Earth remote sensing from geostationary orbit (GEO) can realize high temporal resolution; however, the spatial resolution is commonly worse than observation from low Earth orbit. In order to achieve high-frequency and high-resolution GEO remote sensing, a “Formation Flying Synthetic Aperture Telescope (FFSAT)”with multiple micro-satellites has been proposed. The FFSAT greatly improves the spatial resolution using a synthetic aperture technique. Therefore the relative positions and attitudes between the optical units of each satellite must be controlled with an accuracy better than 1/10 of the observation wavelength. However, even mm-class accuracy control has not been demonstrated on orbit. As a first practical application of the FFSAT, a forest fire monitoring mission using infrared rays is being considered, in which control accuracy requirement is relaxed as its wavelength is longer than visible light. We proposed a point spread function optimization method for controlling formation flying with an accuracy of approximately 1–1,000 times the wavelength (1 μm–1mm) in the absence of sensors, which can measure absolute distance with μm-accuracy. The effectiveness of the method was demonstrated through simulations in which the satellites’ system and the optical system are coupled. The simulation results show that the method can control the formation within the wavelength order.
{"title":"µm-class Control of Relative Position and Attitude for a Formation Flying Synthetic Aperture Telescope with Micro-satellites","authors":"Ryo Suzumoto, S. Ikari, N. Miyamura, S. Nakasuka","doi":"10.2322/TJSASS.64.101","DOIUrl":"https://doi.org/10.2322/TJSASS.64.101","url":null,"abstract":"Earth remote sensing from geostationary orbit (GEO) can realize high temporal resolution; however, the spatial resolution is commonly worse than observation from low Earth orbit. In order to achieve high-frequency and high-resolution GEO remote sensing, a “Formation Flying Synthetic Aperture Telescope (FFSAT)”with multiple micro-satellites has been proposed. The FFSAT greatly improves the spatial resolution using a synthetic aperture technique. Therefore the relative positions and attitudes between the optical units of each satellite must be controlled with an accuracy better than 1/10 of the observation wavelength. However, even mm-class accuracy control has not been demonstrated on orbit. As a first practical application of the FFSAT, a forest fire monitoring mission using infrared rays is being considered, in which control accuracy requirement is relaxed as its wavelength is longer than visible light. We proposed a point spread function optimization method for controlling formation flying with an accuracy of approximately 1–1,000 times the wavelength (1 μm–1mm) in the absence of sensors, which can measure absolute distance with μm-accuracy. The effectiveness of the method was demonstrated through simulations in which the satellites’ system and the optical system are coupled. The simulation results show that the method can control the formation within the wavelength order.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68662531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Cheng, Jing-zhou Zhang, Jingyang Zhang, Yuyan Zhang
1)College of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, China 2)AVIC Nanjing Engineering Institute of Aircraft Systems, Nanjing 211106, China 3)Jiangsu Province Key Laboratory of Aerospace Power System, College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China 4)Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration, Nanjing 211106, China 5)College of Astronautics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
{"title":"Effect of Cutbacks on Tip Leakage Flow and Film-Cooling Effectiveness of a Turbine Blade Tip under Relative Moving Condition","authors":"F. Cheng, Jing-zhou Zhang, Jingyang Zhang, Yuyan Zhang","doi":"10.2322/tjsass.64.293","DOIUrl":"https://doi.org/10.2322/tjsass.64.293","url":null,"abstract":"1)College of Mechanical and Electronic Engineering, Nanjing Forestry University, Nanjing 210037, China 2)AVIC Nanjing Engineering Institute of Aircraft Systems, Nanjing 211106, China 3)Jiangsu Province Key Laboratory of Aerospace Power System, College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China 4)Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration, Nanjing 211106, China 5)College of Astronautics, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"35 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a method to obtain a robust optimal path in an environment with time-varying safety features, such as in the lunar polar region. In designing the path for planetary exploration rovers, we must consider various safety conditions, such as terrain hazards, illumination, and communication visibility to the Earth. Some of the safety features are time-varying, and the optimal path should be searched for both the spatial direction and the temporal direction. In addition, there is no guarantee that all of the sequences will be successfully executed on time due to misoperation, failures, or trou-ble. Therefore, a path that is robust against the delay must be planned so as to guarantee safety even when behind schedule. The authors propose an algorithm called “ Robust Spatio-Temporal Path Planner for the Planetary Rover (R OBUST -STP3R) ” to obtain a path that is robust against schedule delay in a time-varying environment. This method de fi nes a cost function that consists of the distance as well as the region type cost. To add robustness against schedule delays, the authors consider a weighted summation of the time-varying region type cost with regard to the temporal direction. The e ff ectiveness of the proposed method is demonstrated through use in a simulated lunar polar exploration exercise.
