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Aerospace
Volume 9
Issue 7
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Aerospace, Volume 9, Issue 7 (July 2022) – 63 articles

Cover Story (view full-size image): Venusian clouds are conjectured to be a possible habitat for life. We propose a mission to explore the clouds of Venus to evaluate their habitability and to search for signs of life. The spacecraft would launch from Earth with an orbiter and a probe carrying an aerobot. A super-pressure balloon would cycle at altitudes between 48 and 60 km using a combination of ballast drop, gas venting, and the thermal effects of the environment. The gondola design is derived from the Pioneer Venus Large Probe pressure vessel. The aerobot would transmit data via orbiter relay combined with a direct-to-Earth link. The proposed mission could help to elucidate the limits of habitability and the role of unknown chemistry or the possibly life itself in the atmosphere of Venus. View this paper
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15 pages, 3129 KiB  
Article
Flight Departure Time Prediction Based on Deep Learning
by Hang Zhou, Weicong Li, Ziqi Jiang, Fanger Cai and Yuting Xue
Aerospace 2022, 9(7), 394; https://doi.org/10.3390/aerospace9070394 - 21 Jul 2022
Cited by 9 | Viewed by 3189
Abstract
Accurate flight departure time prediction enables the rational use of airport support resources, aprons, and runway resources, and promotes the implementation of collaborative decision-making. In order to accurately predict the flight departure time, this paper proposes a deep learning-based flight departure time prediction [...] Read more.
Accurate flight departure time prediction enables the rational use of airport support resources, aprons, and runway resources, and promotes the implementation of collaborative decision-making. In order to accurately predict the flight departure time, this paper proposes a deep learning-based flight departure time prediction model. First, this paper analyzes the influence of different factors on flight departure time and the influencing factor. Secondly, this paper establishes a gated recurrent unit (GRU) model, considers the impact of different hyperparameters on network performance, and determines the optimal hyperparameter combination through parameter tuning. Finally, the model verification and comparative analysis are carried out using the real flight data of ZSNJ. The evaluation values of the established model are as follows: root mean square error (RMSE) value is 0.42, mean absolute percentage error (MAPE) value is 6.07, and mean absolute error (MAE) value is 0.3. Compared with other delay prediction models, the model established in this paper has a 16% reduction in RMSE, 34% reduction in MAPE, and 86% reduction in MAE. The model has high prediction accuracy, which can provide a reliable basis for the implementation of airport scheduling and collaborative decision-making. Full article
(This article belongs to the Section Air Traffic and Transportation)
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29 pages, 2398 KiB  
Article
Layout Analysis and Optimization of Airships with Thrust-Based Stability Augmentation
by Carlo E. D. Riboldi and Alberto Rolando
Aerospace 2022, 9(7), 393; https://doi.org/10.3390/aerospace9070393 - 21 Jul 2022
Cited by 8 | Viewed by 2331
Abstract
Despite offering often significant advantages with respect to other flying machines, especially in terms of flight endurance, airships are typically harder to control. Technological solutions borrowed from the realm of shipbuilding, such as bow thrusters, have been largely experimented with to the extent [...] Read more.
Despite offering often significant advantages with respect to other flying machines, especially in terms of flight endurance, airships are typically harder to control. Technological solutions borrowed from the realm of shipbuilding, such as bow thrusters, have been largely experimented with to the extent of increasing maneuverability. More recently, also thrust vectoring has appeared as an effective solution to ameliorate maneuverability. However, with an increasing interest for high-altitude airships (HAAs) and autonomous flight and the ensuing need to reduce weight and lifting performance, design simplicity is a desirable goal. Besides saving weight, it would reduce complexity and increase time between overhauls, in turn enabling longer missions. In this perspective, an airship layout based on a set of non-tilting thrusters, optimally placed to be employed for both propulsion and attitude control, appears particularly interesting. If sufficiently effective, such configurations would reduce the need for control surfaces on aerodynamic empennages and the corresponding actuators. Clearly, from an airship design perspective, the adoption of many smaller thrusters instead of a few larger ones allows a potentially significant departure from more classical airship layouts. Where on one side attractive, this solution unlocks a number of design variables—for instance, the number of thrusters, as well as their positioning in the general layout, mutual tilt angles, etc.—to be set according simultaneously to propulsion and attitude control goals. In this paper, we explore the effect of a set of configuration parameters defining three-thrusters and four-thrusters layout, trying to capture their impact on an aggregated measure of control performance. To this aim, at first a stability augmentation system (SAS) is designed so as to stabilize the airship making use of thrusters instead of aerodynamic surfaces. Then a non-linear model of the airship is employed to test the airship in a set of virtual simulation scenarios. The analysis is carried out in a parameterized fashion, changing the values of configuration parameters pertaining to the thrusters layout so as to understand their respective effects. In a later stage, the choice of the optimal design values (i.e., the optimal layout) related to the thrusters is demanded to an optimizer. The paper is concluded by showing the results on a complete numerical test case, drawing conclusions on the relevance of certain design parameters on the considered performance, and commenting the features of an optimal configuration. Full article
(This article belongs to the Special Issue Mission Analysis and Design of Lighter-than-Air Flying Vehicles)
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25 pages, 5389 KiB  
Article
Bivariate-Dependent Reliability Estimation Model Based on Inverse Gaussian Processes and Copulas Fusing Multisource Information
by Rentong Chen, Chao Zhang, Shaoping Wang and Li Hong
Aerospace 2022, 9(7), 392; https://doi.org/10.3390/aerospace9070392 - 20 Jul 2022
Cited by 7 | Viewed by 2124
Abstract
Reliability estimation for key components of a mechanical system is of great importance in prognosis and health management in aviation industry. Both degradation data and failure time data contain abundant reliability information from different sources. Considering multiple variable-dependent degradation performance indicators for mechanical [...] Read more.
Reliability estimation for key components of a mechanical system is of great importance in prognosis and health management in aviation industry. Both degradation data and failure time data contain abundant reliability information from different sources. Considering multiple variable-dependent degradation performance indicators for mechanical components is also an effective approach to improve the accuracy of reliability estimation. This study develops a bivariate-dependent reliability estimation model based on inverse Gaussian process and copulas fusing degradation data and failure time data within one computation framework. The inverse Gaussian process model is used to describe the degradation process of each performance indicator. Copula functions are used to capture the dependent relationship between the two performance indicators. In order to improve the reliability estimation accuracy, both degradation data and failure time data are used simultaneously to estimate the unknown parameters in the degradation model based on the likelihood function transformed using the zeros-ones trick. A simulation study and a real application in the reliability estimation of mechanical seal used in airborne hydraulic pump are conducted to validate the effectiveness and accuracy of the proposed model compared with existing reliability models. Full article
(This article belongs to the Section Aeronautics)
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17 pages, 3056 KiB  
Article
An Innovative Pose Determination Algorithm for Planetary Rover Onboard Visual Odometry
by Botian Zhou, Sha Luo and Shijie Zhang
Aerospace 2022, 9(7), 391; https://doi.org/10.3390/aerospace9070391 - 19 Jul 2022
Viewed by 1684
Abstract
Planetary rovers play a critical role in space exploration missions, where one of the most fundamental algorithms is pose determination. Due to environmental and computational constraints, real-time pose determinations of planetary rovers can only use low-cost techniques, such as visual odometry. In this [...] Read more.
