Empennage: Aft empennage. Match drilling vertical stabilizer.

The last step remaining for me to complete in Section 10 was the match drilling of the vertical stabilizer to the aft bulkhead.  I waited until I was ready to complete Section 11 to do this step, meaning it was delayed by 2 years.  I just needed more space.

Per the plans, it is critical to drill these holes perpendicular to the surface.  A friend of mine created for me a UHMW piece to aid in that process.  It keeps the bit trajectory true.  A well cut piece of wood with a hole drilled on a press would achieve the same result.

Once the holes are drilled, the stab can stand proud to negotiate the slipstream.

The above image also shows that the airframe has been moved to the other side of the garage.  This gives space to fully mount the tail to complete Sections 11 and 12 as well as mounting the engine and prop.

Empennage: Aft empennage. Top side and top skins on. Finally.

It was on 4-Jul-14 that the bottom side skins were attached to the aft fuselage.  At that point, the structure could no longer accommodate the top side and top skins as it would have made it too big to remove from the house.  Thus, following the addition of various cables, rudder guides, static plumbing, bulkhead riveting and the aft deck, the structure imposed as an unwelcome couch-surfing roommate in my living room, along with the wings, until the future (now current) new house could offer the structure the space it beckoned for.  I cleco'd the top skins on just for looks.  They had to be removed so the structure could fit through the door when I moved to the new house.

And so, a little more than one year later, on 17-Jul-15, a gracious friend spent 4.5 hours with me to rivet the structure to near completion.  Just a few rivets remain, including some match drilling for the vertical stabilizer (page 10-28) and this bad boy will be ready for attachment to the forward fuselage.  Sections 11 (Empennage Attach) and 12  (Empennage Fairings) can be completed with the tail attached to the fuse.

The rivets along the longerons and bulkheads were bucked classically with a flat set and bar.  The rivets attaching the top and top side skins were back riveted with me sprawled out in the structure.  The picture of me inside the tail cone is less than modest, so it's left to the reader's imagination.  However here is one showing my wayward hand poking out from the inside of the tail onto the aft deck.  You can also see the fuselage right side skin ready for riveting.

In hindsight, we should have done all of these top half rivets by back riveting with me inside the tail cone.  I was hesitant to do it given how imposing it seemed.  Other than the bearable discomfort of the protracted time in a confined space limiting my movement, it was easily accomplished.

Here is the nearly completed aft fuse.

In case you're wondering why the aft bulkhead no longer seems complete, see this post.

Empennage: Aft fuselage. Replacing aft bulkheads.

When I originally prepared the F-01412A and B aft bulkheads, I made two mistakes.  The fist error was dimpling all the holes in the bulkhead webs in the wrong direction.  To "fix" this, I decided to just dimple them back the other direction.  Many posts abound on VAF regarding this type of error, here being one of them.  Folklore says it's okay to just dimple back the other direction  Who knows if that's true?  I certainly don't.  In either case, the material remains a bit warped after squeezing them the other direciton.  

Now, the second error was my dimpling two holes that should not have been (circled in red below).  In fairness, the plans were specific that they should be dimpled (red box and no exclusion on the figure).  Yet, they should not be.  The reason being that the tiedown bracket would conflict with any rivets in those holes.  So, those holes should remain untouched in the tri-gear version.

To "fix" this, I just flattened those two holes with my squeezer.  But, as you can see in the two images below from my 12-Jan-14 post, the bulkhead web was now fairly warped.  In fact, the shop ends of the rivets seemed quite short probably due to the holes being rather large.

It turns out that the vertical stab rear spar needs to sit flush against the web of the aft bulkhead (below).  Those flattened dimples would make that challenging since they now stick up out-of-plane of the web.  I didn't replace the bulkheads back in January of 2014 because my tech counselor and others thought I've been too liberal in replacing things I didn't like.  Figuring I was being too picky, I opted to keep these bulkheads.

