So I took a few days off the project after finishing the rudder, but jumped right back into things today.  Time for the elevators!  This starts pretty much like the rudder did: first step is to cut and prepare a bunch of stiffeners.  I had expected to do these for one elevator at a time, but the instructions actually have you cut them all and do the back riveting for both elevators before getting into the nuances of the individual units.  I considered not doing them all at once, but decided it probably would be simpler to knock them all out at once.  Plus I could just check stuff off in the instructions instead of having to note steps that I’d only done for one elevator, and so on.

So I sat down in my garage chair with a pair of snips and went to work rough cutting the stiffeners.  32 of them, to be precise.  An hour or so later, I had a bunch of rough cut stiffeners and a tired right hand. (Side note: I think my forearm muscles are growing, presumably due to the exercise regimen of snips, cleco pliers, and rivet squeezers.  Maybe I should market this program as RV90X or something.)

There was a bit of confusion at this point for me.  The plans call for modifying some of the stiffeners for the left elevator, specifically the D/E/F units, by trimming some material off the trailing end.  At first, I misread the plans, which seemed to indicate that I should cut about two inches off each stiffener.  This made no sense whatsoever to me; the left elevator is substantially different from the right due to the trim tab, but these stiffeners were outboard of the trim tab.  As far as I could tell, the skins were identical in this region.  So I got out the laptop and did some Googling.  I found where another builder had had the same confusion, and eventually realized he was reading the plans wrong.  The measurements called out in the plans are not amounts to trim off the end of the stiffeners, they’re distances from a particular rivet hole to where the trim should be made.  Measuring that (correct) way, the trims were far less drastic.  Basically I ended up cutting, at most, an eight of an inch off each stiffener.  I’m still not sure what the purpose of this is…I can only assume that the Van’s folks know what they’re doing. (I’d better hope so!)

With that out of the way, I broke out the bench grinder and went to work cleaning up the cut edges, rounding the corners, and smoothing everything out.  This was pretty tedious.  I’m not sure how long I spent standing in front of that grinder, but by the time I was done, there was gray aluminum dust everywhere.  It was so impressive that I felt compelled to take a picture of my filthy right hand:

Next up was clecoing all the stiffeners into place on the skins and then match drilling.  At this point, it becomes important to keep track of which stiffener goes where; this was simple with the rudder, since there were simply two of each length stiffener, and I only needed to keep track of whether a particular unit was for the port or starboard side.  Not so simple with the elevators.  Well, the right is easy; like the rudder, there are only two of each length.  On the left, however, there are a number of equal-length short stiffeners that go ahead of the trim tab.  So I had to work out a system for both telling top/bottom stiffeners apart and numbering the equal-length units.  For the record, my plan basically says that odd number of punch marks go on the upper stiffeners, and even numbers on the bottom.  The number of punch marks increments from inboard to outboard.  So the innermost stiffener on the top gets one marks, the next three marks, and so on. (I wrote all this down on the instructions in case my memory fails me)

The instructions also call for clecoing the trim cover doubler in place and match-drilling it at this point.  Presumably this is because it gets back riveted just like the stiffeners.  I must confess that I had to cleco that thing in place three times before I finally got all the holes drilled.  There’s no nice linear pattern here like with the stiffeners.  The instructions don’t call for any more prep on this piece before back riveting it into place, but I think I’m going to go ahead and attach the nutplates for the trim cover before I back rivet it to the elevator skin.  I’m sure this will be easier with the doubler not attached to the skin.  But I have to order some more dimple dies before I can do that…I need #6 screw dimple dies for these things.  One lesson I’m gradually learning is that the list of tools Van’s has on their website is by no means complete.

Anyways, next I went back to the garage chair and deburred all the holes in those stiffeners and the trim cover doubler.  Then I dimpled all those holes I’d deburred. I could have comfortably called it a night there, but I decided that I wanted to get the stiffener holes in the skins deburred as well.  I figure I can get the stiffeners prepped and primed next time out, then recruit Josie to help with dimpling and back riveting all at once.

