More rudder fiberglass work

OK, so when we left off, I’d just figured out that the poor fit on the rudder tip was an issue with the counterweight skin shape, not the tip piece itself. So the first order of business was to see about straightening that up. After trying a few more gentle techniques, I decided that I just needed to break out the hand seamers. I suspect that the root of the problem here is that I didn’t square up the flanges on the tip rib way back in 2012 or whatever, which meant that to fix this I needed to target the bend in that area. But a little trial-and-error with the hand seamers got things nice and square, and with that done, the tip piece fit quite nicely.

However, this led to a new problem, regarding clearance between the counterweight area and the vertical stab. Previously, these two pieces were nice and parallel with an even gap between them, but by straightening the upper part of the counterweight, I also caused the leading edge to move downward. Not far enough to actually catch on the stab, but it did result in an unsightly uneven gap, and I still wanted to keep proper clearance here (by which I mean “they’re not touching” wasn’t satisfactory to me). I first addressed this by undoing a bit of my bending, a little at a time, until the gap to the tip when installed started to open up just a bit. Things still weren’t completely parallel, so I removed the rudder and adjusted the rod end bearings. Turning the bottom one in a full turn, and the top one out a full turn, got things looking quite nice.

But at this point I realized I should also be thinking about the rudder base fairing. Just eyeballing things, it seemed like there was an opportunity here for the fairing to interfere with the stab spar head of it…so it was time to switch gears to that piece. This one is a little more fun to fit, because it needs to be notched on each side to allow for the control horns. There aren’t any layout markings or anything provided for this, you’ve just got to figure it out on your own. What makes this even more fun is that the notch isn’t 90° to the upper surface of the fairing.

After thinking this over for some time, I decided to measure things out, using the trailing edge as a reference point. To start with, I identified the distance from the trailing edge to the forward face of the control horn angle, and marked that on each side of the fairing for a starting point. Then I used the width of the lower horn angle to figure out the distance to the other side of the notch, and marked that point on the upper edge. To draw the angled lines, I laid a popsicle stick inside the angle, and used a ruler to draw a line along the bottom of the rudder skin. This gave me a handy sort of angle finder – I just had to align that pencil line with the top of the fairing, then drawing a line along the side of the stick would give me a proper cut line. Then I just had to work out the depth of the angle, and I finally had a starting point for the cutout:

Of course, this wasn’t exactly super precise, and I was conservative with the layout as well, so after making the initial cuts I spent a lot of time carefully expanding the cutout, with repeated trial fitting. I made another sort of fiberglass file with some 40 grit sandpaper glued to a popsicle stick, and really put that thing to work. It took probably three or four iterations on the cutouts before I was even able to get the fairing partially installed. A couple more iterations, and it finally slid into place:

I still wasn’t done, though. The cutout didn’t quite match the horn, and I wanted a nice even gap all around, not like this:

So I marked new cut lines using the horn as a guide, and did even more sanding and such, until I had a nice 1/8” gap all around. I was feeling pretty good about this, and had even started beginning to layout the attach holes, when something (I really don’t remember what) got me to go look up other folks’ work on this. Whatever I was looking for, I found an entirely different concern: seems some folks have issues with the fairing interfering with the tailspring. Additionally, it seems that some trimming might be in order on the leading edge of the fairing. So before I did anything else, I went and tried installing the rudder yet again.

Immediately, the first issue presented itself: the rudder couldn’t possibly go on the way things were now, because the fairing would interfere with the rudder stop attach bolts, as well as the adel clamp I added for routing the tail light wire. In this photo, the rudder needs to go about another inch forward (note that the rod end isn’t even into the hinge points at all):

I needed to solve that problem before I could even see about the tailspring interference. Rather than trying to carefully figure how little to trim off here (read: going through another series of iterations, except this time refitting the rudder repeatedly), I decided to just take the cut along the bottom of the horn forward to the tip. Sadly, this meant that one whole side of each cutout, which I’d painstakingly fit, was going away. Oh well.

