Experimental aeroelastic behavior of forward-swept graphite/epoxy wings with rigid-body freedom

Abstract

An analytical and experimental investigation was made of the aeroelastic flutter and divergence behavior of graphite/epoxy forward-swept wings with rigid-body pitch and plunge freedoms present. A complete, two-sided, 30 deg forward-swept wing aircraft model was constructed and mounted with low-friction bearings in a lowspeed wind tunnel. Four different ply layup wings could be interchanged on the model, namely, [02/90]s, [152/0]s, [302/0]s, and [ -152/0]s. Wind-tunnel tests on the free*'-flying models revealed body freedom flutter, bending-torsion flutter, and a support dynamic instability that could be eliminated by proper adjustment of the support stiffness. Good agreement with linear theory was found for all the observed instabilities. Additional tests on the models with rigid-body pitch only gave lower critical speeds, while tests on the cantilever wings gave higher speeds. The [152/0] s wing gave the best tailored aeroelastic behavior.