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Relative rotor phasing for multicopter vibratory load minimisation

Part of: Written Paper Prizes 2023

Published online by Cambridge University Press:  21 October 2021

R. Niemiec Open the ORCID record for R. Niemiec [Opens in a new window] ,
F. Gandhi  and
N. Kopyt
R. Niemiec*
Affiliation:
Center for Mobility with Vertical Lift, Rensselaer Polytechnic Institute, Troy, NY, USA
F. Gandhi*
Affiliation:
Principal Investigator
N. Kopyt
Affiliation:
Center for Mobility with Vertical Lift, Rensselaer Polytechnic Institute, Troy, NY, USA
*
Emails: niemir2@rpi.edu; fgandhi@rpi.edu
Emails: niemir2@rpi.edu; fgandhi@rpi.edu
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Abstract

This study focuses on vibration reduction for quadcopters and octocopters with elastic, two-bladed, fixed-speed, variable-pitch rotors through the use of relative rotor phasing. The study defines phase modes such as a pitch phase mode with relative phasing between the front and aft rotors, a roll phase mode with relative phasing between the left and right rotors, and a differential phase mode with relative phasing between the clockwise and counter-clockwise spinning rotors for both the quadcopter and the octocopter, as well as additional higher harmonic phase modes for the octocopter. Parametric studies on individual phase modes indicate that, for the quadcopter in forward flight, the pitch and roll phase modes can almost entirely eliminate the 2/rev vibratory forces (at the aircraft level), but the 2/rev vibratory moments cannot be minimised at the same time. By simultaneously using multiple phase modes, a Pareto front can be generated and a solution selected based on the relative emphasis on force or moment vibration reduction. For the octocopter, it was observed that individual higher harmonic modes (specifically the 2c or 2s modes) could almost entirely eliminate both the 2/rev vibratory forces and moments, simultaneously. Compared with vibration levels in forward flight that might, on average, be expected if the rotors were randomly phased, a 62% reduction of a composite vibration index can be achieved on a quadcopter, and complete elimination of vibration was achievable on an octocopter, with appropriate rotor phasing.

Keywords

MulticopterElectric Vertical Takeoff and LandingeVTOLVibration
Type
Research Article
Information
The Aeronautical Journal , Volume 126 , Issue 1298 , April 2022 , pp. 710 - 729
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Copyright
© The Author(s), 2021. Published by Cambridge University Press on behalf of Royal Aeronautical Society

