Fuselage longeron work

We continued with the dreaded section 29, and while it takes some effort to "refine" the parts into the proper shape (i.e. beat them into submission), it has worked out well, and all the longerons are formed and drilled:

Formed and drilled mid-fuselage longeron
Formed and drilled forward fuselage longeron
We failed to find appropriate wood (hardwood 2x4) locally to bend the skins, so we skipped to later steps for now while that comes in the mail. We aligned and match-drilled the baggage door seal angles to the mid-fuselage longeron:

Mid-fuselage longeron attached to baggage door seal

Mid-fuselage longeron attached to both baggage door seals
We then clecoed those longerons into position, and trimmed the lower flanges of the baggage door seal angles:

Mid-fuselage longerons and seat back brace clecoed into position

Trimmed flanges of the baggage door seal angles
We started putting the whole thing together for more match-drilling and to assert alignment:

As another random item from later on, I also bent the clips that attach the lower fuselage channels:

Still a lot to do, especially after that wood comes and we can actually bend and use the skins.

Time lapse:

Total fuselage side skin time: 22.2h

Forward fuselage ribs and bottom skins complete

We riveted the center section side plate to the surrounding parts:

Center section side plate riveted to the bulkhead side channel

Center section side plate riveted to the forward bottom skin and bulkhead side channel

To install the floor panel again, of course I had to remove one of the bolts I previously installed, since it's in the way:

Bolt that prevented me from installing the floor panel

Then we tried to install the landing gear mounts, to drill some holes against the forward floor panels. First, it wouldn't go in, so I had to bevel a corner of the center section bulkhead (per the recommendation on the manual):

Trimmed corner of the center section bulkhead, to fit the landing gear mount

With that, the mount went in (kinda, sorta):

Fitting the landing gear mount

Such a simple task, it should have been - pop the mounts in, make two holes, take it out, done. Except nothing lined up:

Misaligned landing gear mount holes

Turns out the part was catching on the seat rail supports:

Seat rail supports where they were preventing the landing gear mount from sitting in the right position

After trimming that, the front part was catching and also needed some significant trimming:

Aft flange of the seat rail supports that were also interfering with the landing gear mount

Trimmed seat rail support to allow landing gear mount installation

Since that removed a lot of the primer, we touched it up with the rattle-can type:

Primer touch-up on trimmed center section bulkhead corner

Primer touch-up on seat rail support

With that one also out of the way, now the mount flange was not parallel (grrrr), so (per Van's recommendation) we beat it with a hammer back to where it should be:

Landing gear mount flange, not parallel to the side plate

Landing gear mount flange, now parallel to the side plate

Landing gear mount flange with shim in place

With that, over 10 hours of careful work later, we could tighten the bolts and mark the intersection of the rivet hole line and edge distances on the mount:

Installed landing gear mount

Landing gear mount forward brace mount plate in place

Landing gear mount forward brace mount plate with hole locations marked

Landing gear mount forward brace mount plate, drilled for AN3 bolts

The other holes to drill were through the shim and landing gear mount flange:

Landing gear mount flange and shim with holes drilled

Side skin through which the landing gear mount flange holes go

Finally, I removed the side skins, drilled nutplate attachment holes where the landing gear mount "leg" bolt holes are, and riveted the nutplates:

Landing gear mount forward brace mount plate holes with nutplate attachment side holes

Installed nutplates for the landing gear mount forward brace mount plate bolts

With all this, the section is finally complete (except for the few items that this section would have me build but not use, like the seat floors). Now comes the dreaded section 29 (side skins).

