DESIGN, ANALYSIS, AND TEST OF A COMPOSITE TAILORED TILTROTOR WING

A composite tailored tiltrotor wing was designed and tested on a 1/5-scale semispan aeroelastic model to demonstrate that composite tailoring techniques can be used to improve proprotor stability. Structural tailoring of the model-scale wing torque box is accomplished by using unbalanced composite laminates to modify wing bending torsion coupling, which is shown analytically to improve proprotor stability in high-speed airplane mode flight. The analytical methodologies used to develop the math models and predict the improved aeroelastic stability characteristics of the composite tailored wing are discussed. The frequency and damping characteristics of the critical wing beam and wing chord modes were measured during wind tunnel tests performed in airplane mode. The structural modes were excited at their natural frequencies and the damping values were measured from the time history decays following the excitations. The composite tailored-wing aeroelastic stability boundary is compared to the stability boundary of a baseline untailored wing configuration. Finally, the modal damping and measured instabilities are then compared to analytical predictions for both the baseline and tailored-wing configurations.