Patent ID: 8079126

Claim:
A method of fabricating a rolling bladder propellant tank assembly, the method comprising: providing a pair of half-domes each comprising a nanophase metallic material, wherein a bladder support ring extends from at least one of the pair of half-domes; providing a bladder formed of a ductile metallic material; defining a shape of the bladder support ring to help induce the bladder to roll along an interior surface of the propellant tank assembly during operation, with the bladder support ring in cross-section including a curved face and a planar face; positioning the pair of half-domes together to form a cavity therein with a portion of the bladder trapped between the pair of half-domes adjacent to the bladder support ring with the bladder support ring extending radially inward into the cavity relative to adjacent inner surfaces of the pair of half-domes, wherein the bladder is positioned within the cavity; and forming a seal between the pair of half-domes and the bladder by friction stir welding, wherein a friction stir welding pin used to form the seal is aligned with the bladder support ring during the friction stir welding operation, and wherein the friction stir welding pin is spaced from the curved face and the planar face of the bladder support ring during friction stir welding.