Journal Description
Aerospace
Aerospace
is a peer-reviewed, open access journal of aeronautics and astronautics published monthly online by MDPI. The European Aeronautics Science Network (EASN), and the ECATS International Association are affiliated with Aerospace and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, and other databases.
- Journal Rank: JCR - Q1 (Engineering, Aerospace) / CiteScore - Q2 (Aerospace Engineering)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 22.3 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journal: Astronomy.
Impact Factor:
2.6 (2022);
5-Year Impact Factor:
2.6 (2022)
Latest Articles
Negative Medium-Voltage Direct Current Discharges in Air under Simulated Sub-Atmospheric Pressures for All-Electric Aircraft
Aerospace 2024, 11(6), 444; https://doi.org/10.3390/aerospace11060444 (registering DOI) - 30 May 2024
Abstract
The increase in the global temperature due to greenhouse gas emissions is a major concern to the world. To achieve the goal of zero emissions by 2050 in the USA the practical realization of all-electric vehicles, particularly all-electric aircraft (AEA), is important. For
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The increase in the global temperature due to greenhouse gas emissions is a major concern to the world. To achieve the goal of zero emissions by 2050 in the USA the practical realization of all-electric vehicles, particularly all-electric aircraft (AEA), is important. For the design of electrical power systems (EPSs) in all-electric aircraft, a bipolar medium-voltage direct current (MVDC) system of ±5 kV is being investigated. However, several challenges manifest when using such voltages in a low-pressure environment. One of the main challenges is the partial discharge (PD) behavior of the insulation. It is important to study the PD behavior of the insulation by simulating the aviation environment in the lab. This work aimed to study the partial discharge behavior of air under a negative DC voltage in a needle-to-plane electrode geometry by simulating the aviation pressures in the lab. The partial discharge inception voltage (PDIV) and the breakdown voltage (BDV) show an obvious pressure-dependent variation. Regression analysis was performed to better understand the relationship between the PDIV and pressures. Plots were drawn for the average discharge current at each voltage step until breakdown. This paper’s findings can provide valuable insight into the design of EPS for an AEA. To the best of our knowledge, such a study has not been carried out to date.
Full article
(This article belongs to the Special Issue Electric Power Systems and Components for All-Electric Aircraft)
Open AccessArticle
Orbital Pursuit–Evasion–Defense Linear-Quadratic Differential Game
by
Zhen-Yu Li
Aerospace 2024, 11(6), 443; https://doi.org/10.3390/aerospace11060443 - 30 May 2024
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To find superior guidance strategies for preventing possible interception threats from space debris, out-of-control satellites, etc., this paper investigates an orbital pursuit–evasion–defense game problem with three players called the pursuer, the evader, and the defender, respectively. In this game, the pursuer aims to
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To find superior guidance strategies for preventing possible interception threats from space debris, out-of-control satellites, etc., this paper investigates an orbital pursuit–evasion–defense game problem with three players called the pursuer, the evader, and the defender, respectively. In this game, the pursuer aims to intercept the evader, while the evader tries to escape the pursuer. A defender accompanying the evader can protect the evader by actively intercepting the pursuer. For such a game, a linear-quadratic duration-adaptive (LQDA) strategy is first proposed as a basic strategy for the three players. Later, an advanced pursuit strategy is designed for the pursuer to evade the defender when they are chasing the evader. Meanwhile, a cooperative evasion–defense strategy is proposed for the evader and the defender to build their cooperation. Simulations determined that the proposed LQDA strategy has higher interception accuracy than the classic LQ strategy. Meanwhile, the proposed two-sided pursuit strategy can improve the interception performance of the pursuer against a non-cooperative defender. But if the evader and defender employ the proposed cooperation strategy, the pursuer’s interception will be much more difficult.