Planetary rovers play a critical role in space exploration missions, where one of the most fundamental algorithms is pose determination. Due to environmental and computational constraints, real-time pose determinations of planetary rovers can only use low-cost techniques, such as visual odometry. In this paper, by employing the angle-based criterion, a novel pose determination algorithm is proposed for visual odometry, which is suitable for any type of central camera. First, the problem is formulated using the Huber kernel function with respect to the angular residuals. Then, an intermediate coordinate system is introduced between the initial estimation and final refinement. In order to avoid being trapped in periodic local minimums, a linear method is used to further align the reference points between the intermediate and camera coordinate systems. Finally, one step refinement is implemented to optimize pose determinations. The theoretical analysis, the synthetic simulations, and the real experiments show that our proposed algorithm can achieve the best accuracies within similar processing times, compared with the most state-of-the-art algorithms, thereby approving the effectiveness of the proposed algorithm used in planetary rover onboard visual odometry. Full article
(This article belongs to the Special Issue Recent Advances in Spacecraft Dynamics and Control)
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14 pages, 10980 KiB  
Article
A Queuing Network Model of a Multi-Airport System Based on Point-Wise Stationary Approximation
by Xifan Zhao, Yanjun Wang, Lishuai Li and Daniel Delahaye
Aerospace 2022, 9(7), 390; https://doi.org/10.3390/aerospace9070390 - 19 Jul 2022
Cited by 6 | Viewed by 2582
Abstract
A multiple-airport system (MAS) consists of more than two airports in a metropolitan area under a large block of terminal airspace that is managed by one or two air traffic control units. When the capacity of an airport or of the terminal airspace [...] Read more.
A multiple-airport system (MAS) consists of more than two airports in a metropolitan area under a large block of terminal airspace that is managed by one or two air traffic control units. When the capacity of an airport or of the terminal airspace drops, flight delays occur in the MAS system. A quick estimation and predication of traffic congestion in the MAS is important yet challenging. This paper aims to develop a queuing network model of MAS using point-wise stationary queues. The model analyzes the changes of non-stationary queues under the principle of flow conservation to capture flight delay propagation in the system. Regression analyses are performed to examine the relationship between the arrival and departure efficiencies of different airports. The model is validated with the data of Guangdong–Hong Kong–Macao Greater Bay Area airports. Simulation results show that the model can effectively estimate flight delays in the MAS. Full article
(This article belongs to the Collection Air Transportation—Operations and Management)
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20 pages, 3580 KiB  
Article
Looking into the Crystal Ball—How Automated Fast-Time Simulation Can Support Probabilistic Airport Management Decisions
by Oliver Pohling, Sebastian Schier-Morgenthal and Sandro Lorenz
Aerospace 2022, 9(7), 389; https://doi.org/10.3390/aerospace9070389 - 19 Jul 2022
Viewed by 2298
Abstract
Airport management plays a key role in the air traffic system. Introducing resources at the right time can minimize the effects of disruptions, reduce delays, and save costs as well as optimize the carbon footprint of the airport. Efficient decision-making is a challenge [...] Read more.
Airport management plays a key role in the air traffic system. Introducing resources at the right time can minimize the effects of disruptions, reduce delays, and save costs as well as optimize the carbon footprint of the airport. Efficient decision-making is a challenge due to the uncertainty of the upcoming events and the results of the applied countermeasures. So-called ‘what-if’ systems are under research to support the decision-makers. These systems consist of a user interface, a case management system, and a prediction engine. Within this paper, we evaluate different types of prediction engines (flow, event, and motion models) that can be used for airport management what-if systems by comparing them in terms of accuracy and calculation speed. Hence, two different operational situations are examined to evaluate the performance of the prediction engines. The comparison shows that accuracy and calculation speed are opposed. The flow model has the lowest accuracy but the shortest calculation time and the motion model has the highest accuracy but the longest calculation time. The event model lies between the other two models. The acceptable accuracy of a prediction tool is strongly dependent on the respective airport, whereas the calculation time is strongly dependent on the available decision time. Regarding airport management, this means that the selection of a prediction engine has to be made in dependence of the airport and the decision processes. The results show the advantages and disadvantages of each prediction engine and provide a first quantification by which a selection for what-if systems can happen. Full article
(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management)
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18 pages, 6439 KiB  
Article
Impact Load Identification Algorithm of Helicopter Weapon Pylon Based on Time-Domain Response Signal
by Yadong Gao, Xinyu Yu, Likun Chen and Dawei Huang
Aerospace 2022, 9(7), 388; https://doi.org/10.3390/aerospace9070388 - 18 Jul 2022
Cited by 2 | Viewed by 2018
Abstract
Accurately identifying the peak value of impact load acting on the helicopter structure during weapon launch is of great significance to the design and finalization of weapon pylons. Firstly, a method of standardized preprocessing load signal is proposed by analyzing the vibration response [...] Read more.
Accurately identifying the peak value of impact load acting on the helicopter structure during weapon launch is of great significance to the design and finalization of weapon pylons. Firstly, a method of standardized preprocessing load signal is proposed by analyzing the vibration response and the characteristics of the impact load. Then, the test model of the weapon pylon is designed, and the position of the strain gauge is determined; the static load calibration test and the ground impact test are carried out on the test model. Next, the time-domain response measured by the strain gauge is filtered and de-noised. Impact load is processed by a standardized method. The response and load are used to train BP neural network and the mapping relationship between response and load is established. The impact load generated by a specific weapon is statistically processed to obtain the normalized average load time history, and the identified standard load is converted back to the original load pattern. Finally, the network that meets the error requirements is tested. Both the standardized pattern and the original pattern have high identification accuracy, which shows that an effective load identification model can be established based on the time-domain response signal and the standardized processed load signal. Full article
(This article belongs to the Special Issue Structural Dynamics and Control)
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20 pages, 9401 KiB  
Article
The Overall Design of Variable Diameter Ducted Fan in the Aircraft
by Yadong Gao and Yang Xu
Aerospace 2022, 9(7), 387; https://doi.org/10.3390/aerospace9070387 - 18 Jul 2022
Cited by 5 | Viewed by 3004
Abstract
Variable diameter rotor can improve the flight performance of the aircraft both in hovering and forward flying and a duct can improve the rotor performance further both in force and efficiency. In previous studies, those two parts are always studied in the one-factor-at-a-time [...] Read more.