For this, I just used a strip of paper to carry the lower cut line around the forward edge, did the rough cut, and then once again did lots of sanding, this time with a long flat block, until the top of the cut was nice and planar. Well, mostly, as seen in the next photo, it still looks like there’s a little upward turn at the front. I’ll have to go clean that up some more, you know, just in case someone gets on the ground and looks across the rudder at just the right angle:

Finally, it was time to install the rudder yet again. Clearance up front with the adel clamp was of course not an issue any more, and the fairing still clears the spar just fine through the entire range of rudder motion. Even better, there’s not interference with the tail spring after all. It’s pretty close – maybe 1/4” if that – but given the location, I think this is probably fine. There shouldn’t be much deflection in the spring this close to the socket – but I suppose I’ll still ask around with the VAF crew to be sure.

Assuming that’s OK, the next thing I need to decide is whether I want to attach this fairing with pop rivets (as per the plans) or with screws. Going with screws might make it easier for servicing the tail light wiring down the road – for example, when the rudder gets pulled for painting. I think it could be just fine with pop rivets – the service method could be to pull the tail light, disconnect the wiring, and then pull the wire from the fuselage forward through the fairing. I’d just have to make sure that whatever anti-chafe I have up front (probably I’ll add a bulkhead with a snap bushing) has a large enough hole to accommodate the plug. Reinstalling would require fishing the wire back through the fairing, which might be annoying but probably not horribly so. But if I go with screws, then the fairing would just be removed and dealing with removing/rerouting the wires would be a lot easier.

At the moment I’m leaning towards pop rivets for simplicity’s sake, but I figure I’ll let that marinate a bit before I make a decision. I might try and fish the wire through the fairing as it sits now just to get an idea how annoying it’d be…though it occurs to me that without the taillight cutout being there, it’d be hard to get a real idea. Maybe I just figured out the next thing I’ll be doing…

Posted in Empennage, Fiberglass | Hours Logged: 6

Vertical stab and rudder tips

So I continue to be sort of hung up on the horizontal tips, specifically figuring out how I want to modify them to not need so much stretching force to fit. For that reason, I decided to switch gears today and work on the vertical stab and rudder instead, figuring that maybe I’d have better luck there, and develop a bit more confidence in messing with this stuff.

The vertical stab tip was pretty straightforward – it still needed a bit of stretching, but nowhere near the level of the horizontal. I got it to fit nicely just by installing cleco clamps in the open aft end, and went ahead and match-drilled the prepunched holes into the tip. After cleaning those up to ensure a tight fit, I marked a trim line on the aft end of the tip and did the trimming.

Next, I installed the rudder and started trying to get that tip in place. This tip actually wouldn’t slip into place as provided; it was too long and so I did a fair bit of sanding down the flange to get it to fit. I ended up removing a fair amount of material at the trailing edge before it finally went in, and I’ll need to work on the exposed portion before I’m done to get it to match the rudder itself, but that’ll be a job for later.

What I really wanted to get a look at by slipping it into place was how it matched up with the vertical stab tip, and sure enough, they’re pretty far off. If I slide the rudder tip all the way in place, its forward end sits about 1/4” lower than the stab tip:

One possible way to address this would be to not insert it all the way, taking care of the alignment issue when the mount holes got drilled. The problem with doing this is that the flange now doesn’t cover the mount holes, as seen here:

So basically, I had a choice between adding micro filler to the outside of the tip and sanding it to match the stab tip, or needing to scarf in a new layup to lengthen the flange and then fill in the old flag area to match the rudder skin. It didn’t take a lot of thinking to decide that the former was the better direction to go in. With that decision made, I went ahead and match-drilled the holes here as well.

The other issue I had here was that in the middle area of the rudder tip, there was a fair amount of room between it and the rudder counterweight skin. I was hoping that the clecos would pull it flush, but they didn’t; I’ve still got a pretty unpleasant gap in that area:

I tried doing the trick of adding a piece of popsicle stick to stretch the tip, but that still resulted in a poor fit. Eventually, I realized the problem – it’s not the tip, it’s the rudder itself. The counterweight skin isn’t straight like it should be; instead it sort of flares outward towards the open end where the tip should mount, which is why there’s so much of a gap there. I made some initial attempts to bend the skin for a better fit, but didn’t have a lot of success, and this is where I ended up calling it a night. I think what I’ll end up doing for tomorrow is making a bending tool out of scrap wood with a slot, and maybe I can use that to massage the skin to where it needs to be.