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Open AccessArticle
Activity Modeling and Characterization for Airport Bird Situation Awareness Using Avian Radar Datasets
by
Jia Liu, Qunyu Xu, Min Su and Weishi Chen
Aerospace 2024, 11(6), 442; https://doi.org/10.3390/aerospace11060442 - 30 May 2024
Abstract
Birds in airport airspaces are critical threats to aviation safety. Avian radar systems are effective for long-range bird monitoring and hazard warning, but their functionalities are confined to a short-term temporal scale. Spatial–temporal activity modeling and characterization for birds are not studied comprehensively
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Birds in airport airspaces are critical threats to aviation safety. Avian radar systems are effective for long-range bird monitoring and hazard warning, but their functionalities are confined to a short-term temporal scale. Spatial–temporal activity modeling and characterization for birds are not studied comprehensively from historical radar datasets. This paper proposes a radar data analysis framework to characterize bird activities as a long-term functionality complement. Spatial domain modeling initializes data mining by extracting reference spots for data filtering. Bird activities are quantified in the temporal domain. Activity degrees are utilized for periodicity extraction with the daily segment random permutation strategy. Categorical probabilities are calculated to interpret bird activity periodicity characters. Historical radar datasets collected from an avian radar system are adopted for validation. The extracted activity periodicity trends for diurnal birds present prominent consistency with artificial observation records. Migratory bird periodicity trends present a good match with ornithology understandings. A preliminary experiment is presented to indicate the possibility of predicting bird activity levels, especially for migratory birds.
Full article
(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management (2nd Edition))
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Exploring the Psychological Well-Being of Flight Cadets through a Comprehensive Survey Analysis of Self-Awareness and Self-Acceptance
by
Dan Miao, Xiaodong Cao, Bingxu Zhao, Yuan Shi and Yunze Shi
Aerospace 2024, 11(6), 441; https://doi.org/10.3390/aerospace11060441 - 30 May 2024
Abstract
A robust level of self-awareness and self-acceptance is crucial for flight cadets. In this study, a total of 106 flight cadets from various grades and flight training sites were assessed using the self-awareness and self-acceptance scale. The scales were optimized through item analysis,
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A robust level of self-awareness and self-acceptance is crucial for flight cadets. In this study, a total of 106 flight cadets from various grades and flight training sites were assessed using the self-awareness and self-acceptance scale. The scales were optimized through item analysis, reliability, and validity assessments. The finalized scales demonstrated an acceptable level of reliability and validity. Upon analyzing the collected data, it was observed that the overall self-awareness and -acceptance levels among the evaluated pilot students fell within the normal range. However, identifying positive symptoms directly proved challenging. The tested flight cadets exhibited moderate symptoms across each factor, with instances of severe symptoms in academic self-awareness. Notably, flight cadets trained abroad exhibited a lower level of self-awareness and -acceptance compared to those trained in China. But this phenomenon was not reflected in grade difference. Regression analysis revealed that physical and emotional self-awareness dimensions accounted for 62% of the variations in the psychological dimension, while passive self-acceptance explained 72% of the changes in active self-acceptance. Finally, in view of the issues found in the research, corresponding management measures and recommendations are presented to enhance the self-awareness and -acceptance levels of flight cadets.
Full article
(This article belongs to the Special Issue Aerospace Human–Machine and Environmental Control Engineering)
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Modeling and Analysis of the Flap Actuation System Considering the Nonlinear Factors of EMA, Joint Clearance and Flexibility
by
Qi Wan, Chunyu Song, Yong Zhou, Ruiting Tong, Shangjun Ma and Geng Liu
Aerospace 2024, 11(6), 440; https://doi.org/10.3390/aerospace11060440 - 29 May 2024
Abstract
The performance of the flap actuation system directly affects the control effect and the flight quality of an aircraft. The electromechanical actuator (EMA) and the linkage mechanism are important components of the system. In order to achieve the goals of good transmission accuracy
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The performance of the flap actuation system directly affects the control effect and the flight quality of an aircraft. The electromechanical actuator (EMA) and the linkage mechanism are important components of the system. In order to achieve the goals of good transmission accuracy and dynamic response, the influence of nonlinear properties in the transmission chain including the EMA and linkage mechanism should be considered. A co-simulation model at the system-level of the flap actuation system was developed, which takes nonlinear factors of the EMA, the impact dynamics of the linkage mechanism with joint clearance and the rigid–flexible coupling characteristics into account. Moreover, the experiments with different command frequencies and loads were performed. The simulation and experimental results were compared to verify the effectiveness of the co-simulation model. Finally, the effects of nonlinear properties including the contact stiffness and clearance of a planetary roller screw mechanism, EMA anchorage stiffness, number of clearance joints, flexibility and load are discussed. This work can contribute to analyzing the performance of an electromechanical multibody system with nonlinear characteristics, which has crucial academic meaning and engineering application values for the development of systems with high speed, good reliability and long life.
