A model of a three dimensional dual sidestay landing gear mechanism is presented and applied to an investigation of the mechanism downlock sensitivity to attachment point deflections. Motivation for this is provided by a desire to understand the underlying nonlinear behaviour which may prevent a dual sidestay landing gear from downlocking under certain conditions. The model formulates the mechanism as a set of steady-state constraint equations. Solutions to these equations are then numerically continued through state and parameter space, providing all state-parameter dependencies within the model from a single continuation. The analysis flexibility offered by this approach is demonstrated with an investigation into the effects of the aft sidestay angle on retraction actuator loads. It was found that the retraction loads are not significantly affected by the sidestay plane angle, but the landing gear's ability to be retracted fully is impeded at certain sidestay plane angles. This result is attributed to the landing gear's geometry, as the locklinks are placed under tension and cause the mechanism to lock. Sidestay flexibilities are then introduced to enable the downlock loads to be investigated. The investigation into the dual sidestay's downlock sensitivity to attachment point deflections yields an underlying double hysteresis loop, which is highly sensitive to attachment point deflections. Even deflections of a few millimetres were found to prevent the locklinks from automatically downlocking under their own weight, requiring some external force to downlock the landing gear. Sidestay stiffness was also found to influence the downlock loads, although not to the extent of attachment point deflection.
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