I started out my day by heading up to Weiser Air Park for the monthly lunch the local RV builders do. I hadn’t been to one in a few months due to other commitments, so it was nice to go hang out, talk about building, and most importantly drool other everyone else’s airplanes. One the guys who flew in today was in this sweet-looking RV-8. My practical side is a little unsure about painting an airplane in anything vaguely low-visibility, but I have to admit that this is a cool paint job.

After watching everyone depart – a process that culminated with a low high-speed pass from an RV-10 driver – I headed home, feeling motivated to get to work. That got a little sidetracked when I decided to lie down for a few minutes, whereupon staying up late Friday night caught up with me.

Finally, rejuvenated, I went out to the garage. Mindful of how long it’d been since I shot rivets, I did some practice runs with a few scrap pieces before going to work on the spar itself. I was still kind of nervous for the first few rivets, but before long I was getting into a good groove. And that, of course, is when things got interesting. I was on the inboard end of the wing, where the spar reinforcement bars make the top and bottom rivets slightly more difficult to see the shop head side. I had shot four of the five rivets on this rib just fine, and the last one was the topmost. I inserted the rivet, got the gun and bucking bar in place, squeezed the trigger for a bit, then bent down to check my progress.

I was shocked to see a tiny shop head. Wait, did I not get the rivet in all the way? I checked the other side – nope, the manufactured head is flush against the rib flange. What happened?

I was confused by this for longer than I’d like to admit, until the obvious occurred to me – somehow a shorter rivet must have gotten mixed in with the ones I was using. If I’d been in any other hole, I would have seen this before shooting, but it just so happened to be the hole where my vision was obstructed.

Well, time to get drilling. This turned out to be a pain; I got the manufactured head popped off pretty easily, and started trying to punch the rest of the rivet out, but that thing was in the hole quite securely. My level of violence wight he hammer continued to rise before I realized that this was exactly the mindset that caused things to get damaged. It was getting on towards dinner time anyway, so I left things alone, fired up the grill, and cooked off some brats. We ended up watching a movie with dinner, after which I went out and, with my mind calmed down some, got the rivet punched out (though not after drilling all the way through it and using pliers to help encourage it). The hole seemed good but maybe slightly oversized; not enough to need to drill out to the next larger size, but enough that I was worried about the shop head clinching (this tends to happen when there’s extra play in the hole).

Fortunately, there’s a well-known solution to this. I’d never tried it, but you can take a rivet squeezer and give the rivet a tiny bit of squeeze, just enough to swell the shaft and snug things up. It worked like a charm; I shot the rivet and then called it a night.

Tomorrow will be more fun. All the ribs I did today had their flanges facing left, which made it easy for me to shoot and buck. Some of the ribs, though, face the other direction. The only way I’d be able to shoot and buck those would be to switch hands and shoot left-handed. I’m not too confident with that ability, so I’ll probably get Josie tome come out and help.

Not much to see here. I got a somewhat earlier start today because I worked from home for the second half of the day. It sure helps to not have to sit in evening traffic to get home…

Anyway, straightforward stuff today. I started out by finding the outboard-most rib and bolting on the piece of angle that’s used to attach the skeleton to the stands, then I clecoed that rib in place before setting the spar onto the stand. From there, it was a fun game of putting each rib where it went. I guess my binary system worked OK, because I got everything right the first time, without any oddness. Then I took the whole assembly back off the stands and laid it on the workbench to cleco the rear spar on. This seemed preferable to sitting on the floor and trying to line things up and cleco at the same time.

Hey, that looks like part of an airplane:

From there, I grabbed a couple of wing skins and did another one of those “because I can” assemblies:

Then it was time for dinner and we decided to watch a movie afterwards. Maybe tomorrow I can bang some rivets? I’m a little skittish; it’s been over a year since I shot rivets with the gun, and that’s going to be a necessity here. Even better, I’ll almost surely have to use the offset set to get in some of these places. I guess I should probably get some practice in before I go to town on the wings…

Lesson of the day: it takes a lot longer to do, well, everything with the wings. There are more of everything and each piece is bigger…

First, I’ll rewind a bit. Saturday wasn’t entirely unproductive, but mostly so. We had some errands to run in the morning, and when we got home I felt bad enough that I went and laid in bed for several hours. My back has been bothering me off and on for a week or so, and it got pretty bad yesterday (this has been a sporadic occurrence ever since I messed it up slinging boxes for UPS when I was 18).

