Took some time after dinner tonight to go take a look at the fuse again. Even though I wasn’t going to rivet tonight, I decided to kind of do a dry run of the riveting procedure for these skins. My reasoning here is that the riveting procedure here is pretty specific – there are some tight spaces, and things have to be done in a certain order before other tasks close them off entirely. So I went through and clecoed the main bottom skin on as specified, then followed with the forward crossmember and one of the forward side bottom skins.

Overall, I’m feeling good about riveting this stuff – again, there are some tight spaces, but nothing that I can’t get into with one of my thin tungsten bucking bars. There are definitely a lot more rivets here than you might guess from just reading the construction manual, though. I’m thinking I might do well to get all this stuff riveted over the course of this upcoming weekend…

Oh, and I finally took another picture – here’s the main bottom skin and one of the forward side bottom ones clecoed in place:

With the dry run done, I moved on to reconstructing the cooling ramp. I actually put this bit together some time ago, but discovered that I’d fouled up trimming the skin – yay, time for new parts. I ordered those prior to the move out here, and now it was time to get to work on them. Apparently I already trimmed the skin (correctly) previously, so tonight I just clecoed the stiffeners in place, match-drilled, and deburred the holes.

And it turns out it’s a good thing I did this – the rear stiffener for the cooling ramp needs to be match-drilled and riveted to the forward gear crossmember – before it gets riveted in place (part of the planned weekend work). So yeah, I guess I’ll be continuing to work on the cooling ramp this week…

So yeah, that’s it for tonight.

So yeah…it’s been hot. Hot enough that I haven’t been working, in case the long dry spell wasn’t already self-evident. I did actually construct what I intended to be an air-conditioned cubicle around the fuselage a couple months ago – basically just a PVC pipe frame with plastic sheeting draped over it – and I even tried it out once or twice, but still, yeah, nothing got done.

Fortunately, this weekend it’s finally not-hot enough (notice I did not say “cool”) for me to be OK spending time in the hangar, and as a bonus I didn’t have a weekend full of stuff to distract me. And I’ve already been getting back into the building mindset the last few days, so yeah, I finally did stuff again.

Unfortunately, I got off to a rocky start. First order of business was to debar the edges of the left and right bottom skins, which I did on the bench grinder. For straight pieces, this is easy – just run the edge along one of the grooves I’ve worn in the Scotchbrite wheel. For curvy stuff (like these skins), I tend to run the edge laterally across the wheel, working each side of the edge in turn. Well, I guess it’s been so long since I did this that I forgot that doing this with the skin angled *towards* the direction the wheel is spinning is Bad. So yeah, I barely got anything done on Skin #1 when the wheel caught it and put a beautiful little bulge in the edge of my nice skin. Cue lots of grumpiness.

Once I got pas the usual initial THIS PART IS RUINED NOW freakout, I decided to see if I could take the bulge out a bit. A little bit of work with a mallet, and I made it, well, better, but not perfect by a long shot. But the skin still fit OK in place on the plane, albeit with a bit of oil-canning between rivets, but a bit more work on the edge made that better. There’s no structural problem here, just a mild cosmetic one, and it won’t be in a super obvious place, so I decided to build on.

I finished my deburring (much more carefully, you bet), dimpled a bunch of rivet holes, and the skins were all ready to go. Next up, the forward gear crossmember needed some attention – this is the part I had to replace a while back because I prematurely riveted it to the floor and munged up the old one removing it. Both crossmembers needed to be countersunk for the  skin rivet holes, and once that was done, I scuffed, cleaned, and primed the new forward crossmember.

In between all that, I cleaned off all the stuff I’d had sitting on top of the inverted fuselage (following the any-flat-surface-becomes-a-table theorem) so I could put it back on the rotisserie setup and flip it over again. I wanted to get a look at the brake lines in the gear towers – I’m planning on remaking those so they come out of the floor ahead of the gear leg mounts, instead of behind, which will simplify plumbing the short lines from the bulkhead fittings to the gear legs.

