Abstract: Noise due to the rotation of the air propeller or fan of an air-cushion vehicle is reduced by: 1) reducing the cross-sectional area of the interior of a duct encompassing the fan on the downstream side relative to the upstream side; 2) using wide-chord fan blades of chords increasing from blade root to tip; 3) using a duct and a nose cone on the hub of the fan both having a sound-absoring structure; and 4) mounting the engine and the duct on a common rigid support base and reducing to a minimum the tip clearance between the tips of the fan blades and the duct inner wall surface.

Abstract: A propulsive air stream deflecting apparatus for an air cushion vehicle is provided on the hull of the air cushion vehicle for arcuately deflecting the propulsive air stream from the open rear end of the air duct, mounted to the hull. The deflecting mechanism provides a steering thrust to the air cushion vehicle. The deflecting mechanism is pivotable about a vertical pivot mounted to the hull between a propulsive thrust producing position, where the deflecting mechanism is located away from the propulsive air stream issuing from the rear open end of the air duct, and a forward thrust producing position where the deflecting mechanism fully covers the rear open end of the air duct for deflecting the propulsive air stream to create the forward thrust to the hull.

Abstract: A finger skirt for an air-cushion vehicle wherein the bottom edge of each finger skirt, when it is in the state of inflation by the pressurized air for the levitation of the hull, is shaped so that it extends horizontally at the location where it comes in contact with the pressure-receiving surface, the bottom edge being formed so that its cross section is a circular arc.