Variable diameter rotor can improve the flight performance of the aircraft both in hovering and forward flying and a duct can improve the rotor performance further both in force and efficiency. In previous studies, those two parts are always studied in the one-factor-at-a-time method, and the duct is lack diameter change so that it cannot cooperate with the variable diameter rotor. In this paper, the Chinese utility helicopter Z9 is taken as the prototype, and the structural parameters of the variable diameter ducted fan (VDDF) are selected by an orthogonal experiment method. Based on the momentum-element theory, the aerodynamic theoretical model of the disk is established, and the structural parameters that can achieve the best efficiency in hover/propulsion and the best lift/thrust force ratio under different modes are obtained in the orthogonal range by computational fluid dynamics method. The structural parameters of the VDDF under the set working conditions are obtained by a technique for order of preference by similarity to ideal solution (TOPSIS) evaluation and the flight performance of the aircraft equipped with the VDDF is superior to the prototype: The max takeoff weight raises 25%; the hover ceiling raises 90%; the cruise altitude raises 11%; the cruise speed raises 23% and the max speed raises further. However, a better engine may be needed to provide greater power. Full article
(This article belongs to the Section Aeronautics)
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15 pages, 4029 KiB  
Article
Parametric Optimisation Analysis of Micro/Nano-Satellite Flywheels Based on the NSGA-Ⅱ Optimisation Algorithm
by Wei Jiang, Weicheng Xie and Shuai Sun
Aerospace 2022, 9(7), 386; https://doi.org/10.3390/aerospace9070386 - 18 Jul 2022
Cited by 6 | Viewed by 2001
Abstract
As the key mechanism of attitude control of micro/nano-satellites, the flywheel design is mostly based on empirical formulae that do not meet the requirements of lightweight and high-performance micro/nano-satellite platforms. In this paper, the structural shape of micro/nano-satellite flywheels is analysed, and a [...] Read more.
As the key mechanism of attitude control of micro/nano-satellites, the flywheel design is mostly based on empirical formulae that do not meet the requirements of lightweight and high-performance micro/nano-satellite platforms. In this paper, the structural shape of micro/nano-satellite flywheels is analysed, and a set of flywheel optimisation methods is proposed to realise the parametric optimisation analysis of the structural shape. First, the general principle of flywheel efficiency is introduced, the optimisation evaluation factor of flywheel design is proposed, and the parametric model of a flywheel structure is established by using the finite element secondary development technology, which can be used to quickly build a finite element model of different dimensions. Second, the optimisation model of flywheels is established while introducing the approximate model algorithm, greatly improving the optimisation efficiency. Considering the phenomenon that the genetic algorithm falls below local optimisation under a large parameter range, the method of initial optimisation is proposed to reduce the upper and lower limits of the optimisation parameters. Finally, the optimal shape of the flywheel is obtained by using the parametric optimisation model of the flywheel. The finite element analysis results show that the flywheel optimisation evaluation factor proposed in this work can effectively improve the comprehensive performance of the flywheel as the optimisation target, and the corresponding optimisation method can be well applied to the engineering application and design of micro/nano-satellite platforms. This can help guide the structural optimisation design of micro/nano-satellite platforms in the future. Full article
(This article belongs to the Section Astronautics & Space Science)
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9 pages, 1251 KiB  
Communication
Venus Life Finder Missions Motivation and Summary
by Sara Seager, Janusz J. Petkowski, Christopher E. Carr, David H. Grinspoon, Bethany L. Ehlmann, Sarag J. Saikia, Rachana Agrawal, Weston P. Buchanan, Monika U. Weber, Richard French, Pete Klupar, Simon P. Worden, Darrel Baumgardner and on behalf of the Venus Life Finder Mission Team
Aerospace 2022, 9(7), 385; https://doi.org/10.3390/aerospace9070385 - 18 Jul 2022
Cited by 23 | Viewed by 11408
Abstract
Finding evidence of extraterrestrial life would be one of the most profound scientific discoveries ever made, advancing humanity into a new epoch of cosmic awareness. The Venus Life Finder (VLF) missions feature a series of three direct atmospheric probes designed to assess the [...] Read more.
Finding evidence of extraterrestrial life would be one of the most profound scientific discoveries ever made, advancing humanity into a new epoch of cosmic awareness. The Venus Life Finder (VLF) missions feature a series of three direct atmospheric probes designed to assess the habitability of the Venusian clouds and search for signs of life and life itself. The VLF missions are an astrobiology-focused set of missions, and the first two out of three can be launched quickly and at a relatively low cost. The mission concepts come out of an 18-month study by an MIT-led worldwide consortium. Full article
(This article belongs to the Special Issue The Search for Signs of Life on Venus: Science Objectives and Mission Designs)
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19 pages, 6467 KiB  
Article
Design of the ASSUT-FF Algorithm for GTO Satellite CNS/BDS Integrated Navigation
by Bing Hua, Xiaosong Wei, Yunhua Wu and Zhiming Chen
Aerospace 2022, 9(7), 384; https://doi.org/10.3390/aerospace9070384 - 16 Jul 2022
Cited by 2 | Viewed by 1964
Abstract
The velocity and acceleration of geostationary transfer orbit (GTO) satellites change dramatically and periodically, and the operating area extends from hundreds of kilometers to 36,000 km above the Earth’s surface. This leads to the limitation of navigation methods of GTO satellites, the complexity [...] Read more.
The velocity and acceleration of geostationary transfer orbit (GTO) satellites change dramatically and periodically, and the operating area extends from hundreds of kilometers to 36,000 km above the Earth’s surface. This leads to the limitation of navigation methods of GTO satellites, the complexity of perturbation components and the increase of sensor measurement noise. Therefore, in this paper, a celestial navigation system/Beidou navigation system (CNS/BDS) integrated navigation method based on the adaptive spherical simplex unscented transformation federated Kalman filter (ASSUT-FF) algorithm is designed for GTO satellite high-precision autonomous navigation, considering the integrated navigation method and filtering algorithm. A Beidou observation model based on the relative pseudorange/pseudorange rate is established. Even when the GTO satellite moves to the high orbit region, it can still use BDS navigation information to determine the orbit. In addition, the designed adaptive algorithm can still ensure the filter stability in a complex space environment. The CNS/BDS integrated navigation method based on the ASSUT-FF algorithm proposed in this paper can realize continuous and high-precision autonomous navigation of GTO satellites. The simulation results show that the orbit determination accuracy of the proposed navigation method is 96.23% and 84.06% higher than that of the single celestial navigation method and the traditional Beidou geometric positioning correction celestial navigation method, respectively. The performance test results of the adaptive algorithm also show that the ASUT-FF algorithm has good robustness. Full article
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24 pages, 13387 KiB  
Article
OpenAP.top: Open Flight Trajectory Optimization for Air Transport and Sustainability Research
by Junzi Sun
Aerospace 2022, 9(7), 383; https://doi.org/10.3390/aerospace9070383 - 15 Jul 2022
Cited by 3 | Viewed by 3819
Abstract
Trajectory optimization has been an active area of research for air transport studies for several decades. But almost all flight optimizers proposed in the literature remain close-sourced, which presents a major disadvantage for the advancement of scientific research. This optimization depends on aircraft [...] Read more.
