the low-speed rotating forebody to alter aerodynamics, the establishment of an accurate [...] Read more.
Targeting the nonlinear issues of the canard dual-spin aircraft, which relies on the high-speed rotation of the afterbody for flight stability and achieves trajectory correction by adjusting the roll angle of the low-speed rotating forebody to alter aerodynamics, the establishment of an accurate aerodynamic model is crucial for in-depth studies of its ballistic characteristics and design. For this, by taking the effects of canard–body interference, fore/aft body reversal, and other factors into account, an accurate model of the body aerodynamics applicable to large angles of attack is presented. This model theoretically elucidates the intricate relationship between the body aerodynamics and both the flight state and the aerodynamic parameters of the original aircraft. Subsequently, numerical simulations are conducted to analyze the body nonlinear aerodynamic characteristics and their impact on ballistics. The results reveal that all aerodynamic forces and moments acting on the aircraft body, particularly the Magnus force and moment, exhibit strong nonlinearities due to the coupling between the forebody roll angle and the amplitude and phase of the complex angle of attack. Moreover, the established model accurately captures the body aerodynamics and the influence of various disturbance factors, which can significantly alter the controlled angular motions and corrected ballistic calculations. Full article
(This article belongs to the Section Aeronautics)
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26 pages, 8994 KiB  
Article
Output Feedback Fuzzy Gain Scheduling for MIMO Systems Applied to Flexible Aircraft Control
by Guilherme C. Barbosa and Flávio J. Silvestre
Aerospace 2025, 12(6), 557; https://doi.org/10.3390/aerospace12060557 - 18 Jun 2025
Viewed by 263
Abstract
Previous works by our group evidenced stability problems associated with flight control law design for flexible aircraft regarding gain scheduling. This paper proposes an output feedback fuzzy-based gain scheduling approach to adequate closed-loop response in a broader range of the flight envelope. This [...] Read more.
Previous works by our group evidenced stability problems associated with flight control law design for flexible aircraft regarding gain scheduling. This paper proposes an output feedback fuzzy-based gain scheduling approach to adequate closed-loop response in a broader range of the flight envelope. This method applies a variation of the controller gains based on the membership function design for all the varying parameters, such as dynamic pressure. It aims for performance improvement while enforcing global stability gain scheduling. The technique was demonstrated for the flexible ITA X-HALE aircraft nonlinear model and compared to the classical interpolation-based gain scheduling technique. The results revealed that fuzzy-based gain scheduling can effectively handle high-order systems while ensuring global system stability, leading to an overall improvement in performance. Full article
(This article belongs to the Special Issue Aerodynamics, Flight Dynamics and Control of Advanced Air Mobility Vehicles)
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35 pages, 6410 KiB  
Article
Conceptual Design of a Low-Cost Class-III Turbofan-Based UCAV Loyal Wingman
by Savvas Roussos, Eleftherios Karatzas, Vassilios Kostopoulos and Vaios Lappas
Aerospace 2025, 12(6), 556; https://doi.org/10.3390/aerospace12060556 - 18 Jun 2025
Viewed by 484
Abstract
The rapid evolution of military technology has led to an increased interest in Unmanned Combat Aerial Vehicles (UCAVs). This research focuses on the conceptual design of a low-cost, turbofan-powered UCAV, specifically a Class-III aircraft as defined by NATO classification (STANAG 4670), with a [...] Read more.
The rapid evolution of military technology has led to an increased interest in Unmanned Combat Aerial Vehicles (UCAVs). This research focuses on the conceptual design of a low-cost, turbofan-powered UCAV, specifically a Class-III aircraft as defined by NATO classification (STANAG 4670), with a target take-off weight of approximately one tonne. The study adopts a “from scratch” design approach, recognizing the limitations of existing data and the potential for scaling errors. This approach involves a meticulous design process that includes the development of precise requirements, weight estimations, and iterative optimization of the aircraft layout to ensure aerodynamic efficiency and operational functionality. A key element of this conceptual design is its focus on a low-cost profile, achieved through the adoption of a simplified structural layout, and the integration of off-the-shelf components where possible. The design process involves an iterative approach, beginning with fundamental requirements and progressing through the detailed development of individual components and their integration into a cohesive aircraft. The study details the selection of an existing and operational engine due to its power output. The design and analysis of the wing, fuselage, and V-tail configuration are presented, incorporating considerations for aerodynamic efficiency, stability, weight estimation, and internal component layout. The study concludes by outlining recommendations for future work, including high-fidelity CFD simulations, structural analysis, and the integration of advanced electronic systems and AI capabilities essential for the Loyal Wingman concept. Full article
(This article belongs to the Special Issue UAV System Modelling Design and Simulation)
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39 pages, 3674 KiB  
Article
Enhancing Model Generalizability in Aircraft Carbon Brake Wear Prediction: A Comparative Study and Transfer Learning Approach
by Patsy Jammal, Olivia Pinon Fischer, Dimitri N. Mavris and Gregory Wagner
Aerospace 2025, 12(6), 555; https://doi.org/10.3390/aerospace12060555 - 18 Jun 2025
Viewed by 276
Abstract
Predictive maintenance in commercial aviation demands highly reliable and robust models, particularly for critical components like carbon brakes. This paper addresses two primary concerns in modeling carbon brake wear for distinct aircraft variants: (1) the choice between developing specialized models for individual aircraft [...] Read more.