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References

Holden, J. and Goel, N. Fast-Forwarding to a Future of On-Demand Urban Air Transportation. Uber Elevate, 2016. https://www.uber.com/elevate.pdf. Accessed July 28, 2020.Google Scholar
National, Aeronautics and Space, Administration. NASA’s UAM Grand Challenge. NASA. https://www.nasa.gov/uamgc. Accessed October 10, 2019.Google Scholar
Swartz, K. NASA Embraces Urban Air Mobility. Vertiflite Magazine, 2019.Google Scholar
Johnson, W., Silva., C. and Solis, E. Concept vehicles for VTOL air taxi operations, American Helicopter Society International Technical Meeting on Aeromechanics Design for Transformative Vertical Flight, San Francisco, CA, USA, 2018.Google Scholar
Yoon, S., Lee, H. and Pullinam, T. Computational analysis of multi-rotor flows, AIAA 54th Aerospace Sciences Meeting, San Diego, CA, USA, 2016. doi: 10.2514/6.2016-0812 CrossRefGoogle Scholar
Yoon, S., Diaz, P.V., Boyd, D.D., Chan, W. and Theodore, C. Computational aerodynamic modeling of small quadcopter vehicles, 73rd American Helicopter Society Annual Forum, Fort Worth, TX, USA, 2017.Google Scholar
Diaz, P.V. and Yoon, S. High-fidelity computational aerodynamics of multi-rotor unmanned aerial vehicles, 2018 AIAA Aerospace Sciences Meeting, Kissimmee, FL, USA, 2018. doi: 10.2514/6.2018-1266 CrossRefGoogle Scholar
Misiorowski, M., Gandhi, F. and Oberai, A. Computational study on rotor interactional effects for a quadcopter in edgewise flight, AIAA J., 2019, 57, (12), pp 5309–5319. doi: 10.2514/1.J058369 CrossRefGoogle Scholar
Healy, R., Misiorowski, M. and Gandhi, F. A systematic CFD-based examination of rotor–rotor separation effects on interactional aerodynamics for large eVTOL aircraft, 75th Vertical Flight Society Annual Forum, Philadelphia, PA, USA, 2019.Google ScholarPubMed
Healy, R., Gandhi, F., Mistry, M. and Duffy, M. A computational investigation of multi-rotor aerodynamics with hub lateral and longitudinal canting, 76th Vertical Flight Society Annual Forum, Virtual Event, 2020.Google Scholar
Intaratep, N., Alexander, W., Devenport, W., Grace, S. and Dropkin, A. Experimental study of quadcopter acoustics and performance at static thrust conditions, 22nd AIAA/CEAS Aeroacoustics Conference, 2016. doi: 10.2514/6.2016-2873 CrossRefGoogle Scholar
Tinney, C., and Sirohi, J. Multirotor drone noise at static thrust, AIAA J., 2016, 56, (7), pp 2816–2826, doi: 10.2514/1.J0566827 CrossRefGoogle Scholar
Passe, B. and Baeder, J. Computational aeroacoustics of different propeller configurations for eVTOL applications, 8th Biennial Autonomous VTOL Technical Meeting and 6th Annual Electric VTOL Symposium, Mesa, AZ, USA, 2019.Google Scholar
Quackenbush, T., Wachspress, D., Ricci-Moretti, L., Barwey, D., Lewis, R. and Brentner, K. Aeroacoustic modeling of an eVTOL slowed rotor winged compound aircraft, 75th Vertical Flight Society Annual Forum, Philadelphia, PA, USA, 2019.Google Scholar
Jia, Z. and Lee, S. Acoustic analysis of urban air mobility quadrotor aircraft, Transformative Vertical Flight, San Jose, CA, USA, 2020.Google Scholar
Wachspress, D., Yu, M. and Brentner, K. Rotor/airframe aeroacoustic prediction for eVTOL UAM aircraft, 75th Vertical Flight Society Annual Forum, Philadelphia, PA, USA, 2019.Google Scholar
Zhang, J., Brentner, K. and Smith, E. Prediction of the aerodynamic and acoustic impact of propeller-wing interference, Transformative Vertical Flight, San Jose, CA, USA, 2020.Google Scholar
Schiller, N., Pascioni, K. and Zawodny, N. Tonal noise control using rotor phase synchronization, 75th Vertical Flight Society Annual Forum, Philadelphia, PA, USA, 2019.Google Scholar
Pascioni, K., Rizzi, S. and Schiller, N. Noise reduction potential of phase control for distributed propulsion vehicles, AIAA 2019 SciTech Forum, San Diego, CA, USA, 2019, doi: 10.2514/6.2019-1069 CrossRefGoogle Scholar
Smith, B., Niemiec, R. and Gandhi, F. A comparison of multicopter noise characteristics with increasing number of rotors, 76th Vertical Flight Society Annual Forum, Virtual Event, 2020.Google Scholar
Walter, A., McKay, M., Niemiec, R., Gandhi, F. and Jaran, C. An assessment of heave response dynamics for electrically driven rotors of increasing diameter, 8th Biennial Autonomous VTOL Technical Meeting and 6th Annual Electric VTOL Symposium, Mesa, AZ, USA, 2019.Google Scholar
Walter, A., McKay, M., Niemiec, R., Gandhi, F. and Ivler, C. Handling qualities based assessment of scalability for variable-RPM electric multi-rotor aircraft, 75th Vertical Flight Society Annual Forum, Philadelphia, PA, USA, 2019.Google Scholar
Walter, A., McKay, M., Niemiec, R., Gandhi, F. and Ivler, C. Hover handling qualities of fixed-pitch, variable-RPM quadcopters with increasing rotor diameter, 76th Vertical Flight Society Annual Forum, Virtual Event, 2020.Google Scholar
Bahr, M., McKay, M., Niemiec, R. and Gandhi, F. Performance and handling qualities assessment of large variable-RPM control multi-rotor aircraft for urban air mobility, 76th Vertical Flight Society Annual Forum, Virtual Event, 2020.Google Scholar