Full article
(This article belongs to the Section Aeronautics)
Open AccessArticle
Instrument to Study Plume Surface Interactions (PSI) on the Lunar Surface: Science Motivation, Requirements, Instrument Overview, and Test Plans
by
Ariana Bueno, Michael J. Krasowski, Norman Prokop, Lawrence C. Greer, Christina M. Adams and Nilton O. Rennó
Aerospace 2024, 11(6), 439; https://doi.org/10.3390/aerospace11060439 - 29 May 2024
Abstract
Safe landings are imperative to accomplish NASA’s Artemis goal to enable human exploration on the Moon, including sample collection missions. However, a process known as plume surface interaction (PSI) presents a significant hazard to lunar landings. PSI occurs when the engine exhaust of
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Safe landings are imperative to accomplish NASA’s Artemis goal to enable human exploration on the Moon, including sample collection missions. However, a process known as plume surface interaction (PSI) presents a significant hazard to lunar landings. PSI occurs when the engine exhaust of a lander interacts with the surface ejecting large amounts of regolith particles at high velocities that can interfere with the landing, disturb the surface, and damage hardware. To better understand PSI, the particle impact event (PIE) sensor is being developed to measure the kinetic energy and the flux of ejecta during landings, to quantify the potential damage, and to quantify the ejecta displaced. Multiple parameters were estimated to define the PIE instrument requirements. These estimates demonstrate that ejecta can travel at velocities of up to 800 m/s and impact the surrounding area with energies of up to 400 µJ. A significant amount of ejecta can be deposited several 10 s of meters away from the landing site, modifying the surface and causing dust-related challenges. The PIE sensor will be launched for the first time in an upcoming lunar lander. Then, PIE measurements will be used to improve PSI prediction capabilities and develop mitigation strategies to ensure safe landings.
Full article
(This article belongs to the Special Issue Spacecraft Sample Collection)
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Open AccessArticle
Experimental Investigation of Lithium-Ion Batteries Thermal Runaway Propagation Consequences under Different Triggering Modes
by
Juan Yang, Wenhao Liu, Haoyu Zhao and Qingsong Zhang
Aerospace 2024, 11(6), 438; https://doi.org/10.3390/aerospace11060438 - 29 May 2024
Abstract
In the stage of aircraft development and airworthiness verification, it is necessary to master the influence of lithium-ion battery (LIB) thermal runaway (TR) propagation. In this paper, the battery TR propagation behavior under different trigger positions and modes is studied experimentally, and the
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In the stage of aircraft development and airworthiness verification, it is necessary to master the influence of lithium-ion battery (LIB) thermal runaway (TR) propagation. In this paper, the battery TR propagation behavior under different trigger positions and modes is studied experimentally, and the calculation and comparison are carried out from the parameters of real-time temperature, voltage, propagation speed, total energy released, and solid ejecta. When the two adjacent cells at the top corner, side, and center of the module are overheated, TR occurs at about 1000 s for the triggered cells, while the whole-overheating trigger mode takes a longer time. The latter’s transmission speed is extremely fast, spreading 2.67 cells per second on average. The heat generated by the solid ejecta of the whole-overheating trigger mode is 82,437 J, which is more destructive. The voltage of the triggered cell fluctuates abnormally in a precursor manner when the internal active substances in the cell undergo a self-generated thermal reaction. This work can provide a reference for the safety and economical design of system installations and the correct setting of airworthiness verification Method of Compliance (MoC) experiments to verify whether the aircraft can bear and contain the adverse effects caused by LIB TR.
