Leading Edge Rib-to-Spar Drilling

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Well, after a quick run to Lowe’s to pick up a few more pieces of shoe molding for the family room (see my first floor wood floors page and today’s update here), I finished the family room and then headed out to the garage for an awesome two hours worth of building.

Why awesome?

First of all, I picked up these awesome tools for the project. I needed some good 3″ clamps for the spars (where they will attach to the wing stands) and a couple of plumb bobs to help measure twist. Also, I’ve been using my plastic triangle from 7th grade geometry as a square…it’s about time I got a real square.

Tools! Tools! Tools!

Then, I got out the jigsaw with a medium metal cutting blade and cut a couple 5″ pieces of 1.5″ angle. I attached these angles to the outboard ribs, which will allow the ribs to be attached to the wing stands.

I used 1/4" bolts instead of 3/16". I hope I don't die. (Also, don't pay attention to my edge distances...)

Here’s a good shot of what I’m trying to accomplish. The skins will overhang (to the right in this picture) the spar by about an inch from the last set of holes in the spar. I used the 1.5″ angle so I have adequate spacing (don’t have to notch my support angle to accommodate the skins).

This will work great.

Okay, next up, rib preparation. Here are 10 of the 12 leading edge ribs (these 10 have the prepunched holes).

Leading edge ribs.

After spending about an hour deburring edges with the scotchbrite wheel, straightening the flanges to 90° and then fluting between holes to make sure the holes are straight, I numbered the ribs for each of the wings and then got to match-drilling.

The only difficult parts here are that a couple of the W-709 ribs have holes where they don’t need them and don’t have holes where they do need them. The picture below illustrates.

Ignore the row of holes that has a cleco in it already; these are the main rib attach holes. See how the three middle holes leading edge rib lines up nicely with the prepunched holes in the spar? Those are easy to matchdrill to final size.

The outer two holes on the rib get "abandoned" while the two outer holes in the spar are used to backdrill new holes into the rib.

Here, I am using the holes in the spar to drill the new holes in the rib.

Matchdrilling using the spar.

I threw a couple clecos into the new holes. Now there are 5 attach holes, and 2 abandoned holes (you can see them on the outside).

There are 4 total leading edge ribs that get this treatment. It's easy to tell which ones need it as you assemble the leading edge.

Then, I spent another half hour making sure all of the rib-to-main-spar holes were drilled. Now, they are ready for disassembly, deburring, prep for priming, priming, and assembly.

Oh wait. I still have to drill all the rib to rear-spar holes. I’ll do that tomorrow.

Before shutting down for the night, I snapped a picture of the two wings in the stands.

It's awesome to be at a point where I can see two big wings in the garage.

A half hour of attaching the outboard ribs to the wing stands, then 1 hour straightening and fluting rib flanges, then another half hour drilling ribs to the main spar.

I’m waiting on a 2-inch scotchbrite wheel from Cleveland Tools, so tomorrow I’ll drill all the main ribs to the rear spar and then I’ll find something else to do.

2.0 hours of big skeleton work.

Oh, and we shot this video the other day of the pups howling at a fire engine. I won’t ever not find this hilarious.

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