Once again, it’s been one of those days when all the effort seems to be mental, and very little happens from a physical standpoint.

One note from yesterday: after doing some reading, I decided against my idea of temporarily mounting the left wing so I could locate the conduit penetration. Sounds like that would be at least a three-person job, and I’m not sure the benefits would justify the effort and risk – besides, I don’t think there’s real reason to do it right now anyway.

To start the day, I decided to evaluate my idea of going back to running the pitot lines through the conduit, and I did this in the most practical manner possible – by cramming examples of the wires I’d need into the tube, along with the pitot lines. Here I’ve got two 12AWG wires (power/ground for the pitot), one 22AWG (pitot heat status), two 18AWG (landing/taxi light power), and the big shielded wire for the nav/strobe light units. It all fits quite nicely, so I declare this idea to be feasible. This at least settles one packaging concern.

Next, I moved on to looking at the pitot controller. I still can’t finalize the wiring run to the pitot location until I get some supplies, but I figured I could at least work on the connectors a bit. One problem here that had to be solved was with the two 26AWG white wires that go from the controller to the tube. These twisted pairs end in Molex micro-fit connectors, and a couple weeks ago, while trying to clumsily de-pin one of them, I pulled the wire out of the contact. I ordered a proper removal tool from SteinAir, only to find that apparently I need two of them to de-pin, since each pin has two tabs, and the tool only has one prong.

I’d already ordered the necessary parts a while back, including extras, so I just decided that I didn’t need to de-pin after all. I just cut off the old connector, crimped on two new pins, and installed them in a new connector. Done. Also good practice for when I build the intermediate harness later on.

Also, while I was in a crimp experimentation mood, I decided to give my D-sub crimper a try. I cut off a small length of 22AWG and grabbed pins, sockets, and a connector for good measure, all from my last SteinAir order. Crimping the pin was super easy, as was inserting it into the connector with the insertion tool I got from Amazon. Extracting it was a different story – turns out buying this tool from Amazon was a poor choice. The extraction end is malformed and unusable. So now I have a test pin inserted into a connector and I can’t remove it. Fun.

This pretty well transitions into what I spent the rest of the day doing, and that was compiling yet another round of orders. I knew I wanted a actual non-crappy D-sub pin tool from Stein. I also wanted to order the conduit from Amazon that I was looking at last night. Oh, and I wanted some cushion clamps to use for routing the wires at the wingtip, once I had all the materials to actually mount the pitot controller.

And of course, since I was ordering stuff, I wanted to maximize the utility, so there was lots of looking forward to other wiring stuff and adding items. In the process, I sort of firmed up my plans for components under the seat pans – mainly terminal strips for interconnects to wing wiring stuff, but also rough location ideas for the Flyleds controller boards for the nav lights and the landing light wig-wag function.

Now I just need to go actually complete these orders. The real question is, how many days will it be before I realize I need even more things? Also, how much of the cost of building this plane will have gone directly to UPS and FedEx? I don’t want to know…

I’ll tell you, the more time goes by, the more I really come to understand the whole “90% done, 90% to go” maxim among builders. In my mind, I have a whole roadmap of things to be done, mostly revolving around getting the wiring done. Yet every time I go to try and move forward on that, it seems like there are myriad little hangups preventing forward progress.

As of today, I’ve received all the wiring stuff I ordered. A whole lotta wire in various gauges and colors, an absolute boatload of D-sub components from SteinAir, plus the relay and diode I’ll need for tying the busses together. The general goal of this was to be ready to permanently install the conduit runs in the wings and get all the wiring pulled, and specifically the first thing I wanted to address was getting the pitot heat controller installed with its extended wiring harness.

And yet…after thinking about how to run the wiring from the controller to the pitot location, I’ve decided the smart thing to do would be to put in a short run of split loom conduit from the wingtip to the pitot bay. If I were to ever need to replace that wiring, this would vastly simplify the process. It also provides better wiring protection, and finally, enables me to satisfy a concern I had about the wiring service loop.

I’ll need enough slack in the wiring to allow the pitot to be removed from the mount until I get to the preinstalled disconnects. But with no good access to the pitot bay, the best I can hope for is just cramming the wire in there and having it floating around unsecured. It’d probably be OK, but the thought bothers me. With the conduit, though, I can keep the service loop normally at the wing tip, where I can secure it carefully. If I need to remove the pitot, I can just feed the extra wire into the conduit, providing the slack needed at the mount.

