Tracked Air Cushion Vehicle Suspension Models: Analysis and Comparison

In this paper several dynamical models of fluid suspensions for tracked air cushion vehicles are analyzed and compared. Specifically, the models considered conform to: a fifth-order linear suspension, a nonlinear configuration with a constant supply pressure, a nonlinear model with compressor characteristics, and a sixth-order nonlinear model with a supply duct connecting the compressor to the cushion chamber. Nonlinearities included in the analysis are the flexible-skirted cushion capacitance, cushion entrance and exit orifice restrictions, feeding system duct fluid capacitance, and compressor pressure-flow characteristics. Temporal responses are obtained for guideway and external force inputs. Back flow conditions under which the supply compressor can stall are examined. It is shown that the general behavior resulting from linear analysis is in many respects similar to that obtained from the nonlinear analysis. Thus, a linear model could provide a good initial basis for a preliminary design and performance specifications.