By the time I felt ok to get up and walk around some more, it had gotten late, which did have the positive effect of the temperature dropping. I decided that my goal for the night would be to cut the new pieces of wood I needed to extend the jack platforms on the wing stands. I had enough 2×6 left over that I ended up cutting four sections, which I’ll sandwich together and attach to the long support to give me an extra 3” of jack pad length. I also cut some of my leftover 3/4” MDF scraps into the new platforms. I did not, however, actually assemble anything.

Today’s goal was to get the wing ribs primed. I slept in again and got to work just before noon. The first order of business was to make a hole deburring pass on each rib. This included the holes I’d match-drilled to the spars previously, as well as the tooling holes in the rib face. I’d left those alone previously because I thought I’d be running conduit through them. Once that was done, I scraped the part ID sticker off each rib, then took them outside for a good cleaning. This was where I got to really enjoy the Texas heat for the first time. It probably took over an hour to scrub down all the ribs.

Prior to the cleaning, I’d set up a piece of rope across the backyard to hang the ribs from. I then found it necessary to anchor the bottoms of the ribs as well so they wouldn’t swing in the wind too much. Some small-gauge wire I had lying around worked well for this. Here are all the ribs hung up and ready to be sprayed:

Next I got a less in the scaling up that happens when moving to the wings from the empennage. I had two full cans of NAPA 7220 on hand, which I figured would be enough. WRONG. There were still some bare spots when I emptied the second can. Fortunately I still had some SEM leftover, so I used that to finish the job. Both primers are gray, but the SEM is slightly lighter, so my ribs have a sort of amusing mottled look to them.

Here are the finished ribs:

Tomorrow I’ll probably go ahead and fix the jack pad on the assembled wing stand, cleco the left skeleton together, and hang it on the stands for the time being. I probably won’t be able to get to riveting tomorrow. I had originally planned to assemble the other wing stand first, but now I’m thinking I’ll wait until I need it. That means I need to clean up a bunch of stuff I left lying around in anticipation of assembling that thing…so much stuff that I don’t even have workbench space available, which I’ll need to rivet the skeleton.

Hopefully I’ll feel OK after work tomorrow…

Well, not so much of a highly productive day today. I gave in to the urge to sleep in and had some other things to do around the house. But I still found time to get all those holes drilled for the conduit mounts.

The first order of business was to create some kind of template so I could locate the mount holes consistently. The main concern I had here was figuring out a way to reliably locate the template relative to the lightening hole. After some thinking, I decided that the hole itself was the best reference. The circumference of the hole has a slight channel pressed into it, presumably for greater rigidity. I decided to make my template a two-part affair; first there would be a piece of 1/4” ply cut to butt up against the edge of the channel, and on top of that would be a piece of 1×4 I had lying around, which would have the actual holes drilled in it.

The first step was to trace the edge of the channel relative to the rib flange. Yes, that’s a piece of a McDonald’s bag. Go ahead, judge me.

Next I cut the paper in that line and transferred the shape into a piece of ply:

Then I cut the curve on the ply in the bandsaw, ensured everything lined up, and glued the ply piece onto the piece of 1×4. I didn’t get any pictures of this.

At this point, I had some dead time while I waited for the wood glue to set, so I decided to review all the instructions for the wing kit. I was particularly interested in seeing when the wing skins would get match drilled and the ribs dimpled. With the empennage, everything pretty much went together at once, so by the time I got around to priming a rib, it was already fully match drilled and dimpled. Not so with the wings; the skeleton goes together and then the skins are match drilled with the skeletons hanging in the stands. Ergo I’mm be match drilling and dimpling ribs that are already primed. Not that this is a problem really; I even did some tests with dimpling primed pieces a while back and the rattle can primer held up just fine.

Mostly, though, I just wanted to kind of get the big picture in my mind. It looks like once the skeletons get hung, the skins are match drilled, and then work shifts to the leading edge section and the tanks. I’m sure the tanks will be quite a bit of work. Only after those go on for good is it time to rivet some wing skins. then it’s time for the ailerons and flaps!