{"title":"Spatio-Temporal Path Planning for Lunar Polar Exploration with Robustness against Schedule Delay","authors":"H. Inoue, S. Adachi","doi":"10.2322/tjsass.64.304","DOIUrl":"https://doi.org/10.2322/tjsass.64.304","url":null,"abstract":"This paper presents a method to obtain a robust optimal path in an environment with time-varying safety features, such as in the lunar polar region. In designing the path for planetary exploration rovers, we must consider various safety conditions, such as terrain hazards, illumination, and communication visibility to the Earth. Some of the safety features are time-varying, and the optimal path should be searched for both the spatial direction and the temporal direction. In addition, there is no guarantee that all of the sequences will be successfully executed on time due to misoperation, failures, or trou-ble. Therefore, a path that is robust against the delay must be planned so as to guarantee safety even when behind schedule. The authors propose an algorithm called “ Robust Spatio-Temporal Path Planner for the Planetary Rover (R OBUST -STP3R) ” to obtain a path that is robust against schedule delay in a time-varying environment. This method de fi nes a cost function that consists of the distance as well as the region type cost. To add robustness against schedule delays, the authors consider a weighted summation of the time-varying region type cost with regard to the temporal direction. The e ff ectiveness of the proposed method is demonstrated through use in a simulated lunar polar exploration exercise.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper conducts a safety assessment for reduced route spacing for RNP 2 aircraft under a radar environment. Although the criteria for 15 NM separation standards exist, past safety assessment did not consider the surveillance environment. This consideration may reduce the possible route spacing. Here, to account for the surveillance environment, the recently developed ASEPS model is applied. Since this model was intended for deployment on oceanic route systems, the model parameters are modified appropriately while keeping the consistency of the past safety analysis and data analysis. In particular, the parameter of occupancy is set based on one-year flight data in Japanese airspace, and the calculation of action time to resolve the conflict is modified to estimate the collision probability more accurately. The results show that 8 NM route spacing satisfies the safety criteria.
{"title":"Safety Analysis of Reduced Route Spacing for RNP 2 under Radar Environment","authors":"Ryota Mori","doi":"10.2322/TJSASS.64.165","DOIUrl":"https://doi.org/10.2322/TJSASS.64.165","url":null,"abstract":"This paper conducts a safety assessment for reduced route spacing for RNP 2 aircraft under a radar environment. Although the criteria for 15 NM separation standards exist, past safety assessment did not consider the surveillance environment. This consideration may reduce the possible route spacing. Here, to account for the surveillance environment, the recently developed ASEPS model is applied. Since this model was intended for deployment on oceanic route systems, the model parameters are modified appropriately while keeping the consistency of the past safety analysis and data analysis. In particular, the parameter of occupancy is set based on one-year flight data in Japanese airspace, and the calculation of action time to resolve the conflict is modified to estimate the collision probability more accurately. The results show that 8 NM route spacing satisfies the safety criteria.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68662273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Masatoshi Chono, N. Yamamoto, R. Tsukizaki, Takato Morishita, K. Kubota, Shinatra Cho, K. Kinefuchi, Toru Takahashi
1)Department of Advanced Energy Engineering Science, Kyushu University, Kasuga, Fukuoka 816–8580, Japan 2)Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252–5210, Japan 3)Department of Aeronautics and Astronautics, The University of Tokyo, Tokyo 113–8656, Japan 4)Japan Aerospace Exploration Agency, Chofu, Tokyo 182–8522, Japan 5)Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252–5210, Japan 6)Department of Aerospace Engineering, Nagoya University, Nagoya, Aichi 464–8603, Japan 7)Takahashi Denki Seisakusyo, Iwaki, Fukushima 972–8326, Japan
{"title":"Performance of a Miniature Hall Thruster and an In-house PPU","authors":"Masatoshi Chono, N. Yamamoto, R. Tsukizaki, Takato Morishita, K. Kubota, Shinatra Cho, K. Kinefuchi, Toru Takahashi","doi":"10.2322/TJSASS.64.189","DOIUrl":"https://doi.org/10.2322/TJSASS.64.189","url":null,"abstract":"1)Department of Advanced Energy Engineering Science, Kyushu University, Kasuga, Fukuoka 816–8580, Japan 2)Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252–5210, Japan 3)Department of Aeronautics and Astronautics, The University of Tokyo, Tokyo 113–8656, Japan 4)Japan Aerospace Exploration Agency, Chofu, Tokyo 182–8522, Japan 5)Japan Aerospace Exploration Agency, Sagamihara, Kanagawa 252–5210, Japan 6)Department of Aerospace Engineering, Nagoya University, Nagoya, Aichi 464–8603, Japan 7)Takahashi Denki Seisakusyo, Iwaki, Fukushima 972–8326, Japan","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68662819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Matsui, R. Kobayashi, Takashi Okamoto, Kazuhiko Yamada, H. Tanno
An expansion tube is a promising facility to simulate atmospheric entry conditions, although its fl ow conditions have not been completely characterized mainly owing to its short operation time. In this study, laser absorption spectroscopy was applied to diagnose HEK-X expansion tube fl ow in the Kakuda Space Center. The target is an absorption line of an oxygen molecule at 763nm. To increase the sensitivity, optical path length was extended by fi ve times using mirrors. Con-sequently, an absorption pro fi le with a fractional absorption of 2.4 « 0.3% was detected at a shock velocity of 7.65 « 0.05km / s. The estimated translational temperature from the Voigt fi tting was 2750 « 450K.
