My goal for tonight was to get the inner leading edge rib and the joint plate drilled. This position is where the leading edge and the tank will meet; the W-423 joint plate is what hold the two together. This joint plate will be riveted in assembly with the inner leading edge rib, and the exposed edge will have nutplates mounted, which the outer edge of the tank skin will attach to. The fun part is that neither that inner rib nor the joint plate are predrilled. The even more fun part is that the rib flanges face outboard, so they’re not exposed with the leading edge together.

So what has to happen is this: the rib is slid into place inside the leading edge skin, aligned, and the rear flange is drilled in assembly with the main spar and clecoed into place. Then the joint plate is weaseled into pale between the rib and skin, everything is aligned carefully, and the holes are drilled. The tough part is that with the rib flanges out of sight, there’s no real way to get direct feedback about whether the alignment is good.

To start with, I wanted to prebend the joint plate to make it easier to slip into place. The easy way to do this seemed to be to just bend it around the rib itself. First I did a rough check to compare the joint plate length to the length of the rib flange. Turns out there’s a little extra:

Because I’m a little OCD, I had a strong desire to have the same amount of material overlapping the rib flange on both sides. So I measured that overlap above, cut it in half, and made an alignment mark. Next, I drew a layout line 1/2” from the edge of the joint plate. This line will align with the skin holes to help me set the depth correctly. Then I went to town clamping the plate to the rib:

This didn’t really have a huge effect on the plate; only the area at the leading edge of the rib really had any plastic deformation. Still, better than nothing. Next up, time to slip that rib in place and drill the main spar holes. Those holes sit really close to the main ribs aft of the spar, so space is kind of limited. How to deal with this? With an absurdly long drill bit, of course:

I triple-checked alignment between the skin and the rib, added a clamp just as insurance to keep everything in place, and did my drilling. Nothing to it:

Okay, now to slip the joint plate into place. This is where it gets fun. I painstakingly got the plate aligned, then ensured the rib was in place too, tapping to and fro with a mallet. The fun part is that moving the rib tends to move the plate and vice versa, so there’s a bit of tail-chasing that goes on here. Finally I had things straight, and I went around measuring another time just to be sure. But there was an anomaly – according to the instructions, there should be 11/16” of joint plate exposed for the tank to mount to. I had more like a full inch. It seemed like a small amount, but if it interfered with the tank rib, that would be A Big Problem.

To check the fit, I grabbed the inboard tank rib and a Z-bracket, clamped them together, and held them roughly in the spot where they’d live. It was hard to be certain, but I felt that there might well be some interference. So I decided to move the joint plate outboard a bit; instead of having my layout line in the skin holes, I shifted it until it just disappeared. This still left me with some excess joint plate, but only by a couple sixteenths. Once again, I measured, re-measured, measured again, etc. Finally, there was nothing to do but to start drilling.

I wasn’t too worried about accidentally hitting the spar, but I used a drill stop just for good measure. I started with the aft most holed on the top side, drilled, clecoed, re-measured everything, drilled a couple more holes. clecoed, re-measured, and so on all the way to the rib tip. Then I went around to the bottom side and repeated the whole thing. I was pretty obsessive about re-measuring to make sure nothing had shifted.

Finally, all the holes were drilled, and it was time to remove the clecos, pull the rib and joint plate out, and see if I’d violated edge distances anywhere:

Oh boy…nervous…don’t want to have ruined parts…oh boy……..Whew! Everything looks great. If anything, the holes are a little close to the rib face; they’re definitely nowhere near too close to the edges:

That’s it for tonight. Tomorrow, I’ll be moving on to the left tank. I’m continuing to put off right wing work because of another thing I want to settle. Back when I was riveting the left skeleton, I went ahead and riveted three nutplates that will mount the most inboard tank attach bracket. Well, I realized there’s a reason to leave those nutplates off; the tank attach brackets are not predrilled, and have to be drilled using the spar as a guide. I’m confident I can do this effectively with the nutplates in place – all it should entail is drilling the brackets to #30 in assembly, then enlarging the holes for the AN3 bolts. But I want to test that procedure before riveting the left wing skeleton, so I can make an informed decision on whether to rivet the same three nutplates ahead of time there too. If I have problems on the left, I can leave the nutplates off and not waste time.