Full article
(This article belongs to the Special Issue Electric Power Systems and Components for All-Electric Aircraft)
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Open AccessArticle
Effects of Different Initial Conditions on Combustion Process of Ammonium Dinitramide-Based Energetic Propellant in Straight Nozzle
by
Luyun Jiang, Chentao Mao, Jianhui Han, Haichao Cui, Baosheng Du, Yongzan Zheng, Jifei Ye and Yanji Hong
Aerospace 2024, 11(6), 437; https://doi.org/10.3390/aerospace11060437 - 28 May 2024
Abstract
As a new type of green propellant, ammonium dinitramide (ADN)-based energetic propellants have wide application value and development potential in the field of space propulsion. This paper delves into the intricate impact of varying initial temperatures, pressures, and propellant component ratios on critical
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As a new type of green propellant, ammonium dinitramide (ADN)-based energetic propellants have wide application value and development potential in the field of space propulsion. This paper delves into the intricate impact of varying initial temperatures, pressures, and propellant component ratios on critical parameters, including temperature, combustion rate, and heat release, in the straight nozzle of an ADN-based propellant. The findings indicate that an elevation in both initial temperature and ADN ratio expedites the thermal decomposition rate of ADN, thereby elevating the average temperature in the nozzle. However, the elevation in initial temperature has a negative effect on the overall rise amplitude of average temperature. Furthermore, the initial pressure setting is crucial in determining whether the oxidation reaction of the fuel CH3OH occurs in ADN propellants. When the initial pressure is greater than 10 atm, CH3OH is completely consumed, and the final average temperature is about 2650 K, which increases by 558.89% compared with that at 1 atm. Our work aims to provide theoretical guidance and practical optimization strategies for enhancing propellant performance and optimizing thruster structure design.
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(This article belongs to the Section Astronautics & Space Science)
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Open AccessArticle
A Simple Method for Identifying the Natural Frequency of a Micro Satellite with a Primary Structure Made of Aluminum Alloy
by
Kei-ichi Okuyama, Keigo Yoshikawa and Chihiro Oue
Aerospace 2024, 11(6), 436; https://doi.org/10.3390/aerospace11060436 - 28 May 2024
Abstract
Micro satellites must survive severe mechanical conditions during their launch phase. Usually, the structural design of a micro satellite is performed using the internal stress analysis and the natural frequency analysis, which are based on a finite element method (FEM). The validity of
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Micro satellites must survive severe mechanical conditions during their launch phase. Usually, the structural design of a micro satellite is performed using the internal stress analysis and the natural frequency analysis, which are based on a finite element method (FEM). The validity of this structural design is evaluated through vibration tests. In an early stage of development, which has a FEM model of a satellite in the process of creation, presumption of the minimum natural frequency of a satellite may be difficult. In this study, a simple method for determining the longitudinal and lateral minimum natural frequencies of micro satellites during the ascent phase was clarified. The structure of the micro satellites used in this research is made of aluminum alloy, and they have a monocoque structure. The Young’s modulus and moment of inertia of area used to calculate the minimum natural frequencies were determined using the area ratio of the monocoque structure to the entire satellite. When the method proposed in this study is used, the calculated values agree with the vibration-tested values within 10%. In particular, in the case of W6U-type satellites, the two agree within a range of approximately 2% in the longitudinal direction and approximately 5% in the lateral direction. In the early stages of a satellite structure design when a FEM cannot be created, the proposed method will work effectively as the method of determining the minimum natural frequency. In order to simplify the process of micro satellites development, this paper describes a practical estimation method of the minimum natural frequency for micro satellites.
Full article
(This article belongs to the Special Issue Deployable Space Structures and Mechanisms)
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Reliability-Based Topology Optimization with a Proportional Topology for Reliability
by
Noppawit Kumkam and Suwin Sleesongsom
Aerospace 2024, 11(6), 435; https://doi.org/10.3390/aerospace11060435 - 28 May 2024
Abstract
This research proposes an efficient technique for reliability-based topology optimization (RBTO), which deals with uncertainty and employs proportional topology optimization (PTO) to achieve the optimal reliability structure. The recent technique, called proportional topology optimization for reliability (PTOr), uses Latin hypercube sampling (LHS) for
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This research proposes an efficient technique for reliability-based topology optimization (RBTO), which deals with uncertainty and employs proportional topology optimization (PTO) to achieve the optimal reliability structure. The recent technique, called proportional topology optimization for reliability (PTOr), uses Latin hypercube sampling (LHS) for uncertainty quantification. The difficulty of the double-loop nested problem in uncertainty quantification (UQ) with LHS can be alleviated by the power of PTO, enabling RBTO to be performed easily. The rigorous advantage of PTOr is its ability to accomplish topology optimization (TO) without gradient information, making it faster than TO with evolutionary algorithms. Particularly, for reliability-based topology design, evolutionary techniques often fail to achieve satisfactory results compared to gradient-based techniques. Unlike recent PTOr advancement, which enhances the RBTO performance, this achievement was previously unattainable. Test problems, including an aircraft pylon, reveal its performances. Furthermore, the proposed efficient framework facilitates easy integration with other uncertainty quantification techniques, increasing its performance in uncertainty quantification. Lastly, this research provides computer programs for the newcomer studying cutting-edge knowledge in engineering design, including UQ, TO, and RBTO, in a simple manner.