Posted in Empennage, Fiberglass | Hours Logged: 2.5

Starting on empennage tips

Well, I’m finally forcing myself to stop procrastinating on doing fiberglass stuff. The main hangup at the moment is that I’m working hilariously slowly as I navigate this whole new world of technique. Most of what I’ve spent time on has been sort of poking around and finding ways to do things. For example, one of the things I needed to do early on was some trimming of the provided fiberglass tips. But what to use to do the trimming? The bandsaw will cut fiberglass nicely, but it’s hard to use it on one side of a U-shaped fairing. The vibratory saw I bought a while back should be good for this, but which blade to use? Turns out a metal-cutting blade works well there, but a trick I learned along the way is to keep the edge of the blade at an oblique angle to the workpiece. Let it get perpendicular, and the teeth will grab the work and weird things will happen.

So that’s a big intro to the first trimming, which was on the elevator tips. I knew I’d need to cut out a section on the forward ends to accommodate the counterweights, but it also turned out that I needed to trim the flanges down. For whatever reason, these are far too long to not interfere with structure inside the elevator. At least making those long cuts got me pretty decent at working the oscillating saw. Some 40-grit sandpaper on a wood block worked well as a file to get the edges right where I wanted them. After making lots of dust, I had some tips that at least fit where they were supposed to go.

Here’s a look at the notch for the counterweight:

And one trimmed tip slipped into place:

The next fun was figuring out what to do for that leading edge. As can be seen in the photo above, the elevator counterweight skin has a nice curved profile on the forward edge, but both the actual counterweight and the tip itself stick out beyond that. I’d like for this area to have a nice smooth profile, and I’d also like to have fiberglass enclosing the forward end of the counterweight, so I guess I need to trim off some lead. This is convenient, since I need to remove some material to get the elevators properly balanced. But to do that, I need to disconnect the control system so the elevators can swing free…but even when I did that, they’re bound together a bit by the center bearing bolt, and I want them to move independently. I couldn’t for the life of me get that center bearing bolt out, though. I guess I used special tools before, but now I’ve got the vertical stab in the way making the whole thing even more fun. I actually ended up punting on this for the day and moving on to other things…

The other consideration is the stab tips. I mentioned the fitment issues with these in a previous post, and today I worked some more at figuring a way to get them to fit decently. I tinkered with my wood block method from before, but never could get it to work like I wanted, so instead I decided to try putting some small spacers inside the tips to spread them as needed. A piece of popsicle stick, strategically cut, worked surprisingly well to get the tip to fit better, but I kind of don’t like how much force is required to spread the thing. I’m thinking I might want to remove some material on the leading edge of these pieces so they fit better without so much brute force, and then shore them up again once I work that out. I’m not entirely sure how I want to approach this, though…something else to research, I guess.

All in all it feels like I’m not making a lot of progress with this, which is making motivation a little hard. Hopefully I’ll soon get more comfortable with this work, and start to develop a little more flow.

Posted in Empennage, Fiberglass | Hours Logged: 2.5

Vertical stab mounting

Since my nice hardware came in from Aircraft Spruce yesterday, tonight I figured it was time to get the vertical stab attached. This was a bit more of a trial-and-error operation than I intended, because the lower leading edge of the stab interferes with the aft upper skin. On the first mount attempt, there was definite contact being made:

All in all it took me a couple iterations of trimming the stab (I just filed off material instead of doing anything drastic like cutting) before I was happy with the clearance. Then came the fun of getting all the bolts torqued. The three AN4 and two AN3 bolts on the aft spar were pretty easy, but the four AN3 bolts at the front were a different matter. Here again the tight squeeze between the forward spar of the horizontal and the back of the aft upper skin becomes a problem.

The lower two bolts weren’t super awful, but the upper two are so close to the horizontal splice angle that neither a socket nor a box-end wrench will go on. I ended up cutting down a crappy combination wrench to make a stubby 3/8 crescent that I could use to hold the bolt…using my fingertips. Good thing the torque spec for an AN3 is pretty low.

So now the vertical is in place, and I guess I can’t avoid messing with fiberglass now. I ordered a bunch of good sandpaper today, and it looks like it ought to arrive on Monday. In the meantime I can probably start with doing some rough trimming and fitting.

