Forgot to write this up last night, but I got out of work early, what with it being Christmas Eve and all. That meant I was actually home before dark, so I went ahead and finished priming the leading edge ribs before coming in for dinner and a movie and such. Time to start putting stuff together. Might even get to riveting this weekend since I have three days in a row…

Yup, it’s priming time again! With the LE ribs prepped, it was finally time for the joy of scrubbing and priming. Before I got started priming, I decided to try to work out a better way to hold the ribs while I primed them. Most of the time I’ve just been setting parts on on sheet of plywood on saw horses, but it’s tough to get good coverage this way, and things become even more annoying as the spray can gets empty and it won’t pray if not held straight up. When I did the main wing ribs, I rigged up a whole system of little hooks on a string in the backyard, but that had its own annoyances. Even with the ribs secured at the top and bottom, they would twist in the wind, which made things annoying in its own way.

So today I started to think of maybe using the plywood, but at an angle. That would probably hold the ribs steady, but mostly vertical. But how to do it? Nails would be annoying. I hunted around the garage waiting for something to jump out at me, and finally it happened. I had some little twists of aluminum from trimming something a while back, and I cut them into short lengths that I then bent into little s-hooks:

These fit nicely on the 1/4” plywood sheet I use, and as a bonus, they’re not permanently attached and so I have some flexibility for how I use these things. I suspect they’ll continue to be handy. But now I had another little issue: I tried leaning the plywood against a sawhorse, but that put the lower part of the ribs pretty close to the ground, which would probably be an issue for ease of spraying. Maybe I could somehow mount it up higher on the sawhorse…back in the garage to look for something I could use. Aha! I still had the length of 14” tubing that was intended for the fuel pickups, but I didn’t use it. I cut it in half and made two little hooks that hung on the sawhorse, and finally I was in business.

Here’s the final product:

About the only issue is that I can’t easily spray the outside of the flanges, but I found I could easily just hold each rib after I’d sprayed everything else and get those flanges.

The only problem I ran into was…I ran out of primer while spraying the inside of the second batch of ribs. So that kind of put an end to work for the evening. I’ll have to see if I can get to a NAPA tomorrow and get some more 7220 primer, and maybe finish shooting those ribs after work tomorrow.

So my main goal for this week is to be at a point where I can prime the LE components this weekend, and I’m pretty much there. Tonight I started by working on the left tank attach strip. First I reamed the screw holes out to final size, then pulled the strip and dimpled the screw holes. Finally, I clecoed the nutplates on, drilled their rivet holes, and countersunk the holes for the NAS1097 attach rivets.

The attach strip with nutplates clecoed in place:

Next was a good old-fashioned deburring session, featuring the attach strip and all the ribs. Then I went back, dimpled all those parts, and peeled off the part ID stickers. And just like that, I have a big stack of ribs waiting for primer:

The only other part I really need to worry about is the doubler for the stall vane access plate. Since I’m not going to install the stall vane, my intention is to permanently rivet that access plate in place, but I’ll still need the doubler to get that done.

In other news, I’ve placed orders for my fuselage kit and for a set of Grove airfoil gear legs. I won’t be needing the legs any time soon, but Grove only does production runs a couple times a year, so I wanted to go ahead and get my name on the list. Turns out they’re just about to start a run of legs, so I should have mine in March…which won’t be too far behind when the fuse kit shows up. It might get interesting figuring out where to store all this stuff…

Yes! I am still building an airplane. Kind of surprising how being out of town for a week got me out of the working mood. Last weekend might have been a good time to get going again, but instead I was attending an EAA SportAir workshop on electrical wiring and avionics and such. Just like the sheet metal workshop I did prior to starting my tail kit, it was an incredible learning experience. Yesterday, I had my third tailwheel training flight with Joy at Texas Taildraggers (HIGHLY recommended, by the way), followed by the FlightAware Christmas party in the evening.

Truth be told, I came close to spending today bumming around the house too, but around mid afternoon the weather was so great that it seemed a waste to not finish prepping the right leading edge ribs and get them primed. Of course, as soon as I got started working in the garage, a nice rain shower rolled over and it stayed cloudy the rest of the afternoon, so I didn’t prime after all. My new plan is to get the left leading edge parts prepped this week so I can prime everything next weekend.

