So tonight I switched gears back to the forward flow assembly. First order of business was to rivet some nutplates to the lower flanges of both crossmembers. I believe these nutplates are where the gear leg attachment covers will mount. Anyway, here’s a spot where it would have been nice to read ahead in the instructions a bit, because these nutplates are for flush screws, meaning they need to be countersunk. I would have preferred to have done that before priming. In this case, I just spot primed again after I’d installed the nutplates and countersunk the holes.

Nutplates and unprimed countersinks:

Next up was riveting some nutplates to the floor itself. I believe these are related to the forward baggage compartment. Somehow I missed countersinking the rivet holes for these previously, but countersinking for NAS rivets is pretty easy. I ended up clamping the floor vertically to the side of the workbench to get it in a good position for shooting the rivets:

Finally, I clecoed the crossmembers and ribs to the floor itself, in preparation of riveting:

I decided to start off with the rivets between the ribs and crossmembers. The ones on the forward end (background in the above photo) were easy, since there’s ample access on one side. The rear crossmember, on the other hand (foreground above) was tougher since there are ribs on both sides. I was having a really tough time figuring out how I was going to shoot those things when it occurred to me that I could just remove the skeleton assembly from the floor and then I’d have no access problems at all:

It was getting late by this point, so I clecoed the skeleton back to the floor and left it on the workbench. I should be able to back rivet all the flush rivets through the skin tomorrow night, and get the cooling ramp riveted as well. After that, I guess I’ll have to move on to the next assembly to prep, since I probably won’t be able to prime the gear tower and firewall stuff until Saturday, and since those will be getting epoxy primer, I’ll want to let them cure for a few days before I start riveting stuff.

Tonight mostly consisted of getting the parts I have lying around fully prepped and ready for priming this weekend. I double-checked the flush screw countersinks in the gear tower angles and found that they were a little shallow, so I countersunk them all a little more. I’m still being conservative on them though, as countersinking too much will compromise strength, and I definitely don’t want that on an area like this that will be taking a lot of stress.

Next I finished the edges of the lightening holes in the gear tower faces along with the larger holes in the tower sides. (I think those are for fuel lines and engine control cables) I also got in my replacement firewall angle from Van’s today, so I final-drilled that, countersunk the holes as needed, and redrilled the 1/4” hole for the rudder pedal assembly.

And now all the parts for the gear towers and firewall are prepped, marked as needed, and ready for priming. Looks like I’ll be shooting a lot this weekend…

Not much to report tonight. I finished drilling the nutplate holes in the remaining three angle pieces for the gear towers, then went back and countersunk all the nutplate rivet holes. Absent a bit of final prep work, all the gear tower components are ready to be primed and assembled…and of course the priming will have to wait until the weekend.

I guess for the time being I’ll go ahead and rivet the forward floor and cooling ramp assemblies, then see what I can work on next.

I’d kind of hoped to get all the nutplate holes drilled tonight on the gear towers, but that didn’t really work out. It was kind of tedious to get stuff lined up on the doublers – just try holding a nutplate that’s attached to nothing while tightening a screw to hold everything in place. There are jigs available to make it easier to do this stuff, but they’re like $50 apiece, and so far I’ve always managed to convince myself that they’re not worth it. Tonight was the first time I really found it tedious to deal with this task.

Anyway, here’s one of the doublers with the nutplates in place:

I spent so much time on the doublers that I only made it through one of the four angles before deciding to call it a night. Fortunately, the angle went a lot faster, and I can probably knock out the rest of these in short order another night:

With all the match drilling done on the gear towers, next it’s time to do a bunch of countersinking and dimpling. Actually, I get to do a lot more dimpling here than the plans specify thanks to my removable cover mod, since I’m using flush screws there.

Most of the countersinking per the plans is on the right gear tower. All the rivets on the forward side get flush rivets; from what I can tell from the plans, this is because the rear wall of the forward baggage area rests against the gear tower. There are also some nutplates on the forward side, which I imagine are also related to the baggage compartment. Anyhoo, lots of countersinking:

Next I moved on to dimpling the tower cover and the dubbers I fabricated. Here I realized that I’d made a slight error when making those doublers. When I laid out the screw hole locations, I neglected to leave room for mounting the nutplates:

This isn’t really a huge deal though, because there are single-side nutplates available, as seen here:

Problem is, I only have a couple of those on hand. They came with the kit and will presumably be needed dow the road, but I don’t have enough anyway. Which means I get to order more stuff from Spruce. I’m pretty sure I’ll end up paying as much for shipping as for the actual parts, but that’s the way things go, I guess. Kind of makes me wonder: out of all the money poured into an RV build, how much of that was repetitive shipping costs from places like Spruce? Probably more than anyone wants to consider…

Anyway, then I moved on the dimpling the covers themselves. The fun thing about this is that the large screw dimples also warp the material, so after dimpling I get to flatten the material out again. It was mildly annoying on the doublers, but slightly more obnoxious on the covers:

Finally, I dug out my #8 screw countersink bit and countersunk the angles to fit under the dimples on the cover:

The only thing really remaining on these parts is to drill and countersink all the nutplate holes for the covers. Maybe I can get that done tomorrow night.

