Patent ID: RE39521

Claim:
A composite tube structure comprising at least one axially elongated, substantially rigid inner tubular wall member having an outwardly directed substantially cylindrical surface , at least one axially elongated, substantially rigid outer tubular wall member having an inwardly directed substantially cylindrical surface radially spaced from said inner tubular wall outwardly directed surface , and a plurality of substantially rigid ribs helically disposed in the space between the inner and outer walls, inwardly directed surface and the outwardly directed surface, wherein a first plurality of said ribs are disposed in a positive angular direction other than perpendicular with respect to at least one of said surfaces and a second plurality of said ribs are disposed in a negative angular direction with respect to said perpendicular, wherein at least one pair of said positive and negative non - perpendicular ribs that are next adjacent to each other are in contact with both said outwardly directed and said inwardly directed surfaces wherein at least some of said ribs are joined to both said inner and outer walls along over at least a sufficient portion of the axial length of said walls structure; wherein said pair of ribs, to maintain the spacing between said walls together with portions, respectively, of said surfaces intercepted by said ribs, form substantially triangular or trapezoidal truss cells at least over said portion of said structure, and wherein said structure is axially twisted such that said inner and outer members, and at least some of said truss cells, are disposed, over at least a portion of the length of the structure, in a composite of longitudinal and a circumferential directions .