John Sannizzaro came up over the weekend and we knocked out the right wing box. A couple of days later I put the wing in the jig.

Both wings jigged

Next step…leveling the right spar’s ends. Gotta love that SmartLevel and those adjustable support arms! I also double-checked the left spar’s alignment.

SmartLevel on right wing spar

Yesterday I finally came up with a (relatively) inexpensive way to jack up the wing center per the plans. I used some spare threaded rod, Al angle and 2x4s to make these little adjustable supports.

Wing center support

The only feature that isn’t apparent in that picture is the flat surface on top. It’s just a piece of plywood left over from a wing crate, with a nut attached to the bottom with JB Weld. I didn’t want to clamp anything to the spar center lest it be damaged if the support was disturbed or kicked out of place.

With the support in place, all that was left was to use it to remove any sag from the wing box. I didn’t have a plumb-bob or fishing line, but I did have a spiffy new laser level I found on sale at Sears. So in an awesome display of obsessive over-engineering, I used the laser level to get the wing box adjusted and sag-free.

Left wing laser-leveled

The picture is a little dark, but you can see the laser line illuminating a row of rivet holes on the spar. I’ll definitely use the approved solution (fishing line and plumb-bob) to check twist before the skins go on, but the laser works well. And that threaded-rod support made it wicked easy to adjust the spar.

Got the left wing in the jig today after attaching some aluminum angle to the outboard rib as a support. Now I need to come up with some type of center support…

Left wing in jig

Getting the ends level was a snap with the adjustable supports and a digital level. The extra work to fab those supports was definitely worth it!

With the front spar rivets done, squeezing the rear spar rivets was a piece of cake – mostly. I neglected Vans’ instructions to put the rivets’ manufactured heads on some of the thinner rib flanges, and wound up with some distortion of a few flanges. I called Van’s to confirm that this wasn’t a serious error, and they agreed that it was better to leave those rivets in place than to risk damaging the rear spar by removing them.

That only happened on a few ribs; the rest came out fine and I’m glad to be done with this. Here’s the finished left wing box.

Left wing box

One last thing…some extra attention to the plans is appropriate here, especially to the drawing that shows which rear spar rivet holes should be left open for future work. Take some tape and cover up those holes – you’ll save yourself some heartache by not having to remove rivets from them.

Captain John and his wife visited today. Before heading out to a movie and dinner, we riveted the left wing’s front spar and main ribs. Prior to John’s visit, I tried doing a few of these rivets myself – it’s significantly easier to do them with a partner and I was grateful for John’s help. Plus, he’s already done this procedure on his RV-7 wings.

Here we are, riveting the wing walk ribs.

Rib riveting

Two pairs of hands made quick work of all those ribs, and only a couple of drill-outs were required. Here’s the finished product.

Wing walk ribs

I used my Christmas gift from my wife – the Sioux 2X rivet gun – on these rivets. The gun hits a little harder than I expected, but not quite as hard as my Avery 3X gun. It definitely hits a bit faster and feels better, probably because it’s a little heavier and doesn’t transfer quite as much vibration to the hand.

I also tried some Snap-Socs on the rivet set. If you haven’t heard of them, Snap-Socs go over the end of the set and help keep it centered on the rivet. Supposedly they help minimize smilies on the rivet and skins/flanges, and they seem to work as advertised.

I mentioned support arms in my last entry, and I’ve been researching how best to fabricate them. One important part of getting the wings settled in the jig is eliminating any twist before the skins go on. Surfing the Van’s Air Force website, I came across a really neat design by Rudi Greyling of Johannesberg, South Africa. His approach uses aluminum angle arms supported by threaded rods that can be adjusted to precisely level the arm.

One pic will convey the concept better than I can explain, so here’s one for your edification and enjoyment. Click on the picture for a larger version.

Wing jig support arms

Thanks Rudi, that’s a great idea!

I spent a lot of time over the last two days finishing up the wing ribs. Cleaning and etching took most of Friday evening.

Etching the wing ribs

With all those ribs prepped, there was nothing left to do but prime them…so I did. John Sannizzaro kindly lent me the use of his paint booth, otherwise I’d be waiting for a really warm day to do them in the back yard. Even with John’s facilities, priming those ribs took a significant chunk of the day. Here they are in their yellow-primed glory…

Wing rib priming complete!

I’ll be putting support arms on the jig over the next few days, then it’s time to rivet the wing boxes together.

It’s rather anticlimactic to say much about the right wing, because everything is the same…mostly. I found I had to do some mental gymnastics to mirror the left wing’s rib layout, as depicted in the plans, to the right wing.

Here’s the right wing clecoed together…

Right wing clecoed

Today was a big day!

With rib prep done, it was time to start clecoing the wing boxes together. Here’s the left wing box going together.

Left wing box coming together

…and here’s the left wing box clecoed together.

Left wing box together!

I must say that this is a big morale boost, just as much as completing the horizontal stab. I had to leave this set up for a day or so just to admire it. After all the main ribs were match-drilled, the nose ribs went on and were match-drilled.

Left wing nose ribs

After everything was match-drilled, it all came apart for deburring. I commandeered Ellen’s cordless screwdriver after seeing some builders use it for deburring, then realized that I didn’t have any way to attach the 1/4″-28 threaded countersink to the drill. Avery sells a gadget that does this, but I was far too impatient to wait for one.

So I headed to the place where I do my best thinking – the hardware store – and came up with a good idea for attaching the countersink. I bought a 5mm deep-well, 1/4″ drive socket and a 1/4″ drive adapter for the drill. Back at home, I drilled out and tapped the socket for 1/4″-28 threads. The socket and drive adapter snapped right into the drill and I was all set.

Deburring drill adapter

Using the drill I was able to debur both front and rear left spars and wing ribs in only 30 minutes or so. The nice thing about this approach is that I can use those long 1/4″ drive extensions laying around the tool box for deburring in hard-to-reach spots.

Rib prep is complete. You’ve seen pictures of fluted ribs before, so I’m not gonna waste my disk space and your bandwidth on one.

One thing to note here – the fluting process tends to bow the flanges back out a bit. Although the wooden flanging tool puts the flanges right at 90 degrees, I wound up bending the flanges a little past 90 with my hand seamer so that they popped back out to the right position. If I were building that flanging tool now, I’d modify it to put a little extra bend in the flanges to avoid all the extra manipulation with hand seamers.

Before the main ribs went on the wing, I drilled holes for electrical wiring conduit using one of the locations recommended by Van’s – in particular, a 3/4″ hole on the lower portion of the web between the first and second lightening holes.

If you choose to use this approach, beware that Van’s only depicts the hole locations on inboard ribs – the ones with “D” shaped lightening holes up front – and you’ll have to do a layout for the outboard ribs as well. Once I had a pilot hole laid out on all three types of “L” and “R” ribs it was easy to cleco one of those ribs to its opposite – an “L” rib to an “R”, and vice versa – using the tooling holes, and simply match-drill in preparation for opening the holes to 3/4″ with a Unibit. My conduit holes came out fine, and were lined up well enough to accommodate Van’s flexible corrugated tubing.