Fairly uneventful evening, just repeating the work from last weekend, except without ruining any parts this time around. I had one blind rivet through the spar that didn’t set right, and I had to drill it out (CAREFULLY), but that went through with no issues. Beyond that, it was just lots and lots of riveting.

The garage is a hilarious mess at the moment. I guess first order of business tomorrow will be tidying up everything. The real question is, what comes next? I still have all the firewall parts lying around, so I’m not sure whether to get back working on the firewall or set that stuff aside and get the flaps hung. Eh, I’ll figure it out in the morning…

Got my shipment from Van’s today, including the replacement for my botched flap rib. After dinner, I retired to the garage to get this thing up to speed. This is a little more complex than many replacement parts like this, because there are no prepunched holes for the reinforcement plate that rivets to the rib. During initial assembly, all this stuff gets carefully drilled in assembly, but I couldn’t really pull that off here. So instead, I used a piece of scrap wood to create a template to transfer to the new rib.

First I used the tooling holes in the old rib to secure it to the piece of wood:

Next I drilled through a few of the rivet holes into the wood. I stopped at three because all I really care about here is accurately locating the reinforcement to the new rib. Once it’s clecoed in place, I can drill the rest of the holes using the plate as a guide. Completed template:

The plate fit great, and it didn’t take long at all to get all the holes drilled:

Then I deburred, dimpled, scuffed, and cleaned the rib, blew it dry with the air gun, and set it aside to dry a bit more for good measure. While waiting for it to dry, I worked on the hinge halves and the flap assembly. Most of the rivet tails from all my drilling out were still in place, so I got to knock all those out. That, in turn, bent up the hinge halves a bit, so I also worked on them a bit to flatten them.

Finally, I went back to the rib and shot primer on it, just working inside the garage door. Not optimal lighting, but it worked fine for a small job like this:

That’s it for tonight. Tomorrow I start putting all this stuff back together again – hopefully without mucking anything else up…

Well, this day pretty much covered the full range of aircraft-building emotions. Friday I got in my shipment from Cleaveland, with my two new teeny tungsten bucking bars. These things are tiny (cleco for scale):

And they worked great inside the flap, as I expected. I knocked out all the rivets to the top skin in about an hour; most of that was working out how to hold the bucking bar. What I ended up doing was adding a wad of tape on one end of the bucking bar, roughly the same thickness as a finished shop head. By doing this, I could just hold the bar against the skin and it would hold itself more-or-less level.

Next I installed the outboard rib and squeezed its rivets, followed by the spar and hinge halves. Installing the blind rivets between the spar and ribs was somewhat challenging due to the overhanging top skin, but I got it done by shortening the blind rivet stems and using my handy little blind rivet angle tool from Avery. And before long, I had a finished left flap:

So I moved on to the right one. I figured this one would go even faster since I’d worked out my techniques with the left, and I was right…at first. I got the internal ribs and the end rib riveted in place, and installed the spar. Here I inadvertently went a little out of order by riveting the bottom spar flange and the hinge halves before doing the blind rivets to the spar. I didn’t think much of this, but I’d come to regret it later.

It all started when one of the blind rivets, on the inboard end rib, didn’t set correctly. The outside head was sitting proud of the surface by about 1/32”. OK, no worries, I’ll go take care of the rest of the blind rivets and then come back to that one. After all, drilling a rivet out is no big deal, right? Well, not in this case. I got the head popped off the rivet fairly easily, but the rivet shank didn’t want to come out. I kept hitting it with a punch, it’d move a little, then seem to hang up again.

I banged on it for way longer than I should have before stopping to think “maybe something is wrong here.” I reached my fingers through a spar lightening hole, groped over towards the rib…oh boy. I bent the absolute crap out of the rib flange. No no no no no nooooo…I tried to come up with some way to remedy this problem, but I had no ideas that weren’t just totally stupid. I had to make peace with the fact that I was going to have to drill out all those rivets on the spar, remove it, and then remove and replace the rib.

The especially fun part was drilling out the blind rivets in the spar. The ones that were a pain the install because of the skin overhang. I ended up using my angle drill attachment, which worked great until the drill bit snapped. AAARRRHGHGJHLJGKDH:LSJ

Fortunately, I had a slightly longer bit that I was able to use, but just barely. Finally, after drilling out all ~60 rivets between the spar flange, skin, and hinge halves, I got a look at the rib. And boy, did I do a number on that thing:

Well, it’s been a while since I ordered a replacement part from Van’s. Time to break that streak…

Yes, that’s right, in an hour and a half in the garage we shot a grand total of nine rivets. Working inside these flaps is no fun at all. We started out finishing up the bottom skin rivets; most of those I did solo, but the ones at the trailing edges of the ribs require two hands to buck. Those weren’t so bad, unless you count me needing to have my fingers right between the bucking bar and the table, which made shooting the rivets a bit painful.