Predictive maintenance in commercial aviation demands highly reliable and robust models, particularly for critical components like carbon brakes. This paper addresses two primary concerns in modeling carbon brake wear for distinct aircraft variants: (1) the choice between developing specialized models for individual aircraft types versus a unified, general model, and (2) the potential of transfer learning (TL) to boost model performance across diverse domains (e.g., aircraft types). We evaluate the trade-offs between predictive performance and computational efficiency by comparing specialized models tailored to specific aircraft types with a generalized model designed to predict continuous wear values across multiple aircraft types. Additionally, we explore the efficacy of TL in leveraging existing domain knowledge to enhance predictions in new, related contexts. Our findings demonstrate that a well-tuned generalized model supported by TL offers a viable approach to reducing model complexity and computational demands while maintaining robust and reliable predictive performance. The implications of this research extend beyond aviation, suggesting broader applications in component predictive maintenance where data-driven insights are crucial for operational efficiency and safety. Full article
(This article belongs to the Section Aeronautics)
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33 pages, 1265 KiB  
Article
Sizing of Fuel Distribution and Thermopropulsion Systems for Liquid-Hydrogen-Powered Aircraft Using an MBSE Approach
by Abdoulaye Sarr, Joël Jézégou and Pierre de Saqui-Sannes
Aerospace 2025, 12(6), 554; https://doi.org/10.3390/aerospace12060554 - 17 Jun 2025
Viewed by 693
Abstract
Hydrogen-powered aircraft constitute a transformative innovation in aviation, motivated by the imperative for sustainable and environmentally friendly transportation solutions. This paper aims to concentrate on the design of hydrogen powertrains employing a system approach to propose representative design models for distribution and propulsion [...] Read more.
Hydrogen-powered aircraft constitute a transformative innovation in aviation, motivated by the imperative for sustainable and environmentally friendly transportation solutions. This paper aims to concentrate on the design of hydrogen powertrains employing a system approach to propose representative design models for distribution and propulsion systems. Initially, the requirements for powertrain design are formalized, and a use-case-driven analysis is conducted to determine the functional and physical architectures. Subsequently, for each component pertinent to preliminary design, an analytical model is proposed for multidisciplinary analysis and optimization for powertrain sizing. A double-wall pipe model, incorporating foam and vacuum multi-layer insulation, was developed. The internal and outer pipes sizing were performed in accordance with standards for hydrogen piping design. Valves sizing is also considered in the present study, following current standards and using data available in the literature. Furthermore, models for booster pumps to compensate pressure drop and high-pressure pumps to elevate pressure at the combustion chamber entrance are proposed. Heat exchanger and evaporator models are also included and connected to a burning hydrogen engine in the sizing process. An optimal liner pipe diameter was identified, which minimizes distribution systems weight. We also expect a reduction in engine length and weight while maintaining equivalent thrust. Full article
(This article belongs to the Section Aeronautics)
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25 pages, 2540 KiB  
Article
Two-Stage Uncertain UAV Combat Mission Assignment Problem Based on Uncertainty Theory
by Haitao Zhong, Rennong Yang, Aoyu Zheng, Mingfa Zheng and Yu Mei
Aerospace 2025, 12(6), 553; https://doi.org/10.3390/aerospace12060553 - 17 Jun 2025
Viewed by 256
Abstract
Based on uncertainty theory, this paper studies the problem of unmanned aerial vehicle (UAV) combat mission assignment under an uncertain environment. First, considering both the target value, which is the combat mission benefit gained from attacking the target, and the unit fuel consumption [...] Read more.
Based on uncertainty theory, this paper studies the problem of unmanned aerial vehicle (UAV) combat mission assignment under an uncertain environment. First, considering both the target value, which is the combat mission benefit gained from attacking the target, and the unit fuel consumption of UAV as uncertain variables, an uncertain UAV combat mission assignment model is established. And according to decisions under the realization of uncertain variables, the first stage generates an initial mission allocation scheme corresponding to the realization of target value, while the second stage dynamically adjusts the scheme according to the realization of unit fuel consumption; a two-stage uncertain UAV combat mission assignment (TUCMA) model is obtained. Then, because of the difficulty of obtaining analytical solutions due to uncertainty and the complexity of solving the second stage, the TUCMA model is transformed into an expected value-effective deterministic model of the two-stage uncertain UAV combat mission assignment (ETUCMA). A modified particle swarm optimization (PSO) algorithm is designed to solve the ETUCMA model to get the expected value-effective solution of the TUCMA model. Finally, experimental simulations of multiple UAV combat task allocation scenarios demonstrate that the proposed modified PSO algorithm yields an optimal decision with maximum combat mission benefits under a maximum iteration limit, which are significantly greater benefits than those for the mission assignment achieved by the original PSO algorithm. The proposed modified PSO exhibits superior performance compared with the ant colony optimization algorithm, enabling the acquisition of an optimal allocation scheme with greater benefits. This verifies the effectiveness and superiority of the proposed model and algorithm in maximizing combat mission benefits. Full article
(This article belongs to the Section Aeronautics)
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24 pages, 6794 KiB  
Article
A Multi-Scale Airspace Sectorization Framework Based on QTM and HDQN
by Qingping Liu, Xuesheng Zhao, Xinglong Wang, Mengmeng Qin and Wenbin Sun
Aerospace 2025, 12(6), 552; https://doi.org/10.3390/aerospace12060552 - 17 Jun 2025
Viewed by 302
Abstract
Airspace sectorization is an effective approach to balance increasing air traffic demand and limited airspace resources. It directly impacts the efficiency and safety of airspace operations. Traditional airspace sectorization methods are often based on fixed spatial scales, failing to fully consider the complexity [...] Read more.