The downside is that, well, I need some conduit before I can move forward on that. The good news is that I can get that from Amazon and have it here early next week with free shipping. But it’s still a wait…

That brings us to the next hangup of the day. This started with me thinking about the holes I’ll need to cut in the fuselage sides to allow the main wiring conduit to protrude inside, but that moved into a different question related to the pitot tube. I’ve been planning on running the nylon pitot/AOA lines though snap bushings in the ribs alongside the main spar. But then I have to figure out how to get them into the fuselage. I can’t just make penetrations right in line with the line locations, because on the fuselage that’s where the spar center section structure lives. There’s an existing hole nearby, but that’s where the aileron push tubes pass through…routing lines through there seems unwise. So if I stick with location, I’ll have to route the lines in the tight space between the wing root and fuselage aft to some sort of passthrough.

The more I think about this, the more I end up back at my original plan, which was to route the lines through the wiring conduit. Then it can enter the fuselage at the same place as the wiring, thus simplifying everything quite a bit. Additionally, the lines can exit the conduit at the wingtip, and go through the same flex conduit as the controller wiring, and have the same service-loop securing setup as the wires. That has a nice tidiness to it.

The question just remains: how well will everything fit? Well, at least I now have the materials needed to make that evaluation. Something for tomorrow’s to-do list, I guess.

So that brings us to the one bit of tangible work for the day, though there’s an amusing twist at the end. This returns us to the question of making the fuselage penetration for the main conduit. A while back I came up with the idea of making a template that I could use to locate those holes, and tonight I decided to put that into practice.

Basically, the idea was to locate the conduit relative to the bottom of the aft side of the spar. This wasn’t too hard, just required some careful work with a try square, ruler, and other fun stuff. I then transferred my measurements to a piece of scrap 1×4, and drilled a #30 pilot hole. I figured I’d eventually use this to drill a pilot hole in the fuselage, which I’d then enlarge with a unibit.

With the pilot hole drilled, I did a visual test against the conduit bracket on the inboard rib, and it seemed to line up well, so I added the last piece: another scrap 1×4 piece screwed 90° to the other one. The idea is that this piece is slid into the center section and held against its aft side, providing the reference needed to locate the hole.

Here’s the finished piece, sitting by itself and then held in place on the fuselage:

Now, for the amusing twist: I’m not sure I’m going to use this after all. After attaching the 90° piece, I did another sort of test-fit against the end of the wing spar, and then it seemed the hole wasn’t lined up well at all. Granted, this is probably because I had to hold the piece much further from the conduit bracket, but that just made me think that there’s a lot of slop in this setup, and so my overall trust in it is pretty low.

I’m thinking that just figuring out a measuring scheme I can transfer to the fuselage is smarter. Maybe first measure the distance from the bottom of a wing rib to the bracket center, ensuring I’m square against the rib when I do it. Then I can make on the rib where the line intersecting the bracket hits the rib, and measure the straight-line distance from that to the intersection of the rib and the spar. That should be easily transferable to the fuselage, and seems more reliable than my template idea, which kind of feels like the old telephone game where intermediate reps end up garbling the original message.

I’m also thinking now about just seeing if Josie can help me…well…very temporarily install a wing on the fuselage. This would have a couple benefits: I could then run the conduit through the wing in question and directly trace its outline on the fuselage, and have a lot more confidence in the hole location. I could also measure the clearance between the inboard rib and the fuselage at that location, which would help me trim the conduit to final length, and thus eliminate a source of trial-and-error when the time comes to more permanently fit the wing.

Will I do it? I dunno, we’ll see if I still feel positive about the idea after a good night’s sleep. Though first I guess I’ll be finishing up my Amazon order…

So today’s task was to work out the landing light mounting. Way back when, I bought the Duckworks leading edge landing-light kit, and at that time I’d intended to use some sorta-nonstandard Whelen lights, and so the kit I ordered came with blank mounting plates – rather than, say, having an existing cutout for a PAR36 bulb.

In the intervening years, Flyleds became a thing, and I went with their combo light, which we’ve seen before. One of the nice things about this combo light is that it fits in a PAR36-sized cutout (though the unit is a lot deeper than a PAR36 would be), so it’d work great with that Duckworks mount…if only I had it. And in fact. I did consider just ordering two new mount plates, but in the end it seemed stupid to not at least try to cut the mounts I had.

