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Investigation of Lift Offset on Flight Dynamics Characteristics for Coaxial Compound Helicopters

Ye Yuan Orcid Logo, Douglas Thomson, Renliang Chen

Journal of Aircraft, Volume: 56, Issue: 6, Pages: 2210 - 2222

Swansea University Author: Ye Yuan Orcid Logo

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DOI (Published version): 10.2514/1.c035190

Abstract

The coaxial compound helicopters adopt the Lift-Offset (LOS) strategy to improve the rotor performance in high speed flight, which influences the flight dynamics characteristics of the vehicle. Thus, a flight dynamics model and an inverse simulation method are developed to assess the effect of LOS o...

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Published in: Journal of Aircraft
ISSN: 1533-3868
Published: American Institute of Aeronautics and Astronautics (AIAA) 2019
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URI: https://cronfa.swan.ac.uk/Record/cronfa58279
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Abstract: The coaxial compound helicopters adopt the Lift-Offset (LOS) strategy to improve the rotor performance in high speed flight, which influences the flight dynamics characteristics of the vehicle. Thus, a flight dynamics model and an inverse simulation method are developed to assess the effect of LOS on this helicopter. The trim results demonstrate that LOS reduces the collective and the longitudinal cyclic pitch across the flight range, and it also adds the control input of the propeller collective in hover and lower speed forward flight. LOS control strategy reduces the power consumption and increases the maximum flight speed. Also, LOS control strategy is affected by the gross weight. Furthermore, the stability is dependent on LOS due to its effect on the rotor efficiency and flapping motion. From the controllability results, LOS brings about severe coupling between the rolling moment and the collective differential input. Lastly, the Pull-up & Push-over and the Transient Turn Mission-Task-Elements (MTEs) with different LOS control strategies are assessed with inverse simulation. The results show that a reasonable LOS control strategy could not only reduce the power consumption but also have a positive influence on the oscillation in control inputs during the manoeuvre.
Keywords: Flight Dynamics, Rotor Systems, Propellers, High Speed Flight, Aerodynamic Characteristics, Coaxial Rotor, Flapping Frequency, Aerodynamic Efficiency, Fuselages, Flight Testing
College: Faculty of Science and Engineering
Issue: 6
Start Page: 2210
End Page: 2222