Airspace sectorization is an effective approach to balance increasing air traffic demand and limited airspace resources. It directly impacts the efficiency and safety of airspace operations. Traditional airspace sectorization methods are often based on fixed spatial scales, failing to fully consider the complexity and interrelationships of airspace partitioning across different spatial scales. This makes it challenging to balance large-scale airspace management with local dynamic demands. To address this issue, a multi-scale airspace sectorization framework is proposed, which integrates a multi-resolution grid system and a hierarchical deep reinforcement learning algorithm. First, an airspace grid model is constructed using Quaternary Triangular Mesh (QTM), along with an efficient workload calculation model based on grid encoding. Then, a sector optimization model is developed using hierarchical deep Q-network (HDQN), where the top-level and bottom-level policies coordinate to perform global airspace control area partitioning and local sectorization. The use of multi-resolution grids enhances the interaction efficiency between the reinforcement learning model and the environment. Prior knowledge is also incorporated to enhance training efficiency and effectiveness. Experimental results demonstrate that the proposed framework outperforms traditional models in both computational efficiency and workload balancing performance. Full article
(This article belongs to the Special Issue AI, Machine Learning and Automation for Air Traffic Control (ATC))
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17 pages, 1804 KiB  
Article
Semantic Topic Modeling of Aviation Safety Reports: A Comparative Analysis Using BERTopic and PLSA
by Aziida Nanyonga, Keith Joiner, Ugur Turhan and Graham Wild
Aerospace 2025, 12(6), 551; https://doi.org/10.3390/aerospace12060551 - 16 Jun 2025
Viewed by 355
Abstract
Aviation safety analysis increasingly relies on extracting actionable insights from narrative incident reports to support risk identification and improve operational safety. Topic modeling techniques such as Probabilistic Latent Semantic Analysis (pLSA) and BERTopic offer automated methods to uncover latent themes in unstructured safety [...] Read more.
Aviation safety analysis increasingly relies on extracting actionable insights from narrative incident reports to support risk identification and improve operational safety. Topic modeling techniques such as Probabilistic Latent Semantic Analysis (pLSA) and BERTopic offer automated methods to uncover latent themes in unstructured safety narratives. This study evaluates the effectiveness of each model in generating coherent, interpretable, and semantically meaningful topics for aviation safety practitioners and researchers. We assess model performance using both quantitative metrics (topic coherence scores) and qualitative evaluations of topic relevance. The findings show that while pLSA provides a solid probabilistic framework, BERTopic leveraging transformer-based embeddings and HDBSCAN clustering produces more nuanced, context-aware topic groupings, albeit with increased computational demands and tuning complexity. These results highlight the respective strengths and trade-offs of traditional versus modern topic modeling approaches in aviation safety analysis. This work advances the application of natural language processing (NLP) in aviation by demonstrating how topic modeling can support risk assessment, inform policy, and enhance safety outcomes. Full article
(This article belongs to the Section Air Traffic and Transportation)
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78 pages, 31324 KiB  
Review
An Overview of CubeSat Missions and Applications
by Konstantinos-Panagiotis Bouzoukis, Georgios Moraitis, Vassilis Kostopoulos and Vaios Lappas
Aerospace 2025, 12(6), 550; https://doi.org/10.3390/aerospace12060550 - 16 Jun 2025
Viewed by 2462
Abstract
The proliferation of CubeSats in Earth orbit has accelerated dramatically in recent years, with projections indicating continued growth in the coming decades. This review examines the evolution of CubeSat applications, from basic technology demonstrations to complex mission capabilities, including Earth observation, telecommunications, astronomical [...] Read more.
The proliferation of CubeSats in Earth orbit has accelerated dramatically in recent years, with projections indicating continued growth in the coming decades. This review examines the evolution of CubeSat applications, from basic technology demonstrations to complex mission capabilities, including Earth observation, telecommunications, astronomical research, biological experimentation, and deep-space exploration. A notable shift has occurred over the past fifteen years, with CubeSats transitioning from standalone platforms to integrated nodes within larger constellations, particularly for Earth observation and telecommunications applications. We analyze the key enabling factors behind the CubeSat revolution, including decreased launch costs, miniaturized electronics, standardized components, and institutional support frameworks. Through the examination of significant past, current, and planned missions, this paper provides a comprehensive overview of CubeSat capabilities across diverse application domains. The review highlights how these miniaturized satellite platforms are democratizing access to space while enabling innovative scientific and commercial applications previously restricted to larger spacecraft. Full article
(This article belongs to the Section Astronautics & Space Science)
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17 pages, 6509 KiB  
Article
Operation of Vacuum Arc Thruster Arrays with Multiple Isolated Current Sources
by Benjamin Kanda and Minkwan Kim
Aerospace 2025, 12(6), 549; https://doi.org/10.3390/aerospace12060549 - 16 Jun 2025
Viewed by 373
Abstract
Vacuum arc thrusters (VATs) have recently gained significant interest as a micro-propulsion system due to their scalability, low cost, storability, and small form factor. While VATs offer an attractive propulsion solution for CubeSats, conventional propellant feed systems used in VATs require intricate mechanical [...] Read more.
