It was warm enough to work without any heat today so a good opportunity to build the left elevator. First the elevator horn was welded up (top of the first picture) and partially filled with molten lead to balance the finished elevator. I used the same weight as in the right elevator which resulted in a slight nose heaviness which should be counteracted once the elevator is covered and painted. Then the structure was jigged on the building board using drills to set the centre of the spar 1/2" off the board to provide clearance for the hinges, 1/8" under the spar, 5/16" under the 3/8" tubing and 1/4" under the 1/2" tubing. With everything aligned the various components were then half welded to the spar. The frame was then turned over and the welds completed. Next the stainless steel trailing edge was brazed to the frame. The elevator has 4 ribs each made of two pieces of 3/8" rectangular 0.019" wall steel channel. I found a neat way of fabricating these. First the ends were tapered over a 2.5" length using the band saw. Next the forward ends were placed between two jig blocks 3/4" apart to set the spacing for the elevator spar. A nut which was 5/8" across the flats was then slid inside the channels and located about 2" from the jig blocks. A pair of grips was then used to clamp the tapered ends together. The nut inside holds the channels against the jig blocks and creates a gentle curve down to the end. The tapered ends were then welded together, my TIG machine creates a nice stable arc down to very low currents so welding this thin material is relatively painless. The forward ends spring open a bit when the rib is removed from the jig allowing the nut to fall out and when re-inserted in the jig the rib takes up the curve without the internal support. The front ends are then tack welded together. Finally, the front of the rib was cut to final length and shaped to fit the spar using a 3/4" holesaw in the notcher. Each rib was then brazed into place.Next a datum line was drawn on the workbench and the two elevator spars aligned along it. Then the left elevator horn was bolted to the existing one on the right elevator. Tomorrow, the left horn can be welded into place and I can be sure that the two elevators will sit exactly parallel on their respective horizontal stabilisers.