Posted in Empennage, Fuselage | Hours Logged: 1

Elevator rigging done(ish)

Picked up again with my airplane yoga routine this evening. First up was undoing the tedious work from last night, removing the bellcrank pivot bolt and the washers on one side. This was so I could move one washer to the left side (of the airplane) to provide some more clearance between the bellcrank and the forward servo mount bolt. After weaseling the washers back in place and getting the bolt threaded through, I verified that the bellcrank was now clear (on both sides) before adding a fresh lock nut and torquing things (again).

So now I’ve got the clearance I needed, and the bellcrank moves smoothly through its full range of motion:

Next was adding the aft push tube, between the bellcrank and the elevator horns – one last trip in and out of the tail (for now, at least), followed by hooking up the elevators. For this last bit, unlike everything else for this rigging – where I used fresh lock nuts and assumed this was a final (hopefully) installation, I left this un-torqued. I figure there’s a good chance the elevators will come on and off a few times as I’m working on the fiberglass tips, so I’m holding off on “final” installation here.

Here’s a look down the tailbone with he push tube installed:

OK…what next? I’m still waiting on the hardware from Spruce to attach the vertical stab, though it should be here tomorrow. I thought about working on trimming the control sticks, but for that I’d want to basically install the entire interior, and I didn’t really feel like that tonight. Instead I decided to at least look a bit at the fiberglass work, starting with one of the horizontal stab tips.

The first bit of fun with these is that their profile doesn’t really match the stab itself; it won’t sit flush along the flange, which is a problem for fitting:

My first attempt at helping with this was to trace the stab profile onto a piece of scrap wood and cut it to fit; I was hoping to wedge this inside the tip to press it in place:

So far, this helps, but it’s not quite right; I probably need to refine it a bit more, specifically removing more material around the perimeter to account for the thickness of the fiberglass tip. I thought maybe it could just sit a bit further aft and do its job, but a trial fit showed that wasn’t the case.

In any case, I need to get some more supplies before I really go to town on fiberglass, most notably a good supply of sandpaper, since there will be lots of sanding in my future. So no real hurry on getting this figured out, I guess – which is why I called it a (short) night at this point.

Posted in Empennage, Fuselage | Hours Logged: 1

More elevator rigging

Tonight I picked up with the bellcrank yet again. Saturday’s epoxy had the washers nicely held in place, so I crawled back into the tail and went to work. First up was attaching the forward push tube to the bottom of the bellcrank, which actually went together surprisingly easily given the tight quarters.

Next was the center bearing on the bellcrank, which was where things got more interesting. Back when I first installed this, I found that I couldn’t fit the specified washer stack around the bellcrank – one regular and one large washer on each side just wouldn’t go in the space. So I just removed one of the regular washers and then it all fit fine, and I think at the time I figured that it was a “put what fits” type situation.

Tonight, though, as I tried installing all this, I ran into a problem: the large washer on the left side interfered with the forward attach bolt for the autopilot servo. There was simply no way to get it to sit flat where it needed to be. When I crawled back out of the airplane, originally I was just figuring on replacing the large washers with regular ones. Generally large washers are placed around bearings to help capture the bearing – that is, if the bearing were to fail, having it be able to come out of its housing could lead to a system jamming. The large washers, though, are often omitted if the bearing is surrounded by large flat surface that serves a similar purpose. It seemed to me that the two mount pieces might work well for this – but I decided to double-check the plans first.

Turns out I got this wrong the first time around. Instead of the large AN washers I used, the plans specify special super-thin large washers – which also have a slightly smaller OD. Small enough, it turns out, to not interfere with the servo bolt, or so I discovered during my second trip into the tail. This trip got even more fun when, as I tried to weasel the last washer into its gap and push the bolt through, I decided I needed a long, thin tool to get the job done. Not wanting to climb out and back in again, I summoned help from inside, by calling Josie using my Apple Watch. Sometimes technology really is super useful…

Finally, I connected the servo linkage to the bellcrank, then climbed out and finished the job by attaching the forward push tube to the control column. Then it was time for a control check, mainly to verify freedom of movement but also to double check that, with the sticks full forward, the servo linkage was nowhere near going over-center.

The latter definitely checked out:

Freedom of movement was a different matter. While I could move the sticks through their full range of motion, there was a weird sort of “bump” feeling a bit aft of the neutral position. Some investigation revealed the issue: one of the rivets holding the two bellcrank halves together is rubbing on the servo mount bolt head, the same one that was problematic with the washer earlier. The contact is light, not enough to block the stick movement, but enough to be noticeable.

