Abstract : Reported are results of a program to investigate the feasibility of using composite geodesic structure for the blade spar to increase survivability of helicopter main rotor blades. The design investigated consists of a geodesic truss structure spare of elliptical cross section comprised of elements forming a redundant grid-work. This spar is covered with a thin composite expendable skin that forms the airfoil contour. Parametric analyses were conducted to determine the effects of geometry and materials on the strength and stiffness of geodesic structures. Subscale sections of the graphite/epoxy geodesic main rotor blade box spar were fabricated and tested. A graphite/epoxy geodesic helicopter main rotor blade preliminary design was completed, and four full-scale segments of this blade were fabricated and subjected to structural and ballistic tests.