Tonight I just caught the left tower up to where I got the right tower on Sunday; cutting the face into three sections, fitting and drilling the doublers, then finally clecoing everything together and getting everything match drilled.

The whole thing clecoed together:

Detail of the upper doubler (the photo isn’t crooked, there’s a slight angle to the cut here):

As mentioned last night, today’s weather was gorgeous, so my main objective was to get the parts for the forward floor and cooling ramp primed. But that took hardly any time at all, so I spent most of the day working on the right gear tower. I’m modifying my towers, as many other builders have, by making part of the tower face removable. There’s quite a bit of work that has to be done inside these towers, from riveting stuff together in the near term to routing fuel lines and torquing gear bolts in the long term. Normally, all of that work would have to be done working through the lightening holes – not a fun prospect.

The basic idea for this mod is the cut the tower face into three sections, making the center section into the removable cover. The existing rivet holes are drilled up to #19 for #8 flush screws, and doublers are fabricated to allow for nutplates at the top and bottom of the cover.

Here, I’ve marked the cut lines on the right tower face. My initial plan was to make the cuts using a special thin cutoff wheel in my Dremel, so as to minimize removed material, which would leave a gap between the pieces later on. But that didn’t work out to well; the wheel kept binding in the cut, and about the third time this happened, the flexible shaft I as using snapped. Can’t really make these cuts without that shaft, so this was a problem. But after making a test cut in scrap with the bandsaw and comparing, the amount of kerf was essentially identical between the cutoff wheel and the bandsaw. So I just did the rest of the cutting with the bandsaw.

Cut are now finished. To the left is the top of the gear tower. The center piece will be the removable plate, and the right piece will be concealed behind the inner gear weldment.

All three pieces clecoed to the corner angles so I can fab and fit the doublers.

Doublers fabbed from .040 alclad and marked for initial rivet holes.

Rivet holes done and match-drilled to the tower face sections, time to fit the cover plate.

After clecoing the cover plate on, I clecoed the entire tower structure together and match drilled all of the holes, then drilled the cover plate holes out to #19 for the screws. I meant to take a photo of the assembly, but I forgot until I’d already torn everything apart and started deburring, so all I have is a picture of a pile of parts:

I still need to dimple/countersink a bunch of stuff, in addition to drilling all the nutplates for the cover attachment. And then I have to repeat all of this for the left tower. 

Didn’t get out and working until late in the afternoon today, but I did do my first solo tailwheel flight this morning, so it was still a good day. I started out by continuing prep work on the forward floor that I’d clecoed together last night. Basically just a bunch of match drilling, deburring, dimpling, countersinking. Once again I got carried away while dimpling the skin. Only some of the holes get dimpled for flush rivets, but I got in the groove with the C-frame and at some point abruptly realized I’d dimpled five holes that weren’t supposed to be dimpled. At least dimples can be flattened, unlike countersinks which have no such “undo” potential.

Clearly this is something I’m going to have to work on with the fuselage; slowing down a bit and taking care with what I’m doing. To avoid a repeat of my countersink error from the firewall, I made sure to mark the floor braces so I could see the limits of what needed to be countersunk:

With all the forward floor parts prepped and ready for primer, I moved on to the cooling ramp. This is a simple assembly, just a skin piece and two stiffeners. Except first you have to find the (fairly small) stiffeners in a giant pile of parts. I dug around for a solid 20 minutes before I got so frustrated that I decided to cleco together the gear towers instead. (my flimsy rationale for this was that maybe I’d find the stiffeners while setting out the gear tower parts)

These things are pretty sizable:

Surprisingly enough, my tactic worked, and after finishing with the towers I found the stiffeners in short order. The first thing to do on the ramp is to trim the skin a bit. And here is another one of those “why wasn’t this just made like this from the factory” moments. Beats me.

Then it was another round of clecoing stuff together, match drilling, deburring, dimpling, etc.

And now I have a pile of parts ready for primer tomorrow. I guess I’ll actually do some work on the gear towers tomorrow too in between priming and so forth.

Started out tonight by breaking out the C-frame and dimpling most of the rivet holes in the firewall. All these holes will get flush rivets on the forward side. There are a handful of the holes that don’t get dimpled, though; four of them are where a spacer sits on the forward side, and the rest are where two nutplates sit on the forward side. Next I moved on to countersinking all the firewall angles to match those dimpled holes. This went well, except for the part where I countersunk one hole too many:

Yup, that’s one of those holes that doesn’t get dimpled, so it shouldn’t be countersunk on the angle either. Welp, another piece for the scrap bin.

After wrapping up all the countersinking, I set the firewall aside – no more work on that until I get the replacement part from Van’s. So I moved on to the next step, which is the fuselage floor. All I really intended to do was to gather the parts and cleco them together, but once again, it took forever to find some of the parts. But I finally found them, and here’s that assembly clecoed together:

And that’s all for tonight.