Malpica, C. and Withrow-Maser, S. Handling qualities analysis of blade pitch and rotor speed controlled eVTOL quadrotor concepts for urban air mobility, Vertical Flight Society International Powered Lift Conference, San Jose, CA, USA, 2020.Google Scholar
Niemiec, R., Gandhi, F., Lopez, M. and Tischler, M. System identification and handling qualities predictions of an eVTOL urban air mobility aircraft using modern flight control methods, 76th Vertical Flight Society Annual Forum, Virtual Event, 2020.Google Scholar
Withrow-Maser, S., Malpica, C. and Nagami, K., Impact of handling qualities on motor sizing for multirotor aircraft with urban air mobility missions, 77th Vertical Flight Society Annual Forum, Virtual Event, 2021.Google Scholar
Niemiec, R. and Gandhi, F. Effect of elastic blade deformation on trim and vibratory loads of a quadcopter, 73rd American Helicopter Society Annual Forum, Fort Worth, TX, USA, 2017.Google Scholar
US Army Air Mobility Research and Development Laboratory. Vibration Effects on Helicopter Reliability and Maintainability, AD-766 307, 1973.Google Scholar
Loewy, R. Helicopter vibrations: a technological perspective, J. Am. Helicopter Soc., 1984, 29, (4), pp 4–30.CrossRefGoogle Scholar
National, Aeronautical and Space, Administration. Higher Harmonic Control Analysis for Vibration Reduction of Helicopter Rotor Systems, NASA TM 103855, 1994.Google Scholar
Kessler, C. Active rotor control for helicopters: motivation and survey on higher harmonic control, CEAS Aeronaut. J., 2011, 1, (1–4).CrossRefGoogle Scholar
Kessler, C. Active rotor control for helicopters: individual blade control and swashplateless rotor designs, CEAS Aeronaut. J., 2011, 1, (1–4).CrossRefGoogle Scholar
Friedmann, P. On-blade control of rotor vibration, noise, and performance: just around the corner?, J. Am. Helicopter Soc., 2014, 59, (4), pp 041001-1–041001-37.CrossRefGoogle Scholar
Küfmann, P. and Brillante, C. In-flight tracking and vibration control using the DLR’s multiple swashplate system, CEAS Aeronaut. J., 2017, 8, (4), pp 637–652. doi 10.1007/s13272-017-0265-0 CrossRefGoogle Scholar
Küfmann, P., Bartels, R. and van der Wall, B. Rotor performance enhancement via localized pitch control and its effects on hub vibrations and pitch link loads, CEAS Aeronaut. J., 2016, 8, (2), pp 181–196. doi: 10.1007/s13272-016-0233-0.CrossRefGoogle Scholar
Krishnamurthi, J. and Gandhi, F. Chord-extension morphing for active rotor track and balance, 2018 AIAA/AHS Adaptive Structures Conference, Kissimmee, FL, USA, 2018. doi: 10.2514/6.2018-0798.CrossRefGoogle Scholar
Majeti, R., van der Wall, B. and Balzarek, C. Linearly variable chord-extension morphing for helicopter rotor blades, CEAS Aeronaut. J., 2020, 12, (1), pp 55–67. https://doi.org/10.1007/s13272-020-00477-4.CrossRefGoogle Scholar
McKay, M., Niemiec, R. and Gandhi, F. Performance comparison of quadcopters with variable-RPM and variable-pitch rotors, J. Am. Helicopter Soc., 2019, 64, (4), pp 042006-1–042006-14.CrossRefGoogle Scholar
Kopyt, N., Niemiec, R. and Gandhi, F. Quadcopter rotor phasing for minimization of aircraft vibratory loads, Transformative Vertical Flight, San Jose, CA, USA, 2020.Google Scholar
Russell, C., Jung, J., Willink, G. and Glasner, B. Wind tunnel and hover performance test results for multicopter UAS vehicles, AHS Forum 72, 2016.Google Scholar
Russell, C. and Conley, S. The multirotor test bed - a new NASA test capability for advanced VTOL rotorcraft configurations, VFS Forum 76, 2020.Google Scholar
Conley, S., Russell, C., Kallstrom, K., Koning, W. and Romander, E. Comparing RotCFD predictions of the multirotor test bed with experimental results, VFS Forum 76, 2020.Google Scholar
Staruk, W., Butt, L., Hennig, G., Bonny, E., Gray, C., Represa, D. and Toner, R. Wind tunnel testing and analysis of a rigid, variable speed rotor for eVTOL applications, VFS Forum 76, 2020.Google Scholar
Niemiec, R. and Gandhi, F. Development and validation of the Rensselaer Multicopter Analysis Code (RMAC): a physics-based comprehensive modeling tool, 75th Vertical Flight Society Annual Forum, Philadelphia, PA, USA, 2019.Google Scholar
Hodges, D. and Dowell, E. Nonlinear Equations of Motion for the Elastic Bending and Torsion of Twisted Nonuniform Rotor Blades, NASA TN D-7818, 1974.Google Scholar
Peters, D., Boyd, D.D. and He, C. Finite-state induced-flow model for rotors in hover and forward flight, J. Am. Helicopter Soc., 1989, 34, (4), pp 5–17.CrossRefGoogle Scholar
Nowicki, N. Measurement and Modeling of Multicopter UAS Rotor Blade Deflection in Hover, Thesis, KTH - Royal Institute of Technology, 2016.Google Scholar
Niemiec, R. and Gandhi, F. Multirotor coordinate transform for orthogonal primary and redundant control modes on regular hexacopters and octocopters, 42nd European Rotorcraft Forum, Lille, France, 2016.Google Scholar