After an overnight stay in Houston for the FlightAware holiday party, we got back home early this afternoon, and I found a few hours to get a spot of work done. I decided to go ahead and attack stringing the rudder cables, even though I won’t have a rudder to connect them to until my rudder stop comes off backorder and ships (hopefully this week).

Stringing the cables is a fairly straightforward procedure; you feed them in from the rear and just slowly move them forwards. There are two sections of protective plastic tubing around the cables; a short section at the rear avoids chafing where the cables pass through the aft side skins, and a longer section further forward protects where the cables run in close proximity to the rear-seat footwells.

The cables end up passing through essentially every bulkhead from rear to front, and as the cable is threaded through each passthrough, a snap bushing is slid over the cable end and popped into place. Things get interesting, though, when you make it up to the seat floor area. This is where we need to rig that long plastic tube in the footwell area. Here, the cable passthrough is a small detachable piece on each side, which is attached to a seat floor angle with a screw. I’d already riveted the nutplates here, so it was time to do the snap bushing rigging.

We want the plastic tube to be fixed in place, so it gets secured to the snap bushing and the cable guide at its aft end. This is just a matter of cutting a small hole in the tubing, forward of the snap bushing, and threading a zip tie through that hole and the end of the tubing, to secure it to the support.

Here’s the support threaded into place:

And here it is with the zip tie installed. Note that I chose bright orange for really no reason whatsoever:

With that done, I returned to the rudder pedal assembly that I was working on last Friday. I’d mostly reassembled this, save for reattaching the brake pedals, so I got those back in place. I still haven’t installed the cotter pins on these pivot pieces – I thought about doing that today, but decided there’s still no reason to finalize the assembly yet. Then I got the pedals installed on the forward floor.

This was a bit interesting, and where my delaying of riveting the forward bottom skins caught up with me a bit. The pedals attach to two nutplates through the firewall on the forward end, and two nutplates through the floor at the aft end. Well, those aft nutplates aren’t there yet, since they’re riveted as part of the forward lower skin procedure. For now, I just put two bolts through to locate the pedals there, though it occurs to me I can cleco two nutplates in place, and will need to do so to actually test this stuff out. That’ll be another day, though.

From there, I wasn’t quite sure what to do, so I decided it was time to mock up the cockpit a bit more and start evaluating my panel/control layout. Of particular concern was the location I’d chosen for the SDS CPI2 electronic ignition system’s controller. In my mockup, it fits fine on the left panel wing, but in the cockpit, there’s a canopy rail that seemed like it might make access interesting. Also, the forward top skin/glareshield figured in here too, so I dragged that out and clecoed it into place. I also stuck in the throttle quadrant for maximum realism.

It’s really looking airplane-y now:

And then I hopped in and spent a fair amount of time just sort of chair-flying:

And lest anyone thing this was just a chance for me to sit in there and make airplane noises, I was attempting to really evaluate how the cockpit flow would work out, and I’m actually considering making some changes. For one thing, the paper cutouts I have now aren’t quite right. The displays are older Skyview Touch units, whereas I’ll be using newer HDX units. They’re essentially identical in size, though, so this doesn’t really affect the mockup hugely. More notable is that the TSO’d GPS I have is a GTN650; I think I made these before Garmin announced the much more budget-friendly GPS175 earlier this year. The GPS175 has a bit less screen height that the 650, so what I have here is a bit off.

The big remaining question is how I want to lay out my various switches. I’ve already decided that lighting and other similar stuff will go down on the right-side console, and common in-flight switches (that won’t be on the stick grip) I intend to put on the left wing panel, just above the throttle – but that still leaves me with a handful of switches to manage the electrical system. Most of these I’ll only be touching at startup/shutdown, but some will also be emergency-procedure items, ie handling in-flight electrical failures. So there’s the question of location there – I don’t want them in an annoying place no matter what, but I’m not sure how close at hand they need to be. And really, after sitting in here, the panel is so small that I’m not even sure I need to be careful about location – nothing on the panel is going to be hard to reach.

