In the present work, computational analyses on aeroelastic instability of an aircraft wing are conducted. A jet fighter wing with different armament configurations is evaluated. Aeroelastic instability, i.e., divergence and flutter, occurs as the aerodynamic loads interact with the structure and may lead to a catastrophic phenomenon, i.e., amplified deformation or oscillation. In a case of a jet fighter, the armaments affect the inertial, and further, the structural dynamic characteristics of the aircraft or wing. In the current study, the variation of armament’s placement and computational model is investigated. The structure of the wing and its armaments is modelled by means of Finite Element Method (FEM). The aerodynamic model of the wing is constructed using frequency domain – based methods, Doublet Lattice Method (DLM) and Piston theory for subsonic and supersonic regimes, respectively. The shifting of armament center of gravity further from elastic axis causes flutter to occur in a lower speed. In addition, the increase in mass moment of inertia also gives the same effects.