Mid-fuselage bulkhead fabrication almost done

After a quick trip to Germany, made a lot of progress on the mid-fuse bulkheads this weekend.

I started with the aft center bulkhead, which has bars at its ends for added structure:

Aft center bulkhead support bars
They also have two hat stiffeners, which I had to trim back to allow access to buck rivets next to it:

Trimmed hat stiffeners
I put the whole thing together, and did a lot of drilling:

Aft center bulkhead parts
Finally, this spar receives a plastic wear strip on top, which had to be cut to size, drilled then match-drilled to the spar:

Wear strip
I also did something similar for the rear spar bulkhead. This is the spar which attached to the rear of the wings, but I forgot to take pictures while it was still clecoed together:

Rear spar bulkhead parts
 Last there was the rearmost fuselage bulkhead, which was pretty simple and mostly gets done in later sections:

Fuselage bulkhead
Finally, I did a lot of deburring and all the countersinking that was left on these parts.

I also started thinking about how to run wires, pressure lines, oxygen lines, etc. between the forward and aft sections of the plane. I haven't decided on final routes yet, but it's clear that I need at least one more hole for conduits where the center spar is, so I added those to both bulkheads:

Third hole added to forward center section bulkheads

Third hole added to aft center section bulkheads
I plan to add a doubler to those bulkheads just for safety, so I'll enlarge them after the doubler is also in place.

Time lapse:

Total mid-fuselage bulkheads time: 18.9h

Mid-fuselage bulkheads started

The fuselage starts with the center bulkhead, doing lots of drilling:

Forward center section bulkhead parts match-drilled
then also drilling into the steel landing gear mounts:

Forward center section bulkheads with landing gear attachments

Drilled and bolted landing gear attachments
I had to significantly enlarge some holes for snap bushings where the rudder cables run  (it looks too close to the edge, but it's what Van's says to do...):

Snap bushing holes on center and side forward center bulkheads
and finally, a bunch of countersinking for flush rivets and screws:

Countersunk screw and nutplate rivet holes on the side bulkheads

Countersunk nutplate rivet holes on the mid seat rail supports

This was only the first part (the center section) and there are 3 more (the other half of the center section, the rear spar bulkhead and the fuselage bulkhead), so there's still a lot more drilling and countersinking to do.

Time lapse:

Total mid-fuselage bulkhead rivets: 0
Total mid-fuselage bulkhead time: 8.8h

Fuselage kit inventorying

I spent a good 7 hours between inventorying the fuselage kit and putting away all the hardware (which involved reorganizing the hardware bins). Luckily, for the inventorying, I had help from friends:

Rick and Jay helped inventory all the parts :)

Time lapse:

Bottom wing skin cracks

After sanding and priming the lap joint area on the inboard skin (which was a bit tricky given the skin was already riveted in place), I came back the next day to find this:

OMG a crack! :'(
After a few moments of utter panic as I saw a crack propagating, I contacted Van's, which assured me that the area is not structurally significant, and suggested two options:
  • Filling the cracks with JBWeld: I was really surprised by this, as I thought the crack would continue to propagate anyway, but they swear it won't.
  • Cutting off the corner: they say this should be fine, though less aesthetically pleasing due to the reduced thickness

I was way more comfortable with the second option, so I did that - it indeed doesn't look pretty, and I may still need a small doubler around that rivet hole to adjust the thickness, but I'm comfortable that the skin will stay in one piece now:

Cracked corner removed

As if that weren't enough, as I was dimpling the pitot mount screw holes on the other skin, some cracks showed up on the #8 dimples:

Cracks on the pitot mount screw hole dimples

so I had to file those down, which deforms the holes (but should be ok for screws):

Filed pitot mount screw holes
On the outside, it doesn't look perfect, but should not be even remotely visible:

Pitot mast holes on the bottom wing skin
In the meantime we also primed the other parts (such as the left bottom wing skin), and ultimately clecoed them in place and removed the blue pastic around the rivets, so they're ready to rivet and finally be done with the wings!

I'll make a separate post about the wing wiring and electrical planning.

Time lapse:

Total bottom wing skin rivets: 433
Total bottom wing skin time: 67.3h

Fuselage kit arrival

The fuselage kit is here!!

We opened up a lot of space in the garage, thinking that the crates would be huge:

Turns out, the crate is actually much smaller than that of the QB wing:

First glance

Uncrated fuselage kit

Now on to inventorying while I finish riveting the bottom wing skins.