At the rate I’m going, I’ll probably end up finishing all the basic tank fitting on the left wing before moving on to the right. Meanwhile, I’ve got an order list going for Van’s. Come to think of it, I’ll have to make that order before I can really get going on the right wing, since I need to replace the two skins that got ruined in the move. I guess I should go ahead and order the Proseal for the tanks too. I’ve been holding off on that since the stuff has a shelf life of just a few months. Better to wait until I’m  close to doing the tanks, which I think I am now. I figure I might be ready to start sealing those SOBs in the next few weeks.

After taking the dogs for a walk in the arboretum this morning, it was out to the garage in the afternoon to do lots more match drilling. I didn’t realize it at the time, but I was suffering from my first building-related repetitive motion injury. I woke up this morning with an odd ache in my right wrist, like I’d slept on it funny or something, but that didn’t seem right. I forgot about it quickly and moved on with my day…until, just before match drilling, I decided to add a couple clecos to help alignment in some spots. As soon as I squeezed the pliers and tried to twist a cleco into a slightly-undersized hole, that ache made perfect sense.

Anyway, I went to town on the bottom skins and got them all match drilled, and then removed the bottom skins and put them back in their storage stand. The top skins stay clecoed on for the duration, but the bottoms come off to allow access inside the wing. This was a straightforward procedure, so I don’t have any photos of it, but I would like to point out an unsung MVP of this whole process:

I got this little rolling work stool from Harbor Freight, and it’s worth its weight in gold for working on the wings. Much better to sit and roll along instead of hunching over or something. I actually have two of these stools…

The next item is the leading edge, so I put the skin in the nice little cradle I have and started clecoing. This is kind of a challenge, as the skin is mostly bent to shape, but not quite, and it ends up taking some force to pull everything in alignment before inserting clecos. Better yet, the leading edge is large enough that you can’t really put a cleco in the front outside and still reach inside to wiggle a rib around. It wasn’t a horribly frustrating endeavor at all, but a bit tedious.

Then I set the whole assembly on the spar and clecoed it in place. I also began to realize that riveting the spar connections for this thing is going to be interesting. I can barely even reach inside the leading edge assembly to touch the rivet holes, and someone is going to have to hold a bucking bar in there. Whee!

Here’s the wing with the leading edge clecoed in place:

The next thing to do will be to work on the inboard rib for the leading edge. This rib, for whatever reason, isn’t predrilled. There’s also a joint plate that goes between the rib and the skin; the outboard edge of the tank will attach to this plate. The plate has to be fabricated, set in place, and the whole assembly drilled, while maintaining alignment and edge distances. I gather from other build logs that this has been a difficult task for several people. So I’m going to do some reading and research before I jump into this task.

It was about time for me to come in, have dinner, and give my parents a call anyway, so I quit for the evening.

Very productive day today. I picked up where I left off last night with the wing walk doubler. The basic procedure here is to lay the doubler in place under the skin, and then use the skin as a drill guide to drill all the holes to the ribs. I put a piece of my scrap MDF on the bench top to drill into, and used a drill stop to ensure I didn’t drill right through that MDF. The nice thing about clecos is that you can merrily cleco aluminum into the wood underneath it. In this case, I lined up the doubler and initially clamped it in place with cleco clamps. Then I drilled a couple of initial holes and used those to cleco the whole works to the MDF. That gave me alignment so I could remove the clamps and finish drilling the rest of the holes.

I totally meant to get a picture of the finished doubler, but I forgot and all I have is this photo of the skin clecoed down over the doubler:

From here, it was time to cleco all the top and bottom skins in place and match drill them. But first I wanted to see if I could rearrange the camp holding the inboard main spar to the wing stand. I did some tinkering around here, but never did come up with a good idea. I tried just clamping one side of the spar, but that kind of torqued the whole assembly and in general wasn’t going to be conducive to building a straight wing. I was getting a bit frustrated, just about resigned to having a clamp in the way for the foreseeable future, when suddenly an absurdly simple solution came to me. You see, the bolts that hold the horizontal pieces to the stands go all the way through the upright. All I had to do was switch the horizontals to the outboard side of the upright.

