Nasa, in partnership with Lockheed Martin Space Systems and MT Aerospace, has developed the new full-scale friction stir-welded and spun-formed tank dome, for use in large liquid propellant tanks.

The friction stir welding is a solid-state joining process, while spin forming is a metal working process used to form symmetric parts.

MT Aerospace has used the twin processes to develop an 18ft-diameter tank dome using high-strength 2195 aluminum-lithium.

The dome’s diameter matches the tank dimensions of the upper stage of the Ares I launch vehicle as well as the central stage of the European Ariane V launcher.

Patented by MT Aerospace, the concave net shape spin-forming process simplifies the manufacturing process of large tank domes and reduces cost by eliminating machining and assembly welding steps required in traditional manufacturing process.

A flat plate blank, made of the 2195 alloy and constructed by friction stir welding together two commercial off-the-shelf plates, has been used to manufacture the spherical tank dome.

As part of the two-year technology demonstration programme, the team will manufacture and test two additional, full-scale development tank domes in the coming months.