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DWG 12 vs. DWG 38 Conflict: wing skin to center bottom fuselage skin

S

smiller

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My DWG 12 (grid B6) identifies 10 holes to *not* rivet in the W-704 bottom inboard wing skin. Basically every other hole is reserved. The note on the drawing says they are to be dimpled later for 8R8 screws attaching the F-776 center bottom skin per DWG 38.

But, DWG 38 (grid E2/F2) shows only 8 holes for screws, and some of them are different holes than DWG 12 specifies! Instead of every other hole, it's every third hole (except the most aft one). [Note that on DWG 38, the "bottom" of the wing is shown on the top part of the illustration.]

The two drawings are dated within a month or so of each other, and the revision histories do not mention these grid areas.

Looking at my as-yet-untouched F-776 center bottom skin, it appears to not have holes pre-punched here, so my guess is it doesn't really matter whether I follow DWG 12 or DWG 38, but I thought I'd check the collective wisdom here.

So, are there any recommendations or gotchas I should be aware of before I proceed? I'd be inclined to go with the higher number of screws and follow DWG 12, but the top side has a screw in only every 3rd hole, and both DWG 12 and DWG 38 match (for the top side) with 7 holes being countersunk through the skins and wing-walk doubler.
 
Shannon,

In a nutshell you are looking at 2 totally different parts of the plane.

The first set of 10 is on the underside of the wing AFT of the main spar and the latter set is FORWARD of the main spar (on the tank).

No gotchas that I can think of. BUILD ON!!!

You are doing fine. Just follow the plans, man!!!

:) CJ
 
Are you sure? I thought the same initially!

On DWG 38 (grid squares B1/B2 through F1/F2) that inboard edge of the wing is "unfolded" -- with the leading edge in the middle, the wing bottom at the top of the drawing, and the wing top at the bottom (doncha love it?). W-704 (bottom inboard wing skin) is identified in both drawings.
 
They use the same drawing for the 9/9A ...

and it's terribly confusing. Can't tell you how many times I looked at that goofy "unfolded" drawing before I understood what was going on. And when it comes to the wing opposite the root fairing drawing they show, it's even more non-intuitive.
Not to mention how long it takes to find that sketch on Sheet 38 to begin with!
 
There Is a Conflict

It's one of those "Van-ities" they don't bother fixing. I go with the stronger 10 screw count. You can dimple, countersink for and install the plate nuts while building the wing; less time on your back later. Locating the holes later is no more difficult.

John Siebold
 
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