Engineers at NASA’s Marshall Space Flight Center in Huntsville, Ala., and Langley Research Center in Hampton, Va., figured out a better way to manufacture large fuel-tank domes. The technique uses lighter-weight material, significantly reduces the number of pieces needed to create a tank dome, and eliminates numerous complex welding, machining, and inspection steps.

Typically, manufacturing such domes entails using the relatively heavy aluminum alloy 2219, eight gore panels, or pie-shaped pieces, 10 welding steps, and multiple operations and inspections to assemble the pieces into a full-scale dome. In contrast, the new technique uses two commercial, off-the-shelf aluminum lithium 2195 plates and joins them using friction-stir welding to produce a large starting blank. The blank then gets spun-formed to make the tank dome. By using a lighter alloy and slashing the number of welds, the technique could reduce the weight of future liquid-propellant-tank domes by 25%.

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