Trajectory optimization has been an active area of research for air transport studies for several decades. But almost all flight optimizers proposed in the literature remain close-sourced, which presents a major disadvantage for the advancement of scientific research. This optimization depends on aircraft performance models, emission models, and operational constraints. In this paper, I present a fully open trajectory optimizer, OpenAP.top, which offers researchers easy access to the complex but efficient non-linear optimal control approach. Full flights can be generated without specifying flight phases, and specific flight segments can also be independently created. The optimizer adapts to meteorological conditions and includes conventional fuel and cost index objectives. Based on global warming and temperature potentials, its climate objectives form the basis for climate optimal air transport studies. The optimizer’s performance and uncertainties under different factors like varying mass, cost index, and wind conditions are analyzed. Overall, this new optimizer brings a high performance for optimal trajectory generations by providing four-dimensional and wind-enabled full-phase optimal trajectories in a few seconds. Full article
(This article belongs to the Collection Air Transportation—Operations and Management)
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24 pages, 6897 KiB  
Article
Shape Optimisation of Assembled Plate Structures with the Boundary Element Method
by Llewellyn Morse, Vincenzo Mallardo, Zahra Sharif-Khodaei and Ferri M.H. Aliabadi
Aerospace 2022, 9(7), 381; https://doi.org/10.3390/aerospace9070381 - 15 Jul 2022
Cited by 2 | Viewed by 1873
Abstract
A novel methodology is presented for performing sensitivity analyses of assembled plate structures using the Boundary Element Method (BEM). The main novelty of this work is that the exact implicit derivatives of the BEM formulations for assembled plate structures have been derived for [...] Read more.
A novel methodology is presented for performing sensitivity analyses of assembled plate structures using the Boundary Element Method (BEM). The main novelty of this work is that the exact implicit derivatives of the BEM formulations for assembled plate structures have been derived for the first time and incorporated into a newly developed Implicit Differentiation Method (IDM), enabling sensitivity analyses to be conducted for more complex and realistic structures in a more accurate, robust, and efficient manner than previous approaches. Three numerical examples are investigated to validate the derived exact implicit derivatives and to demonstrate how they could be used for a potential application involving the shape optimisation of a complex X-core structure from the canard of a Eurofighter Typhoon fighter jet. Results show that the newly developed IDM is more accurate, robust, and efficient when compared to alternative methodologies using derivatives obtained from methods such as the Finite Difference Method (FDM) and the Finite Element Method (FEM). Full article
(This article belongs to the Special Issue Recent Advances in Computational Mechanics)
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18 pages, 31189 KiB  
Article
Design and Analysis of MataMorph-3: A Fully Morphing UAV with Camber-Morphing Wings and Tail Stabilizers
by Peter L. Bishay, James S. Kok, Luis J. Ferrusquilla, Brian M. Espinoza, Andrew Heness, Antonio Buendia, Sevada Zadoorian, Paul Lacson, Jonathan D. Ortiz, Ruiki Basilio and Daniel Olvera
Aerospace 2022, 9(7), 382; https://doi.org/10.3390/aerospace9070382 - 14 Jul 2022
Cited by 14 | Viewed by 5817
Abstract
Conventional aircraft use discrete flight control surfaces to maneuver during flight. The gaps and discontinuities of these control surfaces generate drag, which degrades aerodynamic and power efficiencies. Morphing technology aims to replace conventional wings with advanced wings that can change their shape to [...] Read more.
Conventional aircraft use discrete flight control surfaces to maneuver during flight. The gaps and discontinuities of these control surfaces generate drag, which degrades aerodynamic and power efficiencies. Morphing technology aims to replace conventional wings with advanced wings that can change their shape to control the aircraft with the minimum possible induced drag. This paper presents MataMorph-3, a fully morphing unmanned aerial vehicle (UAV) with camber-morphing wings and tail stabilizers. Although previous research has presented successful designs for camber-morphing wing core mechanisms, skin designs suffered from wrinkling, warping, or sagging problems that result in reduced reliability and aerodynamic efficiency. The wing and tail stabilizers of MataMorph-3 feature hybrid ribs with solid leading-edge sections that house servomotors, and compliant trailing-edge sections with integrated flexible ribbons that are connected to the servomotors to camber-morph the ribs. Thin laminated carbon fiber composite skin slides smoothly over the compliant rib sections upon morphing, guided by innovative trailing-edge sliders and skin-supporting linkage mechanisms strategically located between the ribs. Sample prototypes were built and tested to show the effectiveness of the proposed design solutions in enabling smooth camber-morphing. The proposed design provides a better alternative to stretchable skins in morphing airplane designs through the concept of skin sliding. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology III)
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17 pages, 7711 KiB  
Article
Conceptual Research on a Mono-Biplane Aerodynamics-Driven Morphing Aircraft
by Tingyu Guo, Liangtao Feng, Chenhua Zhu, Xiaopeng Zhou and Haixin Chen
Aerospace 2022, 9(7), 380; https://doi.org/10.3390/aerospace9070380 - 14 Jul 2022
Cited by 6 | Viewed by 3437
Abstract
The operation of aircrafts with high aspect ratio wings is usually vulnerable to low-standard airports and bad weather. A new concept for a mono-biplane aerodynamics-driven morphing aircraft is proposed. The movable and fixed wings form a biplane mode during takeoff and landing, while [...] Read more.
