Rudder control stuff

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:

Panel rev2

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…

Posted in Fuselage | Hours Logged: 2

Rudder pedal cleanup

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…

Posted in Fuselage | Hours Logged: 1

Control column adjustment

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…

Posted in Fuselage | Hours Logged: .5

Elevator rigging wrap-up

No build activity yesterday, thank to some other stuff going on, but today I got a few hours. My idea of gluing the spacer washers inside the elevator bell crank worked out nicely, and I started off today by reinstalling the bellcrank and pushrods. With everything aft of the control column torqued down, the play in the system was all but gone, so the first step was to clamp the elevators in-trail and then adjust the large aft pushrod until the control sticks were vertical. I measured this by just sticking the magnetic smart level to the stick. It only took a couple turns of the forward rod end to get things nailed down.

That meant it was time to move on to the elevator stops. These are two pieces of aluminum at the tail, positioned so that the elevator control horns contact them at the extreme ends of their travel. Elevator travel is set up by trimming these pieces until both horns contact them at the desired limits.

The rear stop is pretty easy to get to – it’s a piece of angle that also bolts to the vertical stab. The forward one is a different matter – it’s a piece of flat stock that sits between the aft deck and a piece of angle on top of one of the bulkheads. Also there’s hardly any clearance in front of the horns to get to it. Basically, tweaking this piece was going to involve removing it, removing material, then reinstalling it…over and over and over. But I couldn’t even get a straight look at the thing with the vertical stab in place – so I ended up deciding to remove it. It’s beyond me why they have you install the vertical stab prior to trimming these things, there’s absolutely no need for it to be in place at this point.

Anyway, the elevator down travel (controlled by the forward stop) was already sitting within the allowable range (20-25°), so I figured I could probably get away with just removing the material necessary to get both horns to come into contact at the same time – remember that they’re not perfectly in line, the right on sits slightly aft of the left. I used drill bits as discount feeler gauges to figure about how much material needed to be removing, then got the stop out and went to work. It only needed about 1/16” off the one side to even things out:

And I only ended up needing to remove/reinstall it a couple times before everything contacted at once. Here’s a poor attempt to show this piece place. The horns  and center bearing are visible in the foreground, and to the left the stop piece can be seen peeking out from under the aft deck:

The rear stop was much more straightforward. As before, I figured out the rough amount of material to remove to account for misalignment of the horns, and did that work off the airplane with a cutting bit in the Dremel. The rest of the tweaking I did with the stop in place, filing away at each half of the stop. At first I made no effort to make things smooth, I just wanted to be removing material where the horns made contact:

Once the travel was correct and the horns were both making contact at the same time, it was time to remove the stop, make the transition between halves nice and smooth, and clean up all the rough edges:

And then it was time to final check the travel one more time. Acceptable ranges for up and down travel, respectively, are 20-25• and 25-20°. I ended up with just under 25 down and 26 up:

Then I reattached the vertical stab, mainly because it’s about the easiest way to have it stored in a safe place. Next step by the book is to do the rudder control stops, but I think I’m going to diverge from the plans here. The factory rudder stops are small angle pieces mounted outside the tail, which contact the rudder horn at the extremes of its travel. But there’s an aftermarket solution as well – a piece of delrin that attaches to a rudder hinge bracket, and limits the travel by contacting the spar. This will make the tail a little bit cleaner, and should also be less trouble to adjust. Problem is, I don’t have that part on hand yet, so I suppose I’ll order that tomorrow. In the meantime, I can move on to installing the flap motor.

Posted in Empennage, Fuselage | Hours Logged: 3

Elevator rigging refinement

Not a ton to report tonight, and no photos. My intent was to just have a short work session, mainly focused on getting all the rod ends installed correctly with spacing washers, and their bolts torqued down, to take the slop out of the system and get me setup for the upcoming work. Unfortunately this turned out to be easier said than done. The aft end at the elevator horns wasn’t too bad, despite access being a little hairy. The bell crank was actually fine as-is, and the connection for the aft pushrod there actually requires no washers.

The other end of the bellcrank, though, is where things got fun. This spot calls for a couple of thin washers to space out the rod end. Presumably this is to account for lateral movement – since that rod is connected to the control column, it’ll move side-to-side a bit with roll inputs. The problem is, this is the bottom of the bellcrank, it’s in a confined space between the two baggage ribs, and it was hard enough just to get the bolt threaded in there, never mind trying to do the frustrating-in-the-best-of-circumstances work of squeezing washers in. I gave it several tries, and even went so far as to lay down boards in the fuselage, climb in, and try working on my knees – all to no avail.

So I ducked inside for a quick VAF search. And there was a brief moment when I thought I’d found the solution. Someone recommended removing the rod end from the pushrod, installing it on the bellcrank out of the plane, then putting then bellcrank in place and finally threading the rod into it. Seemed like a genius plan, except…the bellcrank can’t be installed with that rod end in place. The extra width means it can’t be loaded in from above, and it’s not physically possible to weasel it in from below.

I came pretty close to admitting defeat at that point, but then decided to take a totally different tact – just gluing the two spacer washers inside the bellcrank. The only concern then would be that sliding the rod end in might knock them loose, so to help with that I bent the two bellcrank ears out just a hair – they’ll be pulled tight again when the pivot bolt is torqued.

