Obtaining the correct distance between wing spars

After adding F-415a/b ribs (R&L) to the fuselage I measured a slightly longer distance between the main wing sparand the rear wing spar attach point previously built. Inasmuch as this was a clear warning in the builders instructions I set out to discover why and correct it.

Turns out that the intersection of floor rib F-415a, bulkhead F406, and rib 415b was a bit sloppy. This added about 1/2" of distance that needed resolved. So I attempted the clamp the entire assembly and put the squeeze on it.

That did not work because F415a/b on boths sides began to buckle under the load. Without the 3/4 X 3/4 X .063 aluminum angles attached, there was no way to compress the whole After adding F-415a/b ribs (R&L) to the fuselage I measured a slightly longer distance between the main wing sparand the rear wing spar attach point previously built. Inasmuch as this was a clear warning in the builders instructions I set out to discover why and correct it.

Accordingly, I cut and fitted the four pieces of aluminum angle which were then drilled and clecoed onto the webbing and provided sufficient strength to compress the assembly and achive the 25 7/8" distance.

Your distance may be slightly different, but as mentioned in the builders manual - this distance must match the distance on the wing or you will be unable to mount the wings to the fuselage when the time comes. 

Once these strenghtened ribs were clamped to bulkhead F-406, it seemed apparent that ribs F-418 needed to be placed next. They determine the distance between bulkhead's F-407 and F-408.

Although one could as easily just use a simple measurements to place the bulkheads; it seems helpful to use the F-418 ribs (with aluminum angles attached) to confirm this distance.