All that worrying and frustration, and I ended up solving it just by undoing and replacing four bolts. *sigh* Now I had plenty of room on the inboard end:

Better yet, this made it far easier to get the wing set up securely. Ever since I found out I made the bases too short, I’d always been looking at the stands with an attitude of “well, I can work around this.” That is, I knew it wasn’t right but I figured I could make do. Now, however, the setup is really and truly right. I can clamp the inboard end down securely, and instead of tweaking things manually to remove twist, I can use the adjustable horizontals and make a truly repeatable setup. Basically, this made me very happy, even if it did mean having to go through the whole routine of leveling the setup, checking for twist, taking the sag out of the spar, etc.

Finally, time to start clecoing the skins on. This isn’t an especially complex procedure – there are four skins, two top and two bottom, plus the wing walk doubler. The main deal is there are a lot – and I’ll repeat, a lot of holes. Even clecoing only every fourth hole or so, I used about 75% of my silver clecos, three coffee cans worth. (I think the coffee can is the official unit of measurement for clecos. You can count them, but that’s way too much work.)

I asked Josie to come out and grab some photos of me actually working on the wing, which is what you get to see now.

I had a helper come out for a bit too. Astute observers will note that I’m scratching his nose with one hand to distract him so I can place the cleco with the other:

And then I was done with the top skin, and there were two dogs, and there had to be a photo op:

OK, on to the bottom skin. But first, here’s a photo from the bottom. The shiny stuff on the left is the wing walk doubler. See, I told you I made it!

OK, now to really put on the bottom skins. Let’s start with the inboard one. Oh wait, something’s wrong here. Argh, the bottom inboard horizontal arm interferes with the skin! And here I thought I was done modifying these stands… (The skin is supposed to align with the rib visible to the left.)

After mulling over this for a bit, I decided to just replace that big piece of angle with a smaller piece from some scrap I had lying around. These pieces are just held in with self-tapping bolts, and they don’t go all the way through the upright. Oh, and they’re long enough to account for those 2×4 blocks. Rather than go run to Home Depot for shorter bolts, I made a little wooden spacer so I could reuse the bolt I had. Excuse me? Ghetto? The term is “redneck engineering,” thank you very much.

Anyway, where was I? Oh yes, clecoing skins. Back to that. Another half-hour or so, and the bottom skins were in place:

OK, time to bust out the drill and reamer and get to match drilling. I started with the top skins. The fun thing here is just how much things scale up from the tail kit. After feeling in danger of a hand cramp from the cleco pliers, I moved on to my right index finger getting tired from squeezing the drill trigger over and over and over and over again. And my arms were tired from holding the thing up. I can’t imagine trying to do this with, say, a heavy cordless drill (though the air hose presented annoyances of its own).

Eventually, the top was done, and it was getting on to about time for dinner. At first I was going to break for food and then match drill the bottom skins, but we decided to watch a movie instead, so that was the end of airplane work for Saturday. Tomorrow I can finish the match drilling, then move on to the leading edge and tank stuff. But at some point I should get to match drilling the right wing; that way I can take advantage of the next good weather weekend and get that thing primed and then riveted together.

Short day in the garage today. I had originally planned to go fly a bit today to stay current, but I fell victim to the notorious fuel-injected Lycoming hot start affliction. I couldn’t get the Arrow started to save my life, and after about five tries, it didn’t even want to turn over. I took mercy on the starter and gave up at that point. I then learned that they’ve been having hard start issues with the plane anyway, and it was going to get new mags installed that very afternoon. So I gave them an extra couple hours to work on that and saved myself a couple hundred bucks. On the way home, I stopped at Home Depot and bought some C-clamps and plumb bobs so I could finalize the left wing on its stand.

Back at home, after goofing off for a bit, I got to work. The first order of business was to finalize the clamping arrangement for the inboard main spar. I had just put some of my quick clamps on for a temporary fix, but now the C-clamps I bought would do the job. But first I needed something to pad between the clamps and the spar reinforcement bars; I don’t want to mar up those beautiful pieces of work. Some scrap wood from the H-stab moving fixture worked great, but only after I drilled some shallow holes to fit over the big shop heads on the spar.

