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Variable rotor speed strategy for coaxial compound helicopters with lift–offset rotors

Part of: 75 year anniversary of Aeronautical Engineering at Glasgow University

Published online by Cambridge University Press:  27 September 2019

Y. Yuan Open the ORCID record for Y. Yuan [Opens in a new window] ,
D. Thomson  and
R. Chen Open the ORCID record for R. Chen [Opens in a new window]
Y. Yuan
Affiliation:
National Key Laboratory of Rotorcraft Aeromechanics, Nanjing University of Aeronautics & Astronautics, Nanjing, China University of Glasgow, Glasgow, Scotland, UK
D. Thomson
Affiliation:
University of Glasgow, Glasgow, Scotland, UK
R. Chen*
Affiliation:
National Key Laboratory of Rotorcraft Aeromechanics, Nanjing University of Aeronautics & Astronautics, NanjingChina
*
[email protected]
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Abstract

The coaxial compound helicopter with lift-offset rotors has been proposed as a concept for future high-performance rotorcraft. This helicopter usually utilizes a variable-speed rotor system to improve the high-speed performance and the cruise efficiency. A flight dynamics model of this helicopter associated with rotor speed governor/engine model is used in this article to investigate the effect of the rotor speed change and to study the variable rotor speed strategy. Firstly, the power-required results at various rotor rotational speeds are calculated. This comparison indicates that choice of rotor speed can reduce the power consumption, and the rotor speed has to be reduced in high-speed flight due to the compressibility effects at the blade tip region. Furthermore, the rotor speed strategy in trim is obtained by optimizing the power required. It is demonstrated that the variable rotor speed successfully improves the performance across the flight range, but especially in the mid-speed range, where the rotor speed strategy can reduce the overall power consumption by around 15%. To investigate the impact of the rotor speed strategy on the flight dynamics properties, the trim characteristics, the bandwidth and phase delay, and eigenvalues are investigated. It is shown that the reduction of the rotor speed alters the flight dynamics characteristics as it affects the stability, damping, and control power provided by the coaxial rotor. However, the handling qualities requirements are still satisfied with different rotor speed strategies. Finally, a rotor speed strategy associated with the collective pitch is designed for maneuvering flight considering the normal load factor. Inverse simulation is used to investigate this strategy on maneuverability in the Push-up & Pull-over Mission-Task-Element (MTE). It is shown that the helicopter can achieve Level 1 ratings with this rotor speed strategy. In addition, the rotor speed strategy could further reduce the power consumption and pilot workload during the maneuver.

Keywords

coaxial compound helicopterflight dynamicshelicopter performancemaneuverabilitycontrol strategy
Type
Research Article
Information
The Aeronautical Journal , Volume 124 , Issue 1271 , January 2020 , pp. 96 - 120
Copyright
© Royal Aeronautical Society 2019 

