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Aeroelastic modelling and stability analysis of tiltrotor aircraft in conversion flight

Published online by Cambridge University Press:  12 September 2018

Z. Li Open the ORCID record for Z. Li [Opens in a new window]  and
P. Xia Open the ORCID record for P. Xia [Opens in a new window]
Z. Li
Affiliation:
National Key Laboratory of Rotorcraft AeromechanicsCollege of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing, China
P. Xia*
Affiliation:
National Key Laboratory of Rotorcraft AeromechanicsCollege of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing, China
*
xiapq@nuaa.edu.cn
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Abstract

In conversion flight, the aeroelastic modelling of tiltrotor aircraft needs to consider the unsteady effect of the rotor wake bending due to the rotor tilting. In this paper, the unsteady models of the rotor wake bending and dynamic inflow have been introduced into the aeroelastic modelling of the tiltrotor aircraft in conversion flight by using Hamilton’s generalized principle. The method for solving the aeroelastic stability of tiltrotor aircraft in conversion flight has been established by using the small perturbation theory and the Floquet theory. The influences of unsteady dynamic inflow on trim control inputs and aeroelastic stability of a tiltrotor aircraft in conversion flight were calculated and analysed. The calculation results show that the required collective pitch increases with the pylon tilting forward and the unsteady inflow is trimmed primarily by the lateral cyclic pitch of the rotor. The wake bending unsteady dynamic inflow can obviously reduce the stability of the flapping modes of the rotor, and have no obvious influence on the lag modes of the rotor and the motion modes of the wing. The instability of tiltrotor occurs in the chordwise bending mode of the wing when the pylon tilts to a certain angle in high speed forward flight.

Keywords

Tiltrotor aircraftconversion flightaeroelastic stabilityrotor wake bendingdynamic inflowunsteady aerodynamic forces
Type
Research Article
Information
The Aeronautical Journal , Volume 122 , Issue 1256 , October 2018 , pp. 1606 - 1629
Copyright
© Royal Aeronautical Society 2018 

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