Composite spar structure having integral fitting for rotational hub mounting

A hollow, longitudinally extended blade-shaped spar structure adapted for mounting on a wind turbine rotational hub for wind responsive movement under centriugal and bending loads, said structure comprising an integrally wound predominantly longitudinally disposed glass filament and thermosetting resin composite cross-sectionally D-shaped spar of a predetermined wall thickness pattern and having a circular inner terminus, and integral therewith a glass and resin afterbody defining with said spar a blade shape;

• a high tensile modulus metal fitting defining female threaded fastener engagement structure adapted to mount said spar to said rotational hub and comprising a generally conical plug having an annular inner terminus defining the locus of said circular inner terminus of said spar;
• said plug having a circumferential land and first and second diametrically larger and smaller respectively outwardly opening mechanical engagement grooves in axially spaced planes normal to the plug longitudinal axis on opposite sides of said land and into which the opposing spar wall portion is locally deflected responsive to winding fabrication of the spar wall on said fitting, and exclusively transversely wound first and second glass filament torodial belts respectively opposite said land and said first and second grooves in radially spaced and congruent relation, said toroidal belts being tensionally wrapped about said spar wall to peripherally compress and confine the respective opposite wall portions locally deflected into said grooves and to relatively increase the binding of the wall portions between said groove-deflected portions against said land in mechanical engagement reinforcing relation against relative dislodgement of the spar wall portion from said plug grooves in the fitting mounted condition of the spar structure, under centrifugal and bending loads induced by wind or the like.