It’s hard to get a photo but hopefully it’s somewhat visible here:

I think I can fix this by just reworking the washer stack around the bellcrank. If I move the regular washer on the right side over to the left, it should offset the bellcrank just enough to provide the clearance I need. If that doesn’t work, then I guess I’ll need to pull the bellcrank out and maybe replace these six rivets with flush equivalents. We’ll see how that goes some other day.

Posted in Fuselage | Hours Logged: 1

Elevator rigging

So today I picked up where I left off last night, starting with getting the forward elevator push tube loosely in its place under the seat floors. Then I got to spend some time reviewing the annoyance of getting this whole system together. For whatever reason, the manual tells you to 1) slide the forward tube into place, 2) bolt the bellcrank to the forward tube, and 3) slide the bellcrank into place. Problem is, the bellcrank can’t go into place from beneath, which is how it would have to be inserted if this procedure was followed. So instead it has to go from above, and then the attach bolt has to be positioned and tightened in the very tight space between the baggage ribs. This was not much fun before the turtledeck was in place, and will probably be even worse now.

Anyway, before I could do any of that, I needed to take a look at the autopilot pitch servo and see how that would fit in with the rest of the procedure. Turns out that the way the servo mounts, it needs to be installed before the bellcrank. I also needed to drill the hole in the bellcrank for the servo linkage, as well as assembling the linkage itself. Finally, there was the consideration of the optional bracket on the servo to limit movement of the arm. Limiting the range of motion is important because if the servo linkage can go over-center, it’ll lock up the controls, which would be bad for fairly obvious reasons. Generally, the control stops and linkage setup should primarily prevent this, and the bracket is a backup.

After thinking all this over, I concluded that I was going to have to install all this stuff twice if I was going to get the limiting bracket set up correctly – that is, installing the servo, bellcrank, and aft pushrod, moving the elevators full down (putting them closest to the over-center position), and checking the alignment of everything. This led to the first of many trips in and out of the tail today. The real fun with this is that the backboards can’t go in place because they block access to stuff I’m working on, so I was left to work using a few random pieces of scrap wood placed across various ribs.

Now, the first problem was with the interference between the limiting bracket and the servo mount bracket. The install kit warned of this interference, and I figured the first temporary install would help me decide how to maybe trim the limiting bracket to fix the problem. Well, turns out the interference was way more than I expected, to the extent that I’d have to basically destroy the limiting bracket to make it work. So I decided not to install it – realistically, given that the elevator stops are beefy structural pieces, any event that allowed the controls to move past those limits would probably already be catastrophic.

The good news here was that I didn’t have to fit up everything, but I still had to pull the servo again to remove the limiting bracket. Then I got to climb in again, reattach the servo, and then start to really think about getting that forward tube and bellcrank put together. Well, that latter part was what broke me for the night. The rod end bearing on the tube installs with a thin washer on either side, which makes for some really fun coordination. Back when I did this before, I glued the washers inside the bellcrank to simplify this, but whatever I used (I think it might have just been superglue) gave up the ghost today. I made one brief attempt to just get them inserted manually, but there was just no way that was happening with the tight confines.

So I pulled the bellcrank out again and embarked upon gluing the washers in place again. This time I used epoxy, in the hopes that it’ll hold a little better. The fun part was figuring out how to clamp the washers in place while they dried, without also epoxying the clamping stuff in place. I ended up putting a short #10 screw through each side of the bellcrank, with a nut to clamp it all in place. Judicious application of the epoxy kept there from being a ton of squeeze-out that might glue everything together. If this was a real structural bond I’d have wanted to be more liberal with the epoxy, but here I just need those washers to stay in place while everything is assembled.

So that’s where it sits tonight – tomorrow when the epoxy’s dry, I should be able to finish getting the put tubes and bellcrank installed, and hopefully confirm that the aft tube length is right and the servo arm lines up as it should. Then I guess I’ll be gettin the rear avionics shelf installed again as well…maybe. Not sure if I should wait on that or not. In any case what I’ll really be moving on to soon is getting the vertical stab attached and then probably looking at the fiberglass work back there.

