Analysis of a Semi-Levered Suspension Landing Gear With Some Parametric Study

A set of nonlinear differential equations describing the response of a semilevered suspension type of landing gear with a single stage oleo-pneumatic shock strut is derived. This includes the kinematics of the articulation of the gear, oil compressibility effect, wheel spin-up as a function of slip ratio, and the hydraulic, pneumatic, and friction forces of the shock strut. A parametric study on a gear of a helicopter has been conducted and the effect of variations in the main orifice diameter, coefficient of discharge of main orifice, initial air volume and pressure, polytropic exponent for air compression process, coefficients of friction at lower and upper bearings and the horizontal velocity of the aircraft during landing on the behavior of the landing gear has been studied.