Upper Wing VIII

8/12/2007

Joining the two uppers was always going to be a time of stress. If something was out of line, out of level, or even dirt under one of the spar jigs, the error would be cast in stone once the splice/doubler join was made. So without further a do, the wings were taken off the bench, and the bench was re-checked for flatness and twist.

I had fabricated the shallow angle splice blocks months earlier, so they were all ready to go. I made a boo boo tho... - I have an existing salvage fuselage that has been mothballed for 18 months, and it has cabanes fitted. Therefore I should have checked the centers between the bracket points on the cabanes before making the upper wing. It turns out that the centers were 1/4 inch off. So I had to fudge a little with the 1/8 ply doubler thickness fore and aft to get an exact fit.

The glue-up turned out to be a pretty smooth event. The splice blocks/doublers would potentially slide all over the place during glue-up, so to remove the vertical slippage factor, I screwed some resting blocks to the bench, the splice blocks then rested on these, so I could focus upon lateral alignment while clamping. The 1/8 ply doublers were fitted later . The destruct test also went well.

The doublers I had made with surplus height, so I could plane down to a flat level because the join in the spars is in fact a shallow compound miter. I wanted the spar join flat so as to laminate the spar filler in one piece. I have decided to omit the lower center section ply [that the gas tank sits on] until the cabane brackets have been fitted later.

Clearcoating was the final task. Seeing as I was at a very monumental moment in the build, I invited the wife to help me brush on the last coat in the center section :)

The only thing not done is the ply leading edges. I have some ply from a previous failed bend idea/attempt 2 years back, which I was going to play with, but I have decided to buy the vacuum molded LE's from Steen. These LE's I used on the lowers last year and fitted like a glove. More importantly, because they were a good fit, there is no post stress in the ply or the wing, which I am sure was the cause of a slight twist in my ailerons a while back. As soon as I add the LE ply, I can take the monolithic bench apart, and make room for finally focusing on the fuselage.