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Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter

Yanqin ZHAO Orcid Logo, Ye Yuan Orcid Logo, Renliang CHEN

Chinese Journal of Aeronautics, Volume: 36, Issue: 9, Pages: 207 - 220

Swansea University Author: Ye Yuan Orcid Logo

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DOI (Published version): 10.1016/j.cja.2023.06.002

Abstract

The Differential Longitudinal Cyclic Pitch (DLCP) in coaxial compound is found to be useful in mitigating low-speed rotor interactions and improving flight performance. The complex mutual interaction is simulated by a revised rotor aerodynamics model, where an improved Blade Element Momentum Theory...

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Published in: Chinese Journal of Aeronautics
ISSN: 1000-9361
Published: Elsevier BV 2023
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URI: https://cronfa.swan.ac.uk/Record/cronfa63636
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Comparisons with the rotor inflow distributions and aircraft trim results from literature validate the accuracy of the model. Then, the influence of the DLCP on the flight dynamics of the aircraft is analysed. The trim characteristics indicate that a negative DLCP can reduce collective and differential collective inputs in low speed forward flight, and the negative longitudinal gradient is alleviated. Moreover, a moderate DLCP can reduce the rotor and total power consumption by 4.68% and 2.9%, respectively. As DLCP further increases, the increased propeller power and unbalanced thrust allocation offset the improvement. In high-speed flight, DLCP does not improve the performance except for extra lateral and heading stick displacements. In addition, the tip clearance is degraded throughout the speed envelope due to the differential pitching moment and the higher thrust from the lower rotor. Meanwhile, the changed rotor efficiency and induced velocity alter low-speed dynamic stability and controllability. The pitch and roll subsidences are slightly degraded with the DLCP, while the heave subsidence, dutch roll and phugoid modes are improved. Lastly, the on-axis controllability, including collective, differential collective pitch, longitudinal and lateral cyclic pitches, varies with DLCP due to its effect on rotor efficiency and inflow distribution. In conclusion, a reasonable DLCP is recommended to adjust the rotor interaction and improve aircraft performance, and further to alter the flight dynamics and aerodynamics of aircraft.</abstract><type>Journal Article</type><journal>Chinese Journal of Aeronautics</journal><volume>36</volume><journalNumber>9</journalNumber><paginationStart>207</paginationStart><paginationEnd>220</paginationEnd><publisher>Elsevier BV</publisher><placeOfPublication/><isbnPrint/><isbnElectronic/><issnPrint>1000-9361</issnPrint><issnElectronic/><keywords>Blade element momentum theory, Coaxial compound helicopter, Differential longitudinal cyclic pitch, Interaction model, Tip clearance</keywords><publishedDay>30</publishedDay><publishedMonth>9</publishedMonth><publishedYear>2023</publishedYear><publishedDate>2023-09-30</publishedDate><doi>10.1016/j.cja.2023.06.002</doi><url>http://dx.doi.org/10.1016/j.cja.2023.06.002</url><notes/><college>COLLEGE NANME</college><department>General Engineering</department><CollegeCode>COLLEGE CODE</CollegeCode><DepartmentCode>GENG</DepartmentCode><institution>Swansea University</institution><apcterm/><funders>This study was supported by A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.</funders><projectreference/><lastEdited>2023-10-23T14:45:47.7206775</lastEdited><Created>2023-06-13T14:21:03.5471151</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Aerospace Engineering</level></path><authors><author><firstname>Yanqin</firstname><surname>ZHAO</surname><orcid>0000-0002-4179-6645</orcid><order>1</order></author><author><firstname>Ye</firstname><surname>Yuan</surname><orcid>0000-0002-7568-0130</orcid><order>2</order></author><author><firstname>Renliang</firstname><surname>CHEN</surname><order>3</order></author></authors><documents><document><filename>63636__28854__3d26cb22978e419d86e97d8bbb12e225.pdf</filename><originalFilename>63636.VOR.pdf</originalFilename><uploaded>2023-10-23T14:42:44.0536769</uploaded><type>Output</type><contentLength>2965069</contentLength><contentType>application/pdf</contentType><version>Version of Record</version><cronfaStatus>true</cronfaStatus><documentNotes>© 2023 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics. 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spelling v2 63636 2023-06-13 Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter cdadbd9e334ad914d7968a538d9522a4 0000-0002-7568-0130 Ye Yuan Ye Yuan true false 2023-06-13 GENG The Differential Longitudinal Cyclic Pitch (DLCP) in coaxial compound is found to be useful in mitigating low-speed rotor interactions and improving flight performance. The complex mutual interaction is simulated by a revised rotor aerodynamics model, where an improved Blade Element Momentum Theory (BEMT) is proposed. Comparisons with the rotor inflow distributions and aircraft trim results from literature validate the accuracy of the model. Then, the influence of the DLCP on the flight dynamics of the aircraft is analysed. The trim characteristics indicate that a negative DLCP can reduce collective and differential collective inputs in low speed forward