My original line of thinking had been to address the brake lines prior to starting to rivet on the bottom skins, but after a second look, I don’t think having them in place will complicate the brake line issue at all – at least not compared to working inside the gear towers themselves. So I’m going to hold off on remaking those, until I get to the point of actually mounting the gear legs. I figure I’ll be able to make a better decision about redoing the lines at that point. (this is provided that I mount the legs prior to putting on the forward top skin, which will definitely make doing the brake lines harder…but hey, I can still punt for now)

Anyway, that was the sum total of work for the day. From here, I get to start riveting these skins in place, which should be interesting given the kinda limited access between the bottom skins and the floor. Still, the procedure in the construction manual sounds like it’ll make it not too bad – in any case, it doesn’t look any more obnoxious than shooting the rivets in the flaps. Shooting rivets will probably have to wait till next weekend though – I get home from work kinda late, and by the time I’ve had dinner, I’m thinking it’ll be at an hour where banging rivets will not endear me to my neighbors (especially the ones with a newborn). I’m sure I can find something else to do – assuming, of course, I can successfully get my weekday work sessions going again.

Hey, maybe I’ll even take some pictures next time!

Did some more work on the forward bottom skins tonight. (still trying to work on that weeknight work ethic…) I match-drilled all relevant holes between the skins and the gear crossmembers and intercostal ribs. Next I removed the skins and final-drilled all #30 holes, along with opening up a few holes for structural screw around the landing gear weldments. Finally, I deburred all the holes I’d just final drilled, and formed the edge of the main bottom skin where it will overlap the mid bottom skins.

Next up, I get to do some countersinking and dimpling, plus I still need to finish the edges of a couple skins. Then it’ll be time for some riveting!

OK, so not a ton of progress tonight, but hey…I actually did some more weeknight work. I know good and well that these short weeknight work sessions are at least as important as longer weekend ones, so I’m happy with myself.

Anyway, tonight I did some final-drilling and dimpling of the left and right forward bottom skins, then clecoed both of them along with the aft forward bottom skin in place. Then I sat down and carefully read through the next few pages in the construction manual, mainly because I found it weird that I was supposed to match-drill everything I’d just clecoed except the holes in common with the floor ribs. Turns out those holes are final-drilled after disassembly, probably because of the minimal clearance between the bottom skin and the forward floor. I imagine it’d be really easy to accidentally damage the floor match-drilling.

So yeah, next time I’ll actually do the match-drilling, then rip everything apart and go on a deburring and dimpling rampage. I might even take some pictures!

Ugh, I really need to get on top of my work ethic. Two weekends ago I was out of town, that’s a valid excuse. The weekend after that? Yeah, there was stuff to do around the house, but I didn’t make time to work on the plane. Though I think the real issue is me never working on weeknights – really, I think those were as much of a contribution to forward progress as longer weekend work sessions. Maybe tonight will be the start of weeknight work sessions again, guess we’ll see.

So all I had left to do tonight was to drill those last two inboard bracket holes, followed by the four holes for the inboard wear plates. I ordered four 5/16” bits, just to make sure I’d have spares if I had problems with bits breaking again. So of course, this time I drilled both of the holes without breaking a single bit. Guess I’m probably set on 5/16” bits for quite some time…

That just left the 1/4” wear plate holes. What makes these fun is that they’re match drilled using existing holes in the inboard gear weldments – that means they’re drilled from inside the cabin, aka drilling upward since the fuselage is currently inverted. I’d previously kinda considered flipping the fuselage to drill these, but that would require me to remove the gear legs, reinstall the inboard brackets, and then flip the fuselage to drill. That seemed like unnecessary work to me, so I drilled from below instead.

This was where my judgment kinda went south. Once I was lying under the fuselage, I realized it was difficult to tell if I had the drill square to the weldment. The first idea I had was to start each of the four holes, then remove everything and finish the 1/4” holes on the drill press where I could ensure they were square. But then I got worried about the potential for the holes to wander a bit, so I decided to just finish the holes from below.

Here’s the problem with doing this – it’s best to drill each hole in one shot, because heating the steel at the tip of the bit and then letting it cool can result in a local heat treating effect, hardening the steel and making further drilling challenging. Once I started drilling the holes completely, I got through the first one OK, but on the second one, I hadn’t made much progress at all when I stopped getting chips out of the hole. A look at the tip of the drill bit showed that it looked to have dulled. Well, that’s what the spare is for – I switched that one in, and finished the second hole, but got the same result with the third, a bit of progress followed by a complete stall.

Another part of the problem here was that since I was drilling from below, there was only so much pressure I could put on the drill – eventually I’d just lift the front of the fuselage off the sawhorses, which seemed like not the greatest idea. What if it moved laterally when I did that, and missed the edge of the sawhorse when I put it back down? That’d be bad news all around.