Vacuum arc thrusters (VATs) have recently gained significant interest as a micro-propulsion system due to their scalability, low cost, storability, and small form factor. While VATs offer an attractive propulsion solution for CubeSats, conventional propellant feed systems used in VATs require intricate mechanical moving parts, increasing overall system complexity and mission risk. A promising alternative is the use of VAT arrays, where multiple thin-layer VATs are arranged in a regularly spaced grid, thus enhancing reliability, increasing total impulse without a mechanical propellant feed system, and enabling integrated attitude control via off-axis thruster placement. However, VAT arrays require a larger power processing unit (PPU) and additional control system, posing challenges within CubeSat volume constraints. To address this, this study proposes a novel PPU design that enables the simultaneous operation of multiple VATs while minimising system mass and volume. Experimental results demonstrate the successful operation of VAT pairs using the proposed PPU concept, validating its feasibility as an efficient propulsion solution for CubeSats. Full article
(This article belongs to the Special Issue Space Propulsion: Advances and Challenges (3rd Volume))
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17 pages, 911 KiB  
Article
FMEA Risk Assessment Method for Aircraft Power Supply System Based on Probabilistic Language-TOPSIS
by Zicheng Xiao, Zhibo Shi and Jie Bai
Aerospace 2025, 12(6), 548; https://doi.org/10.3390/aerospace12060548 - 16 Jun 2025
Viewed by 341
Abstract
The failure mode and effect analysis (FMEA) method, which estimates the risk levels of systems or components solely based on the multiplication of simple risk rating indices, faces several limitations. These include the risk of inaccurate risk level judgment and the potential for [...] Read more.
The failure mode and effect analysis (FMEA) method, which estimates the risk levels of systems or components solely based on the multiplication of simple risk rating indices, faces several limitations. These include the risk of inaccurate risk level judgment and the potential for misjudgments due to human factors, both of which pose significant threats to the safe operation of aircraft. Therefore, a Probabilistic Language based on a cumulative prospect theory (Probabilistic Language, PL) risk assessment strategy was proposed, combining the technique for order preference with similarity to an ideal solution (TOPSIS). The probabilistic language term value and probability value were fused in the method through the cumulative prospect theory, and a new PL measure function was introduced. The comprehensive weights of evaluation strategies were determined by calculating the relevant weights of various indicators through the subjective expert weight and objective entropy weight synthesis. So, a weighted decision matrix was constructed to determine the ranking order close to the ideal scheme. Finally, the risk level of each failure mode was ranked according to its close degree to the ideal situation. Through case validation, the consistency of risk ranking was improved by 23.95% compared to the traditional FMEA method. The rationality of weight allocation was increased by 18.2%. Robustness was also enhanced to some extent. Compared with the traditional FMEA method, the proposed method has better rationality, application, and effectiveness. It can provide technical support for formulating a new generation of airworthiness documents for the risk level assessment of civil aircraft and its subsystem components. Full article
(This article belongs to the Section Aeronautics)
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28 pages, 7775 KiB  
Article
Uncertainty Modeling of Fouling Thickness and Morphology on Compressor Blade
by Limin Gao, Panpan Tu, Guang Yang and Song Yang
Aerospace 2025, 12(6), 547; https://doi.org/10.3390/aerospace12060547 - 16 Jun 2025
Viewed by 238
Abstract
To describe the fouling characteristics of compressor blades, fouling is categorized into dense and loose layers to characterize thickness and rough structures. An uncertainty model for dense fouling layer thickness distribution is constructed using the numerical integration and the Karhunen–Loève (KL) expansion method, [...] Read more.
To describe the fouling characteristics of compressor blades, fouling is categorized into dense and loose layers to characterize thickness and rough structures. An uncertainty model for dense fouling layer thickness distribution is constructed using the numerical integration and the Karhunen–Loève (KL) expansion method, while the Fouling Longuet-Higgins (FLH) model is proposed to address the uncertainty of loose fouling layer roughness. The FLH model effectively simulates the morphology characteristics of actual blade fouling and elucidates how parameters influence fouling roughness, morphology, and randomness. Based on the uncertainty modeling method, models for dense fouling layer thickness and loose fouling layer morphology are constructed, followed by numerical calculations and aerodynamic performance uncertainty quantification. Results indicate a 75.8% probability of aerodynamic performance degradation due to a dense fouling layer and a 97.2% probability related to the morphology uncertainty of a loose fouling layer when the roughness is 50 μm. This underscores that a mere focus on roughness is inadequate for characterizing blade fouling, and a comprehensive evaluation must also incorporate the implications of rough structures on aerodynamic performance. Full article
(This article belongs to the Special Issue Advances in Thermal Fluid, Dynamics and Control)
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20 pages, 7607 KiB  
Article
An Aeroelastic Solution Method Using an Implicit Dynamic Approach
by Weiji Wang, Wei Qian, Zheng Chen and Xinyu Ai
Aerospace 2025, 12(6), 546; https://doi.org/10.3390/aerospace12060546 - 16 Jun 2025
Viewed by 354
Abstract
This paper presents an innovative aeroelastic solution method called the implicit dynamic approach (IDA). The IDA is a novel technique implemented to address the complexities of structural displacement and fluid–structure interactions. At the core of this method lie the Navier–Stokes equations, which are [...] Read more.