Anyway, fast-forward a couple hours (and maybe a nap…), and the template was dry. I used one of the hangers to locate and drill the two holes:

I ended making a few modifications after this; the 1/4” ply is actually a good bit thicker than the lightening hole channel, and I wanted the top part of the block to fit better. So I shaved off some of the ply in the bandsaw and then went to town with the bench grinder. I struggled a bit trying to figure out a way to hold the template in place while I drilled the holes, and then a solution became obvious: the template sat against the rib flange, which had holes for the wing skin. All I had to do was locate it properly, clamp it in place, and drill 3/32” holes through the flange, and then I could just cleco the template in place for drilling. Very nice.

After checking everything about 20 times, I finally took a deep breath and made some holes. It worked out quite nicely:

I think I’ll probably get some washers to put between the pull rivets and the hanger itself, since it’s somewhat soft plastic. Can’t hurt to distribute the clamping force of the rivets a bit.

After this, I repeated this procedure 27 more times. Which was actually four more than I needed; at the inboard end of the wing, there are four ribs spaced closely together to support the wing walk, where people will be stepping as they get in and out of the plane. There’s no need to put a hanger on each one of these, so I was going to skip the two “inner” wing walk ribs, but I kind of got on a roll with the drilling and drilled all of the ribs.

Anyway, that’s it for today. Next steps will be to do a final deburring of the left wing ribs, then prep and prime them. I’m going to wait on the right wing ribs until I have the left ribs primed and at least clecoed back to the skeleton. The reason for this is that while I like my binary marking system, it has no provision for denoting left/right wing ribs. So I figure I’ll just keep the batches separate for now.

Thing is, cleaning and priming all these ribs is going to be an all-weekend project for sure. I’ll probably just wait until next Saturday to do that. This week after work, I can finch the deburring, but that’ll be trivial. Maybe I’ll work ahead a bit and see about building the aileron pushrods or the bellcrank assemblies or something like that. I feel like I’m getting some momentum going here, so I want to keep rolling on something and not get in the habit of not working on things.

Finally, a good productive day. Haven’t had one of these in some time. I started the day off with a trip to Home Depot to pick up my conduit materials. I was sort of hoping for some Class 200 PVC, but I ended up with PEX instead. The Class 200 PVC is very thin-wall, generally used for vertical runs from water heater pressure relief valves. It’s only used vertically since the walls are so thin, and it can’t support much weight. But that also makes it far lighter than normal Schedule 40 PVC, and it would be perfectly suitable for my conduit run. Unfortunately, Home Depot didn’t have any other than some short prefab lengths in the water heater section. I need a 10’ run, and I don’t much feel like going to the trouble of buying several short pieces and joining them together. So I went with 3/4” PEX instead. They even had nice 10’ precut sections, exactly what I need. I also picked up some hangers, which I’ll use to secure the PEX to the ribs with pull rivets.

Back at home, I wanted to do a rough run of the PEX through the assembled skeleton I had just to double-check everything. I even went so far as to mock up both the aileron pushrods with the rod ends and put them in place, so I could see what everything would look like. Here you can see the bellcrank assembly, the small pushrod that runs from the bellcrank to the aileron, and the long pushrod that runs from the bellcrank to the control stick. Below the short pushrod is the PEX pipe, sitting in one of the hangers and temporarily clamped in place.

A closer detail of where the PEX and the pushrod cross paths. There’s a couple inches clearance in here, and the worst case I can envision if the PEX were to come loose of the hangers would be for it to rub against the pushrod. I can’t see any way it could cause a control blockage issue.

On another note related to plumbing, I’ve decided to stick with just this one conduit run. The consensus I’m getting from reading VAF experiences is that I shouldn’t have any issue running coax for the NAV antenna in with everything else. The main source of interference people seem to report is from HID landing lights, and I suspect that by the time I finish this, LEDs will have dropped in price enough that they’ll be the best choice.