Time lapse:

Total forward fuselage ribs and bottom skins rivets: 786
Total forward fuselage ribs and bottom skins time: 131.8h

Fuselage stand

With the work on the bottom fuselage coming to an end, we wanted to free up the work benches and build a lower stand for the fuselage so we could work on it from above. We roughly followed the one build by TASRV10 to build one. This involved a 57" x 48" frame plus 2' legs:

Stand frame, legs and wheels in position

We used a very advanced technique to load test it (jumping up and down on its most fragile point):

Wife load testing the stand

The idea is that the center section bulkhead tips rest on the (48") sides of the frame, and the aft portion of the bottom skin would rest on the 57" part, for which we added some carpet padding:

Adding carpet padding to one end of the stand

That also added to its leisure function:

Wife on stand

Turned out (we hadn't notice before) that at this point of the build, the fuselage is so perfectly balanced on the center section bulkhead, that neither its front nor aft bottom parts though the frame :) but this will likely change when we attach the tailcone.

We then finally transferred the fuselage onto it:

Fuselage on stand
With this we can go back to beating parts into submission.

Time lapse:

Total workshop time: 45.5h (3.1h for this task)

Forward fuselage bottom skins riveted

We did some exciting steps in the fuselage build - we finally mated the mid and forward fuselage assemblies together for good:

Mated forward and mid fuselage assemblies

To do that, we first attached the center section bulkheads with the appropriate spacers (later the wings attach at this location) and some huge (AN9) bolts:

Center section bulkheads attached and torqued

AN9 bolts that attach the fuselage parts (and later the wings)

Thanks to a hint from the interwebz, I knew that I had to rivet the one nutplate from section 44 that goes inbetween the center section bulkheads. Once the whole thing was assembled, it was clear why - it's very very hard to get to later:

Impossible nutplate (if I hadn't done it now...)

We then started riveting the skins and bulkheads together, with one of us on the floor and the other bucking from the top. This included some pretty tricky rivets, like this one:

Very hard-to-reach hole that we needed to buck a rivet in

We had to use an indirect riveting technique to buck those (there were 6 of them):

Indirect riveting setup for bucking the rivet
which, to our own disbelief, gave pretty decent results:

Resulting rivet

With that, we finished riveting the center section bulkheads to the skins:

Forward center section bulkhead flange fully riveted

For the double-flush rivets that sit underneath the landing gear mount, we had to use a shorter rivet than Van's indicates (-3.5 instead of -4), but then they sat almost perfectly flush:

Double-flush rivets in forward center section bulkhead

With that done, I bolted and torqued all the seat assembly parts together:

Forward fuselage assembly bolted and torqued

Forward fuselage assembly bolted and torqued

I then clecoed the center section side plates in place (which was a small challenge in terms of alignment):

Assembled bottom fuselage (not yet fully riveted)

Only that part of the riveting remains to be done, along with some fitting/drilling of the landing gear mount. Like I mentioned before, I'm not finishing the parts that aren't used soon (like the seat floors), and instead leaving those for when they're needed.

Time lapse:

Total forward fuselage ribs and bottom skins rivets: 722
Total forward fuselage ribs and bottom skins time: 113.9h

Mid-fuselage bottom skins complete!

The one last step in this section is a very long one - basically "rivet the whole thing together", so we started doing that. First came the TAS antenna doubler, which I wanted to rivet before attaching the skin (I'll leave drilling the TAS antenna hole for later):

TAS antenna doubler riveted in place
Then we clecoed the skins and started riveting them to the ribs and bulkheads (except for the aft/side holes that are riveted when attaching the side skins or the tailcone). Since the skin is longer than the parts, we needed to improvise a jig to hold it while we riveted:

Size comparison: mid-fuselage parts onto jig vs almost-average-size human :)

Mid-fuselage bottom skins ready to rivet
We got to a good rate of about 2 rivets/minute, which means this still took many hours of work to do all 731 rivets, but gave us good results in the end:

Fully riveted mid-fuselage bottom skins

Fully riveted mid fuselage
With this, the mid fuselage section is complete and ready to attach to the forward fuselage.

Time lapse:

Total mid-fuselage ribs and bottom skins rivets: 1151
Total mid-fuselage ribs and bottom skins time: 92.7h

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