At that time, I really did call it a night.  I got a lot done today, which I have kind of mixed feelings about.  It certainly feels good to be productive and such, but I’m acutely aware that I’m running out of work to do on the empennage, and I still don’t have the wing kit ordered.  I guess there’s just going to have to be some downtime between finishing the empennage and starting the wings.  I guess maybe I could do the fiberglass work for all the tips, though most folks seem to save that for later when there’s lot of other fiberglass work to be done…we’ll just have to see, I suppose.

Lots of stiffeners:

Lots of stiffeners, dimpled.  And the trim cover doubler:

Whew!  Another piece of the puzzle together…when I got out to the garage tonight, the first order of business was squeezing all the skin rivets.  This went pretty fast, even though I had to drill out one rivet when I stupidly used the wrong length.  Whoops.  I ended up using a blind rivet in the last trailing edge hole on the root end on each side…there was no way I was getting in there to squeeze, even with the thin-nose yoke.  Per the instructions, I simply drilled to 7/64 and used a MK-419BS blind rivet.  No problem.  That took all of about an hour.  Now all I had left to do was roll the leading edges and rivet them together.  I figured this wouldn’t take too horribly long.  It didn’t take horribly long, but it did take longer than I expected.

My rolling rig worked pretty well overall.  The only real problem I had was that the very end of each hook was touching the table; this in turn would eventually contact the spar once I’d rolled to a certain degree, thus stopping progress, in some cases before I’d even gotten as much of a roll as I needed.  In a couple cases, I removed the hooks and rolled the pipe sort of freehand to tighten up the roll a bit.  It sounds fairly straightforward when I explain it here, and really, the procedure isn’t that complicated.  However, there’s a lot of somewhat tedious work here- putting the pipe in place, tearing off innumerable strips of duct tape, taping the pipe in place, being careful to get each strip of tape at about the same tension/lineup.

The top two sections ended up coming together nicely, although when I pulled them together the exposed edge wanted to pop up a bit.  So I got out my hand seamers and added a little extra bend at the very edge, which helped that seam tuck in a bit better.  The lower section was a different story.  The rolls there were actually further towards the edge than they really should have been; the result was that when I pulled them together, the edges were rolled in a bit too far.  So I did the opposite down here with my seamers; I used them to straighten the edge a bit.  This got the edges to lie more-or-less flat, close enough that the blind rivets would hold without too much trouble.

Then it was just a matter of going down the line, pulling clecos and setting blind rivets.  And then it was done.  I really wanted to pull down the vertical stab and put the rudder in place just for fun, but it was getting late.  So I placated myself by just screwing in the rod ends that serve as hinges for the rudder.  Here I had a mild moment of potential panic…all three rod ends I screwed in acted the same.  They went in fine for a few turns, then got very tough to turn. (I didn’t force anything)  Suddenly I had a horrible thought: what if the tail kit included two different, but very similar, sizes of nutplates?  If I’d used the wrong ones, there’d be almost no getting to them now.  I’d pretty much just have to start the rudder over again.  A quick look through the parts list shut down this crazy failure fantasy.  I’m still note sure why the rod ends are tough to screw in, but I’ll worry about that later.

The rudder all riveted together:

Here I am painstakingly tearing strips of duct tape and laying them between the pipe and the skin:

And the finished product:

Shorter night in the garage than I figured for tonight.  Had some things to do around the house and didn’t get out there until about 8:00.  Then it didn’t take long before my sore back made me decide to go in and rest. (Side note: I apparently got this sore back from mowing the grass, of all things.  I’m not that old, am I? *sigh*)

Anyways, my MSP-43 blind rivets from Spruce arrived as expected, but before I riveted the control horn brace into place, I wanted to verify what I needed to to the four skin rivets on each side in order to use the CS4-4 blind rivets there.  I knew I’d need to drill out to #30, but what about the dimple?  Luckily, I have a number of scrap pieces sitting around.  I used one of an old ruined rib as my experiment piece; this was a particularly good test, since it was already drilled and dimpled for -3 flush rivets.  So I drilled to #30, dropped a CS4-4 in…yup, sits proud.  Out came the 1/8 dimple die set, I redimpled the hole…rivet sits nice and flush.  Good to go.

