A welding book I had mentioned that stick welding aluminum is no longer done because it is too hard and used the F-1 stick welds as an example of such welds. I think they we not so much welds as strategic strengthening.
I'm surprised they stick welded it. I know they oxy-acetylene welded aluminum aircraft in WW2, (which I've attempted, I found it impossible to do) and TIG welding has existed since the 50s.
