Dynamic Tilting Coupled Flight Dynamics Modeling and Analysis of Tiltrotor Aircraft

To analyze the coupling effects induced by rotor tilting motion, this paper proposes an augmented flight dynamics model that incorporates its dynamic tilting characteristics. In the modeling of tilting components, a nacelle tilting dynamics model is developed by analyzing the multi-body kinematic relationships among the rotor, nacelle, and airframe. The airframe modeling accounts for the wake distortion, aerodynamic interference, and structural parameter variations induced by the rotor's dynamic tilting. Subsequently, the model’s accuracy is validated against flight test data and literature data. Finally, we analyze the mechanism by which dynamic tilting affects aircraft stability. The results indicate that nacelle motion induces a reduction in rotor pitch damping, with the magnitude of reduction initially increasing and subsequently decreasing as the nacelle tilts forward. The longitudinal stability of the aircraft, modulated by nacelle motion, initially deteriorates and subsequently recovers as the nacelle tilts forward. The stability of the nacelle tilt motion is governed by variations in angular velocity.