This paper presents an innovative aeroelastic solution method called the implicit dynamic approach (IDA). The IDA is a novel technique implemented to address the complexities of structural displacement and fluid–structure interactions. At the core of this method lie the Navier–Stokes equations, which are pivotal for resolving the unsteady aerodynamic forces for studying aeroelasticity. This paper develops a time-step-coupling data-solving interface that bridges the structural dynamic and fluid dynamic domains, ensuring a seamless integration of these two critical aspects of aeroelastic analysis. To substantiate the credibility of the IDA, the aeroelastic responses of a two-dimensional wing and the benchmark supercritical wing (BSCW) are analyzed. The results obtained from these models demonstrate the IDA’s credibility and stability. The IDA proves to be reliable in predicting aeroelastic responses and offers a powerful tool for analyzing aeroelastic problems. Full article
(This article belongs to the Special Issue Aeroelasticity, Volume V)
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26 pages, 1223 KiB  
Article
Genetic Algorithm and Mathematical Modelling for Integrated Schedule Design and Fleet Assignment at a Mega-Hub
by Melis Tan Tacoglu, Mustafa Arslan Ornek and Yigit Kazancoglu
Aerospace 2025, 12(6), 545; https://doi.org/10.3390/aerospace12060545 - 16 Jun 2025
Viewed by 407
Abstract
Airline networks are becoming increasingly complex, particularly at mega-hub airports characterized by high transit volumes. Effective schedule design and fleet assignment are critical for an airline, as they directly influence passenger connectivity and profitability. This study addresses the challenge of introducing a new [...] Read more.
Airline networks are becoming increasingly complex, particularly at mega-hub airports characterized by high transit volumes. Effective schedule design and fleet assignment are critical for an airline, as they directly influence passenger connectivity and profitability. This study addresses the challenge of introducing a new route from a mega-hub to a new destination, while maintaining the existing flight network and leveraging arrivals from spoke airports to ensure connectivity. First, a mixed-integer nonlinear mathematical model was formulated to produce a global optimal solution at a lower time granularity, but it became computationally intractable at higher granularities due to the exponential growth in constraints and variables. Second, a genetic algorithm (GA) was employed to demonstrate scalability and flexibility, delivering near-optimal, high-granularity schedules with significantly reduced computational time. Empirical validation using real-world data from 37 spoke airports revealed that, while the exact model minimized waiting times and maximized profit at lower granularity, the GA provided nearly comparable profit at higher granularity. These findings guide airline managers seeking to optimize passenger connectivity and cost efficiency in competitive global markets. Full article
(This article belongs to the Section Air Traffic and Transportation)
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12 pages, 191 KiB  
Review
Technical Challenges and Ethical, Legal and Social Issues (ELSI) for Asteroid Mining and Planetary Defense
by Evie Kendal, Tony Milligan and Martin Elvis
Aerospace 2025, 12(6), 544; https://doi.org/10.3390/aerospace12060544 - 15 Jun 2025
Viewed by 1219
Abstract
Advances in the field of asteroid dynamics continue to yield new knowledge regarding the behavior and characteristics of asteroids, allowing unprecedented levels of accuracy for predicting trajectories and contributing to impact avoidance strategies. Meanwhile, more detailed information regarding the physical composition of asteroids [...] Read more.
Advances in the field of asteroid dynamics continue to yield new knowledge regarding the behavior and characteristics of asteroids, allowing unprecedented levels of accuracy for predicting trajectories and contributing to impact avoidance strategies. Meanwhile, more detailed information regarding the physical composition of asteroids has reignited interest in asteroid mining as a potential new resource sector. This article considers some of the technical, ethical, legal and social issues facing global planetary defense efforts and off-world mining proposals. It considers issues such as claim jumping, weaponization of the space environment and ownership issues for resources extracted from space. Full article
(This article belongs to the Special Issue Advances in Asteroid Dynamics)
24 pages, 2868 KiB  
Article
Intelligent 5G-Aided UAV Positioning in High-Density Environments Using Neural Networks for NLOS Mitigation
by Morad Mousa and Saba Al-Rubaye
Aerospace 2025, 12(6), 543; https://doi.org/10.3390/aerospace12060543 - 15 Jun 2025
Viewed by 419
Abstract
The accurate and reliable positioning of unmanned aerial vehicles (UAVs) in urban environments is crucial for urban air mobility (UAM) application, such as logistics, surveillance, and disaster management. However, global navigation satellite systems (GNSSs) often fail in densely populated areas due to signal [...] Read more.
The accurate and reliable positioning of unmanned aerial vehicles (UAVs) in urban environments is crucial for urban air mobility (UAM) application, such as logistics, surveillance, and disaster management. However, global navigation satellite systems (GNSSs) often fail in densely populated areas due to signal reflections (multipath propagation) and obstructions non-line-of-sight (NLOS), causing significant positioning errors. To address this, we propose a machine learning (ML) framework that integrates 5G position reference signals (PRSs) to correct UAV position estimates. A dataset was generated using MATLAB’s UAV simulation environment, including estimated coordinates derived from 5G time of arrival (TOA) measurements and corresponding actual positions (ground truth). This dataset was used to train a fully connected feedforward neural network (FNN), which improves the positioning accuracy by learning patterns between predicted and actual coordinates. The model achieved significant accuracy improvements, with a mean absolute error (MAE) of 1.3 m in line-of-sight (LOS) conditions and 1.7 m in NLOS conditions, and a root mean squared error (RMSE) of approximately 2.3 m. The proposed framework enables real-time correction capabilities for dynamic UAV tracking systems, highlighting the potential of combining 5G positioning data with deep learning to enhance UAV navigation in urban settings. This study addresses the limitations of traditional GNSS-based methods in dense urban environments and offers a robust solution for future UAV advancements. Full article
(This article belongs to the Special Issue Advances in UAV Technology: Dynamics, Guidance, Navigation, and Control of Transformative Aerial Vehicles)
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23 pages, 5424 KiB  
Article
Interactive Maintenance of Space Station Devices Using Scene Semantic Segmentation
by Haoting Liu, Chuanxin Liao, Xikang Li, Zhen Tian, Mengmeng Wang, Haiguang Li, Xiaofei Lu, Zhenhui Guo and Qing Li
Aerospace 2025, 12(6), 542; https://doi.org/10.3390/aerospace12060542 - 15 Jun 2025
Viewed by 312
Abstract
A novel interactive maintenance method for space station in-orbit devices using scene semantic segmentation technology is proposed. First, a wearable and handheld system is designed to capture images from the astronaut in the space station’s front view scene and play these images on [...] Read more.
