Design and stiffness analysis of an overconstrained landing gear retraction mechanism with four side-stays

Abstract

It is the first mission for a landing gear retraction system to extend the structure during the phases of take-off and landing of the flight. Besides, the structure should be available to improve the reliability, strength and stability of the system while reducing the influence of the landing gear on the total drag. However, a large number of airplane accidents are due to the malfunctions or failures of the landing gear retraction system. In this paper, a novel design of retraction system is proposed. Instead of having only one side-stay to execute the desired motion, this new design proposed an over-constrained mechanism with four side-stays, which augments the structural strength and stability of the landing gear system with six over constraints. With such configuration, a second actuating motor to retract the landing gear can be inserted regardless of the first actuator to augment the reliability on the execution of the mechanism. Analyses on the properties of the landing gear retraction system with four side-stays show that the landing gear strut has a vertical motion, which decreases the working and storage spaces used for the system. Finally, this paper examines the statics and the stiffness coefficients of the retraction system with respect to its structure parameters. This provides the optimum structure for the landing gear system in terms of strength and reliability.