Abstract:

A hydraulic model of landing gear shimmy dampers is introduced into the shimmy equations replacing the linear or quadratic damping coefficients. The fluid compressibility caused by contained free air is taken into consideration in the differential equation of the dampers, in which variable bulk moduli are adopted. Then the shimmy equations are employed to simulate the aircraft nose landing gear shimmy. The shimmy frequencies are obtained through the FFT. The simulation results, such as the amplitudes and the frequencies of shimmy, the effects of the fluid compressibility, etc. agree well with those measured in the taxi test of the prototype of K8 aircraft.

Key words: w heel shimmy, landing g ears, landing gear shimmy damper s, digital simulation, hydra ulicdamper s