A bifurcation study of a dynamic model of a nose landing gear mechanism subjected to external disturbances

This paper presents a new modelling approach for the analysis of landing gear mechanisms. By replacing the mechanism's rotational joints with equivalent high-stiffness elastic joints, numerical continuation methods can be applied directly to dynamic models of landing gear mechanisms. The effects of using elastic joints are considered through two applications --| an overcentre mechanism, and a nose landing gear mechanism. In both cases, selecting a suffcient stiffness for the elastic joint is shown to provide accurate contiuation results. The advantages of this new modelling approach are then demonstrated by considering the unlocking of a nose landing gear with a single uplock/downlock mechanism, when subjected to different orientations and magnitudes of gravitational loading. The unlocking process is shown to be qualitatively insensitive to changes in both load angle and load magnitude, ratifying the robustness of a previously- proposed control methodology for unlocking a nose landing gear with a single uplock/downlock mechanism.