Empennage: Aft fuselage. Rudder stops and bulkhead.

The vertical stabilizer, rudder, horizontal stabilizer and elevators are now all at a point where they just need their skins and trailing edges.  I'm waiting for my RV-9A friend to help me buck those.  Though I could do it myself, I'd rather have four hands to mitigate denting.

Thus, I continue working through the sections.  Next up is the aft fuselage.  Lots of angle, J-stiffeners and longerons to cut and deburr.  After that it's on to fabricating the horizontal stabilizer attach bar support and the rudder stops.  These are provided as thick aluminum angles with only the rivet holes pre-drilled.  So, you have to draw the cut lines...

...then cut them.  I still need to sand the forward faces of the rudder stops smooth.  Need access to a belt sender for that.

After that, it's on to match drilling the bulkhead for the vertical stabilizer.  Fairly routine work, but I made the mistake of dimpling in the wrong direction.  As I was looking at the parts in the way I dimpled, I realized it wouldn't sit flush against the vertical stabilizer.  A quick reread of the plans indicated my error.  Easily fixed just dimpling the other way.  The dimples look healthy - no indication of cracking.  Update 12-Jan-14:  See how poorly this bulkhead ultimately looked.  Update 29-Jun-15:  The bulkhead was replaced after installation in aft empennage.

Empennage: Elevators. Left elevator parts primed.

Nothing more exciting them priming.

Empennage: Horizontal stabilizer. Ribs and stringers riveted to front spar.

The ribs and stringers are riveted to the front horizontal stabilizer spar.  Was able to squeeze every rivet save four.

Where the spar attaches to the empennage's tail cone, there is a lot of reinforcement.  This suggests a lot of loading occurs here.  And there probably is.  However, the horizontal stabilizer from the -14 comes from the -9 (except the 4 inspar ribs, which are from the -10) and yet is not attached to the aft fuselage in the same way as in the -9.  This is why there are those square patches of 9 rivets on both sides of the doubler:  In the -9, these holes are to hold attach brackets.  Because the -14 has forward attach bars located on the aft empennage bulkheads rather than on the stab spars, those pair of 9 holes do not secure the attachment elements.  Instead, 1/4" holes are drilled into the doubler on each side of both spars so the attach bars on the bulkhead can grasp on to the horizontal stabilizer with AN4 bolts (a total of six, four aft and two fore).  This approach is unique to the -14.  Even the -10 has forward attach brackets on the spars.

Attachment approach used in the -14.

 

Here is the shop head side of all that.
 

The two inside "inspar" ribs each have four AN470AD4-4 rivets fastening them to the stringer web.  Because those two ribs are at a 12.5 degree angle, access to those rivets is a challenge.  I ultimately settled on the following approach and it worked well for me

Empennage: Elevators. Dimpling the trailing edge of the tip ribs.

Dimpling the trailing edge holes in the elevator tip ribs is not possible with a C frame or squeezer.  Rather than drop some $50 on a dimpling vise for four dimples, I had to think of a way to make do with what I had.  One tool in my collection is a pop rivet dimpler set.

Turns out, the nails were too long to slide in the trailing edge and I didn't want to flare out the ribs to accommodate the nail.  So, I tried cutting down the nail to a length that let me slide the parts into the trailing edge.  But, by the time enough of the nail was cut off, there wasn't enough length remaining for the pop rivet tool to bite on to.  I then tried placing the parts with the stubby nail into the hole to dimple (the nail is necessary for proper alignment of the dies in the hole) and squeezing them with a channel locks. Well, I just couldn't balance the die properly to get a nice dimple.

Then I thought about using the rivet gun somehow.  What if I used a footed bucking bar to hold the female die in place and use the mushroom set on the male die?  As long as the stubby nail was short enough to avoid sticking out of the male die yet long enough to center the dies in the hole, it should work.  The mushroom set would ensure the applied force is balanced across the back face of the male die, as with the foot of the bucking bar on the female side.

A footed bucking bar and the dies (note, female die has the stubby nail).

Female die with stubby nail in.

A footed bucking bar in place.

Lined up and ready to go.

Worked great on all four holes in each rib!

Empennage: Elevators. Trailing edge ribs cut and left elevator ready for priming.

The elevator and trim tab trailing edge ribs are made of foam.  It must be a way to get ribs in there (rather than a stiffener) but still keep the exterior profile of the control surface continuous.  The foam is very strong yet cuts like butter on the band saw.  The key is to go very slowly and deliberately, slightly outside the cuts lines so it's easy to smooth out with the block sander.  I used inexpensive spray adhesive for the templates.

The left elevator, assembled.  The clamped wood blocks were placed to give me something to work against when I was aligning the horn for match drilling.

 And the trim tab.

When the weather gets warmer, I'll clean and etch the parts for priming.  Then it's time to start riveting the elevators followed by aft fuselage (tail cone) work.