Abstract: The invention relates to a tetrahedral beam that can be compactly stowed, sequentially deployed, and widely manipulated to provide a structurally sound yet highly maneuverable truss structure. The present beam is comprised of a plurality of repeating units comprised of tandem tetrahedra sharing common sides. Tetrahedra are comprised of fixed length battens 12 joined by joint 14 into equilateral triangles called batten frames. Apexes of adjacent triangles are interconnected by longerons 16 having mid-point folding hinges 20. Joints 14 are comprised of gussets 24,34 pivotably connected by links 25. Joints 14 permit two independent degrees of rotational freedom between joined adjacent batten frames, and provide a stable structure throughout all stages of beam deployment, from packaged configuration to complete deployment. The longerons and joints can be actuated in any sequence, independently of one another. The present beam is well suited to remote actuation.

Abstract: The present invention is in the field of collapsible structural members. It discloses a foldable beam possessing superior qualities of: light weight, compactness for transportation, quick deployment with minimum use of force, and high strength. These qualities are achieved through the use of a series of longitudinally rigid segments, hinged along one side and threaded by one or two cables along the opposite side. Tightening the cables holds the beam extended. Loosening the cables permits the segments to fold away from the threaded side. In one embodiment the segments are connected by canted hinges with the result that the beam may be folded in a helix-like configuration around a cylinder. In another embodiment the segments themselves may be hinged to fold flat laterally as the beam is folded, resulting in a configuration that may be helixed around a shorter cylinder.