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References

REFERENCES

Rand, O. and Khromov, V. Compound helicopter: Insight and optimization, J AM HELICOPTER SOC, 2015, 60, (1), pp 1–12.CrossRefGoogle Scholar
Yeo, H. and Johnson, W. Optimum design of a compound helicopter, J AIRCRAFT, 2009, 46, (4), pp 1210–1221.CrossRefGoogle Scholar
Garavello, A. and Benini, E. Preliminary study on a wide-speed-range helicopter rotor/turboshaft system. J Aircraft, 2012, 49, (4), pp 1032–1038.CrossRefGoogle Scholar
Ormiston, R.A. Revitalizing Advanced Rotorcraft Research—and the Compound Helicopter: 35th AHS Alexander A. Nikolsky Honorary Lecture, J AM HELICOPTER SOC, 2016, 61, (1), pp 1–23.CrossRefGoogle Scholar
Puri, A. A survey of unmanned aerial vehicles (UAV) for traffic surveillance, 2005, Department of computer science and engineering, University of South Florida, pp 1–29.Google Scholar
Guo, W. and Horn, J. Rotor state feedback control for rotorcraft with variable rotor speed, AIAA Guidance, Navigation, and Control Conference, Chicage, Illinois, 10-13 August, 2009. AIAA-2009-5797.CrossRefGoogle Scholar
Padfield, G.D. Helicopter flight dynamics: the theory and application of flying qualities and simulation modelling. John Wiley & Sons, 2008, New Jersey, US.Google Scholar
Burgess, R.K. The ABCTM Rotor — A Historical Perspective, American Helicopter Society 60th Annual Forum, Baltimore, Maryland, USA, 7-10 June, 2004, 60, pp 2306–2352.Google Scholar
Yeo, H. and Johnson, W. Investigation of maximum blade loading capability of lift-offset rotors, J AM HELICOPTER SOC 2014, 59, (1), pp 1–12.CrossRefGoogle Scholar
Klimchenko, V., Sridharan, A. and Baeder, J.D. CFD/CSD Study of the Aerodynamic Interactions of a Coaxial Rotor in High-Speed Forward Flight. 35th AIAA Applied Aerodynamics Conference, Denver, Colorado, 5–9 June, 2017. AIAA-2017-4454.CrossRefGoogle Scholar
Schmaus, J.H. and Chopra, I. Aeromechanics of Rigid Coaxial Rotor Models for Wind-Tunnel Testing, J AIRCRAFT, 2019, 54, (4), pp 1486–1497.CrossRefGoogle Scholar
Han, D., Wang, J., Smith, E. and Lesieutre, G.A. Transient loads control of a variable speed rotor during lagwise resonance crossing, AIAA J, 2012, 51, (1), pp 20–29.CrossRefGoogle Scholar
Han, D., Pastrikakis, V. and Barakos, G.N. Helicopter performance improvement by variable rotor speed and variable blade twist, AEROSP SCI TECHNOL, 2016, 54, pp 164–173.CrossRefGoogle Scholar
Han, D. and Smith, E.C. Lagwise dynamic analysis of a variable speed rotor, AEROSP SCI TECHNOL, 2013, 29, (1), pp 277–286.CrossRefGoogle Scholar
Han, D. Study on the Performance and Trim of a Helicopter with a Variable Speed Rotor, Acta Aeronautica et Astronautica Sinica, 2013, 34, (6), pp 1241–1248. (In Chinese)Google Scholar
Steiner, J., Gandhi, F. and Yoshizaki, Y. An investigation of variable rotor RPM on performance and trim. American Helicopter Society 64th Annual Forum, Montreal, Quebec, Canada, 29 April-1 May, 2008, 64, pp 697–705.Google Scholar
Guo, W. and Horn, J.F. Helicopter flight control with variable rotor speed and torque limiting. American Helicopter Society 65th Annual Forum, Grapevine, Texas, 27–29 May, 2009, 65, pp 1617–1627.Google Scholar
Blackwell, R. and Millott, T. Dynamics design characteristics of the Sikorsky X2 technologyTM demonstrator aircraft. American Helicopter Society 64th Annual Forum, Montreal, Quebec, Canada, 29 April-1 May, 2008, 64, pp 886–898.Google Scholar
Bagai, A. Aerodynamic design of the X2 technology demonstratorTM main rotor blade, American Helicopter Society 64th Annual Forum, Montreal, Quebec, Canada, 29 April-1 May, 2008, 64, pp 29–44.Google Scholar
Ferguson, K. and Thomson, D. Flight dynamics investigation of compound helicopter configurations, J AIRCRAFT, 2014, 52, (1), pp 156–167.CrossRefGoogle Scholar
Yuan, Y., Thomson, D. and Chen, R. Propeller Control Strategy for Coaxial Compound Helicopters, P I MECH ENG G-J AER, October 2018 (Online publish), doi: 10.1177/0954410018806796.CrossRefGoogle Scholar
