Empennage: Rudder. Leading edge curled.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder.

This post might seem out-of-sequence, however I had been putting off finishing the leading edge and working on the fairings and in favor of securing experienced help.  

In the case of the rudder leading edge, I wasn't pleased with how my elevator leading edges came out, back in August 2014.  So I asked my RV-9A friend to roll my rudder leading edge as I was pleased with how he did his.

The leading edge must follow the templates laid out on page 7-13. 

In the left image (looking up the forward edge of the rudder), you can see that the HW-00004 Tie Wrap Clip was broken so I'll have to replace it.

Empennage/Lighting: Suntail rudder light purchased.

Picked up AeroLEDs SunTail anti-collision strobe and position light from Van's when I visited the home base.

The kit will be available in the future as OP-56.

Empennage: Rudder. Trailing edge riveted.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder. 

The trailing edge on the rudder has been riveted.  To mitigate a curved edge, I picked up some angle iron. 

The edge turned out fair.  It's reasonably straight but since we alternated the rivet orientation to give the rudder a cleaner appearance, there is a minor waviness to it.  In fact, it's the skins that are wavy.  The trailing edge wedge seems fine.  Might be due to excessive pressure from the riveting gun.  We did have to turn it up to drive the rivets properly.  My guess is the angle iron flexed too much.  Perhaps it should have been thicker.  Oh well, you get the airplane you build, not the one you want!

Might be able to work those out using the technique outlined in Section 5.

Empennage: Rudder. Stiffeners, ribs, spar and horn riveted.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder.

To get the stiffeners riveted on the rudder, you do a sort of "reverse peel", starting at the bottom and working your way to the top, pulling each aft stiffener rivet.  Then you pull the forward pair of stiffener rivets.  With the stiffeners locked together, it's a more solid feeling rudder than other models.

A few shots of how the pull rivets look.  Aft end.

Forward end.

Be careful to avoid this unfortunate problem.  Sand this to fit around around the horn's protrusion so it seats nicely before riveting.

At first we tried to buck the horn brace rivets with a tiny bucking bar stuffed inside.  After messing up the first rivet and drilling it out, thinking it was time for pop rivets, it donned on me that we could squeeze them with my longeron yoke.  Duh.  No problem.

Not shown in the above picture is the bottom, forward-most AN426AD3-4 rivet that holds the skin to the horn brace (in the above image, it would be the lowest cleco'd hole).  We could not fully squeeze it with any of the yokes I have.  Didn't seem feasible to buck it.  We left it about halfway squeezed.  I'm okay with leaving it as-is, but I'll put it on my squawk list so I can remember to keep it in my mind should I later find a way to do it or meet someone who has.

Here the rudder sits waiting for the trailing edge to be riveted.

Empennage: Rudder. Counterbalance rib riveted to spar.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder.

I wouldn't normally post for such a mundane task, however I wanted to document my approach here.

Squeezing rivets sometimes causes thin parts to distort, especially rib flanges.  Since this rib will be holding up a hefty bit of mass, best to keep the flange as flush against the spar as possible.  So for the rudder counterbalance rib, I wanted to buck the two AN470AD4-4 rivets with their manufactured heads on the forward side. 

Bucking the rivets would require an offset rivet set.  With the requisite higher air pressure and spinning rivet set, I wanted two hands on the gun.  So I propped the bottom side of the rudder spar up with wood blocks.  The top side of the spar, with the shop head(s) protruding, was rested against my dumbbell bucking bar with a steel plate under it (the latter mitigates the dampening of the gun blows by the wood).  In no time, I had two great shop heads and a nice flush rib flange.

Empennage: Rudder. Spar riveted.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder.

The rudder spar is essentially complete and awaits its mating to the skin.  When I was ready to rivet the horn and its associated parts together, I noticed the plans had two holes that my parts did not, except for R-00917.  The missing hole on the left is critical for the tie clip, the right one must be for symmetry.

No such holes for me.

Thinking I may have missed a match-drilling step in the plans, I checked back and noticed nothing.  I needed those holes, so I match-drilled the holes into the spar and R-606PP using R-00917, then cleco'd on the horn to match drill it too.  After deburring and spot priming (above right shows the departure of some primer since I cleco'd without a full cure), everything came together just fine.

However, the rivet lengths called out for the plans are incorrect for the horn (including its nutplate).