Full article
(This article belongs to the Special Issue Computing Methods for Aerospace Reliability Engineering)
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Multiple-Bird-Strike Probability Model and Dynamic Response of Engine Fan Blades
by
Siqi Wang, Jinhui Li, Haidong Lin, Zhenhong Deng, Baoqiang Zhang and Huageng Luo
Aerospace 2024, 11(6), 434; https://doi.org/10.3390/aerospace11060434 - 28 May 2024
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Bird strikes pose one of the most significant threats to aviation safety, often leading to substantial loss of life and economic damage. Many bird strike incidents involve multiple birds. However, in previous bird strike studies, the problem of multiple bird strikes has often
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Bird strikes pose one of the most significant threats to aviation safety, often leading to substantial loss of life and economic damage. Many bird strike incidents involve multiple birds. However, in previous bird strike studies, the problem of multiple bird strikes has often been neglected. In this paper, the bird slicing process of a rotating engine fan is examined, and a probability model is introduced to assess the risk of multiple impacts on the fan blades. In addition, this paper utilized an implicit–explicit calculation method. The parameters of blade root stress, tip displacement, plastic deformation, and energy were selected to investigate the effects of the time interval and strike position of a bird strike on the dynamic response of and damage to the blades. The results indicated that the position of bird strikes has a more pronounced effect on blade damage compared to the time interval between impacts. Damage to a blade is most severe when the blade root is struck multiple times. Multiple bird strikes may not always lead to a significant increase in maximum blade tip displacement, and may even have a dampening effect.
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Open AccessArticle
Effects of Different Structural Film Cooling on Cooling Performance in a GO2/GH2 Subscale Thrust Chamber
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Jixin Xiang, Yujie Jia, Zhiqiang Li and He Ren
Aerospace 2024, 11(6), 433; https://doi.org/10.3390/aerospace11060433 - 27 May 2024
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To investigate the wall cooling of the thrust chamber in an engine, two film-cooling structures, namely, a circular hole structure and a slot structure, were designed. Numerical simulations were performed to study the coupled flow and regenerative cooling heat transfer in thrust chambers
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To investigate the wall cooling of the thrust chamber in an engine, two film-cooling structures, namely, a circular hole structure and a slot structure, were designed. Numerical simulations were performed to study the coupled flow and regenerative cooling heat transfer in thrust chambers with different structures. The influences of parameters such as the film mass flow rate and film hole size on wall cooling were analyzed. Experiments were conducted in a thrust chamber to validate the accuracy of the numerical calculation method. The results indicate that the slot-structured film adheres better to the wall than the circular-hole-structured film, and the film closely adhering to the wall provides better insulation against hot gas, resulting in a reduction of approximately 6% in wall temperature. When the film hole size changes, the change in circumferential wall temperature in the upstream region of the slot-structured film is more pronounced. This paper aims to provide a reference for the design of the cooling structure at the head of the thrust chamber in engineering and suggests directions for optimization and improvement.
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Open AccessArticle
Cyclic Ablation Properties of C/SiC-ZrC Composites
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Hailang Ge, Lu Zhang, Huajun Zhang, Fang Wang, Xiguang Gao and Yingdong Song
Aerospace 2024, 11(6), 432; https://doi.org/10.3390/aerospace11060432 - 27 May 2024
Abstract
To reveal the ablation performance of C/SiC-ZrC composites under different ablation modes, C/SiC-ZrC composites were prepared using chemical vapor deposition, precursor infiltration, and pyrolysis. Single ablation and cyclic ablation tests were conducted on the C/SiC-ZrC composites using an oxyacetylene flame, in order to
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To reveal the ablation performance of C/SiC-ZrC composites under different ablation modes, C/SiC-ZrC composites were prepared using chemical vapor deposition, precursor infiltration, and pyrolysis. Single ablation and cyclic ablation tests were conducted on the C/SiC-ZrC composites using an oxyacetylene flame, in order to obtain ablation parameters, as well as macroscopic and microscopic ablation morphology for the different ablation modes. The results show that the linear ablation rate and mass ablation rate of different ablation modes decrease with increasing time. The linear ablation rate and mass ablation rate of cyclic ablation are 12% and 24.2% lower than those of single ablation. Within the same ablation time, the C/SiC-ZrC composites subjected to cyclic ablation exhibit shallower and more evenly distributed pits, caused by high-temperature airflow ablation. The material surface has a white oxide layer composed of SiO2 and ZrO2, and the carbon fibers inside are wrapped by oxide particles, enhancing the ablation resistance of C/SiC-ZrC composites.
