Flutter/limit cycle oscillation analysis and experiment for wing-store model

A delta wing experimental model with an external store has been designed and tested in the Duke University wind tunnel. The wing structure is' modeled theoretically by using von I Karman plate theory that allows for geometric strain-displacement nonlinearities in the plate wing structure. A component modal analysis is used to derive the full structural equations of motion for the wing/store combination system. A three-dimensional time domain vortex lattice aerodynamic model including a reduced-order model aerodynamic technique and a slender-body aerodynamic theory for the store are also used to investigate the nonlinear aeroelastic system. The effects of the store pitch stiffness (attachment stiffness), the span location of store, and the store aerodynamics on the critical flutter velocity and limit cycle oscillations (LCO) are discussed. The correlations between the theory and experiment are good for both the critical flutter velocity and frequency but not good for the LCO amplitude, especially when the store is located near the wing tip. The theoretical structural model needs to be improved to determine LCO response, and improved results are shown in the companion paper as obtained with a higher-order structural model.