Anyway, down to details. Last time out, I’d deburred the right LE ribs and such, so all that was really left before they were ready for priming was to dimple/countersink the rivet holes as needed. I ended up running into some problems here; way back when I drilled the rivet holes in the inboard LE ribs, I felt they were a little closer to the rib web than I’d like, but I figured they were fine. Turns out they were close enough to make dimpling a bit difficult due to the size of the dimple dies. I managed to get all the holes done OK, save for one at the nose of the rib. There was no way to get the regular die in there, and none of my other special dimpling tools fit either.

So on the spur of the moment, I decided to countersink the hole instead. Bad idea; I neglected to consider the thickness of the material, and the resulting countersink went all the way through the material and enlarged the hole. Stupid. At first I considered fabricating a small doubler plate to go inside, but that would still leave a bit of a void in the hole. Finally, I realized this was a great place to use a NAS1097 oversize rivet; the enlarged hole was still smaller than #30, so this is a perfect solution. I’ll just enlarge this hole and the other two holes to #30 and things will be fine.

Here’s the enlarged hole with a rivet to show how oversize it is:

With the right LE parts ready for priming, I went to work on the left LE. I pulled the two outboard rivets and drilled the nutplate holes for the landing light reflector mount. About that time, dinner was ready, so I went in to eat, and after that, I got to doing some research for my fuselage kit order, which I intend to send in tomorrow. I think I’ve decided on the items I’ll add/delete from the kit – I’m going to do rear seat rudder pedals, mainly because the formation clinics I’ve seen require them, and I do want to do form down the road. I’m also doing electric aileron trim, and I’ll be chucking the heavy stock steel gear legs in favor of lightweight Grove units; in fact, I’ll probably end up ordering the super-slick airfoil legs.

Ordering the fuse kit really starts the clock ticking; I’ll need to have the wings off the stands before that kit arrives, or I’ll have nowhere to put it. But I don’t think that’s a huge challenge to be honest; I only need to get as far as riveting the top skins before they can go into storage. My plan is to leave the bottom skins off for the time being to facilitate installing an autopilot servo and any other internal stuff I may end up needing as time goes on.

Well, not an especially productive weekend. Saturday was eaten up with tailwheel training and a friend’s birthday, and today seemed to really want to be a lazy do-nothing day. I went along with that for the most part, but figured I should get something done this weekend.

First up, I finished drilling the nutplate holes for the landing light reflector. Nothing to crazy here; the nutplates get clecoed in place through the pilot holes and they’re used as a template to drill the rivet holes. I wanted to mock up the reflector between the ribs for a photo op, but I realized it couldn’t really be done without the nutplaptes riveted in place – something I’m not going to do until I have the ribs primed.

So what next? Well, I guess I might as well start general prep for this assembly. i already had two ribs out, so I pulled the rest after marking them so I could put them back in their places later. First item of business was the joint plate, to which the fuel tank will attach with screws. I reamed the screw holes out to full size, deburred, and then went to work drilling for the tank attach nutplates. And this is where I messed up.

I started just like I had done with the reflector mount nutplates, by clecoing all the nutplates through the screw hole. After aligning them like I wanted, I went down the line, drilling one of the rivet holes in each one. The next step would have been to put a cleco through that hole before drilling the other, but I realized I’d made a stupid mistake. With the reflector mount, I was clecoing through a small pilot hole, so the nutplate was guaranteed to be centered. Not so much here; the screw hole was much larger than the right size cleco for the nutplate. Thus there was no guarantee the nutplate was centered.

If I’d dimpled the screw holes first (these will be flush screws), then there would have been positive location. So I pulled all the nutplates, got out the c-frame and dimpled the screw holes. I figured I’d put the nutplates back on after that and maybe, by some miracle, they’d all line up. And surprisingly, they almost all did, except for two, which looked kind of like this:

Ugh. My first inkling was to chuck this part and replace it; after all, it’s just a simple strip with a bend in it to match the leading edge profile. No problem to replace, right? But then I thought about it more; this part has to align with three other parts – the inboard leading edge rib, the leading edge skin, and the tank skin. The more I tried to imagine how I’d drill the new parts it would align properly, the more I realized it was going to be a tough task.

