I studied the plans extensively and there definitely is an offset in the wing attach holes as designed. Glenn Patterson offered this excellent graphic means of determining the amount of the offset: "Find the center of each spar on the pattern (1/2 the wing depth on the spar lines). Measure up from the centerline of the front spar 1.5" to locate the front attach point and mark that point. Go to the rear spar and find the centerline of the spar. Measure 1.125 from the centre of the rear spar to locate the rear attach point and mark it. Measure from the front attach point down to the chord line and measure from the rear attach point down to the chord line. The difference between the front and rear measurements to the chord is the offset. That amount of offset will set the chord line in the vertical position and everything will line up.”
The argument in favor of jigging with the holes line up goes back to instruction originally given by Bob Barrows, "Also insure that the spar root attach bolts main and rear spar are plumb with each other" when he referred to putting the wings in the vertical jig. Bob assembled his wings differently than most builders in that he assembled his spars and center ribs on a flat table then he put his wings in the vertical jig. So his spar frame was already square before he put his wings in the vertical jig.
I went out to the shop and jigged the wings so the holes lined up. By doing this the center line as depicted on the mylar wing drawing is not plumb and level. Also with the main spar sitting squarely on the top (front) of the center ribs, the spar is not sitting level in the vertical axis. If you force the spars to level then the top and bottom (front and back) of the center ribs do not fit square to the spar. The wing frame box is not square and true.
Next I jigged the wing with the offset. Everything lined up square and true.
