Abstract: A fluid flow control system for connecting a source of pressurized fluid with a region of varying pressure, comprises a fluid supply duct having an inlet end connectable to the pressure source end and an outlet end connectable to the region of varying pressure, a vent duct disposed between the inlet and outlet ends, and a vent valve sensitive to change in pressure within the supply duct and operable so as to control the escape of fluid from the supply duct. The vent valve preferably comprises a flexible wall member of hollow, inflatable form. In operation of the system, a relatively small amount of fluid is allowed to escape when pressure at or adjacent the outlet end of the supply duct is substantially less than that at or adjacent the inlet end thereof, and a relatively large amount of fluid is allowed to escape when the pressure differential is reversed. The system is particularly useful as a "ride" control for gas-cushion vehicles operating over rough ground or water.

Abstract: A marine vehicle, which may comprise a sidewall gas-cushion vehicle, is provided with a pair of steering rudders, a sensor for detecting incipient undesirable motions of the vehicle, and an electrical, mechanical, and/or hydraulic system, or a hybrid thereof, for operating the rudders so as to apply restoring forces to the vehicle. The steering rudders are mounted beneath the vehicle and on opposite sides of the longitudinal axis thereof, being disposed in planes which are inclined to the vertical and which intersect above the rudders. The sensor for detecting incipient undesirable motions of the vehicle may comprise an angular rate and/or an accelerometer. The signal output of the sensor is applied to a band pass filter of pre-determined transfer function and the filtered sensing signal is applied to a summing point, to which is also applied a steering command signal.

Abstract: Fluid-cushion supported apparatus, which may comprise a sidewall gas-cushion vehicle, is supported by a cushion of pressurized air formed and contained between the vehicle body and the surface. The front or bow end of the cushion is contained by an inflatable flexible skirt system comprising a row of ropes or like filamentary support members disposed in spaced, substantially parallel, relationship, with their end portions attached to the vehicle body. Flexible sheet material is draped over the support members so as to form loops extending laterally therebetween. The loops are also curved between the end portions of the support members.

Abstract: A gas-cushion vehicle is provided with a system for reducing dynamic variations in cushion gas pressure. The system comprises a gas-flow outlet connection between a space occupied by cushion gas and the atmosphere. A flexible wall member of inflatable form is disposed within the connection and is operable so as to allow cushion gas to escape to the atmosphere as cushion pressure tends to increase, and to impede the escape of cushion gas as cushion pressure tends to decrease. The flexible wall member provides a flexible barrier maintaining a pressure differential between the space occupied by cushion gas and the atmosphere. Dynamic variations in cushion pressure will alter this pressure differential and the resistance to the escape of cushion gas offered by the wall member will then alter accordingly, so that, if the cushion pressure rises, the resistance will be too weak to contain this pressure and the wall member will deflect to allow cushion gas to escape through the connection.

Abstract: A sidewall gas-cushion vehicle is provided with movable buoyancy members, each comprising a buoyant portion of relatively large volume and a web support portion of relatively little volume. The buoyancy members are pivotally connected to the bottoms of the sidewalls by way of their web support portions to the sidewalls, the members being movable about axes extending substantially parallel to the longitudinal axis of the vehicle. In fully submerged operative positions extending below the sidewalls for low speed operation, sufficient hydrostatic forces are applied to the fully submerged buoyant portions of the members to provide buoyancy lift for the vehicle and to counter unwanted movements of the vehicle. In inoperative positions retracted alongside the sidewalls for high speed operation the buoyant portions lie substantially above the operational waterline.

Abstract: A sidewall gas-cushion vehicle is provided with hydrofoils carried in recesses defined by the sidewalls and capable of being extended into an operable position or of being retracted into an inoperative position. The foils may be used to generate lift forces and/or to counter unwanted movements of the vehicle, such as heave, roll and pitching motions. The lift forces can be made positive or negative.

Abstract: A sidewall gas-cushion vehicle is provided with a panel movable in the bottom of the vehicle body in response to changes in cushion pressure whereby the cushion volume is increased as cushion pressure tends to increase, and vice-versa. Panel movement is controllable so as to vary the degree of response to changes in cushion pressure, and upward movement of the panel is retarded by dash-pot devices.