I decided to weld the top spar carry-throughs to the upper longerons because I just couldn't see not joining those thick-walled cross tubes. The joints that I welded would be covered by the verticals in the fuselage, so I just welded what was to be hidden. Since this is such a critical joint, I pre-heated each one with a work lamp since it's about 60 degrees in the shop. That's a little too cool for welding 4130.
I aimed the lamp on each joint (there are four), waited until it was warm, then welded it. Overhead welding...yeeeha!. The welding class finally pays off. After welding, I put the lamp back on it, that allowed it to cool much more slowly to insure the ductility of the joint. It was kind of a long process, but I feel an important one. After that was done, I fit the verticals at Station D-N. I also changed the tubing on the cargo door side from .035 to .049 wall thickness to ensure a good compression load on that side. This change was initiated by Dallas Shell and Dan Riffee and approved by Bob Barrows.