So I decided to go with my original plan for that second wear plate. Using the drill press would give me more control over the hole, and maybe I could make it through with my one remaining 1/4” bit. So I pulled the gear legs, took the wear plate over to the drill press, and sure enough, got the holes drilled with little drama. (It probably helped that it was a lot easier to lube the drill bit this way)

That just left the moment of truth – would the holes line up? Good news – they did. After that, I set about cleaning up – there were loads of metal shavings all over the fuselage and the floor around it, oily parts from the Boelube I’d been using, and holes to deburr to boot.

So now it looks like I get to skip back to fitting the forward bottom skins…tomorrow, I guess.

So I started out today by removing those bottom skins I’d clecoed in place yesterday. Sure, they looked nice and all, but they were in the way for the next steps, which were…um…let me go look at the manual (for the first time in a couple weeks, I might add). Upon consulting the manual, I was a little surprised to discover that there was basically nothing left to do except actually drill the holes for the gear legs. I’m not exactly sure what other intermediate steps I expected, but there weren’t any.

So I went and triple-checked everything, ensuring the tape measures were properly lined up and straight, moving the left until they were equidistant from the tail, and then putting my sheet of plywood in place to check parallel again. Then I verified the positioning of the outboard wear plates (3/16” in from the longeron edge), reverified the gear leg positions, got out the drill and drill bits, checked everything again, etc. It’s always a bit nerve-wracking when committing to something like this – once I drill that first hole, the legs sure better be aligned, because they’re not moving without some major modifications (by which I mean probably rebuilding a lot of stuff).

Following the manual, I started with the 3/8” holes in the outboard brackets. For the drill, I left the air drills in the cabinet and got out my big hammer drill (albeit with the hammer turned off – this ain’t concrete). Copious reading at VAF had taught me that when drilling through these steel weldments, it’s pretty important to use a high-torque drill, and to drill the entire hole without stopping. Stopping means that steel that got heated up by the drilling cools of rapidly and maybe gets some heat treating along the way, making continued drilling unpleasant.

Anyway, the outboard holes went off without a bitch, aside from the aforementioned nerves when committing to that first hole. Next I moved on to the 5/16” holes for the inboard brackets, and this is where things got interesting. I went at the first hole, the drill going through nicely, until abruptly things went wonky and I realized that…the drill bit had broken. Mind you, this was a brand-new bit I bought last year for this specific purpose.

The aftermath:

I was pretty upset at first, because I wasn’t sure if the bit had broken through yet, and if it hadn’t – well, the broken part was below the top of the bracket, so extracting it would be pretty interesting. Fortunately, when I crawled under the fuselage to look, I saw that it had broken through. I also saw that I’d made an error of judgment – I’d thought there was nothing below the hole I was drilling to get in the way, when in fact there’s a sort of flange in the weldment that goes across the path of the bit at an angle. The tip of the bit was resting against this flange, so I concluded that the bit had hit the flange, caught a bit, and been deflected sideways, causing the breakage.

Extracting the rest of the bit was easy enough, but I was worried about the damage I might have done to that flange. Surprisingly enough, though, I saw only a single tiny nick – not what I was expecting at all, but in a good way. Well, that was a bit of a relief…

Fortuitously, when I ordered these bits for the landing gear, I bought two of each. Always good to have a backup on hand, right? I was certainly proving it now. I removed the broken bit, installed the backup bit, and moved on with my day. This time, I anticipated the possibility of hitting the weldment when I broke through. I didn’t have a drill stop for a bit this large, but the side handle on the hammer drill allowed me to position my left hand such that it could stop the handle when I broke through and prevent overtravel.

So again, I started drilling…and I got an almost-exact repeat of the previous attempt. I calculated I was almost through when the second bit broke! This time I knew I hadn’t gone far enough to contact the weldment, and a look under the fuselage confirmed it. So now I was just confused…the only thing I can figure, in retrospect, is that the bit was binding at the moment of break-through, hard enough that the high-torque drill just snapped it. I’m still not sure why this wasn’t an issue with the larger bit – though I imagine the larger diameter would make it a bit stronger.

In any case, the good news was that I got two of the four holes drilled, but the bad news was that I’d now destroyed both of my bits. No more 5/16” holes today. I think this time I’ll order four of the things, so I’ll still hopefully have two left over after I’m done.

