Gas-cushion vehicles

A gas-cushion vehicle provided with a means for forming a vehicle-supporting cushion of pressurized gas between the vehicle body and the surface over which the vehicle travels and provided with a means for containing the vehicle-supporting cushion about its periphery, the vehicle comprising:

• a gas-flow outlet connection through a portion of the vehicle between a space occupied by cushion gas and the atmosphere, the gas-flow outlet connection having a sealing surface;
• and,
• a flexible, hollow wall member disposed within the outlet connection and inflatable to an operating pressure, the sealing surface of the gas-flow outlet connection and the inflatable member together forming a valve which is automatically operable in response to variations in cushion pressure so as to allow cushion gas to escape to the atmosphere by collapsing when cushion pressure exceeds the operating pressure, and so as to impede the escape of cushion gas by reinflating when cushion pressure falls below the operating pressure, whereby dynamic variations in gas cushion pressure are substantially reduced without disturbing the vehicle-terrain interface.