Once I got to clamping, though, I realized things were going to be tight. The bases I made for the wing stands are barely long enough to fit the wings, a problem that annoys me greatly. You see, when I first sketched out those bases, I figured that the lengthwise pieces should be 120” long. This was especially convenient, since I could just buy 10’ 2x6s and not have to cut them. But then I reviewed my plans before I got to building, and somehow I convinced myself that 120” might be too long for the spars, and so I cut each piece down a couple inches. So basically, I second-guessed myself for no good reason and actually created more work out of it. *sigh*

Anyway, thanks to that little bit of stupidity, things are pretty tight on the inboard stand. The clamp kind of has to sit in this position, which is going to put it in the way when I’m skinning and so forth:

However, after reviewing the plans, I see that the fuel tanks sit a bit further outboard than the skins, so I think I may be able to flip this clamp and get some better working room. But I discovered that towards the end of the night, so I’ll wait until tomorrow to test that theory.

Next task was to put the plumb bobs on strings and hang one from the main spar on each end of the wing. Then I could measure the distance from the string to the rear spar and ensure that I had the same measurement at both ends, and in turn ensure I wouldn’t build any twist into the wing. I was actually a bit surprised by this, as I found about a 3/16” difference with the skeleton hanging naturally. So I did some adjustment of things before clamping the skeleton down fully, and now it’s nice and square.

Now, what to do from here? My original plan was to start working on the right wing skeleton; I could go ahead and cleco/match-drill the ribs, then deburr and try and get everything primed this weekend. But the weather has been spotty lately, with frequent afternoon storms and showers, and since I prime outside, that’s a bit of a problem. I decided instead to move forward with the left wing. The general path from here on out is to fit and match-drill the wing skins, fit the leading edges, and then move on to the joyous world of fuel tanks and Proseal.

First though, a wing walk doubler must be made. This goes under the main wing skin on the inboard part of the wing; this is where people will walk while getting in and out of the aircraft, so some extra structural strength is needed here. This is also one of those parts of the project where Van’s does not give you a nice prefab, prepunched piece; you get to cut these to size out of a larger sheet. And since the finished product is relatively large (9 3/8” x 26”), it’s too big for me to cut stuff on the bandsaw. Time to break out the snips

This led to an amusing farce during which I was looking at my three pairs of snips, trying to remember/figure out which was which: straight? left? right? ARGH. Well, straight was easy to figure out, and I’m making a straight cut, so I’ll just use those. It wasn’t so bad once I just got to work. After rough cutting with the snips, I attacked the edges with the vixen file to smooth them and shape to the final size, and then all the edges got cleaned up on the scotch brite wheel. The next step is to clamp this in place on the inboard wing skin and use the skin as a drill guide, but it was getting late by this point , so I knocked off for the night. As such, all I have right now is a rectangular piece of sheet. Holes will be forthcoming:

Side note: the little strip of aluminum I cut off with the snips curled up into an amusingly consistent spiral. It actually looks kind of cool. I should save these and sell them as modern art sculptures or something.

Short night tonight. We had a storm roll through and flood come streets while also disabling stoplights. As a result, my commute home was pretty ugly – instead of the normal ~20 minutes, it was over an hour. It honestly took so much out of me that I took a nap when I got home.

After that, though, I wanted to at least get the left wing on the stand. Josie helped me put it in place, and I set about getting it clamped in place. This ended up requiring me to modify the stands a bit – the pieces of angle to support the rear spar weren’t positioned quite right, so I had to do some customization. Nothing too serious though, and now the wing skeleton is securely in place. The only other thing I really need to do is get a couple of plumb bobs so I can ensure there’s no twist in the wing before I go to town match-drilling the skins and so forth.

Good news: Fixing that rib issue was pretty easy. I popped out to the garage after dinner and went to work. First order of business was to drill out the other two rivets holding the offending rib to the rear spar. That went fairly well, though it was a pain to drive the rivets out of their holes. I’m gradually learning that thicker materials = lots more grip strength for the rivet shaft = way more work to drive out. This is also another point in favor of putting the manufactured head on thinner material, because having to bang hard on a rivet to knock it out when it’s backed up by a thin rib is kind of scary. It’s really easy to bend the thin rib flange.

