The craziness continues!
My continuing flirtation with Aviation:
I've purchased a 90% complete Mitchell U-2 Flying Wing!
(Which in Aviation math usually means, 90% is left to be done.)
Center Section Rib Repair
The lower rib-cap of the left outer rib on the center-section had buckled. I believe the buckling was caused by the fabric having been excessively tight. The extent of the damage was not really evident until after we removed the fabric. So I had to fashion a new structure for that outer rib. The original design calls for a 2 inch wide rib-cap spanning a standard wooden rib and a faux foam rib. But the foam was not sufficient to prevent the rib-cap from buckling under the pressure of the fabric, so I took a different approach:
Sorry, I got involved solving the
problem and forgot to take a picture of the bucked rib-cap.
First I removed the damaged rib from the wing and made an exact duplicate by clamping the new rib components directly on top of the old rib. I had to use a lot of weight to ensure that both the new and old ribs were flat (at least as flat as the table).
|Next I cut stand-offs for
between the new and old ribs and installed the assembly at the end of the
wing-section. Since I had cut the old rib out with a thin saw, I had
to insert some 1 mm shims at both ends of the assembly to center the
assembly in the proper chord-wise position.
|Once the epoxy cured, the clamps were removed and the whole assembly was painted white except the top and bottom surfaces which the common cap is to be epoxied to.|
Note: the wing's center-section was upside down during this repair. So the reflexed curvature of the wing appears in these pictures to be on the bottom surface of the wing but it is not!
|Finally I cut two, 1 mm thick rib-caps and covered them on the inside with strips of 7 oz. carbon fiber. The rib cabs were then epoxied and clamped into place spanning the new outer-rib assembly.|