Abstract: Structural elements of great thickness are provided by having limited extent ribbing projecting from each surface structure coupled by junctions having extents which combined with the ribbing extents bridges the distance between the surface structures of the structural elements.

Abstract: Structural elements such as baffles are formed from spaced, laterally disposed, longitudinally extended structures having longitudinally distributed ribbing, and rib segments fixed to the structure ribbing normal to the structure to form closed figures in a laterally and longitudinally extended pattern.

Abstract: A structural element suitable for walls, tanks and bulkhead structures comprising opposed, axially extended surface structures and ribbing interposed therebetween in freely movable relation responsive to a temporary first relative dimensional condition of the surface structures and ribbing, and in blocking relation against separation of the surface structures responsive to a persistent second relative dimensional condition of the surface structures and ribbing.

Abstract: A structural element core adapted to space apart opposed first and second, laterally and longitudinally extended, generally planar surface structures, the core comprising a closed figure pattern of ribbing defined by a plurality of periodically intersecting laterally or longitudinally disposed and vertically stacked fibers and a fiber supporting plastic matrix, the fibers and matrix being radially deflected at their locus of intersection with oppositely disposed fibers and matrix sufficiently to be vertically stacked to the same height at their locus of intersection as between. comprising opposed first and second. The core is usefully combined with one or more planar surface structures to form a structural element e.g., an aircraft panel.

Abstract: A structural element comprising opposed first and second, laterally and longitudinally extended, generally planar surface structures each having a closed figure pattern of ribbing projecting therefrom toward the opposite surface structure, a third structure disposed between the first and second surface structures in ribbing-engaging relation therewith, the opposed ribbing being interlocked across the third structure in registered, mating relation.

Abstract: A structural element comprising opposed first and second, laterally and longitudinally extended, generally planar surface structures each having a closed figure pattern of ribbing projecting therefrom toward the opposite surface structure, the ribbing being of respective heights to bridge the space between the surface structures, the opposed ribbing being interlocked in registered, mating relation.

Abstract: An acoustic filter in which the internal flow element is acoustically decoupled from the surrounding vessel to lower noise emanating from the filter by securing the filter bulkheads to the internal flow element rather than welding to the vessel wall. The connection of the bulkhead to the vessel is mechanically discontinuous and reduced vibration transmission to the vessel from the internal flow element is obtained. The internal flow element is a unitary body with channels which are readily formed. The filter vessel is better able to move relative to the bulkheads in response to pressure and temperature changes with the invention design.

Abstract: A tank drain assembly for swimming pool filters is provided characterized by an improved locking and orienting structure individually locking collector tubes into their respective sockets in the manifold surrounding the common drain port of the filter tank, each such structure comprising spring finger means segmentally formed on the socket end of the tubes, and a finger receiving recess within the tube socket sized and located to operatively orient the tube apertures responsive to receiving the finger means in tube locking relation.

Abstract: A pool cover having solar energy heating capability is provided comprising sheet material adapted to furl about a reelless locus in a storage position and to be deployed in an extended position. The cover includes means continuously resiliently urging the sheet material into its furled position for storage, and means selectively overcoming and resisting said urging, comprising inflatable structure selectively inflated in sheet material deploying relation. The cover includes a wall portion responsive to solar energy to transfer heat to water, such as pool water, in contact therewith.