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(This article belongs to the Special Issue Current Trend of High Temperature and Pressure Materials in Hypersonic Vehicles)
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Numerical Simulation and Experimental Study on the Aerodynamics of Propulsive Wing for a Novel Electric Vertical Take-Off and Landing Aircraft
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Junjie Wang, Xinfeng Zhang, Jiaxin Lu and Zhengfei Tang
Aerospace 2024, 11(6), 431; https://doi.org/10.3390/aerospace11060431 - 27 May 2024
Abstract
The electric vertical take-off and landing (eVTOL) aircraft offers the advantages of vertical take-off and landing, environmental cleanliness, and automated control, making it a crucial component of future urban air traffic. As competition intensifies, demands for aircraft performance are escalating, including forward flight
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The electric vertical take-off and landing (eVTOL) aircraft offers the advantages of vertical take-off and landing, environmental cleanliness, and automated control, making it a crucial component of future urban air traffic. As competition intensifies, demands for aircraft performance are escalating, including forward flight speed and payload capacity. The article presents a novel eVTOL design with propulsive wings and establishes methodologies for propulsive wing unsteady numerical simulation and wind tunnel experiments, analyzing its aerodynamic characteristics and lift enhancement mechanism. The results indicate that the cross-flow fan (CFF) provides unique airflow control capabilities, enabling the propulsive wing to achieve remarkably high lift coefficients (exceeding 7.6 in experiments) and propulsion coefficients (exceeding 7.1 in experiments) at extreme angles of attack (30°~40°) and low airspeeds. On the one hand, the CFF effectively controls boundary layer flow, delaying airflow separation at high angles of attack; on the other hand, the rotation of the CFF induces two eccentric vortices, generating vortex-induced lift and propulsion. The aerodynamic performance of the propulsive wing depends on the advance ratio and angle of attack. Typically, both lift and propulsion coefficients increase with the advance ratio, while lift and drag coefficients increase with the angle of attack. The propulsive wing shows significant advantages and prospects for eVTOL aircrafts in the low flight velocity range (0–30 m/s).
Full article
(This article belongs to the Special Issue E-VTOL Simulation and Autonomous System Development)
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Anti-Icing System Performance Prediction Using POD and PSO-BP Neural Networks
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Handong Mao, Xiaodan Lin, Zhimao Li, Xiaobin Shen and Wenzhao Zhao
Aerospace 2024, 11(6), 430; https://doi.org/10.3390/aerospace11060430 - 26 May 2024
Abstract
The anti-icing system is important for ice protection and flight safety. Rapid prediction of the anti-icing system’s performance is critical to reducing the design time and increasing efficiency. The paper proposes a method to quickly predict the anti-icing performance of the hot air
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The anti-icing system is important for ice protection and flight safety. Rapid prediction of the anti-icing system’s performance is critical to reducing the design time and increasing efficiency. The paper proposes a method to quickly predict the anti-icing performance of the hot air anti-icing system. The method is based on Proper Orthogonal Decomposition (POD) and Back Propagation (BP) neural networks improved with the Particle Swarm Optimization (PSO) algorithm to construct the PSO-BP neural network. POD is utilized for data compression and feature extraction for the skin temperature and runback water obtained by numerical calculation. A lower-dimensional approximation is derived from the projection subspace, which consists of a set of basis modes. The PSO-BP neural network establishes the mapping relationship between the flight condition parameters (including flight height, atmospheric temperature, flight speed, median volume diameter, and liquid water content) and the characteristic coefficients. The results show that the average absolute errors of prediction with the PSO-BP neural network model on skin temperature and runback water thickness are 3.87 K and 0.93 μm, respectively. The method can provide an effective tool for iteratively optimizing hot air anti-icing system design.