The operation of aircrafts with high aspect ratio wings is usually vulnerable to low-standard airports and bad weather. A new concept for a mono-biplane aerodynamics-driven morphing aircraft is proposed. The movable and fixed wings form a biplane mode during takeoff and landing, while they form a high aspect ratio monoplane mode when cruising. This novel form of morphing can obtain a high cruise L/D while reducing nearly 50% of the takeoff and landing wingspan. However, the wing area is kept unchanged while morphing. The aerodynamic force on the movable wing is controlled by the deflection of the flaps to drive the morphing. No additional driving actuator is needed. In this way, although the morphing scale is large, the penalty on the complexity, structural strength, weight, and internal space of the wing is low. Taking the RQ-4A “Global Hawk” as the design baseline, morphing of the mono-biplane could further extend the cruise wingspan and aspect ratio for a better range without increasing the takeoff and landing span. When the wingspan was restricted, it was shown that this morphing scheme could reach a range extension of more than 50% when compared with an aircraft with the same wing load and different layouts. The feasibility of this mono-biplane aerodynamics-driven morphing concept was initially verified through ground vehicle tests. The possible influence of the morphing process on aircraft stability and control is also discussed. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology III)
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15 pages, 5540 KiB  
Article
Flow Feature in Supersonic Non-Isobaric Jet near the Nozzle Edge
by Valeriy Zapryagaev, Ivan Kavun and Nikolay Kiselev
Aerospace 2022, 9(7), 379; https://doi.org/10.3390/aerospace9070379 - 13 Jul 2022
Cited by 2 | Viewed by 3420
Abstract
Using the example of studying the supersonic underexpanded jet initial section, the issue of interpreting the experimental visualization data and Pitot pressure measurement data using the results of numerical calculations (2d RANS k-ω SST) is discussed. It is shown that the gradient S-shaped [...] Read more.
Using the example of studying the supersonic underexpanded jet initial section, the issue of interpreting the experimental visualization data and Pitot pressure measurement data using the results of numerical calculations (2d RANS k-ω SST) is discussed. It is shown that the gradient S-shaped feature of the gas-dynamic structure near the nozzle exit, observed in the form of a barrel shock, is a characteristic that separates the expansion and compression regions, and downstream is transformed into a barrel shock. It has been established that the reason for the observed S-shaped curvature of this feature is the axisymmetric nature of the jet flow. Full article
(This article belongs to the Special Issue Jet Flow Analysis)
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30 pages, 3565 KiB  
Article
Concurrent Trajectory Optimization and Aircraft Design for the Air Cargo Challenge Competition
by Nuno M. B. Matos and Andre C. Marta
Aerospace 2022, 9(7), 378; https://doi.org/10.3390/aerospace9070378 - 13 Jul 2022
Cited by 2 | Viewed by 2554
Abstract
A coupled aerostructural aircraft design and trajectory optimization framework is developed for the Air Cargo Challenge competition to maximize the expected score based on cargo carried, altitude achieved and distance traveled. Its modular architecture makes it easily adaptable to any problem where the [...] Read more.
A coupled aerostructural aircraft design and trajectory optimization framework is developed for the Air Cargo Challenge competition to maximize the expected score based on cargo carried, altitude achieved and distance traveled. Its modular architecture makes it easily adaptable to any problem where the performance depends not only on the design of the aircraft but also on its flight trajectory. It is based on OpenAeroStruct, an aerostructural solver that uses analytic derivatives for efficient gradient-based optimization. A trajectory optimization module using a collocation method is coupled with the option of using b-splines to increase computational efficiency together with an experimentally-based power decay model that accurately determines the aircraft propulsive response to control input depending on the battery discharge level. The optimization problem totaled 206 variables and 283 constraints and was solved in less than 7 h on a standard computer with 12% reduction when using b-splines for trajectory control variables. The results revealed the need to consider the multi-objective total score to account for the different score components and highlighted the importance of the payload level and chosen trajectory. The wing area should be increased within allowable limits to maximize payload capacity, climb to maximum target height should be the focus of the first 60 s of flight and full throttle should be avoided in cruise to reduce losses and extend flight distance. The framework proved to be a valuable tool for students to easily obtain guidelines for both the model aircraft design and control to maximize the competition score. Full article
(This article belongs to the Section Aeronautics)
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17 pages, 957 KiB  
Article
On the Estimation of Vector Wind Profiles Using Aircraft-Derived Data and Gaussian Process Regression
by Marius Marinescu, Alberto Olivares, Ernesto Staffetti and Junzi Sun
Aerospace 2022, 9(7), 377; https://doi.org/10.3390/aerospace9070377 - 13 Jul 2022
Cited by 4 | Viewed by 2392
Abstract
This work addresses the problem of vertical wind profile online estimation at a given location. Specifically, the north and east components of the wind are continuously estimated as functions of time and altitude at two waypoints used for landing on the Adolfo Suarez [...] Read more.
This work addresses the problem of vertical wind profile online estimation at a given location. Specifically, the north and east components of the wind are continuously estimated as functions of time and altitude at two waypoints used for landing on the Adolfo Suarez Madrid-Barajas airport. A continuous nowcast of the wind profile is performed in which wind observations are derived from the aircraft states and assimilated into the model. It is well known that wind is one of the utmost contributors to uncertainties in the current and future paradigm of Air Traffic Management. Accurate wind information is key in continuous climb and descent operations, spacing, four dimensional trajectory-based operations, and aircraft performance studies, among others. In this work, wind data are obtained indirectly from the aircraft’s states broadcast by the Mode S and ADS-B aircraft surveillance systems. The Gaussian process regression is adapted to this framework and used to solve the problem. The presented method allows to construct a complete vector wind profile at any specific position that is continuous in time and altitude; namely, there is no need for grid points and time discretisation. The Gaussian process regression is a very flexible estimator which is statistically consistent under general conditions, meaning that it converges to the underground truth when more and more data are dispensed. In addition, the Gaussian process regression approach provides the whole probability distribution of any particular estimation, allowing confidence intervals to be computed naturally. In the case study presented in this paper, in which the wind is constantly estimated, the Gaussian process regression model is iteratively updated every 15 min to capture possible changes in the wind behaviour and give an estimation of the wind profile every half a minute. The method has been validated using a test dataset, achieving a reduction of 50% of the prediction uncertainty in comparison to a baseline model. Moreover, two popular wind profile estimators based on the Kalman filter are also implemented for the sake of comparison. The Kalman filter outperforms the baseline model, but it does not outperform the Gaussian process regression with errors higher by around 35%, in comparison. The obtained results show that the Gaussian process regression of aircraft-derived data reliably nowcast the wind state, which is key in Air Traffic Management. Full article
(This article belongs to the Special Issue Advances in Air Traffic and Airspace Control and Management)
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24 pages, 1647 KiB  
Article
The Stability Analysis of a Tether for a Segmented Space Elevator
by Shihao Luo, Naigang Cui, Xiaowei Wang, Youhua Fan and Haitao Gu
Aerospace 2022, 9(7), 376; https://doi.org/10.3390/aerospace9070376 - 12 Jul 2022
Viewed by 2173
Abstract
The space elevator system is a space tether system used to solve low-cost space transportation. Its high efficiency, large load and other characteristics have broad application prospects in the aerospace field. The stability analysis is the foundation of the space elevator system research. [...] Read more.