Anyway, I’m leaning towards something like this:

Its not quite as OCD symmetrical as previous designs, but I don’t think it looks horribly unbalanced or anything, and I like how it moves some of the controls. Shifting the displays right a bit means that the left display (PFD) is a little closer to centerline. I may even run that screen normally split between the flight controls and engine instruments, and have the left one be all map all the time. This also moves the com radio down closer to where my hands will be, and the power distribution switches all end up where they’re easily reachable by my “free” left hand.

One thing that may be smarter would be to swap the intercom and autopilot panels. I like having the intercom panel by the radio, since they’re sort of associated, but the intercom isn’t something I’ll be messing with frequently. The AP panel, though, is way more likely to be used in-flight. Of course, functions for both the AP panel and radio will also be able to be accessed through the touch screens.

Anyway, I could go on about this all night, but I should probably sleep at some point. So I’ll just stop here…

Not a lot to report tonight. In preparation for rigging the rudder cables, I brought the rudder pedals up from where they’d been sitting for some time. This revealed a couple things that needed addressing – first, the exposed steel of the slide bar had rusted, and second, the assembly in general was pretty dirty. So I ended up just tearing the entire assembly apart for a good cleaning. After getting the rust off the slide bar, I gave it a coat of CLP and then hit it with the heat gun in hopes of getting the stuff to cure a bit. Everything else just got a good wipe-down.

I need to dig out the applicable plans page, double-check all the hardware, and get everything pinned. Most of the bolts here are drilled and use castle nuts, but when I assembled this the first time I decided to wait on the cotter pins. I think now is probably the time to final-assemble this thing. That’ll have to wait until Sunday, though – tomorrow is a busy work-related day, with a fly-out event in the morning and the holiday party in the evening…

Well, first up, I did order the rudder stop I mentioned earlier – unfortunately, it’s on backorder and won’t ship until probably next week. I did spend a little bit of random time this week thinking about cockpit layout stuff, which culminated in me temporarily hanging the instrument panel, with some paper cutouts of avionics taped to it. I also ordered my front stick grip from Tosten – I’m thinking I can go ahead and fit it to the front stick, and get that stick cut down as needed to go under the panel. I also want to see how the MS grip would work for the rear stick. Originally I’d planned on doing a simpler Tosten grip (I’m using the multifunction MS grip up front), but the other grips have a significant forward can’t to them, which others have said is problematic for clearance to the front setback. The MS is more upright, and I can get one without all the optional buttons.

Anyway, this is all kind of revolving around me wanting to get the cockpit somewhat together-is, so I can spend some time sitting in there, chair-flying and deciding how I feel about my panel/switch/control layout. Which is something I want to do before I finalize everything and get to ordering, probably in the next couple months.

For tonight, the first thing I wanted to do was some final adjustment of the control column. The column hangs from two rod-end bearings, front and rear. When I initially installed this, I took a guess as to how those should be adjusted, which controls where the column actually hangs. I couldn’t find any sort of spec for the adjustment, no matter how hard I looked, so eventually I asked on VAF, and someone pointed it out – it was right on the plans page I’d been looking at. So I wanted to just get those adjusted to the proper length, then double-check all the rigging afterwards. I wasn’t sure if it might affect the resting point of the sticks, but it didn’t seem to.

Next I’d expected to work on the rudder pedals, and maybe route the rudder cables, but I got an unexpected call from a neighbor, which resulted in me helping a local Apache crew with some training, by driving a Humvee around the neighborhood while being stalked by said Apache. So that’s why I only got half an hour in tonight…

As alluded to yesterday, today was all about doing the fitting work for the control stick pivot bushings. The nature of these joints is that the bronze bushing, when its pivot bolt is torqued, will be held in place between the “ears” of the control column. The control stick, in turn, will rotate around the bushing. With this in mind, it’s necessary to work down the ends of the bushings, getting them to the proper length to be trapped between the ears, as well as adding a slight angle to match the slight taper of the column ears.