I did go ahead and drill the two remaining 1/4” holes on each outboard wear plate – since the bracket holes had been drilled, everything was set in place and there wasn’t any reason not to drill the holes. There are also two holes in each inboard wear plate, but they have to be drilled from inside the fuselage, through prepunched holes in the weldments. Not sure yet if I’m going to drill those from below, with the fuselage inverted, or figure some way to drill them after the fuselage is upright again. I’ll have to think that one through a bit.

Anyway, here’s a look at the fully-drilled mounts for the right gear leg:

I’m not sure if I’ll be doing any more work until next Monday now. This coming weekend I’ll be at the MotoGP race in Austin, and most of this week will be waiting for new drill bits, followed by getting all my gear together to camp trackside. But I took the following Monday off, so I ought to be able to make that into a nice work day, I think…

So when we left off last time, I’d marked the gear crossmembers for clearance cuts, but I was concerned about edge distance. A bit of research confirmed what I was already pretty sure was the case – this is pretty normal for the larger Grove gear leg brackets, and violating edge distance here isn’t likely to be an issue. I do still think I might drop an extra rivet between the two here just for a bit more insurance.

So today, I started out by making those cuts in the crossmembers. As per usual for making cuts with corners like this, I started by drilling a hole at the corner, then used the Dremel cutoff wheel to make the other cuts. Then there was a lot of filing, checking, double-checking, filing again, etc etc, until I finally felt OK with the clearance:

Next, the forward bottom skins also had to be trimmed around the brackets. Once again, this just involved a lot of trial and error after making the initial cuts. I think I probably put each skin on four or five times over the course of refining the trim lines. The clearance is still a bit tight in some places (see photo below), but I don’t think I’m going to remove any more material right now, at least not until I really and truly align the gear and drill the holes:

So yeah, that was basically the summary of my work day. Here, just as a bonus, is a photo with the bottom skins clecoed in place:

Eight months? Really? I figured it had been maybe six at the most, but 8+? Wow. Kind of reminds me of the last time I moved, when I said something like “it might be a couple months before I work again” and it ended up being six or so… This move has been even more interesting. For one thing, there was more stuff (including that pesky airplane, which got a truck all to itself), and for another, there’s a lot less space inside for storage, so getting stuff put away has been a challenge. (and to be honest, it’s still not really “done”)

But hey, I’ve got a nice roomy hangar to build in now, no more cramped garage!

Anyway, last week I made the first useful move, scooting the fuselage away from the wall where it had been sitting for a while, and flipping it over on the sawhorses. Today I first had some general housework to do (mowing and such), then it was off to Home Depot for some shop materials. Back in Atlanta, I’d built a neat little vertical rack for hanging up plans sheets. It was a useful thing, but unfortunately it became a casualty of the move as the truck filled up with stuff. I never felt like I had enough room in the garage at the old house for such a thing, so I just kept the plans laid out on a workbench. With all the newfound space, I decided it was time to build the second incarnation:

One small improvement from the last version is provision for binder clips at the top and bottom of the sheet. It’s kind of necessary out here, because it’s almost always windy, and we have the hangar doors open most of the time. Pretty sure that without the extra clips, there would be some…incidents.

So with that done, it was time for some real work, and time to finally put these nice Grove gear legs to work. The basic gist of fitting the gear legs goes like this: There are three predrilled holes in each inboard weldment, and that’s it. Only one of those holes is for the gear leg itself, where a 7/16” bolt goes through the leg. That bolt becomes the pivot point for future fitting, which involves carefully aligning the gear legs and eventually drilling the final few holes in the outboard and inboard weldments, at which point the legs better be aligned… (at least there are shims available for the inevitable alignment tweaking)

So first up, I final-drilled the predrilled holes in the inboard weldments, then put the inboard and outboard wear plates in place, followed by the legs themselves and the inboard brackets, all held in place by that single 7/16” bolt. Now, the next task according to the manual is to put the outboard brackets in place and trim the landing gear crossmembers for clearance. For the factory legs, I believe this trimming is pretty minimal, but the Grove brackets are a little bigger. My real issue, though, is that the location of those outboard brackets (and by extension, the extent of the trimming) is indeterminate until the alignment is at least roughly set. Again, maybe this is less of an issue with the factory legs, but for the trimming I’ll need to do, I felt it was best to jump ahead to the alignment.

