Research on the down locking performance of dual side stay landing gear for large civil aircraft

The side brace and drag brace of the dual side stay landing gear are always in two planes during the process of retracting and extending, which is a typical statically indeterminate mechanism. Taking the prototype of a certain type of civil aircraft landing gear principle as the research object, using LMS virtual lab.motion and AMEsim software to establish a simulation model to analyse the effects of unlocking actuator, down lock spring, and aerodynamic load on the landing gear's locking performance. The research found that the effective size of the annular flow passage of the unlocking actuator can prevent the impact load caused by the rapid deployment of the locking link. A large down-lock spring load can help keep the landing gear in the down position, but if the load is too high, it affects the design of the unlocking actuator. Heading aerodynamic loads can cause delays in locking the AFT side brace of the landing gear, with excessive heading aerodynamic loads even preventing the landing gear from achieving the downlock position. Wing deformation can lead to displacement of the landing gear attachment points, affecting the downlock status of the landing gear.