Gear Walk Instability Studies Using a Vibration Model of a Reduced Scale Landing Gear System

Abstract

Gear walk is a dynamic instability condition that can pose serious harm to an aircraft and its passengers. The instability is believed to be borne as a result of braking, in which vibration of the landing gear can be induced generating motion reminiscent of a walking movement. This paper focuses on the theoretical account of a Reduced Scale Landing Gear (RSLG) apparatus and studies gear walk phenomenon. The mathematical approach involves lumped-parameter model representation of the RSLG that accounts for the landing gear’s struts, the wheels and the caliper-disc brake dynamics. The theoretical treatment of the RSLG apparatus entails consideration of the structure of the device that includes the account of dynamic response of the assembly consisting of a fuselage, two struts and two wheels. Various physical and geometrical parameters are determined and included in the mathematical model of the apparatus. It is demonstrated that the occurrence of gear walk vibration is greatly influenced by the structural stiffness of the system. Both synchronous and 180° out of phase motion of the struts are generated in a parametric study in which structural stiffness is varied.