Abstract: A flexible coupling comprised of one or more flex frames connected in series between end fittings has the legs of its flex frames so dimensioned as to provide the coupling with a uniform bending stiffness with respect to bending moments in planes at all angles to the rotational axis. This is achieved by having each flex frame itself be of uniform bending stiffness with the other coupling components designed so as to have substantially no influence on the coupling's bending characteristics, or by using in the coupling at least one "compensator" flex frame specifically dimensioned to have a non-uniform bending stiffness compensating the non-uniform bending stiffnesses of the other coupling components.

Abstract: In a piano a panel, which takes the place of the usual cast iron string plate or frame, is provided for supporting the strings. The panel is a sandwich construction making it exceptionally strong and capable of withstanding the string loads without bending or otherwise yielding and without requiring auxiliary support such as the massive wooden backs or trusses to which cast iron string plates are usually attached. The string panel has a relatively thick low modulus of elasticity core layer, a portion of which is made of laminated hard wood to serve as a pin block, and relatively thin layers of high modulus of elasticity material, such as steel, bonded to the core layer. If desired the string panel may be used as the main frame of the piano to which other major components, such as the soundboard, key bed, side cheeks, housing and feet, are directly attached.

Abstract: A flexible tension member, or sling, useful as a line to hoist, lower or suspend something or as a tension loaded part of a structure or device has eyes at both of its ends for attachment to other parts or loads. The sling is comprised of a plurality of strands of cord extending between its opposite ends and twisted to form two side-by-side ropes of opposite twist direction. The various cord strands may be part of a single endless cord and the eyes at the opposite ends of the sling may have end fittings with thimbles for efficiently transferring loads from the cord strands to the end fittings.

Abstract: A soundboard assembly for use in a piano, harpsicord or similar stringed musical instrument comprises a thin, laminated soundboard consisting of a center sheet of wood and two outer layers of composite material. The center wooden sheet has a substantially unidirectional grain and the two outer layers of composite material are made of unidirectional carbon fibers embedded in a resin matrix. A plurality of ribs, which may also be made as laminations of wood and layers of composite material, are secured to one face of the soundboard, and the ribs, grain of the wood, and direction of the carbon fibers are so related to one another and to the associated bridge as to produce a desirable reaction from the soundboard in response to string vibrations transmitted to it through the bridge.

Abstract: A back frame for a piano or like instrument is comprised by a laminated composite structure having outer laminates of sheet steel and an intermediate laminate which is formed by a reconstituted wood product. The steel laminates are joined to the intermediate laminate and the intermediate laminate is substantially thicker than the sheet steel to offset the outer laminates from one another and increase the stiffness of the structure. A plurality of integral beam elements extend through the laminated structure in the same general direction as the tensioning load of the strings in the piano, and the elements are spaced from one another and define openings in the frame through which sound is emitted from the sounding board of the instrument.

Abstract: A hub assembly for a helicopter rotor system having a monolithic thin-wall hub shell made from composite material and including centrally apertured upper and lower wall portions integrally joined at the outer periphery of the shell and spaced apart at inner regions. The upper and lower wall portions cooperate to define a plurality of bearing sockets angularly spaced relative to the axis of rotation and connecting webs extending between angularly adjacent sockets. Elastomeric blade retaining bearing assemblies supported within the sockets retain and support rotor blades for articulate movement. Each bearing assembly has a seating surface which cooperates with an associated bearing surface on the socket in which it is contained to prevent relative rotation therebetween. Mounting flanges on the helicopter rotor shaft and retaining flanges on the hub shell are arranged to permit the rotor system to be lowered on the rotor shaft when the retaining flanges are disconnected from the mounting flanges.

Abstract: A key bed for a piano or the like is comprised by a laminated structure having two outer layers of sheet steel and an intermediate layer of a wood product. The steel layers are bonded to the intermediate layer, and the intermediate layer is substantially thicker than the outer layers of steel to offset the outer layers from one another and thereby increase the stiffness of the key bed.

Abstract: A piano case or frame includes a laminated key bed and side arms joined with the bed at each end. The key bed supports the keyboard and associated portions of the piano action, and is assembled with each side arm of the frame by means of a rabbet joint. Fastening screws extending through the laminated bed into barrel nuts within each of the side arms develop significant pressure in the rabbet joints to hold the key bed and the supported keyboard in a level, undistorted position.

Abstract: A hub assembly for an articulated rotor system mounted on a rotor shaft comprises three plates centrally secured to the rotor shaft. The plates include generally radially disposed and axially spaced apart upper and lower plates and a cone shaped pan plate. The upper plate and pan plate have outer marginal portions transversely connected in adjacent relation and central portions connected to the rotor shaft in axially spaced apart relation. The upper plate and pan plate cooperate with the rotor shaft to form a truss for supporting blade retention assemblies equally spaced about the rotor shaft axis and mounted intermediate the upper and lower plates. One of the plates has a scalloped central aperture which cooperates with the scalloped mounting flange on the rotor shaft to facilitate angular orientation for bolt alignment during hub assembly installation.