So I clecoed the skin back to the skeleton one last time, and drilled the eight holes in question out to #30, pulled everything apart, deburred, and dimpled to the larger size.  Easy enough; now I clecoed the horn brace back into place and proceeded to set the MSP-43 rivets between the horn and the brace.  Next were the three solid rivets between the brace and the root rib, also easy.

Before clecoing the skin back into place for the last time, I needed to put a dab of RTV at the trailing edge where each pair of stiffeners meet.  According to the instructions, this ties the stiffeners together and prevents cracking of the skin from vibration.  All I know is that it feels a little odd to take my shiny clean skin and shoot a mess of RTV in there, but oh well.

Finally, I got the skin clecoed on, and this was the point where I decided to call it a night.  All the remaining skin rivets can be hit with the squeezer, so they should go quickly tomorrow.  The only place I see the potential for delays are at the trailing edges, where clearance is tight.  Hopefully I can get in there with the thin-nose squeezer yoke, but if not, the plans provide for alternate blind rivets in there.  We’ll see how that goes.  And, of course, how my edge-rolling setup works out.

Ordered the blind rivets I need to continue with the rudder from Spruce today, so they’ll be here tomorrow.  Tonight I wanted to put together my rig to use when I get around to bending the leading edge of the rudder. (and subsequent control surfaces)

The basic idea here is that you use a length of pipe to roll the edges.  This pipe gets taped to the edge of the material, and then as the pipe is twisted, you end up with a nice round bend in the aluminum.  The potential difficulty-based on reading other builders’ experience, of course, not my own-is keeping the pipe down on the table and pulled tight against the edge being bent.  While reading about this, I ran across a nice setup that seemed very useful.  Dan Horton from VAF simply used a few u-bolts to hold the pipe down against the table in place, and as the pipe was turned, the rudder would naturally slide towards the pipe.  Proper tension pretty much takes care of itself.

I liked this idea, but I didn’t like the idea of drilling holes in my nice workbench to mount the u-bolts, especially when you consider that every time I needed to space the bolts differently, I’d have to probably drill even more holes.  I wasn’t sure how else I would do it, but I went to Lowes after work anyway, figuring I’d just walk the hardware aisles and try to brainstorm a solution.  Eventually, I hit on a simple, flexible, nondestructive idea.  The only material I needed in addition to the length of pipe was some steel bar stock.  When I got home, I cut the bar stock into four 9″ lengths, then put two right-angle bends in one end of each piece.  The resulting “hook” can be clamped to the side rail of the table, and the bent portion hooks over the table and holds the pipe itself.

Of course, it remains to be seen whether this works as well in practice as it does in my head…

A couple pictures of the rig: (I still need to fine-tune a few things, but I’ll wait until I’m ready to roll the dges to do that)

I did not, in fact, get the rudder completely riveted today.  I’m starting to think that it might be fun to keep track of every time I say “I’m pretty sure I can get XYZ done tomorrow evening” and I end up being horribly wrong.  I guess it’s a good thing that I’m amused by this instead of being annoyed.

Weather was good this morning, so I was able to get the parts primed.  I also still had to finish deburring and dimpling the rudder skin; I figured I could effectively multitask these things, and it worked pretty well.  Put some pieces on my priming board, shoot primer, go inside and deburr a couple edges, back out to the driveway, shoot more primer on any thin spots, back inside, etc.  In this way I had all the deburring done by the time all the skeleton parts were primed.  The only unexpected thing that came up during this time was drilling the holes for the leading edge of the rudder.