Here again, things get fun. The method described in the manual seems pretty arcane to me, involving plumb bobs hung from the inboard and outboard portions of each leg, and another at the tail on centerline. As best I can tell, the idea is to use the bobs on the gear legs to get both legs in the same plane, and then use the bob at the tail to square that plane to the fuselage centerline. What we’re really going for is to A) have the faces of the gear legs parallel to each other (i.e. zero toe) and B) have the faces parallel to centerline. My issue with the plans method is that A) iit seems like a roundabout method to get the faces parallel to each other and B) it depends on the forward edge of the gear leg being perpendicular to the face, which I don’t trust. Here again, maybe it’s different for the Grove legs than the factory ones, I dunno.

Another builder, Matt Dralle, took a different approach that I think is kind of deviously simple. He used two long pieces of aluminum angle, match-drilled to the axle bolt holes, and bolted to each leg. He then used a sheet of plywood between the angles to get (and keep) the legs parallel to each other, leaving only the task of getting them parallel to the fuselage. I decided to modify this approach a bit, replacing the plywood with two identical-length wood planks, mainly because I don’t have a good vehicle for getting a 4×8 sheet of plywood home.

Drilling the angles was easy enough, as was bolting them in place:

Next up was cutting the planks. I just used a couple 1×4 common boards. I measured the distance between the angles at the gear legs, marked one board, double-checked the marked board against the angles, clamped both boards together (gotta make sure they’re the same length!), and cut them with the chop saw. But somehow, despite my double-checking, the resulting boards were 1/4” too short for the gap between the angles. Harrumph. But at least it was a nice round number like 1/4”. So I just grabbed some 1/4” plywood scraps and made little spacers to nail to the ends of the boards:

Much better! Now to just put them in place at the ends of the angles and see how smart I am! Except…wait…if I put a board on one end and snug the angles up to it, the angles at the other end are too far apart for the other board to even sit in there. Um, what? I looked again and realized the angles were distorted ever so slightly; if I sighted down them from front to back, they were a bit concave (as viewed from outside the fuse). So I applied some brute force to them until they were straight. That should fix the problem! Nope, same thing…hm. It turns out that the act of putting the board at the end of the angles appears to bend the ends out a bit. So I’m not just going to be able to rest the boards in place. I’m thinking that I’ll just end up clamping the boards to the angle ends to keep everything in place, and I’ll just have to add the step of sighting down the length of the angles to check that they’re straight before committing the any drilling.

We’ll see how that goes another day, cause that was where I decided to call it a day. Overall, it wasn’t huge in terms of time invested, but hey, I did something, which is way more than I’ve been doing…

So this actually covers some short work sessions both from Saturday and today. Saturday turned into an interesting day; I’d found an interested hangar home for sale by its owner a few days before, and we contacted the guy and decided kind of on a white to go check it out that day, since the man was available to show it. And it was pretty cool, and pretty affordable, and so we’re going to try and make a move on it. So that whole thing kind of took up the rest of the weekend in research, discussion, etc. Neither of us have bought a home before, so this is uncharted territory.

But enough about that. All I got done this weekend was to mount the seatback support weldment and get it screwed/bolted/riveted in place. There are a lot of fasteners that attach this thing; I assume that it has a pretty major role in stiffening the fuselage structure around the cabin. On each side there are four #8 structural screws, eight AN3 bolts, and ten rivets. Access to those AN3 bolts is especially fun, since they bolt through the support plates. That means reaching into the narrow space between the plate and the skin and trying go install a tiny nut on a tiny bolt. Here again, the rotisserie proved its worth; by rolling the fuselage 135°, it was much easier to see what I was doing.

I was expecting the rivets to be somewhat unpleasant, but they were actually pretty easy. Torquing the bolts was far more work. So now I have a seatback support:

Bolts through the support plate:

Screws and rivets in the cockpit rail (for some reason the camera thought I was taking a photo of the inside of the plane and focused there):

With that done, I rolled the fuselage inverted again and took it off the rotisserie, back to the sawhorses:

Next up, I get to mount the main gear legs. You know, if we end up getting that hangar, it’ll be convenient that I’m to the point of mounting the gear legs. Moving this thing will be far easier if I can just put it on wheels and roll it around naturally. But I’m getting ahead of myself…