So that’s sitting on the workbench letting the superglue cure (yes, I used superglue…), and we’ll see if tomorrow I can go back to making useful progress on this thing. Tonight wasn’t a lot of fun, but it was still educational. Also, I can’t begin to think of how obnoxious it’d be to install these pieces with the aft top skin on. Rather than leaning over the side, I’d have to be lying in the cabin with my head stuck into the tail…that’ll be fun one day…

Posted in Empennage, Fuselage | Hours Logged: 1

Elevator rigging – first pass

So…not a ton of detail to provide tonight, despite this being a solid two-hour work session. Basically, what I did was install the control column + sticks into the fuselage, and then rig up the pushrods all the way back to the elevators. Seems straightforward, but there was definitely some tedium to be found here. In general, it was annoying working leaning over the side of the fuselage (really makes me miss being able to roll the fuselage with the rotisserie), and in addition to that, there are some interesting limited access spots, oh, and it’s just dealing with things designed to move around.

In the end, while I got everything hooked up, there’s a lot of slop in the system, because I didn’t go to the trouble of installing all the proper spacer washers on rod ends, or of torquing down any of those connecting bolts – I just threaded them through and put a nut on to keep anything from falling out. Since the point of all this rigging is to get the pushrods adjusted properly, and to set up the elevator up/down stops, I think I need to do all this the right way…even though it’s going to be highly annoying.

I did reward myself after all this was done bye installing the forward seat floor and front seat, then throwing in a lawn chair cushion so I could climb in and make airplane noises:

And I figured a short video of the sticks moving the elevators was worth capturing:

Posted in Empennage, Fuselage | Hours Logged: 2

Control column/stick fitting

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…

Posted in Fuselage | Hours Logged: 4

Control column stuff

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.

Posted in Fuselage | Hours Logged: 1.5

Pushrods. That’s all, just pushrods

No, really, that’s all I did today, just work on pushrods.

First up was the large pushrod that will go from the bell crank back to the elevator horns. This one is made from large-diameter, thin-wall tubing. Just trim it to length, clean up the cut area, fit the rod end inserts, then mark and drill the holes. Marking the holes is kinda fun, you just stretch a strip of paper around the tube, fold it three times to make eight sections, then wrap it around the tube again and mark where each crease is – and now you’ve got eight evenly-spaced holes!

See, look, paper:

I recruited Josie’s help to get those holes drilled – trying to support the entire rod (which is a good 5’ long) while positioning it precisely at the drill press isn’t really a one-person job. Then there was a lot of priming, followed by some riveting, and this thing is done:

Next up, basically the same process is repeated for the smaller of the two pushrods; this one will connect the bellcrank to the rear stick. This one is smaller-diameter tubing, but with a thicker wall, and the rod end inserts here are male instead of female. Additionally, the inserts here are plated, unlike the previous ones, so they don’t need priming. I got as far as drilling the small one, cleaning it up, and priming the outside tonight. I figure I’ll let that dry overnight and tomorrow I can deal with priming the inside and getting those inserts in place.

In between priming the second pushrod (ie while letting the coat on one end dry so I could then hold that end while priming the other one), I grabbed the third pushrod of the night, which will connect the front and rear control sticks. This one, at least, is prefabricated, with the inserts already in place and the whole thing powdercoated. All I had to do was thread in the proper rod ends. Well, actually first I had to clean the thing, because mud daubers had built nests in both ends of the thing. I ended up having to run a tap through the inserts to get all the crud out.

But hey, now this one is done too:

And that’s it for tonight. Maybe tomorrow I can get that second pushrod done, and then move on to prepping the actual control column, which I believe is the next thing on the list. Which will put me a little bit closer to actually rigging the controls and making control surfaces move…

Posted in Empennage, Fuselage | Hours Logged: 3

V-stab mounted, elevator horns drilled

So in between smoking a turkey, eating said turkey, taking the obligatory post-turkey nap, and giving the parents a call, I did find some time to get out and work on the plane.

First up was picking up where I left off on the vertical stab. I laid out the four extra rivet holes, as directed by Van’s to account for the edge distance issues, drilled them in the splice plate, and then used those as a guide to drill through the spacer and spar. Then I deburred the new holes before riveting everything together:

Then it was back over the fuselage, where I bolted the stab in place, semi-permanently this time:

Next up was drilling the elevator control horns for the pushrod attach point. These holes aren’t pre-drilled, as the horn parts frequently have some variance in them; it’s for the same reason that the pivot holes in the horns are drilled in assembly as well (waaaay back in the empennage build phase).

To start with, both elevators are clamped into a neutral position, in line with the stab. The position of the horns is examined, and the one that’s furthest back is chosen as the on to drill the first hole in. The reason for this is that the hole is laid out relative to the forward and bottom edges of the horn, to ensure proper edge distance. Since the second horn will be located further forward, we can be sure that the edge distance there will be OK as well; if we did it the other way, we’d potentially have an edge distance violation on the second horn.

Anyway, in my case the right horn was further back, so I laid out and then drilled the bolt hole there (note that here I’ve moved the left elevator to get its horn out of the way for the photo):

The next challenge is to drill a hole in the other horn in the matching location. The problem here is that there are a couple inches between the two horns, so we need to make sure that we drill straight across. To do this, a drill guide block is made from hardwood. In my case, I reused the piece of poplar that I’d previously used as a drill block for the horizontal stab. I had to trim it a bit to get it the proper width for a snug fit between the horns, and then I drilled a new 3/16” hole using the drill press to make sure it was properly square. Then the block gets clamped between the horns, in alignment with the first hole:

And then the hole gets drilled:

And that’s it – a quick pass with the deburring tool to clean up the holes, and these guys are now ready to accept the pushrod, which I’ll be fabricating next.

Posted in Empennage, Fuselage | Hours Logged: 1.5