The space elevator system is a space tether system used to solve low-cost space transportation. Its high efficiency, large load and other characteristics have broad application prospects in the aerospace field. The stability analysis is the foundation of the space elevator system research. Based on the new segment space elevator system model, in this paper, the stability of the system at the equilibrium point is analyzed by Lyapunov stability theory; And based on the criterion that the change rate of the system restoring torque and the anchor point tension are greater than 0, the maximum offset angle of the system inside and outside the equatorial plane is analyzed. The results show that the segment space elevator is stable near the equilibrium point; The maximum deflection angle of the space elevator inside and outside the equatorial plane is related to the design stress of the anchor point; When the space elevator is offset outside the equatorial plane, it will only lose stability because the restoring torque reaches the maximum value; When the space elevator is offset in the equatorial plane, and due to the design stress of the anchor point is small, it will lose stability because the tensile force of the anchor point is reduced to 0, and when the design stress of the anchor point is large, it will lose stability because the recovery torque reaches the maximum value; The stability of the space elevator outside the equatorial plane is better than that in the equatorial plane. Full article
(This article belongs to the Section Astronautics & Space Science)
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17 pages, 3619 KiB  
Communication
Design Principles for a Contrail-Minimizing Trial in the North Atlantic
by Jarlath Molloy, Roger Teoh, Seán Harty, George Koudis, Ulrich Schumann, Ian Poll and Marc E. J. Stettler
Aerospace 2022, 9(7), 375; https://doi.org/10.3390/aerospace9070375 - 12 Jul 2022
Cited by 8 | Viewed by 3895
Abstract
The aviation industry has committed to decarbonize its CO2 emissions. However, there has been much less industry focus on its non-CO2 emissions, despite recent studies showing that these account for up to two-thirds of aviation’s climate impact. Parts of the industry [...] Read more.
The aviation industry has committed to decarbonize its CO2 emissions. However, there has been much less industry focus on its non-CO2 emissions, despite recent studies showing that these account for up to two-thirds of aviation’s climate impact. Parts of the industry have begun to explore the feasibility of potential non-CO2 mitigation options, building on the scientific research undertaken in recent years, by establishing demonstrations and operational trials to test parameters of interest. This paper sets out the design principles for a large trial in the North Atlantic. Considerations include the type of stakeholders, location, when to intervene, what flights to target, validation, and other challenges. Four options for safely facilitating a trial are outlined based on existing air-traffic-management processes, with three of these readily deployable. Several issues remain to be refined and resolved as part of any future trial, including those regarding meteorological and contrail forecasting, the decision-making process for stakeholders, and safely integrating these flights into conventional airspace. While this paper is not a formal concept of operations, it provides a stepping stone for policymakers, industry leaders, and other stakeholders with an interest in reducing aviation’s total climate impact, to understand how a large-scale warming-contrail-minimizing trial could work. Full article
(This article belongs to the Special Issue Aircraft Emissions and Climate Impact)
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14 pages, 4543 KiB  
Article
Numerical Solution for the Single-Impulse Flyby Co-Orbital Spacecraft Problem
by Haoxiang Su, Zhenghong Dong, Lihao Liu and Lurui Xia
Aerospace 2022, 9(7), 374; https://doi.org/10.3390/aerospace9070374 - 11 Jul 2022
Cited by 3 | Viewed by 2560
Abstract
The traversal inspection of satellites in satellite constellations or geosynchronous orbits has been a focus of research. A large number of variable orbit requirements in the “single-to-single” mode severely affects the efficiency of inspections. To address this problem, this study investigated the problem [...] Read more.
The traversal inspection of satellites in satellite constellations or geosynchronous orbits has been a focus of research. A large number of variable orbit requirements in the “single-to-single” mode severely affects the efficiency of inspections. To address this problem, this study investigated the problem of a single-impulse flyby co-orbiting two spacecraft and proposed a derivative-free numerical solution method that used the geometric relationship between the two intersections of the target and transfer orbits of the flyby problem in order to transform them into a nonlinear equation in a single variable for a given impulse time. The validity of the proposed method was verified using numerical examples. While the Lambert problem is one of the bases for solving the variable orbit problem, on-star intelligent control also raises the requirements for speed. To address this problem, this study also investigated the Lambert problem in a single-impulse flyby co-orbiting two spacecraft and determined the iterative initial value by constructing a quadratic interpolation equation between the inverse of the transfer time and the vertical component of the eccentric vector, the derivative-free quadratic interpolation cut-off method was proposed. Using 100,000 random tests showed that computational efficiency was improved by more than one order of magnitude compared with commonly used methods, with a calculation error of less than 10−6. Full article
(This article belongs to the Collection Space Systems Dynamics)
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26 pages, 4970 KiB  
Article
Layout Design of Strapdown Array Seeker and Extraction Method of Guidance Information
by Hao Yang, Xibin Bai and Shifeng Zhang
Aerospace 2022, 9(7), 373; https://doi.org/10.3390/aerospace9070373 - 11 Jul 2022
Cited by 3 | Viewed by 2238
Abstract
This paper proposed a multi-view surface array to enlarge the field-of-view (FOV) from 45° × 45° to 72° × 75° and improve the estimation precision of guidance information. First, based on circular and rectangular FOV sensors, the superposition characteristics of FOV in the [...] Read more.
This paper proposed a multi-view surface array to enlarge the field-of-view (FOV) from 45° × 45° to 72° × 75° and improve the estimation precision of guidance information. First, based on circular and rectangular FOV sensors, the superposition characteristics of FOV in the +-shaped layout and the X-shaped layout were explored and analyzed. Secondly, normalization processing was applied to obtain the equivalent measurement value of the central sensor and the corresponding error distribution. Based on such measurement value and error distribution, the filtering model could be constructed, which could effectively solve the problem of observation number variation caused by multiple sensors. Thirdly, a multivariate iterated extended Kalman filter (MIEKF) was proposed to make full use of multiple measurements. By iterating multiple unequal observations and making full use of the known error distribution information, the noise of filtered data was found to be effectively reduced and the estimation precision of guidance information was improved. Finally, based on a 6-DOF trajectory simulation, the correctness and effectiveness of the proposed method were verified. Simulation results show that MIEKF can improve the estimation accuracy of the line-of-sight (LOS) angle by at least 30% and the estimation accuracy of the LOS angle rate by nearly 80% compared with EKF. Full article
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25 pages, 27300 KiB  
Article
High-Order CFD Solvers on Three-Dimensional Unstructured Meshes: Parallel Implementation of RKDG Method with WENO Limiter and Momentum Sources
by Weicheng Pei, Yuyan Jiang and Shu Li
Aerospace 2022, 9(7), 372; https://doi.org/10.3390/aerospace9070372 - 11 Jul 2022
Cited by 1 | Viewed by 1902
Abstract
In aerospace engineering, high-order computational fluid dynamics (CFD) solvers suitable for three-dimensional unstructured meshes are less developed than expected. The Runge–Kutta discontinuous Galerkin (RKDG) finite element method with compact weighted essentially non-oscillatory (WENO) limiters is one of the candidates, which might give high-order [...] Read more.