Now that I’d satisfied myself with the plumbing, I decided that since I already had the whole skeleton clecoed together on the bench, I might as well go ahead and match-drill the spars to the ribs. I made a somewhat unpleasant discovery in the midst of this though – it seems that the garage outlet circuit isn’t up to powering both the compressor and air conditioner. Which is kind of odd – I’d thought this might be an issue before, so I made a point one night of running both at the same time, and I had no issues. No such luck today though…I’d gotten through a few holes when the compressor kicked on briefly, followed by darkness and a deep silence caused by my music stopping as well. Well, time to go reset the breaker. Fortunately, the garage seems to maintain temperature fairly well for short periods while the A/C is off. I guess I’ll just have to be sure I turn it off before I do a bunch of drilling.

With the ribs match-drilled, I now need to keep track of each rib’s position on the spar. Most likely I could switch them around with no issues, but it’s good practice to be sure. On the tail, I used a simple system of punch marks for this, but here I have far more ribs (14 per side to be precise). I went full nerd on this topic and devised a binary marking system. Doing it this way means that each rib only needs four punch marks; I just number them from inboard to outboard. Hopefully these marks don’t disappear under the primer…

Here’s an example of a mark. This is 0111, which is #14, or the most outboard rib. It’s hard to see, but there’s one “low” punch followed by three “high” punches.

Finally, after taking a break inside for some dinner, I set about finishing the evening by doing my last row of tank attach countersinks. Not really difficult work, though I was cognizant of how long it had been since I did this last. I got back in the groove pretty quickly, but still, I’m way more confident doing stuff like this when I’m in practice. I’d better keep up the work!

Finished row of nutplates:

Tomorrow I think I’ll make another Home Depot run for some 1/4” plywood. I want to make templates so I can drill the rivet holes for the conduit hangers. I also need to get another pack of five hangers; I forgot to count the ribs before I went this morning, so I guesses at the number of ribs and came out a little low. If I can get those holes drilled, I can make a final debarring pass on the ribs and start thinking about priming them and riveting the skeletons together! Which also means I need to start thinking about building my wing stands…

Not really so much of a work day today, more research and head-scratching. I spent some time searching around for how other builders had done their wing plumbing, then went out to the garage to try and visualize things a little better. The big concern here is the control system for the ailerons; obviously I can’t have the plumbing interfere with flight controls.

The “standard” Van’s instruction calls for running black ribbed conduit for the electrical stuff, and using grommets through existing tooling holes for the pitot lines. However, this setup has some downsides in my opinion.

• The ribbed conduit will probably be more difficult to route wires through since the interior isn’t smooth.
• Running the pitot lines through grommets would make replacing those lines a potentially unpleasant task; not that these lines wear out frequently or anything, but why complicate things unnecessarily?
• Speaking of unnecessary complications, why have three separate line runs? I don’t see why the pitot lines would need to be separated from the wiring.

Considering all these things, I was leaning towards skipping the conduit and instead running something like 3/4” PVC or PEX through the existing lightening holes. Several builders have done this, and it seems simpler than drilling holes to run conduit through. But this also puts the conduit further into the wing interior, which goes back to the “don’t interfere with flight controls” issue.

To give myself peace of mind, I decided to mock up the aileron control system in the left wing. I already had the main spar sitting on the bench with the ribs clecoed on, so I got out the rear spar and clecoed that in place as well. Next, I loosely put the aileron bell crank in place. This piece converts the side-to-side movement of the main aileron pushrod (which attaches to the control stick in the cockpit) to forward-backward movement of the smaller pushrod that directly actuates the aileron. The smaller pushrod was my main concern, so after putting the bell crank in place, I laid the rod in place using the bell crank and the rear spar passthrough holes as references.

This confirmed what I pretty much knew anyway: The small pushrod sits towards the top of the wing, and leaves plenty of room to run 3/4” tubing through the second lightening hole at its lowest point. I’ll probably go ahead and get the tubing I’m going to use tomorrow or this weekend just to make really really really sure it’s OK.

The only thing I haven’t really accounted for is possibly wanting a second, isolated wiring run. I’m debating whether I’ll want to put in a wingtip VOR antenna at all. I intend to have this plane be IFR certified, and while it doesn’t seem that a VOR antenna is required, it might be prudent to have one as a backup to GPS. That, in turn, raises the question of possible noise from the electrical wiring. I’ll need to keep researching to determine if this will be a problem. For the time being, though, I think the single conduit run will probably be just fine for everything.