Then we flipped the flap, clecoed the top skin holes, and I started trying to figure out how in the world to buck those things. I didn’t have the top skin clecoed while I was doing the bottom rivets, so it was easy to lift the bottom and get some extra room to work. Not only was that luxury gone, but I also had the downward-curving part of the top skin blocking my access. I could barely even get my hand inside the flap at all, much less actually hold a bucking bar.

After much thought, I created a pretty hilarious redneck-engineered solution. I used a spare flap rib to cut a piece of wood at an angle matching the angle between the flap skins. Then I taped that wedge to my mini tungsten bucking bar, and finally I taped a paint stirrer stick to that assembly so I could hold it in place.

The final product:

This setup allowed me to just rest the thing on the bottom skin, butt it against the rivet tail, an then just apply forward pressure while Josie operated the rivet gun. As the shop head formed, the bucking bar slide forward to keep striking the tail. It actually ended up working far better than I expected, and we made four beautiful rivet tails in no time.

I’d hoped to use that same device on the next line of rivets forward on the flap, but with more space to deal with, the bucking bar didn’t align correctly, and the tail of the rivet got mauled. So I decided to go ahead and call it a night after drilling that rivet out. I’m going to seek advice from VAF just to see if anyone has any other great ideas. My tool idea works well, but it’s rather painstaking since it seems I’d have to remake the tool for each row of rivets. But I guess if that’s what it takes…

So I haven’t been especially productive the past week or so, but tonight I finally got back out and got some stuff done. I started out by doing the solo riveting on the left flap: riveting the ribs to the bottom skin and then the joint between the top and bottom skins. The rest will have to wait until I have help.

The lap joint didn’t turn out quite as nice as the right flap, I don’t think. Or maybe this macro shot just makes it look worse than it is:

Next up, I worked out my aileron alignment jig. A couple of operations require positioning the aileron in-trail, most notably rigging the bell cranks and hanging the flaps. This position is defined by a line passing through two tooling holes in the main wing rib, so the alignment tool takes the form of a length of aluminum angle, in which bolt holes are cut to attach it to the ribs, with some standoff to allow clearance for the aileron hinge. That part is pretty simple:

With this setup, the aileron can then be held so it’s at the midpoint of the angle piece. However, I wasn’t 100% satisfied with that; it would require a second set of hands carefully holding the aileron while other stuff (like flap hinge drilling) was taking place. My solution was to drill a third hole in the angle right at the trailing edge of the aileron. I then took a chunk of 5/16” dowel I had lying around and sanded one end down until it fit snugly into the trailing edge bend. Then that dowel fits into the hole and into the trailing edge, holding the aileron in place:

As you can see, that last hole was off by a touch, but it doesn’t prevent the dowel from doing its job. This should make rigging and such significantly easier. I might actually go ahead and rig the bell cranks and pushrods tomorrow night…

Whew, finally back to work. First order of business tonight was to start riveting the joint between the top and bottom skin. I’d been intending to have Josie come out and help with this, but she was working late again, so I examined the situation again and decided that I could shoot these rivets solo. And in fact it turned out to be really straightforward; I had no problems at all. The only tough spots where where the two skins are also riveted in assembly with the ribs.

Here, access was tight enough that even the tungsten bucking bar was to big. I had a different bucking bar that would fit, but holding it in the tight space was going to require both hands. So I got Josie to pause work long enough to come out for about five minutes and help me shoot those. Overall, they weren’t bad at all.

The joint turned out really nice. I was a little concern I overdid it rolling the top skin edge, but the lap joint is really tight, with no gap visible at all:

Next I flipped the flap over and clecoed the top skin to the top of the ribs. This is where things are going to get fun for sure. Doing the bottom rivets, I could pull the top half of the skin out of the way for better access, but that’s no longer possible with everything clecoed together. And to make matters worse, the downward cube of the leading edge of the top skin really limits access inside the flap. There’s no question this is going to be a two-person job:

Since there was nothing else I could do with the right flap, I moved on to working on the aileron bellcranks. I’d temporarily assembled the left one once just to watch the aileron move; now it was time to do it for real. First I used a green scotchbrite pad wrapped around a drill bit to clean up the inside of the bellcrank pivot point, then I chucked each bushing into the drill and gave it a once-over with the green pad. That made the bushings nice and shiny:

Then I clamped the bell cranks in the vice, covered each bushing with a coating of grease, and installed both bushings:

Finally, I bolted each bellcrank in turn into a pair of brackets so I could bench-test them and ensure that they moved freely even when torqued down. Better to do this on the bench than in the wing!

And that’s it for tonight. If I can’t get Josie to help me tomorrow night, I’ll probably just move on to doing the solo riveting on the left flap. I also need to fabricate some spacers for the bellcranks and aileron hinge brackets before things can go together properly.