flight, and the negative longitudinal gradient is alleviated. Moreover, a moderate DLCP can reduce the rotor and total power consumption by 4.68% and 2.9%, respectively. As DLCP further increases, the increased propeller power and unbalanced thrust allocation offset the improvement. In high-speed flight, DLCP does not improve the performance except for extra lateral and heading stick displacements. In addition, the tip clearance is degraded throughout the speed envelope due to the differential pitching moment and the higher thrust from the lower rotor. Meanwhile, the changed rotor efficiency and induced velocity alter low-speed dynamic stability and controllability. The pitch and roll subsidences are slightly degraded with the DLCP, while the heave subsidence, dutch roll and phugoid modes are improved. Lastly, the on-axis controllability, including collective, differential collective pitch, longitudinal and lateral cyclic pitches, varies with DLCP due to its effect on rotor efficiency and inflow distribution. In conclusion, a reasonable DLCP is recommended to adjust the rotor interaction and improve aircraft performance, and further to alter the flight dynamics and aerodynamics of aircraft. Journal Article Chinese Journal of Aeronautics 36 9 207 220 Elsevier BV 1000-9361 Blade element momentum theory, Coaxial compound helicopter, Differential longitudinal cyclic pitch, Interaction model, Tip clearance 30 9 2023 2023-09-30 10.1016/j.cja.2023.06.002 http://dx.doi.org/10.1016/j.cja.2023.06.002 COLLEGE NANME General Engineering COLLEGE CODE GENG Swansea University This study was supported by A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions. 2023-10-23T14:45:47.7206775 2023-06-13T14:21:03.5471151 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Aerospace Engineering Yanqin ZHAO 0000-0002-4179-6645 1 Ye Yuan 0000-0002-7568-0130 2 Renliang CHEN 3 63636__28854__3d26cb22978e419d86e97d8bbb12e225.pdf 63636.VOR.pdf 2023-10-23T14:42:44.0536769 Output 2965069 application/pdf Version of Record true © 2023 Production and hosting by Elsevier Ltd. on behalf of Chinese Society of Aeronautics and Astronautics. Distributed under the terms of a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). true eng https://creativecommons.org/licenses/by-nc-nd/4.0/
title Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter
spellingShingle Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter
Ye Yuan
title_short Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter
title_full Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter
title_fullStr Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter
title_full_unstemmed Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter
title_sort Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter
author_id_str_mv cdadbd9e334ad914d7968a538d9522a4
author_id_fullname_str_mv cdadbd9e334ad914d7968a538d9522a4_***_Ye Yuan
author Ye Yuan
author2 Yanqin ZHAO
Ye Yuan
Renliang CHEN
format Journal article
container_title Chinese Journal of Aeronautics
container_volume 36
container_issue 9
container_start_page 207
publishDate 2023
institution Swansea University
issn 1000-9361
doi_str_mv 10.1016/j.cja.2023.06.002
publisher Elsevier BV
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Aerospace Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Aerospace Engineering
url http://dx.doi.org/10.1016/j.cja.2023.06.002
document_store_str 1
active_str 0
description The Differential Longitudinal Cyclic Pitch (DLCP) in coaxial compound is found to be useful in mitigating low-speed rotor interactions and improving flight performance. The complex mutual interaction is simulated by a revised rotor aerodynamics model, where an improved Blade Element Momentum Theory (BEMT) is proposed. Comparisons with the rotor inflow distributions and aircraft trim results from literature validate the accuracy of the model. Then, the influence of the DLCP on the flight dynamics of the aircraft is analysed. The trim characteristics indicate that a negative DLCP can reduce collective and differential collective inputs in low speed forward flight, and the negative longitudinal gradient is alleviated. Moreover, a moderate DLCP can reduce the rotor and total power consumption by 4.68% and 2.9%, respectively. As DLCP further increases, the increased propeller power and unbalanced thrust allocation offset the improvement. In high-speed flight, DLCP does not improve the performance except for extra lateral and heading stick displacements. In addition, the tip clearance is degraded throughout the speed envelope due to the differential pitching moment and the higher thrust from the lower rotor. Meanwhile, the changed rotor efficiency and induced velocity alter low-speed dynamic stability and controllability. The pitch and roll subsidences are slightly degraded with the DLCP, while the heave subsidence, dutch roll and phugoid modes are improved. Lastly, the on-axis controllability, including collective, differential collective pitch, longitudinal and lateral cyclic pitches, varies with DLCP due to its effect on rotor efficiency and inflow distribution. In conclusion, a reasonable DLCP is recommended to adjust the rotor interaction and improve aircraft performance, and further to alter the flight dynamics and aerodynamics of aircraft.
published_date 2023-09-30T14:45:48Z
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score 11.028886

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