A novel interactive maintenance method for space station in-orbit devices using scene semantic segmentation technology is proposed. First, a wearable and handheld system is designed to capture images from the astronaut in the space station’s front view scene and play these images on a handheld terminal in real-time. Second, the proposed system quantitatively evaluates the environmental lighting condition in the scene by calculating image quality evaluation parameters. If the lighting condition is not proper, a prompt message will be given to the astronaut to remind him or her to adjust the environment illumination. Third, our system adopts an improved DeepLabV3+ network for semantic segmentation of these astronauts’ forward view scene images. Regarding the improved network, the original backbone network is replaced with a lightweight convolutional neural network, i.e., the MobileNetV2, with a smaller model scale and computational complexity. The convolutional block attention module (CBAM) is introduced to improve the network’s feature perception ability. The atrous spatial pyramid pooling (ASPP) module is also considered to enable an accurate calculation of encoding multi-scale information. Extensive simulation experiment results indicate that the accuracy, precision, and average intersection over the union of the proposed algorithm can be better than 95.0%, 96.0%, and 89.0%, respectively. And the ground application experiments have also shown that our proposed technique can effectively shorten the working time of the system user. Full article
(This article belongs to the Section Astronautics & Space Science)
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25 pages, 9825 KiB  
Article
Noise Reduction Mechanism and Spectral Scaling of Slat Gap Filler Device at Low Angle of Attack
by Yingzhe Zhang, Peiqing Liu and Baohong Bai
Aerospace 2025, 12(6), 541; https://doi.org/10.3390/aerospace12060541 - 15 Jun 2025
Viewed by 398
Abstract
Slat noise poses a significant challenge during aircraft landing. Slat gap filler (SGF) technology has shown promise in mitigating slat noise, yet its noise reduction mechanisms and characteristics remain unclear. This study numerically investigates the noise reduction mechanisms of SGF and analyzes its [...] Read more.
Slat noise poses a significant challenge during aircraft landing. Slat gap filler (SGF) technology has shown promise in mitigating slat noise, yet its noise reduction mechanisms and characteristics remain unclear. This study numerically investigates the noise reduction mechanisms of SGF and analyzes its noise characteristics using the high-lift common research model (CRM-HL). The lattice Boltzmann solver simulates the unsteady flow field, and the Ffowcs-Williams and Hawkings (FW-H) equation predicts far-field noise. The computed results exhibit a satisfactory concordance with experimental measurements. Furthermore, the near-field flow dynamics have been elucidated through proper orthogonal decomposition. The findings demonstrate that the SGF alters the distribution patterns of flow dynamics and pressure fluctuations, thereby effectively attenuating the mode energy. Moreover, our findings demonstrate that SGF significantly reduces slat noise. The noise reduction mechanism can be attributed to decreased surface pressure fluctuations on the leading edge of the main wing, and a shifted broadband noise peak to a lower frequency due to the enlarged slat cove flow vortex caused by SGF. Finally, a scaling analysis of the slat noise spectra indicates that the SGF noise spectra align well with baseline slat noise spectra when the characteristic length scale is determined by the vortex structure. Full article
(This article belongs to the Special Issue New Developments in Aeroacoustics Research: From Fundamentals to Applications)
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20 pages, 1803 KiB  
Article
Prediction of the Drogue Position in Autonomous Aerial Refueling Based on a Physics-Informed Neural Network
by Xin Bao, Yan Li and Zhong Wang
Aerospace 2025, 12(6), 540; https://doi.org/10.3390/aerospace12060540 - 14 Jun 2025
Viewed by 256
Abstract
Autonomous aerial refueling (AAR) technology is of crucial importance in the aviation field. Accurately predicting the position of the refueling drogue is a core challenge in implementing this technology. An innovative method of a physics-informed neural network (PINN), a fusion of supervised learning [...] Read more.
Autonomous aerial refueling (AAR) technology is of crucial importance in the aviation field. Accurately predicting the position of the refueling drogue is a core challenge in implementing this technology. An innovative method of a physics-informed neural network (PINN), a fusion of supervised learning and unsupervised learning, integrating physical information with an attention-augmented long short-term memory (AALSTM) neural network is proposed. By constructing a physical model of the refueling drogue, accurate physical constraints are provided for the prediction model. Meanwhile, an AALSTM neural network architecture is designed to predict partial states of the refueling drogue and parameters of the dynamic model. An attention-augmented mechanism is introduced to enhance the ability to capture key information. Simulation experiments verify that introducing an attention-augmented mechanism based on the conventional LSTM can improve prediction accuracy. The PINN significantly outperforms the conventional LSTM method in prediction accuracy, providing strong support for the development of AAR technology. Full article
(This article belongs to the Special Issue New Sights of Intelligent Robust Control in Aerospace)
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32 pages, 4695 KiB  
Article
Entry Guidance for Hypersonic Glide Vehicles via Two-Phase hp-Adaptive Sequential Convex Programming
by Xu Liu, Xiang Li, Houjun Zhang, Hao Huang and Yonghui Wu
Aerospace 2025, 12(6), 539; https://doi.org/10.3390/aerospace12060539 - 14 Jun 2025
Viewed by 714
Abstract
This paper addresses the real-time trajectory generation problem for hypersonic glide vehicles (HGVs) during atmospheric entry, subject to complex constraints including aerothermal limits, actuator bounds, and no-fly zones (NFZs). To achieve efficient and reliable trajectory planning, a two-phase hp-adaptive sequential convex programming (SCP) [...] Read more.
