Really interesting article by the Huntsville Times’ Lee Roop, NASA, companies unveil breakthrough spacecraft welding process about an event yesterday held at Marshall Space Flight Center to announce a new process of making domes, or common bulkheads, that cuts both cost and weight by 25%.
The process is called spin-forming and it replaces the previous process of making domes for such structures as the ends of rocket fuel tanks, pressurized sections and other uses for which a dome is desired. Currently, creating a dome requires taking curved, pie shaped pieces of metal and welding them into a dome. This can result in…say, 10 welds, all of which have to be inspected and verified, raising costs. And all of that welding adds weight. While friction-stir welding would remove the issue of weight in creating domes, it would not remove the other costs due to inspection of each stir weld.
Spin-forming takes two commercially available, off-the-shelf plates, stir-welds them into a into flat metal disc and spin-forms that disc into a dome. Initially, spin-forming was not very useful as the metal used in the process was heavier and weaker than that currently used in aerospace applications. Alcoa came up with an aluminum-lithium (Al-Li 2195) alloy that can be spun-formed and is both lighter and stronger than the previous material. The final result is a process that can produce a dome that is 25% lighter, is stronger, and less expensive and requires only one weld.
The initial dome is sized for the Ares I second-stage, which is 18′ (5.49 m) in diameter.
This effort was funded by NASA’s Experimental Technology Development Program Office at Langley for NASA’s Exploration Systems Mission Directorate in Washington, as part of Project Constellation, at $14 million over 4 years. Key partners included Marshall Space Flight Center, Langley Research Center, Lockheed Martin, MT Aerospace and Alcoa. For those who say that Constellation has not resulted in any new technologies, in contrast to the efforts by commercial launchers, this effort stands as a reminder that NASA’s Constellation program has indeed delivered new technology.