Underwing Missile Control-Surface Effects on Aircraft Limit Cycle Oscillations

摘要

The flutter characteristics of the F-16 are very sensitive to the weapon carriage configuration. The aircraft has two dedicated missile carriage stations on the outboard portion of each wing located at and near the wing tip. Carriage of AIM-9 missiles at these locations is known to contribute to the nonlinear flutter behavior referred to as limit cycle oscillations (LCOs). The study of missile carriage effects on LCO can aid in the understanding of the underlying mechanisms that drive and limit these oscillations. Investigations of this nature are central to the future development of a theoretical foundation for predicting the occurrence of LCO. It was shown inthat wing deformations during LCO are very similar to wing deformations predicted by linear flutter analyses, especially at the onset of the LCO. These similarities established the connection between flutter and LCO, implying that the fundamental instability mechanism is the same. However, the wing deformation characteristics during LCO were observed to vary significantly with respect to the Mach number and load factor, leading to the conjecture that these deformation changes indicated an alteration in the underlying driving mechanism. The influence of the Mach number on the LCO wing deformation characteristics suggests that a "bounding" mechanism that turns a divergent flutter oscillation into a limit cycle oscillation could be aerodynamic in nature.