Posted in Fuselage | Hours Logged: 3

Tailcone closeout stuff

Tonight I picked up with the intent of working towards getting the elevator control system reinstalled. In all probability this wouldn’t be the last time, but to my way of thinking everything from the bell crank back at least ought to be able to stay in place. First up, though, I needed to finish up work back where the ADAHRS units were, specifically routing the pitot/AOA lines and securing them for good.

This was kinda fun, all in all I think I removed and replaced the backboards back in the tail at least twice. I needed them out of the way to initially route the lines back from the seat floor area, but then of course needed them back in place to crawl back into the tail again – except there was one issue, with the way the lines were going to route up the bulkhead, the next-to-aftmost board had to be left out. I could only hope that I wouldn’t need to be that far back.

After putting the boards back and collecting the hardware and tools I needed for the adel clamps, I squirmed back into place to where I could reach the ADAHRS. One thing I wanted to do before buttoning things up back here was to double-check the electrical connections, and this turned out to be a good call. Both the D-sub network connectors were snugged down (I figured the most likely thing would be that I didn’t tighten the thumbscrews), but when I gave the OAT connectors a pull test…a wire came out of one of them. I was kind of expecting to have a bare wire come out – which would have been really fun – but it turned out the pin just hadn’t been seated in the connector. I just had to pull the connector and reinsert the pin, which would have been dirt simple any other time, but here it took about 15 minutes thanks to the cramped space.

Finally, I got back to the pitot lines, first inserting them into the connectors, then pulling the slack back forward and installing the two adel clamps. This, too, was made rather enjoyable thanks to the location. In some ways it was more fun than the connector – instead of lying on my back and reaching over my head, as it were, I was on my side and trying to use a screwdriver in one hand and a wrench in the other.

Once the adel were in place, I crawled out, removed the backboards again, pulled all the slack forward, and secured the lines to the aft bottom skin where I added a zip-tie pad – this will ensure the lines stay well clear of the rudder cable. The lines are visible in the lower right of this photo, and the red silicone tape can just be seen at the zip tie pad:

Next, I went to work on the control system. I decided to basically work through the entire fit procedure again, to make sure everything was still adjusted correctly. This meant installing both sticks on the control column on the bench, adding the pushrod between them, and making sure both sticks were parallel. Then the sticks came out again and I got the control column back in the fuselage, and the sticks and intermediate pushrod reattached yet again.

Next were the other two push tubes. A while back I disassembled these and gave them a coat of epoxy primer, after the rattle can primer got scraped up a lot just with the previous fitting work. The smaller forward push tube just gets set to a specified length, so I readjusted the rod ends, tightened the jam nuts, and added torque seal for good measure. This was about the time I decided I wouldn’t be installing the tubes tonight – I’d like for the torque seal to dry first, But I did pull down the larger aft tube as well, and reset the rod ends to where they were before (I took notes on this). This should be the proper length, but I’m not going to torque-seal these rod ends until I’ve verified the length…which will happen another day.

So that was the night’s work. I should be able to finish double-checking this stuff this weekend, and get it installed for good. The only complication I need to consider is the autopilot pitch servo – I need to review those installation instructions and see about getting that permanently installed at the same time I do the bell crank.

Posted in Fuselage | Hours Logged: 2

Finished attaching the horizontal stab

No time for a real session tonight but I figured I’d go try to get that last bolt in just for fun. Seems like it often works this way, but this time I got it started in the hole from below on the first try. The only complication was that it was a snug fit – not sure if the spacer between the aft deck and the stab was slightly misaligned or what. This was good in that once I got the bolt started, it stayed there, but bad in that I couldn’t get it pushed all the way through with my awkward hand positioning.

So I grabbed myself a ~2’ piece of scrap wood, crawled back into the tail, and was able to reach way back and get the bolt tapped all the way through, without having to even go horribly far back. Then it was pretty easy to get the nut on from above and get things torqued. So as of now the stab is officially permanently mounted.

I wouldn’t mind moving right on to adding the vertical stab, but I want to get new bolts to attach it – I think I mentioned last night that I decided to use all-new hardware for final-mounting the tailfeathers. This is a requirement anyway for the lock nuts, but I decide to go one step further and use virgin bolts as well. It’s cheap insurance for flight-critical attach points.

Maybe tomorrow I’ll start removing the back boards in the tail and get the elevator control system back in place.