{"title":"Temperature Measurement of HEK-X Expansion Tube Flow by Laser Absorption Spectroscopy","authors":"M. Matsui, R. Kobayashi, Takashi Okamoto, Kazuhiko Yamada, H. Tanno","doi":"10.2322/TJSASS.64.193","DOIUrl":"https://doi.org/10.2322/TJSASS.64.193","url":null,"abstract":"An expansion tube is a promising facility to simulate atmospheric entry conditions, although its fl ow conditions have not been completely characterized mainly owing to its short operation time. In this study, laser absorption spectroscopy was applied to diagnose HEK-X expansion tube fl ow in the Kakuda Space Center. The target is an absorption line of an oxygen molecule at 763nm. To increase the sensitivity, optical path length was extended by fi ve times using mirrors. Con-sequently, an absorption pro fi le with a fractional absorption of 2.4 « 0.3% was detected at a shock velocity of 7.65 « 0.05km / s. The estimated translational temperature from the Voigt fi tting was 2750 « 450K.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68662875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The penetration of sonic booms into the ocean and an estimation of the extent of their in fl uence are important topics for supersonic and hypersonic aviation. Most prior studies were conducted assuming a fl at-water surface. However, it is known that the e ff ect of the surface waviness is not negligible in the case of real ocean environments. In the present study, the numerical method analyzes the two-dimensional fl ow fi eld of sonic boom propagation across the air and water is proposed. When the fl ight Mach number of an aircraft is higher than 4.4, the underwater fl ow fi eld becomes supersonic, and a sonic boom is generated there. The numerical results show that, in the underwater subsonic regime, the penetrating waves have the form of evanescent waves under either fl at or wavy water surface, but the waviness-induced ripples with the smaller decay rate are responsible for deeper penetration. In contrast, in the supersonic underwater fl ow, the surface waviness hardly a ff ects the penetration depth of underwater sonic booms, although it can slightly weaken the boom intensity. The e ff ect of the amplitude of surface waviness on the underwater penetrating wave was also investigated. :
{"title":"CFD Study on Penetration of Sonic Boom Applying a Wavy-Water Model","authors":"Po-Hsun Chen, Kojiro Suzuki","doi":"10.2322/tjsass.64.273","DOIUrl":"https://doi.org/10.2322/tjsass.64.273","url":null,"abstract":"The penetration of sonic booms into the ocean and an estimation of the extent of their in fl uence are important topics for supersonic and hypersonic aviation. Most prior studies were conducted assuming a fl at-water surface. However, it is known that the e ff ect of the surface waviness is not negligible in the case of real ocean environments. In the present study, the numerical method analyzes the two-dimensional fl ow fi eld of sonic boom propagation across the air and water is proposed. When the fl ight Mach number of an aircraft is higher than 4.4, the underwater fl ow fi eld becomes supersonic, and a sonic boom is generated there. The numerical results show that, in the underwater subsonic regime, the penetrating waves have the form of evanescent waves under either fl at or wavy water surface, but the waviness-induced ripples with the smaller decay rate are responsible for deeper penetration. In contrast, in the supersonic underwater fl ow, the surface waviness hardly a ff ects the penetration depth of underwater sonic booms, although it can slightly weaken the boom intensity. The e ff ect of the amplitude of surface waviness on the underwater penetrating wave was also investigated. :","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Abstracts of the Papers Published in Journal of the Japan Society for Aeronautical and Space Sciences (Vol. 69, No. 4, Aug. 2021)","authors":"","doi":"10.2322/tjsass.64.292","DOIUrl":"https://doi.org/10.2322/tjsass.64.292","url":null,"abstract":"","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"11 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The aeroacoustic fi elds of twin jets and the equivalent single jet were experimentally investigated using particle image velocimetry (PIV), schlieren visualization, and acoustic measurement. The present study focuses on the aeroacoustic fi elds of the twin jets, and the e ff ect of the interaction between each jet was investigated using various nozzle spacing. The PIV results indicated that strong interaction causes elliptical jet growth on a cross-stream plane and a decrease in the Reynolds stress of the inner shear layer on a plane containing both jet axes. The dynamic mode decomposition of the double-pulsed schlieren images extracted the interaction of each jet, which relates to the Mach wave generation. The noise of the twin jets was basically quieter than the noise of an equivalent single jet because of a shielding e ff ect and a reduction in the Reynolds stress resulting in a decrease in the overall sound pressure level.