My calculations (shown below) revealed more appropriate numbers (shown above in red).  Thicknesses were measured with my caliper.  I didn't have a -7.5 length, so I ground down several -8 lengths.  For the -8.5 (holds the nutplate), I could have ground down a -11 (the next highest length I had), but went with a -8 instead as called for in the plans. The shop head is a bit short, but hey, it's for a nutplate, right?

	1/8” Rivet
Rib/Spacer	0.035	0.035
Spar	0.035	0.035
Doubler	0.069	0.069
Horn	0.135	0.135
Nutplate		0.063
Additional	0.188	0.188
Total Length	0.461	0.524
Size (in 1/16”)	7.376	8.376
Rounded Up	7.5	8.5
Rounded Down	7	8

Here's the spar.  I'm just missing the counterbalance rib as I'm waiting for #10 dimple dies (dice?).  Ya, I could probably force dimple it with a screw, but tools are cool, right?

Empennage: Rudder. Stiffeners and clips rivited.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder.

The rudder skins have 7 stiffeners each (similar to the ailerons, they don't have ribs...I'm curious why that is...perhaps to avoid using pop rivets on control surfaces?).  It's easy to back rivet these in.  Only need to be careful and realize the back rivet plate's extent under the work piece so you don't attempt to buck a rivet without the plate's backing (I just barely dented the left skin from the rivet set collar on the last, bottom rivet).

To complete this task, I taped all the rivets in (left) so they stayed in place when the skin is flipped over (right).  Then I set the stiffeners in place (center) and went to town with the rivet gun.

The shear clips get attached to the right skin's stiffeners.  Interestingly, the plans call for LP4-3s to be used.  I believe this is to prevent distortion of the parts, rather than for accessibility.  Because a pull rivet expands from the distal end (relative to the manufactured head) inwards, nothing can expand either between or within parts.  Anyway, it's a tight fit to get the rivet puller in there, so I used the advice from Chapter 5 and fashioned a wedge tool from some scrap VA-140 Trailing Edge Wedge.  Below is how it's used (I only have two hands so I couldn't align and pull everything tight for the shot, but the illustration should still be understandable).

Here is the right skin with its stiffeners and riveted together.  Notice the lap joint is primed since it will be squished under the left skin soon.

 And for good measure here's the left skin.

Empennage: Priming. Rudder and horizontal stabilizer.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder.

Nothing exciting here.  Just routine priming with Stewart Systems.  Got the remaining rudder parts and skins completed.  As well as the rear horizontal spar, caps, doubler and skins. 

Still need to flute, drill, etc. then prep and prime the horizontal spar ribs.  I will group those in with some priming of elevator parts.

Empennage: Rudder. Assembly for trailing edge match drilling.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder.

Cutting the many stiffeners is easily accomplished with the band saw using the sliding miter guide set to the appropriate angle with the part cleco'd into a wood block for alignment.

Next was assembly of the skeleton for the skins.  Remarkably, I was short AN470AD4-6 rivets so I couldn't attach the nutplates yet.

Right skin on.

The trailing edge wedges, like for the ailerons and flaps, must be match drilled to the skins.  I used a wood block cut to 84 degrees to ensure my drill was orthogonal to the wedge's chord.  I positioned the VA-140 wedge so that it aligned with the bottom of the skins.  Turns out the holes in the skins are such that, by aligning the wedge just so, I only needed one cut of the wedge at the top to trim it to size.

It's interesting that the right skin lap joint has a hole in the middle that is not used.  Only one of those middle holes is match-drilled from the left lap joint.

Empennage: Rudder, vertical and horizontal stabilizers priming.

I decided to redo my rudder due to the trailing edge.  Here is the post outlining the new rudder.

When priming for the empennage, being a smaller portion of the aircraft as opposed to the wings, it makes sense to try to aggregate many parts together.  This helps minimize the amount of time spent cleaning, etching, spraying primer and on the wait for curing.  Thus, I jumped ahead to get many of the rudder and horizontal stabilizer match drilled, countersunk, etc. so they can be primed in the same batch as the vertical stabilizer parts.

Primed:  All vertical stabilizer parts.  Front horizontal spar, doubler and stringers.  Rudder ribs and spar.

I use Stewart Systems for priming.  Being water-based, it's far less toxic to use though I still wear my respirator.  The vast majority of aerosol doesn't get airborne.  It just falls and collects as dust.  Do not, however, use water-based primers for steel.