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

Second primer test: success!

Following the great advice I received on VAF, I mixed the primer components (and the mixture) a lot more this time, plus I adjusted the pressure to 20psi with the trigger pulled (which was about 70psi static). This time the results were great

Here's a comparison with the previous test:

This finally looks like properly-primed aluminum, and I think I'm ready to prime the other parts and start actually riveting :) I'll do that after I finish deburring and countersinking all the parts from the Horizontal Stabilizer.

Time lapse:

Horizontal stabilizer disassembled

The horizontal stabilizer has been fully assembled, drilled, then disassembled. The next step will be to deburr it (a few thousand holes plus many edges).

Time lapse:

Total horizontal stabilizer time: 51.7h

First primer test

Everything is here for priming!! The actual primer, the Prekote, and now tools and safety equipment.

Equipment for priming
(on the back, two containers full of parts to be primed)

Mixing Mate for the primer cans + assembled dryer/desiccator

So we went ahead and did a first test, with very disappointing results:

Not having any clue what I'm doing wrong, I posted to VAF. I'm assuming I'll have a few more rounds of testing before I can move on to priming the real parts.

Time lapse of the test:

Horizontal stabilizer assembly

In the last weeks I prepared all the horizontal stabilizer parts, match-drilled the ribs and front spar, and then finally got the skins set up into the cradles and started mounting the parts in them, including the stringers.

Skins with the front spar, ribs and stringers

I got plenty of help, both from my wife and from a visiting friend:

♫ I'll fly high with a little help from my friends ♫
(I did install the Sonos in the garage, so now I get music while working)

Setup to bend the inboard spars by exactly 9°

Front spar + ribs assembled and drilled

Cradles for the stabilizer skins

♫ Skins in the craddle and the silver spoon ... ♫

Ribs mounted into the skin

Front spar and ribs mounted into the skin

Stringers mounted into the skin and ribs

Next steps are to finish clecoing all the parts to the skin, adding the rear spar assembly and final-drilling all the skin holes.

Total horizontal stabilizer time: 39.9h
Time lapse (some camera angles turned out to not be very good):

Horizontal stabilizer spars

I did some more work on the horizontal stabilizer front and rear spars, including fabricating some parts for it.

Spar and doubler

It's a looooong spar

Part marked for trimming

Trimmed and drilled parts

Time lapse:

Total horizontal stabilizer time: 20.7h

Back to work! More horizontal stabilizer and deburring

Now that I'm done studying for my checkride, I'm back to working on the RV :)

Some new tools arrived, including - finally - the primer and the Prekote! So expect priming tests and actual priming soon (I still need to buy the gun for priming)

Akzo 463-12-8 primer

Another important one that arrived is an additional deburring tool, with which I spent some time deburring those tight corners, such as between flanges.

New deburring tool

Finally, I got some more random steps of the horizontal stabilizer done (it was late, so didn't want to make much noise), like marking parts for trimming and clecoing some parts together.

Part marked for trimming and drilling

More work on Wednesday, after I'm back from a business trip.
As usual, time lapse of everything:

Total horizontal stabilizer time: 4.9h