An aeroelastic stability study for a wing-pylon-tilt rotor system in hover

A simple structural model is combined with the two-dimensional quasi-steady aerodynamics to examine the aeroelastic behavior of a three-bladed wing-pylon-tilt rotor assembly in hover. The structural model accounts for the chordwise, transvers, and torsional wing and blade deformations, as well as for rigid pylon pitching motion with respect to the wing in its deformed position. The model accounts for the equivalent viscous damping associated with blade and wing elastic deformations and damping associated with rigid pylon pitching motion. This study examines the effect of various system parameters on its aeroelastic behavior. It presents the stability boundaries over a practical range of rotor speed in terms of blade-to-wing bending rigidity ratio, uncoupled pylon pitching frequency, and equivalent viscous damping, associated with flexible wing and blade deformations and rigid pylon pitching motion.