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Open AccessArticle
Gaze Movements of Helicopter Pilots during Real and Simulated Take-Off and Landing Maneuvers
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Daniel H. Greiwe and Maik Friedrich
Aerospace 2024, 11(6), 429; https://doi.org/10.3390/aerospace11060429 - 24 May 2024
Abstract
Most accidents and serious incidents of commercial air transport helicopters occur during standard flight phases, whereby a main cause is pilots’ situational awareness. Enabling pilots to better assess their situational awareness can make an important contribution in reducing the risk of fatal accidents.
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Most accidents and serious incidents of commercial air transport helicopters occur during standard flight phases, whereby a main cause is pilots’ situational awareness. Enabling pilots to better assess their situational awareness can make an important contribution in reducing the risk of fatal accidents. One approach is to examine a pilot’s gaze behavior with the help of eye tracking. This paper reports the results of a case study with eye tracking measurements during real flight and simulator studies of a standard mission profile. The general gaze behavior is characterized by a dominant, external view, and the airspeed and altitude indicator as the most important flight instruments. A real-world applicability of gaze data obtained in the simulator could be shown.
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(This article belongs to the Special Issue Vertical Lift: Rotary- and Flapping-Wing Flight)
Open AccessArticle
Tailoring 3D Star-Shaped Auxetic Structures for Enhanced Mechanical Performance
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Yulong Wang, Naser A. Alsaleh, Joy Djuansjah, Hany Hassanin, Mahmoud Ahmed El-Sayed and Khamis Essa
Aerospace 2024, 11(6), 428; https://doi.org/10.3390/aerospace11060428 - 24 May 2024
Abstract
Auxetic lattice structures are three-dimensionally designed intricately repeating units with multifunctionality in three-dimensional space, especially with the emergence of additive manufacturing (AM) technologies. In aerospace applications, these structures have potential for use in high-performance lightweight components, contributing to enhanced efficiency. This paper investigates
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Auxetic lattice structures are three-dimensionally designed intricately repeating units with multifunctionality in three-dimensional space, especially with the emergence of additive manufacturing (AM) technologies. In aerospace applications, these structures have potential for use in high-performance lightweight components, contributing to enhanced efficiency. This paper investigates the design, numerical simulation, manufacturing, and testing of three-dimensional (3D) star-shaped lattice structures with tailored mechanical properties. Finite element analysis (FEA) was employed to examine the effect of a lattice unit’s vertex angle and strut diameter on the lattice structure’s Poisson’s ratio and effective elastic modulus. The strut diameter was altered from 0.2 to 1 mm, while the star-shaped vertex angle was adjusted from 15 to 90 degrees. Laser powder bed fusion (LPBF), an AM technique, was employed to experimentally fabricate 3D star-shaped honeycomb structures made of Ti6Al4V alloy, which were then subjected to compression testing to verify the modelling results. The effective elastic modulus was shown to decrease when increasing the vertex angle or decreasing the strut diameter, while the Poisson’s ratio had a complex behaviour depending on the geometrical characteristics of the structure. By tailoring the unit vertex angle and strut diameter, the printed structures exhibited negative, zero, and positive Poisson’s ratios, making them applicable across a wide range of aerospace components such as impact absorption systems, aircraft wings, fuselage sections, landing gear, and engine mounts. This optimization will support the growing demand for lightweight structures across the aerospace sector.
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Open AccessArticle
Solar Sail Optimal Performance in Heliocentric Nodal Flyby Missions
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Giovanni Mengali, Marco Bassetto and Alessandro A. Quarta
Aerospace 2024, 11(6), 427; https://doi.org/10.3390/aerospace11060427 - 24 May 2024
Abstract
Solar sails are propellantless propulsion systems that extract momentum from solar radiation pressure. They consist of a large ultrathin membrane, typically aluminized, that reflects incident photons from the Sun to generate thrust for space navigation. The purpose of this study is to investigate
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Solar sails are propellantless propulsion systems that extract momentum from solar radiation pressure. They consist of a large ultrathin membrane, typically aluminized, that reflects incident photons from the Sun to generate thrust for space navigation. The purpose of this study is to investigate the optimal performance of a solar sail-based spacecraft in performing two-dimensional heliocentric transfers to inertial points on the ecliptic that lie within an assigned annular region centered in the Sun. Similar to ESA’s Comet Interceptor mission, this type of transfer concept could prove useful for intercepting a potential celestial body, such as a long-period comet, that is passing close to Earth’s orbit. Specifically, it is assumed that the solar sail transfer occurs entirely in the ecliptic plane and, in analogy with recent studies, the flyby points explored are between and from the Sun. The heliocentric dynamics of the solar sail is described using the classical two-body model, assuming the spacecraft starts from Earth orbit (assumed circular), and an ideal force model to express the sail thrust vector. Finally, no constraint is imposed on the arrival velocity at flyby. Numerical simulation results show that solar sails are an attractive option to realize these specific heliocentric transfers.
