OVERVIEW OF UTIAS RESEARCH ON THE DYNAMIC STABILITY OF AIR CUSHION VEHICLES.

Dynamic instabilities have been encountered by a number of Canadian operators of air cushion vehicles. This paper gives an overview of research at the University of Toronto, Institute for Aerospace Studies (UTIAS), dedicated to understanding the phenomenon. Included is a brief review of theoretical and experimental work on the destabilizing effect of cushion air supply ducts. The duct-plenum system is shown to behave as a Helmholtz resonator with the slug of air in the duct oscillating on the plenum air spring. For this work, a unique facility was developed which used a large hollow sphere as a pneumatic filter to isolate the duct-plenum system from the fan. The paper also outlines recently completed work on limit cycle oscillations, skirt material damping, large air cushion platforms, and air cushions hovering over water.