The instructions don’t mention anything specific about final or match-drilling these holes, but since (to my knowledge) all of the fastener holes are undersized from the factory, I figured that they would probably need attention.  And since I was already deburring holes, it would be easier to final drill them and deburr them the same time as everything else, unless there was some compelling reason to wait.  I checked the prepunched holes against the called-out blind rivet-yep, definitely undersized.  So I went ahead and final-drilled them to #30.

Dimpling the skin-skeleton holes was the last step before starting assembly.  The instructions start with putting together the tip rib assembly; first riveting the counterweight skin on before fitting the rudder counterweight.  Here, I committed my first mistake of the day.  Since I had added the doubler on the leading edge after splitting that flange, I knew that I was going to have to figure out for myself the proper rivet length.  The plans called for an AD426-3.5 rivet, so I grabbed the next longer length, a -4, and dropped it into the hole.  The old Mark I eyeball said that the tail looked long enough, so I proceeded to squeeze it.  Hmm, looks a little small.  For some reason, my brain didn’t register that there was a problem until I squeezed the second one.  Even then, it didn’t sink in just how horribly undersize the shop heads were until I started squeezing the rest of the skin-rib rivets.  With proper shop heads to compare them to, it was painfully obvious how inadequate those two rivets were.

They don’t even cover the edge of the dimpled doubler:

At this point, I had to stop for a bit; Josie and I had plans to catch a one-time showing afternoon movie at a local theater, so I got in a shower and we departed for a few hours.  When I came back, I got those offending rivets drilled out and replaced with -4.5s.  Much better.

On to the counterweight itself.  The two mounting holes in the tip rib have to be enlarged to #12 and dimpled for a #10 screw, and the counterweight has to be countersunk under that same dimple.  Here I ran into another issue: in the tool list Van’s published, they list a dimple die for a #8 screw, but not a #10.  I sort of saw this coming; when I was researching some other issues a couple days ago, I found that other builders had run into this same problem.  Several folks had simply used the #8 dimple die, then enlarged the dimple to final size using the screw itself as a die and the countersunk weight underneath.  This worked well for me as well; I felt a little weird about doing this ghetto dimple, but hey, it works.

Now to start assembling the rest of the skeleton.  First up, I riveted the upper two reinforcement plates to the spar.  These are found at each point where the rudder hinges attach; there’s just a doubler plate as well as a nutplate which the rod end bearing which serves as the hinge mounts.  These were pretty easy, except for the part where I riveted the first nutplate to the wrong side of the spar.  I could have been mad, but in truth I actually found it hilarious, simply because it was such a dumb mistake.

Next up, the lower end of the skeleton, probably the most complex part of the assembly.  Lots of pieces are attached here: a spacer strip, the root rib, the lower reinforcement plate, the nutplate for the rod end, the rudder horn, an the rudder horn brace.  Following the instructions, I clecoed everything except for the horn brace into position.  Shooting all those rivets was pretty easy; next I slid the horn brace into position, and immediately realized this was going to be interesting.  There are four rivets between the brace and the horn, and one side of this joint is inside the brace, accessible only through the lightening hole in the brace.  How in the world was I going to squeeze solid rivets in there?  My squeezer wouldn’t reach in there; well, maybe with a longeron yoke, but I don’t have one of those.  Maybe I could buck in there if I had a small tungsten bucking bar, but…yeah, don’t have one of those either.

Then I consulted the plans again and found some useful information: it’s apparently acceptable to substitute LP4-3 blind rivets here.  Hooray, I’m no longer at an impasse!  That sense of jubilation didn’t last long…I only have two LP4-3 rivets from the hardware bags, and I need four.  Well, this is a good time to call it a night anyway.  I figured I’d order the required rivets from Spruce; they’d be here Tuesday and I’d hardly miss a beat.  Oh wait, Spruce doesn’t have this particular rivet.  But VAF came in handy again, as I learned that Cherry MSP-43 rivets are an acceptable substitute, and Spruce does have those.  