And really, the task is pretty simple. Vertical positioning of the light is a no-brainer – just put it on centerline. The horizontal position is more interesting, though – the mount spans the entire bay in the leading edge, but the cutout is small, so the light obviously needs to be aligned with the cutout. So I spent some time with a ruler, reaching inside the bay, to measure the distance from each rib to the corresponding side of the cutout, and the width of the cutout itself. Armed with this information, I marked off the rough size of the light on the plate – a 4” square (technically it’s round but the square works fine for this). Then I installed the mount in the wing and verified the lineup. Actually, I did this twice, because the first time I measured a bit wrong and put the mark an inch off. Which is, of course, why we start with just marker…

This photo (and a few subsequent ones like it) is a bit awkward – the wings are still in the cart, leading edge down, so I’m basically shooting up from the floor to get this angle. Yeah, I did a decent amount of squirming on the floor today:

With the position verified, it was time to make the cutouts. I actually decided to make these about 4.25” instead of 4”, to provide a little more clearance for some of the components. This ended up being unnecessary, for reasons we’ll cover later, but oh well. My fancy hole-cutter tool, which hadn’t been used in some time, made short work of this:

Next I did some more positioning lines, which allowed me to position a light unit in each mount, and use the prepunched mount holes in the lights as a drill template for the mounts. This gave me my mounting screw locations, and allowed me to cleco the lights into the mounts for the first time:

Now, that photo – in particular, the way the lights are located behind the mounts – belies a whole ton of head-scratching. At issue was the question of how exactly these lights would be installed (and potentially removed for maintenance at a later time). Put simply, there seems to be no way for the lights, as delivered, to be inserted into the bay of the leading edge. There are two possible avenues here – in through the leading edge cutout, or through the lightening hole in the outboard rib.

It does seem to be possible to get the unit in through the leading edge cutout, but only with the taxi light projector removed. That would mean installing that thing inside the wing, a somewhat fiddly operation thanks to the long screws and springs involved (that is, the mechanism for aiming the light). I did not like this idea at all, so I decided that I’d plan on going in through the rib. The catch here is that the installation process for these will entail first installing the mount, then installing the light. That, in turn, means that if I’m putting the light in through the rib, it has to go behind the mount.

Still, there was the problem that the light wouldn’t fit through the rib hole either. The useful news here is that while the combo light circuit board is rectangular, the actual circuit traces are confined to a 4” circle. The rest of the board is fair game for trimming to fit a particular application, and that’s exactly what I did.

My original plan was to mark a circle just a bit larger than the mount cutouts, and use that to trim the boards, retaining two “ears” where the screw holes were located. This plan lasted about as long as it took for me to try and figure out how to trace the cut line with a marker. That was challenging enough, but making the cut would be not much fun either. So I decided to start small, and simply mark 45° cut lines starting at my potential mounting “ear” locations. I figured worst case, if those cuts weren’t good enough, it’d be material I’d be removing anyway for the circular cut idea.

Removing the corners still didn’t quite allow the light to pass through the rib, but by simply trimming a bit off the top and bottom of the boards, I was in business. It still takes some careful maneuvering to get the light through, but it’s doable. The resulting trimmed light unit has a sort of elongated octagonal shape:

This just left the question of attaching the lights to the mounts. Normally, if you were installing the lights from the front, you’d install nutplates on the back of the mounts, to receive the mounting screws. That wouldn’t work in this case, so there were two options: either install the nutplates on the front of the mounts, so the mount screws were installed from inside the wing, or install the nutplates on the light itself, so the screws would go in from the front. The latter seemed like a better option: first, I wouldn’t have unsightly nutplates visible in my landing light cutout, and second, trying to line up the screwed working through the lightening hole sounded like no fun.

So I drilled the lights for the nutplates and got them installed, and then, it was finally time for a full-up test fit. First, the mount went in, then the light, and the result looks pretty good:

From the back side of the bay, we can see that the heat sinks have plenty of room:

So that’s pretty much the end of this bit. The one remaining question is how I’ll handle the wiring for these; this is particular interesting since the wires for the three landing light projects attach on the front of the unit, while the wires for the taxi light attach on the rear. I intend to run all four wires to a single Molex connecter in the wingtip, and I’d like for the wiring pigtail to be removable along with the light unit; so I may have to get creative with that. Worst case, i guess I could just use two two-position connectors instead of a single four-place. In any case, I can’t really do anything with this until the wire comes in.

So now I guess I gotta figure out something else to do that doesn’t involve wire. Maybe I should dig up the aileron trim servo and see about getting that system done; I worked on that years ago, got frustrated, and moved on. Perhaps I’m better skilled now than I was then…