Experimental and theoretical study of gust response for a wing–store model with freeplay

An experimental delta wing/store model with freeplay in a periodic gust field has been designed and tested in the Duke wind tunnel. The wing structure is modeled theoretically using von Karman plate theory that accounts 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 system. A 3-D 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 freeplay gap, the gust angle of attack and the initial conditions on the gust response are discussed. The quantitative correlations between the theory and experiment are reasonably good, but in the range of the dominant resonant frequency of this nonlinear system, i.e. at larger response amplitudes, the correlations are not good. The theoretical structural model needs to be improved to determine larger amplitude motions near the resonant frequency.