Shimmy vibration analysis of unmanned aircraft coupled with landing gears

The stability of aircraft during taxiing is an important issue in the development of landing gear and airworthiness certification. Incidents and abnormal problems consistently arise due to landing gear shimmy. The integration of a model involving tricycle landing gear and aircraft structure is a major advancement in addressing shimmy oscillations. A formulated nonlinear mathematical modeling approach integrates airframe motions with landing gear modes, which provides deep insights into their coupling effect. It effectively determines the critical speed region and types of shimmy oscillations that can occur. An increase in landing gear shimmy intensifies lateral forces on landing gear components, which affects the yaw motion of the aircraft. The optimization of aircraft mass, the critical value of torsional damping, and their influence on directional stability are investigated. This work is useful in the conceptual design of landing gears and in avoiding the potential risks associated with shimmy oscillations to extend the lifespan of landing gears.