I also learned something else useful: Four skin rivets on each side at the root also have one side inside that horn brace.  The plans call out a CS4-4 blind rivet as an acceptable option, which sounds good to me.  What I hadn’t thought about until I read some posts on the subject is that those are -4 rivets, and thus need a larger hole.  So if I’m going to use them, I need to enlarge and re-dimple those holes now, before I put everything together and they become inaccessible.  I’ll almost certainly be using them, given the likelihood of fouling up solid rivets in those holes…glad I found this out now!

I’m starting to notice that as the empennage build goes on, the instructions are becoming less and less specific.  There’s a lot of hand-holding early on, but now there are extra little details that aren’t always spelled out, things that would be clear to a knowledgable builder.  My understanding is that this trend continues into the following kits, probably because the instructions would be a giant book otherwise.  So it seems as if the empennage instructions are gradually “teaching” me to figure things out myself and catch potential pitfalls before they become problems.  Nice.

I guess I’ll see you all back again on Tuesday, once my stuff from Spruce shows up.  I might even finish the rudder that night. (WHY DO I KEEP SAYING THESE THINGS?!?!?!)

No priming today.  My paint booth (aka driveway) was intermittently rained out.  So instead I just cleaned and prepped all the skeleton pieces.  This way tomorrow I can go straight into priming and see where things go from there.

Kudos to Van’s for timing.  The day after I finished the vertical stab, a package showed up at my front door containing the replacement parts for the rudder.  I celebrated by waiting an additional another day before getting back to work.

This story actually starts on Thursday night, when I had my shortest night of work on the plane ever, at maybe ten minutes.  The first order of business was to redo the R-703/-713 alignment.  I was enthused right off the bat, because the new rib and counterweight skin seemed to not be as misaligned as the first set.  I got out my shiny new Avery fluting pliers and put a gentle flute in the forward flange of R-703.  I checked it against the counterweight skin…not quite.  I applied the pliers again with a bit more force, then checked…still not quite there.  One more time with the pliers, good amount of force this time…hmm, that “flute” looks very angular.  Oh great, I squeezed too hard and cracked the flange.

Given the difficulty I’d now had with two of these things, along with the potential self-loathing I’d feel if I ordered yet another tip rib, I decided to try something different.  My plan was to cut a relief in the middle of that flange, between the two rivet holes.  This would take care of two problems: first, it would completely excise that material I’d cracked, and it would also make it a lot easier to align the holes with the counterweight skin.  It didn’t seem to me like this would compromise strength, but I figured it was prudent to solicit second opinions.  So I asked the great community at VAF what they thought of my idea.  No objections, and one guy had the good idea to add a doubler if I was worried about strength; I decided the doubler was an excellent idea.

Back out in the garage today, I put my plan into action.  I knew that the base of my relief cut needed to be radiused properly to avoid stress concentration, so I decided to start my work there.  I marked out a decent centerline, centerpunched a hole, and drilled it to 3/16″.  Then I marked my cut lines, and the bandsaw made quick work of those.  A cutting bit on my Dremel cleaned up the transition between the bandsaw cuts and the drilled hole, and I finished by dressing the cut edges.  Next I clecoed the counterweight skin in place before rough-cutting a strip of .032 alclad for the doubler.  Clamped that in place (making sure the strip followed the curve of the flange), drilled through the two holes, cleaned up the doubler, and everything was good to go again.

After match-drilling the new rib to the rudder skin, the only thing left was to drill the R-717 attach strips I fabricated a while back.  These strips sit inside the root rib, and they’re drilled by clamping them into place and using the skin and rib as a drill guide.  Slight problem here is that the rib and skin obviously need to be aligned properly for this to work right, but trying to align three sheets and clamp them together isn’t exactly easy.  My “solution” (if you want to give it that much credit) was to cleco the skin to the rib on one side for general alignment, then clamp the attach strip to the other side for drilling.  Worked like a charm.