This paper addresses the real-time trajectory generation problem for hypersonic glide vehicles (HGVs) during atmospheric entry, subject to complex constraints including aerothermal limits, actuator bounds, and no-fly zones (NFZs). To achieve efficient and reliable trajectory planning, a two-phase hp-adaptive sequential convex programming (SCP) framework is proposed. NFZ avoidance is reformulated as a soft objective to enhance feasibility under tight geometric constraints. In Phase I, a shrinking-trust-region strategy progressively tightens the soft trust-region radius by increasing the penalty weight, effectively suppressing linearization errors. A sensitivity-driven mesh refinement method then allocates collocation points based on their contribution to the objective function. Phase II applies residual-based refinement to reduce discretization errors. The resulting reference trajectory is tracked using a linear quadratic regulator (LQR) within a reference-trajectory-tracking guidance (RTTG) architecture. Simulation results demonstrate that the proposed method achieves convergence in only a few iterations, generating high-fidelity trajectories within 2–3 s. Compared to pseudospectral solvers, the method achieves over 12× computational speed-up while maintaining kilometer-level accuracy. Monte Carlo tests under uncertainties confirm a 100% success rate, with all constraints satisfied. These results validate the proposed method’s robustness, efficiency, and suitability for onboard real-time entry guidance in dynamic mission environments. Full article
(This article belongs to the Section Aeronautics)
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25 pages, 7850 KiB  
Article
A Novel Curve-and-Surface Fitting-Based Extrapolation Method for Sub-Idle Component Characteristics of Aeroengines
by Yibo Cui, Tianhong Zhang, Zhaohui Cen, Younes Al-Younes and Elias Tsoutsanis
Aerospace 2025, 12(6), 538; https://doi.org/10.3390/aerospace12060538 - 14 Jun 2025
Viewed by 397
Abstract
The component characteristics of an aeroengine below idle speed are fundamental for start-up process simulations. However, due to experimental limitations, these characteristics must be extrapolated from data above idle speed. Existing extrapolation methods often suffer from insufficient utilization of available data, reliance on [...] Read more.
The component characteristics of an aeroengine below idle speed are fundamental for start-up process simulations. However, due to experimental limitations, these characteristics must be extrapolated from data above idle speed. Existing extrapolation methods often suffer from insufficient utilization of available data, reliance on specific prior conditions, and an inability to capture unique operating modes (e.g., the stirring mode and turbine mode of compressor). To address these limitations, this study proposes a novel curve-and-surface fitting-based extrapolation method. The key innovations include: (1) extrapolating sub-idle characteristics through constrained curve/surface fitting of limited above-idle data, preserving their continuous and smooth nature; (2) transforming discontinuous isentropic efficiency into a continuous specific enthalpy change coefficient (SECC), ensuring physically meaningful extrapolation across all operating modes; (3) applying constraints during fitting to guarantee reasonable and smooth extrapolation results. Validation on a micro-turbojet engine demonstrates that the proposed method requires only conventional performance parameters (corrected flow, pressure/expansion ratio, and isentropic efficiency) above idle speed, yet successfully supports ground-starting simulations under varying inlet conditions. The results confirm that the proposed method not only overcomes the limitations of existing approaches but also demonstrates broader applicability in practical aeroengine simulations. Full article
(This article belongs to the Special Issue Numerical Modelling of Aerospace Propulsion)
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19 pages, 3627 KiB  
Article
Numerical Analysis of Pulse Decay Characteristics in Solid Rocket Motors for Different Finocyl Grain Configurations
by Fengnan Guo, Fengrui Li, Hongfeng Ji, Lin Fu and Xuyang Gao
Aerospace 2025, 12(6), 537; https://doi.org/10.3390/aerospace12060537 - 13 Jun 2025
Viewed by 787
Abstract
Combustion instability is an abnormal working state that often occurs in advanced solid rocket motors (SRMs), which can arouse pressure oscillations, increase the risk of mission failure, and even cause structural damage. In this paper, a numerical simulation method is adapted to analyze [...] Read more.
