First rivet is in! (plus VS dimpling)

Now that the main structure of the vertical stabilizer is primed, I went ahead and dimpled it:

Lots of dimpled holes
I later found out about Cleaveland's substructure dimple die, which makes a lot of sense to use, so I ordered that and will use it instead of the regular die in the future (I may or may not redo these using that one).

After the dimpling, I decided to go ahead and follow the next step in the instructions, which is to rivet the rudder stops to the upper hinge bracket:

First 6 rivets! Only 102938102938 to go :p

It even turned out to be the correct size for the shop heads :)
I could have gone on riveting the other parts, but there's a small primer fix needed on the rear spar (somehow I forgot to deburr the flange edges, so had to redo it which removed the primer) before I can continue.

Time lapse:



Total vertical stabilizer time: 34.1h

Vertical Stabilizer priming

We finally got to the point of priming the vertical stabilizer. We realized we needed a larger table/bench for this, so we used the lid from the empennage kit box.

Wife mixing the Akzo
For all the markings that could be unambiguously redone, I simply took pictures to make the process easier:

Markings to be preserved photographically (i.e. I can redo them easily from the picture)

I also found a few holes and edges which I had not deburred properly, so I did that before priming.
We started getting a good sense of how much primer is needed for the parts - we mixed 4oz and that covered the parts just right, on a single side - so another 4oz was the right second mix to do the other side.

Primed parts
While the skin wasn't primed yet, this is enough to assemble and rivet most of the VS structure. More priming to come soon...

Time lapse:



Total vertical stabilizer time: 31.2h




Vertical stabilizer conduit mod


As I mentioned before in Empennage Mods, I made the changes required to run wires through the vertical stabilizer. For now this will be an empty conduit, but at some point in the future I may decide to run wires for e.g. a camera.

This was strongly based on Mouser's mod, with a few changes: I didn't add a plate to the bottom, I'll rivet the top doubler to the bottom of the top rib and I'm only running one conduit (I'm assuming that whatever power I need will not be enough to produce interference on data cables).

Before I did anything, I went through the Standard Aircraft Handbook - which didn't say anything about conduits - and the Aviation Mechanic Handbook - which lays out the rules for how much you can fill the conduit and their minimum bending radius. I'm not filling conduits now, but the bending radius got me thinking how I'd route it from the bottom of the stabilizer into the fuselage, so I decided to look at how the connection is made - as seen on manual page 11-6, the vertical stabilizer sits over part F-1014, near two big holes. To make the smallest (biggest radius) bend possible, the best thing seems to be routing closer to the VS spar (the forward side of the aft hole through the ribs):


For the bottom rib, unlike Mouser's, I decided not to use a mounting plate/doubler, since that nose rib has to be removed and replaced during assembly, and I'd rather not add much slack to the conduit (the above book does say that the reasonable slack is 1/2"). I also considered adding one of the MIL-style circular connectors at the top, but as cool as it'd look, decided against it for simplicity, sanity and weight.

I started by marking the corners of the flanges of the top rib over a thicker piece of aluminum (blue markings below), then drew lines and the respective rounded corners to cut the doubler from. Resulting dimensions are annotated below:

Markings for the doubler
I cut the doubler into the rough shape I had outlined, then found its center (midpoint on each edge) to mark the point of the center (conduit) hole. I also marked rough locations of the locations for AN470-AD4 rivets near the corners:


I drilled the rivet holes with a 1/8" bit, then drilled the center hole and enlarged it to 5/8" with the unibit. It fit nicely under the rib as intended:


I then clamped them together and match-drilled the doubler holes into the rib, using a #30 bit for the rivet holes, and the same unibit for the conduit hole.

At this point I grabbed the conduit to check that it fit through the hole, which it didn't - silly me, 5/8" is the measurement for the inside of the conduit, so I went back and enlarged the conduit holes further to about 1/16" short of the external diameter (to give a tight fit in addition to the silicone glue to hold it in place). With this, the conduit fits just right.

For the lower ribs, the work was simpler - just adding something to hold the conduit, for which I followed Mouser's suggestion and used the Panduit LHMS-S5-C cable ties. I held them into the lightening hole, marked the hole position, then drilled it to #30:


Finally, I deburred all the edges and holes then cleco'ed the whole thing together to see what it looked like, and I'm happy with the results:

Conduit passing through the vertical stabilizer
Doubler to support the conduit

Conduit sticking out the top (needs some finish after assembly)

Time lapse:



Total vertical stabilizer time: 27.7h




Horizontal stabilizer ready to prime/rivet

This one took a lot longer than the previous sections (partly because I had to study for two exams in the meantime), but it's finally done!

The last part of the work was a LOT of deburring and countersinking, which overall took me over 13h of work (for all HS parts).

Lots of machine-countersunk holes

Time lapse:



Total horizontal stabilizer time: 65.9h

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