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Abstract. The flutter of a tapered viscoelastic wing carrying an engine and subjected to a follower thrust force is investigated. The wing is considered as a cantilever tapered EulerBernoulli beam, made of a linear viscoelastic material where Kelvin-Voigt model is assumed to represent the viscoelastic behaviour of the material. In addition, quasi-steady and unsteady aerodynamic forces models are introduced along with the follower thrust force. The mass and inertia of the engine are modelled in order to achieve more realistic behaviour of the engine upon flutter characteristics of the system. Moreover, the governing equations of motion are derived through the Extended Hamilton's Principle. The generalized function theory is used to more accurately consider the contribution of the mass and its follower force in the governing equations. The resulting partial differential equations are solved by Galerkin method along with the classical flutter investigation approach. Parametric studies highlighting the sensitivity of the chord-wise engine location, the span-wise engine location, and the vertical engine location on the flutter speed and flutter frequency are reported. It is found that the location of the engine in the three directions play an important role in the dynamic stability of the wing. IntroductionAeroelasticity is the term used to denote the field of study concerned with the interaction among aerodynamics, elasticity, inertia forces, and the phenomena that can result. Aeroelastic phenomena are usually classified as being either static (as the divergence) or dynamic (as the flutter). Divergence is a phenomenon that occurs when the moments resulting from aerodynamic forces overcome the elastic restoring forces due to structural stiffness. The flutter is defined as a dynamic lack of stability that occurs in a flexible structure subjected to aerodynamic loads at certain speed and frequency -called the flutter speed and the flutter frequency -which cause the structure to undergo divergent oscillations. Bending-torsion aeroelastic instabilities have been investigated by many authors. References [1] and [2] studied the flutter phenomenon of a uniform wing by analysing a set of partial differential equations governing the motion of the wing. The use of quasi-steady aerodynamic theory for aeroelastic analysis of the lifting surfaces is a good approximation in the field of aeroelasticity as found in [3][4][5][6], and others. In Reference [7], a systematic approach based on Galerkin method was developed to investigate the flutter speed and frequency for a wing subjected to quasi-steady aerodynamic forces. The quasi-steady aerodynamic model can be used for low frequencies with acceptable results as investigated in [8]. However, Reference [9] observed that the quasi-steady

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