But, since installing the bulkhead into the aft fuselage, it's been bothering me a lot.  Every time I would walk by the aft fuselage (after all, in my old house, it had been on my couch, overhanging into my kitchen), I would look at the bulkheads and try to visualize how to remove and replace them. There is precedent for this on other RV models as some folks change their tri-gears to tail gears (stories exist on VAF about the conversion, but I haven't found any documentation of such with pictures).  In December of 2014, I devised a plan:  Drill out all the rivets holding the aft bulkheads in, drill out a few longeron and stiffener rivets holding the side skins in so I can pull those skins back a bit, and replace the aft bulkheads with the new ones, as illustrated below.  Following replacement, I didn't expect accessing the rivets to buck them to be too challenging.

In February of 2015, I asked one of my blog readers, with whom I frequently correspond and who hadn't yet reached Section 10, if he'd be willing to cleco a full layup of the aft fuselage to see if my plan would work.  Indeed, in early May of 2015 he was able to remove the aft bulkhead with it cleco'd in.  Below is what he sent me as evidence.  What a kind thing to do for me.  Thanks Ken!  So this was the proof I needed to execute my plan.  And I didn't need to remove any of the stiffener rivets.

I counted some 70 rivets that needed to be removed.  Yikes.  Lots of chances for mistakes.  But, I was able to pull out the aft bulkhead without issue.  The only expense was a bloody finger, but that's a common malady when building an RV.

The new bulkhead (left) and the old (right).  You can see the difference in the surface profiles:  Flat vs. warped.

It took a lot of effort to get the new bulkhead in.  Primarily because I had to be careful to ensure that the flanges nested on the inside of the longerons, rather than sliding between the longerons and the skin, like they desperately wanted to do.

Here is the bulkhead installed with every rivet that could be squeezed.  I left off the F-14113-L/R rudder stops for now because it will make it easier to buck the remaining rivets.

And unlike the original rear bulkhead (left), there are no overlapping flange tabs (right).  Either my original F-01412B bulkhead was miscut or they fixed whatever the issue was by the time I ordered the replacement part.

For completeness, here's an inside shot.  Just a few more rivets to buck and it's done.

Empennage: Aft fuselage. Side skins cleco'd on.

With the aft deck in place, I cleco'd in the side skins.  As usual, space is at a premium for me.  The height of the aft empennage is 36 inches.  My front door has a width of 35 inches with the door off the hinges.  So if I tilt the aft fuse on its side with the side skins, it could be extracted from my hangar house since the former is slightly compressible with the top skin off.  I'll test this hypothesis before I rivet the side skins in place.  Otherwise, I'll finish riveting the side skins in the garage and hoist the assembly up to the rafters for storage (which is admittedly better than the couch).

Empennage: Aft fuselage. Aft deck.

Be mindful of the rivet lengths called out for in the plans here.  Many are not correct.  A rivet sizer is valuable.

I was able to squeeze more of the rivets here among three different yokes:  1) 3", 2) longeron and 3) 4" deep no-hole.  The remaining rivets (most the ones aft of the horizontal stab attach support angle) were bucked.  The ones in the corners at the bulkheads were extremely difficult to do.  I don't have any suggestions yet other than to be mindful of your bucking bar so it doesn't slip and wreak havoc.

Working in the living room wastes a lot of time:  I keep going up-and-down the stairs to obtain and return tools!

Here is the aft deck fully riveted except for one AD470AD3 and the pesky corner rivets called out in red in the plans shot below.  That lone AN470AD3 rivet just aft of the stab attach bars should not be a length -4 as called out for, but a length -5 (the material thickness is about 0.160" so with 1.5x protruding prior to bucking, the length should be 0.301 which is a -4.81 size rivet, or a -5).

 

I'm still mulling over how to buck those corner rivets.  I managed to buck two of them with reasonable results.  One of them clenched over and another I didn't try.  So I'll probably drill out the clenched rivet and try again.  Once I research some different bucking bar shapes, I'll post on how I ultimately managed these guys.