Combustion instability is an abnormal working state that often occurs in advanced solid rocket motors (SRMs), which can arouse pressure oscillations, increase the risk of mission failure, and even cause structural damage. In this paper, a numerical simulation method is adapted to analyze the combustion instability problem of a typical finocyl grain SRM, and the working process and pressure oscillation of different-structure SRMs are compared and analyzed. Firstly, the acoustic finite element analysis (FEA) method and the large eddy simulation (LES) method for SRM combustion instability analysis are given. Then, the numerical simulation method presented in this paper is verified by comparing the present results with the experimental data of Ariane-5 P230 motor, and finally, the pressure oscillation characteristics of SRMs with different structures by external pulse excitation are studied. The simulation results show that the pressure decay rate of the front finocyl grain structure is faster than that of the rear finocyl grain structure under the same external excitation. The excitation position has a relatively minor influence on the decay characteristics of pressure oscillations. The results can provide a certain reference for the combustion stability design of SRMs. Full article
(This article belongs to the Special Issue Combustion of Solid Propellants)
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14 pages, 1615 KiB  
Article
Investigation on the Properties of Phenolic-Resin-Based Functional Gradient Thermal Protection Composite Materials
by Jiangman Li, Weixiong Chen and Jianlong Chang
Aerospace 2025, 12(6), 536; https://doi.org/10.3390/aerospace12060536 - 13 Jun 2025
Cited by 1 | Viewed by 666
Abstract
Crosslinked phenolic resin was prepared using hexamethylenetetramine (HMTA) as a crosslinking agent in hydrochloric acid solution. The ablation-heat-resistant material was prepared by a pressure-assisted RTM (resin transfer molding) process with reinforcing material (quartz fibre 2.5D needle-punched fabric/satin fibre cloth/fibre mesh tire) and matrix [...] Read more.
Crosslinked phenolic resin was prepared using hexamethylenetetramine (HMTA) as a crosslinking agent in hydrochloric acid solution. The ablation-heat-resistant material was prepared by a pressure-assisted RTM (resin transfer molding) process with reinforcing material (quartz fibre 2.5D needle-punched fabric/satin fibre cloth/fibre mesh tire) and matrix (crosslinked phenolic resin). The thermal stability of the cured product was studied by a thermogravimetric analyser (TG and DTG). The mechanical properties, heat resistance, and ablation properties of the composites were tested. The ablation morphology, element analysis, and phase structure of the composites were analysed by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD), respectively. The results show that the phenolic resin has a lower initial viscosity and a longer pot life at 80 °C, and a higher carbon residue rate (70.18%). The tensile strength of the composites is close to 40 MPa, the tensile modulus is higher than 1.35 GPa, the compression modulus is higher than 10 MPa, and the elongation at break is higher than 1.55%. SiO2, SiC, and ZrO2 ceramic phases were formed after ablation, which effectively improved the ablation performance of the composites. Full article
(This article belongs to the Special Issue Thermal Protection System Design of Space Vehicles)
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22 pages, 5403 KiB  
Article
Modeling Microgravity Using Clinorotation in a Microfluidic Environment: A Numerical Approach
by João Fernandes, Dara Machado, Graça Minas, Susana O. Catarino and Diana Pinho
Aerospace 2025, 12(6), 535; https://doi.org/10.3390/aerospace12060535 - 12 Jun 2025
Viewed by 367
Abstract
Microgravity simulation is essential for studying particle dynamics in space-related applications where traditional gravitational effects are absent. This study presents a numerical investigation of particle behavior in a clinostat-driven microfluidic channel, aiming to simulate microgravity conditions. A computational model was developed in COMSOL [...] Read more.
Microgravity simulation is essential for studying particle dynamics in space-related applications where traditional gravitational effects are absent. This study presents a numerical investigation of particle behavior in a clinostat-driven microfluidic channel, aiming to simulate microgravity conditions. A computational model was developed in COMSOL Multiphysics to analyze the impact of channel size, particle diameter, and rotational speed on particle trajectories and establish sets of parameters for assuring microgravity conditions. The results revealed that stable microgravity-like conditions could be achieved within specific parameter ranges, e.g., larger channel radii requiring lower rotational velocities for particle suspension. However, the tendency for gravitational settling increased with particle size or under suboptimal rotational speeds. These findings provide insights into the effectiveness of clinorotation as a microgravity simulation method and establish a foundation for optimizing experimental designs in space research and biomedical applications. Full article
(This article belongs to the Section Astronautics & Space Science)
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19 pages, 8614 KiB  
Article
Shell-Stripping Mechanism of Red Sandstone Under Hypervelocity Impact with Aluminum Spheres
by Yizhe Liu, Quanyu Jiang, Zishang Liu, Minqiang Jiang, Yadong Li, Zhenghua Chang, Kun Zhang and Bingchen Wei
Aerospace 2025, 12(6), 534; https://doi.org/10.3390/aerospace12060534 - 12 Jun 2025
Viewed by 306
Abstract
To investigate the size effect on fragmentation phenomena during hypervelocity impact, scaled experiments were conducted using a 30 mm smooth-bore ballistic range (DBR30) driven by a detonation-driven two-stage launching system. Unique stripping of sandstone target was observed, revealing that free-surface unloading waves govern [...] Read more.
To investigate the size effect on fragmentation phenomena during hypervelocity impact, scaled experiments were conducted using a 30 mm smooth-bore ballistic range (DBR30) driven by a detonation-driven two-stage launching system. Unique stripping of sandstone target was observed, revealing that free-surface unloading waves govern peak pressure attenuation and fragmentation patterns. By establishing a shock wave attenuation model, the typical failure characteristics of different regions were distinguished, including jetting, crushing, and cracking. Parameter λ was defined to distinguish two forms of destruction, Class I (stripping-dominated) and Class II (cratering-dominated). Given the significant difference between the compressive and tensile strength of sandstone, the influence of the size effect on its failure characteristics was notable. This research also provides a valuable reference for understanding the evolution and formation mechanisms of binary asteroids. Full article
(This article belongs to the Special Issue Asteroid Impact Avoidance)
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