The other option would be to drill the offending holes out to #30 and use a larger flush rivet. In almost all circumstances, this would be a complete no-no; there are very specific distances required between the center of a rivet hole and the edge of a material, to ensure proper strength. Nutplates, however, are a special case. Here, the rivets don’t serve any real structural purpose; they merely hold the nutplate in place while the screw is tightened. Once that’s done, the screw and nutplate are taking the entire load.

With that in mind, along with the difficulty of putting in a new part, I went with the larger hole. First I modified two nutplates by drilling one side out to #30 on the drill press. Then I clecoed them back in place on the joint strip and used the nutplate as a guide to drill out the hole in the plate. Then I could drill the other side of the nutplate as normal.

Here’s one of the modified nutplates. Not that the left hole is larger than the right, and as a result there’s less material around the hole:

With that crisis averted, I sat down and went through the drudgery of deburring all the rivet holes in all the ribs. I suppose next time I’ll repeat all these steps for the left leading edge, and then one night there will be a lot of dimpling to do. Not sure how much I’ll get done this week though, and then I’m out of town for a week or so for Thanksgiving, and the following weekend (Dec 6), I’m doing an EAA workshop on electrical wiring. So it might be a while before I can prime this stuff and be ready for final assembly…

Had a bunch of stuff to do around the house this evening, but I made a little time to go do a touch of work anyway. I just put the template back on the right wing and drilled the pilot holes for the lens mount. Then I put the right leading edge in the cradle, removed the two outboard ribs, and drilled the pilot holes for the reflector mounts. Then the quick-disconnect on my air hose failed and vented quite a lot of compressed air into the shop, so I replaced that and then decided to call it a night. So not much done, but hey, something is still better than nothing.

Well, after a fort-of celebratory night off after closing out the second tank, tonight I went back to work on the landing light cutout, this time in the right leading edge. I learned a little from last time, most notably with the protective vinyl getting in the way. So this time, I marked the general area of the cutout and preemptively removed the vinyl:

Then, as before, I traced the cutout and went to work rough cutting it with the Dremel cutoff wheel. Except I got a little sloppy at one point and let the wheel get away from me:

Fortunately, it’s just barely outside the line, so no big deal to just trim all that out when I finish the cutout. It’s not like these cutout are going to be precisely matched down the millimeter or anything. Sadly, that was not the last time I was sloppy. While easing out to the cutout line with the cutting bit, I let it wander out of the hole at the curved area, and the result was this lovely scratch:

Ugh. I went ahead and finished the hole itself with the file and flap wheel, and then I set about removing that scratch. It ended up being more of an operation than I expected, mostly due to it being on the curve where any imperfection was really obvious. But after about half an hour of work, first with the flap wheel, then with emery cloth, and finally with a green scotchbrite pad, things were looking good as new:

I decided to stop short of drilling the pilot holes around this one though; I’ll leave that for another night. Maybe tomorrow I can drill those and then locate and drill the reflector mount holes in the ribs. I think that once that’s done, there really won’t be much left to do on the leading edges but to deburr, dimple, prime, and then assemble. The simplicity is quite a relief after the fun of the tanks…

The 24-hour waiting period ran out today, by which I mean I didn’t abruptly think of anything really stupid that I did last night while tracing the light cutout. So tonight I went right to work cutting the hole. Well sort of…there was still that lead-up period where I had to convince myself to really go ahead and cut a hole in my nice leading edge piece.

First, I rough cut the hole with a cutoff disc in the Dremel:

Next I switched to a high-speed cutting bit and eased all the edges out to where they needed to be: (sorry for the blurry photo, the camera apparently wasn’t sure what to focus on)

Then I fine-tuned the hole with a file and cleaned up the edges with a flap wheel in the Dremel:

Finally, I put the template back in place and drilled the pilot holes for the lens mount points:

I need to do a little research on the rest of this thing. I sat down and reread the instructions, but I’m not at all clear on exactly how the reflector (to which the bulb mounts) will attach to the ribs while allowing for adjustment. The instructions are good for the most part, but they could do with some better photos and/or drawings of the reflector assembly. I don’t think this will be much trouble, but I definitely want to get it right…