A 4.75-ft-diameter, dynamically scaled, swept-tip proprotor was tested up to 200 kts. The stability roots (frequencies and damping) were collected for wing-pylon beam, chord, and torsion motions. The impacts of both gimbaled and gimbal-locked hubs were measured. Predictions from an in-house rotor aeromechanics solver were compared with data to understand the stability behavior and identify gaps in prediction capabilities. The data showed that swept-tip blades increased the damping of the wing ch