Abstract: In an inflatable lifting device comprising an upper platform to support a load, a lower base platform and a flexible, fluidtight diaphragm interposed between the two platforms for inflation to lift the load, the improvement comprising a diaphragm of truncated conical configuration. In some practices of the invention, two such diaphragms are effectively stacked on top of each other to increase the jacking height of the device. Constructuion of the conical diaphragm provides approximately uniform strength of the diaphragm around its entire periphery. Safety means are provided to prevent over-pressurization of the diaphragm at its maximum lifting height. Means are also provided to prevent collapse of the loaded device in the event the fluid supply line should inadvertantly be disconnected.

Abstract: A controllable lifting rotary wing for an aircraft wherein each rotor blade is of torsionally flexible construction and control may be accomplished by twisting the rotor blades. The root end of each blade is mounted to a central hub by means which allow both beamwise flapping and blade twist. The blade root mounting angle may be either variable or fixed. The blade twists uniformly from this root angle to a variable tip angle. Twist of the rotor blades is accomplished through the mechanism of shear flows. Blade twist angle may be automatically established by a balance of dynamic forces on the blade which cause twist angle to increase as root mounting angle is increased. Alternatively, blade twist angle may be manually controlled also. A unique feature of the torsionally flexible blade is that it is hollow throughout its entire span so it is well suited for ducting gases through the interior of the blade to tip-mounted jet propulsion units if desired.

Abstract: In an air cushion load transport vehicle, an annular sealing assembly comprising an annular inflatable hanger on the underside of a load-bearing base and an annular sealing means on the underside of the hanger confines a load-supporting air cushion that is continuously supplied with compressed air during operation. Stability is promoted by a number of design features in the inflatable hanger, the annular sealing means, the flexible connection between them and the load support structure. These include means for automatically closing off flow through hanger damping eyelets during initial hanger pressurization together with means to keep the eyelets open at all operating hanger heights. Additional covered ports are provided in the outer hanger wall positioned to automatically vent if the hanger is over-inflated thereby avoiding dynamic instability. A check valve is incorporated into the device to prevent damage from inadvertantly inflating the hanger before the cushion is pressurized.

Abstract: A controllable lifting rotary wing for an aircraft wherein each rotor blade is mounted in such a manner that it has freedom to oscillate in pitch about its feathering axis. The aerodynamic center on each rotor blade is displaced forward of this feathering axis over at least a portion of the span. Cyclic aerodynamic forces on this spanwise portion cause the blade to change pitch sinusoidally once-per-revolution of the rotor whenever the rotary wing aircraft experiences a change in flight attitude or velocity. The result is that the rotor blades automatically and continuously change pitch to cancel out cyclic lateral flapping moments which are normally produced on a helicopter rotor blade by such a flight disturbance. This rotary wing has greatly improved stability by virtue of this self-feathering action. Cyclic pitch control moments are applied to the rotor blades by indirect means which do not interfere with automatic blade feathering. Means for control of collective pitch of the blades are also provided.

Abstract: An annular sealing member extends to ground level to minimize loss of fluid from a lifting cushion. This member includes an inflatable seal hanger envelope mounted on the underside of a fluid cushion vehicle. The inflatable hanger envelope is inflated from the lifting fluid cushion through a tube. The length of this inflation tube is great compared with its bore diameter, thereby producing a pressure drop in the fluid as it flows between the fluid cushion and the hanger envelope. The hanger envelopes of adjacent fluid cushions are also interconnected when the vehicle is supported on four or more fluid cushions. These interconnections divide the total number of fluid cushions into only three independent groups to produce a statically determinant support for the fluid cushion vehicle.