Posted in Empennage, Fuselage | Hours Logged: .5

Changing course and working on the tail

So…after thinking over my next move quite a bit, I’ve decided to change up what I’m working on. Originally my plan had been to try and get the canopy cutting done this fall, before winter set in. The idea there is that cold temperatures increase the chances of cracking the canopy ($$$), and I figured otherwise I’d likely be getting to the point of canopy work sometime around the coldest part of the year. Thing is, at this point I’m a good month or more behind where I thought I might be, so rethinking things isn’t totally out of line.

What really pushed me in this direction was considering what I’d need to do to work on the canopy bubble. Broadly, there are two parts of the cutting portion of the program: first, the entire bubble gets progressively trimmed until it fits on the fuselage and frame correctly, and second, the bubble gets cut into two pieces, forming the windshield that gets affixed to the roll bar and forward upper skin, and the bubble that get attached to the sliding frame.

After doing a decent amount of reading on this work, one thing I really want to do is to attach the uncut bubble to the roll bar before cutting, to better ensure a really good fit. But I can’t do that until the forward upper skin is permanently riveted in place, and I’m nowhere near ready to do that. So that means either I don’t attach the bubble beforehand, or I don’t make the big cut right now.

Even setting that decision aside, no matter what I do right now I still have to put the canopy back in storage for a while after trimming and/or cutting. And honestly, I think I’d feel better just storing it as-is instead of after trimming, when I feel like it might be even a slight bit more prone to cracking unless I support it really carefully. Bottom line, I don’t think there’s a real need to try and rush into the canopy work right now, and I don’t see myself making such rapid progress that I’m at a point where I need to be cutting it any sooner than, say, next March, maybe later.

So, what to work on instead? I could pick back up with the wiring inside the airplane, maybe working on the stick grip wiring, but I think I need the control column in place before I can really do that, and with that installed getting in the fuselage and moving around is a little tougher. Instead, I decided to start thinking in terms of closing stuff out at the tail and working my way forward. This means permanently attaching the empennage, reinstalling the elevator control system, and maybe even moving on to fiberglass work, depending on how things progress with my engine order.

So that leads me to tonight. I figured I’d try and work on really attaching the horizontal stab, but first I needed to remove it again. I never did permanently install the two elevator control stop pieces I worked on a while back, and getting that riveting done would have been somewhere between difficult and impossible with the stab mounted. So I pulled that off, set it aside, and got the two stop pieces riveted (and, in the case of the aft stop, bolted) in place.

Next, I reinstalled the stab, this time inserting brand new bolts that I ordered specifically for final installation. The four bolts that attach the rear spar to the vertical stab bars were easy enough to torque, but the four bolts that drop in through the forward spare and down into the fuselage are another matter. Torquing these, I think, has to be a two-person job, with one person working inside the tailcone. If I contort my hand really carefully, I can touch the bolts inside the fuselage, but doing anything like starting the buts or operating a torque wrench isn’t happening.

I did decide, however, to see about crawling back into the tail and at least starting the nuts. I was under the impression that accessing the bolts that way would be no fun at all, but it turns out to be physically impossible as far as I can tell. I could probably do it if the ADAHRS mount wasn’t back there, but that’s riveted in place now and removing those rivets would be tough to do without causing damage. So I think I’ve got no choice but to find/bribe a very small person to crawl in there and help me out with this.

So that’s where I finished the night. Thing is, I’m kinda stuck until I get those bolts installed, since the next steps I’d be taking would involve adding even more stuff back there, and probably starting to remove the backboards that I lay on while crawling into the cave. Or maybe I’ll try going back out, inserting the bolts from below, and installing the nuts above. That might be doable, and wouldn’t require trusting, say, a neighborhood kid with properly torquing fasteners that attach an extremely critical piece of structure.

We’ll see, I guess.

Update: Well, my idea worked out fairly well. I was able to get three of the four bolts inserted from below, working through the aft deck, and I got those four torqued as well. The last one is proving to be a real bear to get the bolt inserted – that’s the hardest part. If i could get that done I’d be pretty much home free. Maybe I’ll give that one another try tomorrow evening, for tonight I’ve had my fill of contorting my arm and wrist.

Posted in Empennage, Fuselage | Hours Logged: 3