After that, the rudder came apart and there was deburring-aplenty to be done.  One decent-sized pile of metal shavings later, I was thinking of calling it a night, but decided to get the skeleton pieces dimpled.  This way, on my next work day, I can move right into prepping and priming.  Dimpling went great until I got to the narrow ends of the tip and root rib.  I knew ahead of time that these were tight spaces that would need special tools, so the last time I ordered from Cleaveland, I made sure to order their pop-rivet dimple die sets.  At the time I clapped myself on the back for planning ahead.  Tonight, I discovered that there wasn’t even enough room to get the mandrel for that dimple die set in there.  ARGH!  After some head-scratching, I came up with a solution: I cut down one of the mandrels, only using it to position the small dimple dies in the rivet hole.  Then I was able to get my Main Squeeze with the thin yoke around them, and viola!  Nice little dimples!

I have plans tomorrow afternoon, but I’m hoping maybe I can get out before that and get these pieces prepped and primed tomorrow.  I also still need to dimple and otherwise prep the rudder skin, but I can easily do that between cots of primer.  Assuming I can get things primed tomorrow, I don’t think it’s out of line at all to think I can have the rudder done this weekend. (I should know better by now than to count my pre-hatching chickens like this, but I just can’t help it…)

Here’s that pesky tip rib after I made my relief cut: (edges still haven’t been finished at this point)

And here it is with the counterweight skin and fabbed doubler clecoed in place:

And here’s a small pile of parts waiting to be deburred:

And yes, I really did finish it up after midnight.  More on that later…

All I had left to do today was to squeeze all the skin rivets around the perimeter of the stab, then use a combination of solid and blind rivets to attach the rear spar to the rest of the skeleton.  But first I had two bad flush rivets to drill out, a reminder of what happens when I keep working even after I get tired.  At one point, I thought I was getting pretty good at drilling out flush rivets without damaging the holes, but I must have backslidden, as I enlarged one of those two holes.  Oh well, that’s what I have the oops rivets for.  With those drill-outs out of the way, I proceeded to squeeze all those other skin rivets.  Well, almost all of them.

In general, there are some minor access issues working on the rear of the stab; the lower end of the spar web has a reinforcement riveted in, and where the skin rivets happen to be near a rivet in the reinforcement, the squeezer has to be placed carefully to ensure the shop head stay under the die.  Those weren’t too bad, but there were four that were a real pain.  As if the spar reinforcement isn’t bad enough, about midway up the spar are a set of rudder hinge brackets.  Yup, even less clearance. This was actually where I left off last night; my first attempt to squeeze one of these ended up with the shop head malformed due to slipping of the squeezer die.

Today I was much, much more careful, and I was able to get three of the four pesky rivets done with the Main Squeeze and my thin-nose yoke.  The fourth and last rivet was not so easy.  Despite careful positioning, I malformed another shop head.  Then I enlarged the hole drilling it out.  As if trying to squeeze a -3 rivet i there wasn’t bad enough, now I had to use an oops rivet with an even larger shank.  I wasn’t quite sure what to do with this, so I decided to move on to riveting the rear spar on.  That went pretty fast, but I had yet to come up with any ideas about that last skin rivet.  I decided to call it a night, maybe seek help on VAF, and finish tomorrow.

A couple hours later, I was still thinking about that pesky rivet.  It occurred to me that the shape of the die was really the problem; if I removed some material, I could get in the tight space better and get that thing squeezed.  But I wasn’t about to carve up my shiny new $150 yoke for the Main Squeeze.  Oh wait…why not just modify one of my flush rivet dies and use it with the old squeezer?  Worst case, I ruin a $20 die that’s easily replaceable.

So that’s how I ended up firing up the bench grinder at roughly 12:15 AM.  The modified die worked like a charm, and now I had the satisfaction of going to bed with the completed stab in my garage.  But first, I had to pull the horizontal stab down and set up the good old “pose-with-your-shiny-new-stabs” photo.