In aerospace engineering, high-order computational fluid dynamics (CFD) solvers suitable for three-dimensional unstructured meshes are less developed than expected. The Runge–Kutta discontinuous Galerkin (RKDG) finite element method with compact weighted essentially non-oscillatory (WENO) limiters is one of the candidates, which might give high-order solutions on unstructured meshes. In this article, we provide an efficient parallel implementation of this method for simulating inviscid compressible flows. The implemented solvers are tested on lower-dimensional model problems and real three-dimensional engineering problems. Results of lower-dimensional problems validate the correctness and accuracy of these solvers. The capability of capturing complex flow structures even on coarse meshes is shown in the results of three-dimensional applications. For solving problems containing rotary wings, an unsteady momentum source model is incorporated into the solvers. Such a finite element/momentum source hybrid method eliminates the reliance on advanced mesh techniques, which might provide an efficient tool for studying rotorcraft aerodynamics. Full article
(This article belongs to the Section Aeronautics)
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21 pages, 2438 KiB  
Article
Analysis of Bilateral Air Services Agreement Liberalization in Australia
by Iryna Heiets, Richard C.K. Yeun, Wim J.C. Verhagen and Jiezhuoma La
Aerospace 2022, 9(7), 371; https://doi.org/10.3390/aerospace9070371 - 11 Jul 2022
Cited by 1 | Viewed by 4581
Abstract
This paper examines an assessment of the level of air transport services liberalization in Australia in order to generate recommendations on what key market access features of Air Services Agreements should be revised to reflect the changes in air transport characteristics, including the [...] Read more.
This paper examines an assessment of the level of air transport services liberalization in Australia in order to generate recommendations on what key market access features of Air Services Agreements should be revised to reflect the changes in air transport characteristics, including the increase in air cargo traffic during the COVID-19 period. The different variants of the key market access features of ASA, levels of air transport liberalization and the extent of air transport service liberalization between Australia and 104 partner countries were analysed using descriptive study, comparison analysis and the ALI index. The ALI index is calculated for four different weighting schemes. Passenger capacity in 41 bilateral agreements contain restrictions of frequency, capacity and aircraft type. The analysis of cooperative arrangements indicated that Australia has a single aviation market only with New Zealand. The cargo capacity analysis identified different types of capacity restrictions based on weekly cargo service, volume, destinations, designated airline and aircraft types. In conclusion, cargo capacity analysis illustrates that the level of liberalization is high, but the air services agreements between Australia and other countries in the first and second cargo capacity groups should be revised to reflect the increase in air cargo traffic during COVID-19. Full article
(This article belongs to the Section Air Traffic and Transportation)
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18 pages, 37728 KiB  
Article
Aerial Footage Analysis Using Computer Vision for Efficient Detection of Points of Interest Near Railway Tracks
by Rohan Sharma, Kishan Patel, Sanyami Shah and Michal Aibin
Aerospace 2022, 9(7), 370; https://doi.org/10.3390/aerospace9070370 - 9 Jul 2022
Cited by 8 | Viewed by 3819
Abstract
Object detection is a fundamental part of computer vision, with a wide range of real-world applications. It involves the detection of various objects in digital images or video. In this paper, we propose a proof of concept usage of computer vision algorithms to [...] Read more.
Object detection is a fundamental part of computer vision, with a wide range of real-world applications. It involves the detection of various objects in digital images or video. In this paper, we propose a proof of concept usage of computer vision algorithms to improve the maintenance of railway tracks operated by Via Rail Canada. Via Rail operates about 500 trains running on 12,500 km of tracks. These tracks pass through long stretches of sparsely populated lands. Maintaining these tracks is challenging due to the sheer amount of resources required to identify the points of interest (POI), such as growing vegetation, missing or broken ties, and water pooling around the tracks. We aim to use the YOLO algorithm to identify these points of interest with the help of aerial footage. The solution shows promising results in detecting the POI based on unmanned aerial vehicle (UAV) images. Overall, we achieved a precision of 74% across all POI and a mean average precision @ 0.5 (mAP @ 0.5) of 70.7%. The most successful detection was the one related to missing ties, vegetation, and water pooling, with an average accuracy of 85% across all three POI. Full article
(This article belongs to the Special Issue Applications of Drones)
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29 pages, 4117 KiB  
Article
A New ϵ-Adaptive Algorithm for Improving Weighted Compact Nonlinear Scheme with Applications
by Ziquan Huang, Shichao Zheng, Dongfang Wang and Xiaogang Deng
Aerospace 2022, 9(7), 369; https://doi.org/10.3390/aerospace9070369 - 9 Jul 2022
Cited by 2 | Viewed by 2005
Abstract
To improve the resolution and accuracy of the high-order weighted compact nonlinear scheme (WCNS), a new ϵ-adaptive algorithm based on local smoothness indicators is proposed. The new algorithm introduces a high-order global smoothness indicator to adjust the value of ϵ according to [...] Read more.
To improve the resolution and accuracy of the high-order weighted compact nonlinear scheme (WCNS), a new ϵ-adaptive algorithm based on local smoothness indicators is proposed. The new algorithm introduces a high-order global smoothness indicator to adjust the value of ϵ according to the local flow characteristics. Specifically, the algorithm increases ϵ in smooth regions, which can help cover up the disparity in smoothness indicators of sub-stencils and make the nonlinear scheme approach the background linear scheme. As a result, optimal order accuracy can be achieved in smooth regions, including critical points. While near discontinuities, the algorithm decreases ϵ, thereby strengthening the stencil selection mechanism and further attenuating spurious oscillations. Meanwhile, the new algorithm makes nonlinear schemes scale-invariant of flow variables. The results of approximate dispersion relation (ADR) show that the new algorithm can greatly reduce spectral errors of nonlinear schemes in the medium and low wavenumber range without inducing instability. Numerical results indicate that the new algorithm can significantly improve resolution of small-scale structures and suppress numerical oscillations near discontinuities with only a minor increment in computational cost. Full article
(This article belongs to the Section Aeronautics)
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18 pages, 6020 KiB  
Article
A Passivity-Based Velocity Control Method of Hardware-in-the-Loop Simulation for Space Robotic Operations
by Jun He, Mingjin Shen and Feng Gao
Aerospace 2022, 9(7), 368; https://doi.org/10.3390/aerospace9070368 - 8 Jul 2022
Cited by 2 | Viewed by 1827
Abstract
The hardware-in-the-loop (HIL) simulation is an important approach to test space robotic operations, rendering virtual free-floating dynamics on robotic facilities. However, this approach suffers from velocity divergence due to intrinsic time delay in the control loop. This paper proposes a passivity-based control strategy [...] Read more.
