H-B Launch Vehicle Test Flight (H-B TF1) was successfully launched on September 11, 2009 from the Tanegashima Space Center, with carrying the H-Transfer Vehicle (HTV) Demonstration which transports supplies to the International Space Station (ISS). The H-B is an upgraded version of current H-A to meet the requirement of HTV launch, and one of the major items to be new developed is the 5.2m-daiametr first-stage tank. The enlargement of propellant tank diameter causes higher load with internal

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... ssure, the state-of-art welding manufacturing technologies, friction stir welding, is adopted in order to increase the high reliability of the tank structure. This paper describes the results of development process of H-B tank by applying the friction stir welding to the axial and circumferential directions with the self-reacting tool called bobbin tool which eliminates the use of conventional backing metals.