{"title":"Aeroacoustic Fields of Supersonic Twin Jets at the Ideally Expanded Condition","authors":"Y. Ozawa, T. Nonomura, Y. Saito, K. Asai","doi":"10.2322/tjsass.64.312","DOIUrl":"https://doi.org/10.2322/tjsass.64.312","url":null,"abstract":"The aeroacoustic fi elds of twin jets and the equivalent single jet were experimentally investigated using particle image velocimetry (PIV), schlieren visualization, and acoustic measurement. The present study focuses on the aeroacoustic fi elds of the twin jets, and the e ff ect of the interaction between each jet was investigated using various nozzle spacing. The PIV results indicated that strong interaction causes elliptical jet growth on a cross-stream plane and a decrease in the Reynolds stress of the inner shear layer on a plane containing both jet axes. The dynamic mode decomposition of the double-pulsed schlieren images extracted the interaction of each jet, which relates to the Mach wave generation. The noise of the twin jets was basically quieter than the noise of an equivalent single jet because of a shielding e ff ect and a reduction in the Reynolds stress resulting in a decrease in the overall sound pressure level.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The shaftless ducted rotor (SDR) is a new type of ducted rotor system built using a ducted-rotor-motor integration design. Based on unstructured sliding grid technology, the e ff ects of four key parameters, such as rotor disk height, number of blades, the center hole radius and the blade root mounting angle, on the aerodynamic characteristics of the SDR were investigated. The calculation results show that the thrust performance gradually improves as the rotational speed increases. It is di ff erent from traditional ducted rotors where the rotor is installed near the lip of the duct to obtain the optimal aerodynamic performance, the rotor of the SDR is installed away from the duct entrance to obtain the best aerodynamic performance. Additionally, the number of blades is increased to improve peak thrust and ducted thrust performance; however, this results in decreasing the power load. The central hole radius of the SDR should not be too small, as this can result in an excessive blocking e ff ect when the central air fl ow passes through the paddle. Finally, when the rotational speed is con-stant, increasing the blade root mounting angle results in a large increase in thrust, but this decreases the power load as well.
{"title":"Research on the Influence of Key Parameters on the Aerodynamic Characteristics of Shaftless Ducted Rotors","authors":"Suiyuan Shen, Qing-Hua Zhu, Jinfa Xu","doi":"10.2322/tjsass.64.40","DOIUrl":"https://doi.org/10.2322/tjsass.64.40","url":null,"abstract":"The shaftless ducted rotor (SDR) is a new type of ducted rotor system built using a ducted-rotor-motor integration design. Based on unstructured sliding grid technology, the e ff ects of four key parameters, such as rotor disk height, number of blades, the center hole radius and the blade root mounting angle, on the aerodynamic characteristics of the SDR were investigated. The calculation results show that the thrust performance gradually improves as the rotational speed increases. It is di ff erent from traditional ducted rotors where the rotor is installed near the lip of the duct to obtain the optimal aerodynamic performance, the rotor of the SDR is installed away from the duct entrance to obtain the best aerodynamic performance. Additionally, the number of blades is increased to improve peak thrust and ducted thrust performance; however, this results in decreasing the power load. The central hole radius of the SDR should not be too small, as this can result in an excessive blocking e ff ect when the central air fl ow passes through the paddle. Finally, when the rotational speed is con-stant, increasing the blade root mounting angle results in a large increase in thrust, but this decreases the power load as well.","PeriodicalId":54419,"journal":{"name":"Transactions of the Japan Society for Aeronautical and Space Sciences","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68663770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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