The hardware-in-the-loop (HIL) simulation is an important approach to test space robotic operations, rendering virtual free-floating dynamics on robotic facilities. However, this approach suffers from velocity divergence due to intrinsic time delay in the control loop. This paper proposes a passivity-based control strategy to handle the simulation divergence. A HIL simulation system with an industrial robot is modelled and its divergence problems are analyzed through numerical simulations. Then, through representing the HIL simulation system in a passivity network of view, the passivity observer (PO) of the dynamic system is established. The PO includes the effect of a real contact damping on energy flow of the passivity network during a contact process. Thus, a passivity controller is defined. Moreover, a real-time estimation method for contact damping is presented. Finally, collision experiments against a virtual wall and real collision experiments are both implemented. The experimental results show that the simulation divergence due to the time delay can be prevented by the proposed control strategy, and that the velocity characteristics with high fidelity are rendered on the HIL simulation system. Full article
(This article belongs to the Section Astronautics & Space Science)
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24 pages, 6887 KiB  
Article
Optimization and Improvement of Display Interaction System Based on Complex Command and Control Tasks
by Wei Wang, Xuefeng Hong, Jue Qu, Ning Xu and Tong Chen
Aerospace 2022, 9(7), 367; https://doi.org/10.3390/aerospace9070367 - 7 Jul 2022
Cited by 1 | Viewed by 1884
Abstract
A complex command and control task was selected as the test task, which included observing the overall and local situation, the interactive operation and situation display of detection equipment, the erection and launch of air defense equipment, and the check and display status. [...] Read more.
A complex command and control task was selected as the test task, which included observing the overall and local situation, the interactive operation and situation display of detection equipment, the erection and launch of air defense equipment, and the check and display status. The disadvantages of the traditional two-dimensional display interactive system include poor intuitiveness, insufficient information display dimension and complicated interactive operation. The mixed reality display interaction system can avoid these problems well and has the advantages of good portability and high efficiency, but this display interaction system has the problem of high cognitive load. Therefore, based on the premise of completing the same complex task, how to select and improve the display interaction system has become a problem worthy of urgent research. Based on the same complex command and control task, this paper compared the traditional two-dimensional display interaction system and the mixed reality display interaction system and analyzed the performance and cognitive load of the two systems. It is concluded that when completing the same task, the performance of the mixed reality display interaction system is significantly higher than that of the traditional two-dimensional display interaction system, but the cognitive load is slightly higher than that of the traditional two-dimensional display. Cognitive load was reduced while task performance was improved through multi-channel improvements to the mixed reality display interaction system. Considering the effects of performance and cognitive load, the improved multi-channel mixed reality display interaction system is superior to the unimproved mixed reality display interaction system and the two-dimensional display interaction system. This research provides an improvement strategy for the existing display interaction system and provides a new display interaction mode for future aerospace equipment and multi-target, multi-dimensional command and control tasks in war. Full article
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12 pages, 243 KiB  
Review
Supersonic Combustion Modeling and Simulation on General Platforms
by Shizhuo Huang, Qian Chen, Yuwei Cheng, Jinyu Xian and Zhengqi Tai
Aerospace 2022, 9(7), 366; https://doi.org/10.3390/aerospace9070366 - 7 Jul 2022
Cited by 6 | Viewed by 3250
Abstract
Supersonic combustion is an advanced technology for the next generation of aerospace vehicles. In the last two decades, numerical simulation has been widely used for the investigation on supersonic combustion. In this paper, the modeling and simulation of supersonic combustion on general platforms [...] Read more.
Supersonic combustion is an advanced technology for the next generation of aerospace vehicles. In the last two decades, numerical simulation has been widely used for the investigation on supersonic combustion. In this paper, the modeling and simulation of supersonic combustion on general platforms are thoroughly reviewed, with emphasis placed on turbulence modeling and turbulence–chemistry interactions treatment which are both essential for engineering computation of supersonic combustion. It is found that the Reynolds-averaged Navier–Stokes methods on the general platforms have provided useful experience for the numerical simulation in engineering design of supersonic combustion, while the large eddy simulation methods need to be widely utilized and further developed on these platforms. Meanwhile, the species transport models as a kind of reasonable combustion model accounting for the turbulence–chemistry interactions in supersonic combustion have achieved good results. With the development of new combustion models, especially those designed in recent years for high-speed combustion, the turbulence–chemistry interactions treatment for numerical simulation of supersonic combustion based on general platforms is expected to be further mature in the future. Full article
(This article belongs to the Special Issue Supersonic and Hypersonic Transportation Systems)
26 pages, 10485 KiB  
Article
Design and Analysis of a Novel Floating Docking Mechanism for On-Orbit Refueling
by Zhicheng Sun, Shipeng Li, Huan Zhang, Haiming Lei and Xiaodong Song
Aerospace 2022, 9(7), 365; https://doi.org/10.3390/aerospace9070365 - 7 Jul 2022
Cited by 3 | Viewed by 2602
Abstract
The docking mechanism is a key component for on-orbit refueling technology. In this paper, the design and analysis of a novel floating docking mechanism for on-orbit berthing-based refueling is presented. Compared with traditional berthing and docking, the berthing here is high in success [...] Read more.
The docking mechanism is a key component for on-orbit refueling technology. In this paper, the design and analysis of a novel floating docking mechanism for on-orbit berthing-based refueling is presented. Compared with traditional berthing and docking, the berthing here is high in success rate and low in impact, which is accomplished by stretching out a docking subassembly instead of pulling back the client spacecraft. However, the berthing also has two problems: initial deviations between two spacecraft and an additional force generated by a hard alloy refueling pipe, which both seriously affect the docking operation. Thus, the docking mechanism is designed to have alignment abilities and decrease the additional force as much as possible. Based on the principles above, we introduced spring pins and a helical refueling pipe to design a light, compact, and simple docking mechanism. To further reduce the additional force, we proposed an elliptical-helical pipe and analyzed its mechanical properties. Finally, simulations and experiments were conducted to validate the proposed mechanism. The results show that the proposed mechanism with an elliptical-helical pipe has a high tolerance for linear and angular misalignment and superior dynamic performance during docking. Full article
(This article belongs to the Special Issue Recent Advances in Spacecraft Dynamics and Control)
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