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(This article belongs to the Special Issue Spacecraft Orbit Transfers)
Open AccessArticle
An Engine Deterioration Model for Predicting Fuel Consumption Impact in a Regional Aircraft
by
Manuel de Jesús Gurrola Arrieta, Ruxandra M. Botez and Axel Lasne
Aerospace 2024, 11(6), 426; https://doi.org/10.3390/aerospace11060426 - 24 May 2024
Abstract
A deterioration cycle model is presented, designed to consider the turbomachinery efficiency losses that are expected during real engine in-service operations. The cycle model was developed using information from practical experience found in the literature to account for both short- and long-term deterioration
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A deterioration cycle model is presented, designed to consider the turbomachinery efficiency losses that are expected during real engine in-service operations. The cycle model was developed using information from practical experience found in the literature to account for both short- and long-term deterioration effects; the former occurring during the first flight cycles, the latter due to regular in-service operation. This paper highlights the importance of analyzing the inter-turbine temperature margin () to track engine deterioration to determine the extent of an in-service engine life. The proposed model was used to assess the and fuel consumption impact in the CRJ-700 regional aircraft (powered by two CF34-8C5B1 engines) for three representative missions: short (0.4 h), average (1.4 h), and long (2.5 h), considering different levels of engine deterioration, from the new engine level up to fully deteriorated. The fuel consumption at the new engine level (zero deterioration) was validated against a real-time engine model embedded in a Level-D flight simulator, the so-called Virtual Research Flight Simulator located at the Laboratory of Applied Research in Active Control, Avionics, and AeroServoElasticity. The errors found in this validation for the trip mission fuel consumption in the short, average, and long missions were −3.6, +0.9, and +0.6%, respectively. The cycle model predictions suggest the for a new engine is 55.2 °C, whereas for a fully deteriorated engine, it is 26.4 °C. Finally, in terms of fuel consumption, the results presented here show that an average CF34-8C5B1 engine shows an increase in the cumulative fuel consumption of 2.25% during its life in service, which translates to a 4.5% impact in aircraft fuel consumption.
Full article
(This article belongs to the Section Aeronautics)
Open AccessArticle
Flutter Characteristics of a Modified Z-Shaped Folding Wing Using a New Non-Intrusive Model
by
Wuchao Qi, Shimiao Wu and Sumei Tian
Aerospace 2024, 11(6), 425; https://doi.org/10.3390/aerospace11060425 - 24 May 2024
Abstract
Unmanned aerial vehicles (UAVs) with folding wings can serve in multiple mission profiles, usually accompanied by sudden changes in flight speed. These bring great challenges to the aeroelastic design of UAVs, especially in the calculation of flutter characteristics. This paper developed a new
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Unmanned aerial vehicles (UAVs) with folding wings can serve in multiple mission profiles, usually accompanied by sudden changes in flight speed. These bring great challenges to the aeroelastic design of UAVs, especially in the calculation of flutter characteristics. This paper developed a new non-intrusive aeroelastic model to quickly calculate the flutter characteristics of Z-shaped folding wings at different folding angles. First, the original Z-shaped folding wing was designed to be enhanced. Beams and ribs were arranged inside each wing segment to enhance the structural strength performance. Control surfaces were arranged in the middle-wing and outer-wing to enhance the aerodynamic control performance. Second, a parametric aeroelastic model at any folding angle was reconstructed based on the input file of Nastran software for the flutter calculation of the folding wing in the unfolded state. Finally, the effects of parameters such as folding angle, hinge stiffness between different wing segments, and hinge stiffness of the control surfaces on the flutter characteristics of the folding wing were investigated. The results show that the enhancement scheme could significantly increase the flutter speed and flutter frequency of the folding wing. The hinge stiffness between each wing segment had a significant impact on the flutter characteristics of the folding wing, but flutter at the control surface basically did not occur.
Full article
(This article belongs to the Special Issue Active Flutter Suppression and Gust Load Alleviation)
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