Unboxing time lapse:


The only step to be done on the flaps section is attaching them. This starts by "press-fitting" (read: hammering in) some brass bushings:

Brass bushings in flap attachment

The attachment hardware goes through the bushings:

Flap attachment hardware

and the control hardware needs to be installed (but the actual control hookup only happens after the wings are attached to the fuselage):

Flap control attachment

Time lapse:

Total flaps rivets: 0!
Total flaps time: 0.7h

Bottom wing skin priming and lap joint

I've been very slowly making progress on the bottom wing skins - slowly mostly because of weather not allowing me to prime parts repeatedly for the past few months (below 59˚F which is the minimum for Akzo).

When I got a chance, I primsed many of the smaller parts that were lying around, like the inspection covers and the pitot tube attachment parts:

Primed pitot mount and access cover parts
I riveted the L-shaped bracket for the pitot tube:

Pitot mount bracket
I then got to the dreaded lap joint, which requires tapering the ends of the skins so they overlap properly. I started by testing on a scrap piece, and got OK results with the Dremel:

Simulated lap joint on a scratch piece
I then moved to the real outboard skin for the right wing:

Section of the outboard wing skin which overlaps with the inboard skin
Being much larger, it soon became clear that the Dremel would not suffice, so I got a random orbital sander, which did the job (not without a few hours of effort to get that tip to half the thickness and a smooth ramp in):

Sanding the edge of the outboard wing skin for the lap joint

Wing skin lap joint thickness
Wife primed that skin and I dimpled it:

Right bottom outboard wing skin, primed
Being a quickbuild kit, the inboard skin was already riveted on, so that was more difficult to sand and prime:

Overlapping inboard skin area which overlaps with the outboard skin
After a few hours of sanding (switching between the Dremel, the orbital sander and a sanding block), the end result is quite decent, and the lap joint looks flush:

Lap joint after sanding
Next is priming the inboard skin strip that got sanded, and repeating it all for the left wing, then finally riveting those skins in place. This week's weather promises some significantly warm weather, so that should happen soon :)

Time lapse:

Total bottom wing skin rivets: 433
Total bottom wing skin time: 54.1h

Aileron static wicks

Still following the Dayton-Granger recommended static wick placement for the RV-10, I measured and realized that I can indeed fit two wicks on the wingtips (though I'll likely want to use Clickbond nutplates to make that easier to attach). IThe third wing wick goes on the ailerons, and since the QB ailerons come fully built, I used #8 rivnuts:

Installing aileron rivnuts

The end result looks clean (which is a surprise given it was my first time installing rivnuts):

Rivnuts installed on the aileron

Static wick installed on the aileron

From my test on a piece of scrap before, I knew this would create a gap:

Rivet static wick installation test on scrap piece

I'll later either fill the gap with conductive cement or a strip of metal to ensure conductivity.

Time lapse:

Total aileron rivets (including the rivnuts): 4
Total aileron time: 2.1h

Tailcone mod riveting

We came back to the tailcone for a few unfinished items - notably, we riveted the NACA vents and the static ports:

Riveted tailcone NACA vent
Riveted static port

We then ran the static port tubing:

Static port tubing

It still needs attaching to the top brackets, which should be quick.

Time lapse:

Total tailcone rivets: 1858
Total tailcone time: 223h

Aileron trim attachment and wiring

Attaching the aileron trim servo to the pushrod is pretty simple, and involves marking the neutral position, then attaching a bracket 6 inches to each side:

Aileron trim attachment points in right torque-tube-to-bellcrank pushrod

The servos and pushrods will then be connected by springs.

For securing the servo wires, I used a Panduit RAMH-S6-D attached through the same screw as the servo:

Aileron trim servo connector attachment

This will keep the wires away from the moving side of the servo and can hold a connector in place. For the connector, I picked a mini AMP CPC 5-pin (1445820-11445829-3, 1445856-1) which has pins for the 26-gauge servo wires (770985-1770986-1). Those pins are 26-22 AWG, so I can just 22 on the other end and not have to deal with tiny wires.

Mini CPC for aileron trim servo

Crimped all the pins (it was slightly annoying, since the pin edges do NOT sit flush on the wire end of the crimper when the pin is this small), slipped on braided sleeving and some heat-shrink (just in case):

Aileron trim servo pins crimped

Inserted the pins into the receptacle and closed it up:

Cable coming out of aileron trim servo, with connector

Shell size 11 is small, but not that small (unfortunately shell size 8 only takes up to 4 pins, and I needed 5).

Full connector/receptacle pair atached to aileron trim mount

(and, for my own record, the pinout I used was 1,2-power; 3-green, 4-blue, 5-orange)

With this, the only thing left on the aileron trim is actually installing it in place and wiring it to the AP servo, which will come much later.

Time lapse:

Total aileron trim rivets: 16
Total aileron trim time: 8.1h

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