HEAVE STIFFNESS OF AN AIR-CUSHION VEHICLE BAG-AND-FINGER SKIRT

The heave stiffness of a bag-and-finger flexible skirt air cushion is investigated analytically and experimentally. The investigations use a two-dimensional section of the skirt confined between end-plates and moving in heave. This simplified geometry facilitates analysis involvi ng a minimum of empiricism. Experiments show that the airflows, includ ing leaks between fingers and at the end-plates, can be modeled as ori fice-like. The analysis assumes that the fingers can be modeled as rig id massless bodies. Three models of the bag, based on combinations of massless inelastic membranes and rigid links, are investigated. The pr edictions and experiments are in good agreement and show that modest g eometry changes can have large effects on heave stiffness. It is sugge sted that these simple skirt models can provide useful insights into t he dynamics.