I approached this task essentially in two phases. The bushings were a good 1/8” or so too long, so I started by removing material from the ends to shorten them to roughly the correct length, prior to working on the angle. To do this, I used my calipers to get a rough idea of the width between the ears at the widest point of contact, then used that to mark the bushing. Then I simply chucked the bushing into my drill, and clamped the drill into the vise to make a poor man’s lathe. I just used a vixen file against the spinning bushing to gradually remove material while retaining the square end profile:

Once the overall bushing length was about right – which is to say, I could slip it between the ears about 1/8” short of the pivot hole – I got to work on adding the angle. To do this, I put sharpie marks on one side of the bushing, at each end – these were to mark what would become the “high” point of the angle, that is, the widest point. Then I simply used a plain file to very gradually work an angle to each end of the bushing. This was just a trial-and-error process – tweak the angles a bit, do a test-fit, tweak them a bit more, over and over again.

Pretty soon – on a geological time scale, at least – I had a nice snug fit at both ends:

But this is only half the work for this particular pivot point. The next bit that needs attention is the sleeve on the control stick itself, in which the bushing rotates. This sleeve also needs to have material gradually removed, so that it’s slightly shorter than the shortest length dimension of the bushing. Since the stick rotates around the bushing, these ends need a hair of clearance to the column ears – but not too much, in which case the stick will be able to slide back and forth on the bushing.

This actually took more time than the bushing itself, partially because unlike the soft bronze of the bushing, the stick is steel. Additionally, each time I removed a bit of material, it raised a slight burr inside the sleeve, along with depositing removed material inside the sleeve. Both of these wanted to make the bushings bind, so each instance of removing material meant deburring the end of the sleeve and cleaning out the sleeve with a rolled-up paper towel. Oh, and the only way to really test the fit was to insert the bushing, orient it correctly in the column, insert the pivot bolt, torque it down, and see if the stick moved freely.

And then I repeated all of these steps again for the front stick.

Next up was drilling the hole that will allow for the rear stick to be removed. Nothing too crazy here, just laying out the hole points on opposite sides of the stick base, and drilling #12 on the drill press in assembly with the stick itself:

And then comes the real fun! Both sticks get bolted in place on the column, and the interconnect pushrod is threaded through the column and attached to both sticks. The length of this rod was previously set based on the plans callout, but now that can be fine-tuned; the goal is to get both sticks parallel. I started to try to figure out a way to use a tape measure to do this, before realizing this was a perfect job for the digital level – just move the forward stick to the limits of its travel, get its angle from level, then compare that to the angle of the rear. They were pretty close – only off by half a degree, So of course, I adjusted the rod ends to make that better, because filing those bushings really put me in a mood for precision. So now I have the sticks within a tenth of a degree of parallel.

And of course I had to take a photo of the assembly:

So that was a good solid work day. Looks like the next task will be hanging this assembly in the fuselage, and then presumably connecting it to the elevators themselves. Which probably means that I’ll have no choice to sit in the fuselage and make airplane noises…

Well, today was mostly a lazy goof-off day, so not a ton of progress. I got the final pushrod done – just had to prime the inside of the thing, get the rod ends inserted and riveted, and that was that. That let me move on to the next big thing – the control column.

The basic deal with the control setup is this: we start with the control column, a large tubular thing that hangs from two rod-end bearings, fore and aft. Roll inputs will cause this entire assembly to swing left/right, sort of like a pendulum, from those bearings, and attach brackets at the bottom of the column will move the aileron pushrods. Meanwhile, the control sticks mount on pivot points at the forward and aft end of the column, which allow for pitch input. These inputs move the three longitudinal pushrods I just got done prepping.

The first operation here is to work on those pivot points between the column and the sticks. The sticks pivot on bronze bushings, which will be trapped between the column parts when torqued down. Since there’s some variance in the control column weldment, these bushings first need to be worked to establish a nice snug fit in the column. This is made especially fun because the two “ears” on the column, between which the bushing sits, are not parallel, which means I’ll have to not only trim them to length, but also put a matching angle on each end of the bushing. If I just made the ends square, then torquing the pivot bolt would tend to bend the bushing a bit, thus binding the controls.

So anyway, I didn’t do any of that today. I did get the various pivot holes final-drilled on the column, and then did some finish work on the bushings and their matching channels in the sticks to get a nice smooth fit. Out of the box, both bushings fit pretty tight and didn’t easily move. A little bit of work with some emery cloth on the channels, plus a little polish on the bushings, took care of that.

It’ll be another day that I get going on the ends of these bushings. Maybe tomorrow.

Oh, and no photos, today, oh well.