Ferguson, K. and Thomson, D. Performance comparison between a conventional helicopter and compound helicopter configurations, P I MECH ENG G-J AER, 2015, 229, (13), pp 2441–2456.CrossRefGoogle Scholar
Ferguson, K.M. Towards a better understanding of the flight mechanics of compound helicopter configurations. Diss. University of Glasgow, 2015.CrossRefGoogle Scholar
Gaonkar, G. and Peters, D. Review of dynamic inflow modeling for rotorcraft flight dynamics, 27th Structures, Structural Dynamics and Materials Conference, San Antonio, TX, U.S.A, 19–21 May, 1986, pp 89–110.CrossRefGoogle Scholar
Adiletta, G., Guido, A.R. and Rossi, C. Nonlinear dynamics of a rigid unbalanced rotor in journal bearings. Part I: theoretical analysis. Nonlinear Dynam, 1997, 14, (1), pp 57–87.CrossRefGoogle Scholar
Feil, R, Rauleder, J and Hajek, M. Vibratory Load Predictions of a High-Advance-Ratio Coaxial Rotor System Validated by Wind Tunnel Tests, Proceedings of the 43rd European Rotorcraft Forum Milan, Italy, September 12–15, 2017.Google Scholar
PhelpsIII, A.E. and Mineck, R.E. Aerodynamic characteristics of a counter-rotating, coaxial, hingeless rotor helicopter model with auxiliary propulsion, NASA-TM-78705, NASA Langley Research Center, 1978.Google Scholar
Ruddell, A.J. Advancing Blade Concept (ABC) Technology Demonstrator, USAAVRADCOM TR 81-D-5, United Technologies Corp Stratford ct Sikorsky Aircraft Div, April 1981.Google Scholar
Walsh, D., Weiner, S., Arifian, K., Lawrence, T., Wilson, M., Millott, W. and Blackwell, R. High Airspeed Testing of the Sikorsky X2 Technology TM Demonstrator. American Helicopter Society 67th Annual Forum, Virginia, Beach, Virginia, USA, 3–5 May, 2011, 67, pp 2999–3010.Google Scholar
Hess, R.A., Wang, S.H. and Gao, C. Generalized technique for inverse simulation applied to aircraft manoeuvres, J GUID CONTROL DYNAM , 1991, 14, (5), pp 920–926.CrossRefGoogle Scholar
Celi, R. Optimization-based inverse simulation of a helicopter slalom manoeuvre, J Guid Control Dynam, 2000, 23, (2), pp 289–297.CrossRefGoogle Scholar
Murray-Smith, D.J. The inverse simulation approach: a focused review of methods and applications, MATH COMPUT SIMULAT, 2000, 53, (4), pp 239–247.CrossRefGoogle Scholar
Thomson, D. and Bradley, R. Inverse simulation as a tool for flight dynamics research—Principles and applications, PROG AEROSP SCI, 2006, 42, (3), pp 174–210.CrossRefGoogle Scholar
Standard, Aeronautical Design. Handling Qualities Requirements for Military Rotorcraft. ADS-33E-PRF, Redstone Arsenal, Alabama: US Army Aviation and Missile Command, Aviation Engineering Directorate, 2000.Google Scholar
Reddinger, J.P. and Gandhi, F. Physics-based trim optimization of an articulated slowed-rotor compound helicopter in high-speed flight, J Aircraft, 2015, 52, (6), pp 1756–1766.CrossRefGoogle Scholar
Ho, J.C. and Yeo, H. Assessment of comprehensive analysis predictions of helicopter rotor blade loads in forward flight, J Fluid Struct, 2017, 68, pp 194–223.CrossRefGoogle Scholar
Hong, J., Peters, D.A. and Ormiston, R.A. A dynamic-inflow-based induced power model for general and optimal rotor performance, J Am Helicopter Soc, 2018, 63, (2), pp 1–11.CrossRefGoogle Scholar
Thomson, D.G. and Bradley, R. Development and verification of an algorithm for helicopter inverse simulation, Vertica, 1990, 14, (2), pp 185–200.Google Scholar
Thomson, D.G. and Bradley, R. Mathematical definition of helicopter manoeuvres, J Am Helicopter Soc, 1997, 42, (4), pp 307–309.CrossRefGoogle Scholar
Soneson, G.L., Horn, J.F and Zheng, A. Simulation testing of advanced response types for ship-based rotorcraft. J Am Helicopter Soc, 2016, 61, (3), pp 1–13.CrossRefGoogle Scholar
Shepherd, M.J., MacDonald, A., Gray, W.R. and Cobb, R.G, March. Limited simulator aircraft handling qualities evaluation of an adaptive controller. In 2009 IEEE Aerospace conference, Big Sky, Montana, USA, 7–14, March, 2019, IEEE, pp 1–12.CrossRefGoogle Scholar