Anyway, with that rib freed, I unclecoed the other three wing walk ribs, and as I had hoped, I was able to pull the spar end out of the way enough for me to get in there and straighten the rib face. After that, it was straightforward to squeeze a new rivet; the hole seemed a touch oversize, but by pre squeezing the rivet a bit, I was able to get it set OK.

From there, I went to work on the rest of the wing walk ribs. These were straightforward too, until I got to the two inboard-most ribs. Here, there’s a lot of reinforcement material on the spar; there’s the long reinforcement fork that stretches outboard about 18”, plus another smaller reinforcement plate that only covers these two ribs. End result, there’s a lot of material thickness here. The plans call for -8 rivets here, but when I put one in and checked the length with my gauges, it seemed a little short. On the other hand, the -9 seemed a little long. I debated a bit and finally decided to just follow the plans.

Wrong choice. The shop head I made was way too thin. Time to drill out another one…I got the head off no problem, but tapping the rest out was a serious pain. Remember what I said about more material = more grip? This is where I really became convinced of that. I was really worried about bending the rib flange, so I ended up putting a couple of small C-clamps around the rivet to hold everything in place. It worked like a charm, but also scratched off some of my primer:

So I used the -9 rivets for those two inboard ribs, and that was the end of my rear spar riveting. Look Ma, no clecos!

FYI, the still-open holes in both of these pictures are for the flap brace and aileron gap seal, respectively. They get left open since those pieces won’t go on until much later.

I still had a bit of SEM primer left, so I went ahead and touched up the primer I’d messed up while taking care of that rivet:

And that settles the left skeleton! Tomorrow I’ll plan on moving this wing back to the stand and getting everything all straight and level for upcoming construction. Then I guess I’ll get to working on the right skeleton. I think things should end up being timed pretty well for me to clean and prime the right wing ribs this weekend, and maybe by next weekend I’ll have both skeletons on their stands. Then the real fun will start. (fuel tanks! Proseal! Oh my!)

Came home today to find a nice little present courtesy of Avery Tools. Longeron yoke, some long-reach 1/8” clecos, and a tube of Boelube for good measure. Finally, I can get back to this wing skeleton!

I got Josie to help me pull the skeleton off the stands and put it back on the workbench. Everything was still clecoed together, so it was just a matter of going to town on some rivets. Well, sort of…one consideration on this rear spar is that there are several different material thicknesses together, and thus several different rivet lengths to use. And there are also holes that need to be left open to accommodate the aileron gap seal and flap brace down the road.

I started on the outboard end; this is a particularly unusual spot in that it gets flush rivet instead of the typical universal head rivets. The reason for this is that the outboard aileron hinge bracket sits on top of this spot.

Outboard flush rivets:

The mocked-up aileron hinge bracket to illustrate why those flush heads are required:

From there I went on down the line and things progressed pretty quickly. The nice thing about squeezing rivets is that once you’ve got the squeezer adjusted for a particular rivet length and material thickness, you can breeze on down the line making nice consistent shop heads without the trial-and-error that comes with the rivet gun. Things went great until I got to the inboard end. It seems that I had a rib with a slightly bent flange, and I didn’t catch it before squeezing a rivet:

That’s a problem. I didn’t think much of it at first; after all, I’m to the point that drilling out rivets doesn’t stress me much. I drilled and popped the manufactured head off, then started tapping it with a punch, but it wasn’t moving. Then it occurred to me why: with that kind of a gap between the rib and spar, the rivet undoubtedly swelled up in the space between. I doubt it’d be possible to drive the rivet out without damaging the rib. So this is going to be a more involved repair than I originally thought.

The good news is that this is the fourth-most-inboard rib, and I haven’t squeezed any rivets in the other three ribs. My hope is that I can drill out the other two rivets in this bad rib and then be able to pull the rear spar out of the way enough to get this bad rivet out and straighten the rib flange. Worst case, I might have to drill out the five rivets in the main spar and remove the rib entirely. Hopefully I can avoid that, as the manufactured heads of those rivets are towards the inside of the skeleton, and drilling them out will be a chore…not to mention the concern of damaging the main spar in the process.

It was late by the time I realized the problem I had, so I decided this was a good time to call it a night. Much better to sleep on the problem instead of trying to attack it all willy-nilly. Tomorrow we’ll see if I can get this all fixed up.