That took me, working solo, 5.25 hours.  And I forgot to rivet in the nutplates on the longerons, so now I'll have to buck those rather than squeeze them.  D'oh!  In the end, I think it's easier with the nutplates off anyway, since bucking bar access is easier without them.

Below are the results of removing the rightmost deck angle (F-1412C) rivet.  As always, I start the process with my punch, then I drill a #52 through the shaft.  Then a #42 through most of it, but not all.  Then, with a lot of pressure, I drill the head with a #33 to twist it off.  Then I used my #40 punch to drive the rivet out.  You can see why I wanted this rivet out (left).  Then I was concerned when my #52 hole seemed so off-center (center) but after removal, it was clear my drilling was spot on (right).

Empennage: Aft fuselage. Riveting bellcrank to bulkhead.

As previously mentioned, the plans neglect to instruct you to rivet the bellcrank ribs to the forward bulkhead.  I didn't realize this until after the bottom skins were on the bellcrank ribs.  Too bad, because it would have been easy to do prior to then.  I was able to squeeze the middle rivet and buck the top rivet.  But the bottom rivet would require a double offset set which is akin to taking your life in your hands (see next paragraph).  So I used an LP4-3 on the left side.  Problem solved.

This is what happens when you use a double offset set in an awkward position.  I tried this on the right side (the view is looking forward from the right aft).  This rivet will need to be removed and replaced with an LP4-3. 

Here's what that looks like after removal.  Yuck.  I had to get a 12" #52 bit to use in conjunction with my 12" #40 and #30 bits.  You can see I wasn't centered on the manufactured head, but I didn't do much damage to the bulkhead hole as I went very shallow into the head.

For perspective, the rivet of interest is circled in red below.

Empennage: Aft fuselage. Static plumbing installed.

Installing the static plumbing is fairly easy.  One challenge was removing the mandrels from the AD-42-BSLF blind rivets (which serve as the static ports).  I ultimately used a #52 drill to drive them out after failing with a punch.

Don't push too hard on the F plastic tee.  You'll break it.  $0.80 replacement from Van's (couldn't source it locally).

I used a longer length than the plans call out for the static line tee upsizer.  Don't worry, I later cut the top straight.

Left side sealed in.

Right side sealed in.

Easily tested by blowing in the distal tube and feeling for air coming out of the ports.

As an aside, some folks choose to install a more robust static line setup, an example of which can be found here.

Empennage: Aft fuselage. Rudder guides.

The rudder guides are installed in the aft fuselage.  The plans call for AACQ4-4 rivets backed by NAS1149FN416P (a.k.a., AN960-4L) washers.  There are two parts to the rudder cable guides and their thicknesses differ.  Below are the left cable guides.

On the smaller cable guide (F-01497B), the pull rivet retained a significant length of the mandrel. Must be related to the thickness of the guide as the right side (not shown) did the same.  The AACQ4-4 rivet has a grip length of 0.126-0.250. 

The rivet is a "Q Rivet" with a special interference mandrel (brochure here).  You can watch this fun animation showing how it's supposed to work..  I'm guessing I'll have to pull those two rivets out and stack some more washers to get the thickness within the grip length.

Empennage: Aft fuselage. Routing L1082 cable through aft bulkhead.

The L1082 cable is supposed to go through the hole in the aft bulkhead.  Presumably so it can power the light on the rudder.

But the cable has a sort of bolus where the black wire is soldered to the white cable's shield.  It's further layered by some shrink wrap.  So it won't fit through the aft bulkhead's hole.

I tried squishing that bolus with some pliers, but all it did was shorten it one dimension by lengthening it in another.  So I took the shrink wrap off and it fit through the hole with just a bit of coaxing (!).

As a sort of related aside, you can pull bushings out to fit things in later that wouldn't otherwise fit (the plans don't have you place the wiring in a good order, so sometimes you find yourself in a bit of a pickle).