Chapter 5 – The Empennage (Rudder)
Lorin’s RV-9A Builders Log
Table of Contents:
Chapter 5 – The Empennage (Rudder)
Apr 24, 2005 – Cut & Prepped RS Stiffeners (4 hours
today – 106.25 total)
Apr 26, 2005 – Drilled Stiffeners to Rudder skins (1.5
hours today – 107.75 total)
Apr 29, 2005 – Removed Skin Vinyl (1.5 hours today – 110
total)
Apr 30, 2005 – Completed Skin Preparation (6.5 hours
today – 116.5 total)
May 1, 2005 – Back Rivet Jig & Final Prep (3 hours
today – 119.5 total)
May 2, 2005 – Final Prep for Stiffener Assembly (2 hours
toady – 121.5 total)
May 3, 2005 – Completed Stiffener assembly (2 hours today
– 123.5 total)
May 6, 2005 – Started Rudder Skeleton (2 hours today –
125.5 total)
May 8, 2005 – Continued Skeleton (1.5 hours today – 127
total)
May 14, 2005 – Completed Skeleton & Drilling Skin
(5.5 hours today – 132.5 total)
May 19, 2005 – Prepped Parts (2.5 hours today – 135
total)
May 20, 2005 – Primed parts (.75 hours today – 135.75
total)
May 21, 2005 – Assembled Rudder skeleton (4 hours today –
139.75 total)
Jun 5, 2005 – Skinned Rudder / Started Trailing Edge (5
hours today – 144.75 total) -
Jun 6, 2005 - Completed Rudder (3 hours today – 147.75
total)
Apr 24, 2005 – Cut & Prepped RS Stiffeners (4 hours today – 106.25
total)
Since I couldn’t work on the VS for
awhile (waiting for the replacement skeleton parts) – I pulled out the blank
angles for all the rudder stiffeners.
After marking the lines for the long shallow angles (from center to
center of the locator holes), I rough cut them on the band saw – making sure to
stay “outside the line”. Next, I sanded
each stiffener down to its final shape & size using a 1” belt sander. This was very easy and went fairly
quickly. So lastly, all that was left
was a couple of minutes cleaning them up with a scotchbrite wheel.
Next I laid out each of the
stiffeners on the skin and then marked where to cut them. At the same time I took the opportunity to
mark them left or right. A quick snip
with metal masters and they were ready for the next step which was removing the
rough burrs and rounding the edges with belt sander. Once more I touched up each of the stiffeners with a scotchbrite
wheel. I was very pleased with how they
came out – and then took a few final minutes to clean up all the outside edges
with a scotchbrite pad.
Apr 26, 2005 – Drilled Stiffeners to Rudder skins (1.5 hours today –
107.75 total)
I read a lot of builders were
using a sacrificial table top to help build & cleco their rudder skins
& stiffeners. So, I found an unused
smooth MDF board and set it on the workbench.
It was large enough to support the entire skin and it worked great for
continuing the assembly. I drilled and
clecoed the stiffeners – starting at the center of each section and moving
outward (drilling every second hole and clecoing as I went). As I got more comfortable with the process
it soon went very quickly.
Fig 5-1
Apr 29, 2005 – Removed Skin Vinyl (1.5 hours today – 110 total)
After all the ribs had been
match drilled – I disassembled the parts, deburred the ribs and then dimpled
the ribs with the Avery Hand squeezer. I
finished the day’s work by cleaning all the stiffeners with acetone and priming
the parts. Moving on to the skins – I
removed the sections of vinyl from the areas under the ribs on the outside and
inside surface using a metal yardstick and the soldering iron with a rounded
tip.
Fig 5-2
Apr 30, 2005 – Completed Skin Preparation (6.5 hours today – 116.5
total)
In a rare moment of inspiration I decided use the padded C-frame table to support the skins while deburring all the holes. This made it easy to work on and kept them flat. However, be careful when deburring!! – The skin is very thin (.016) and you don’t want to take off too much material. Next came the dimpling. By now I was getting pretty good at judging where the dimple die was under the skin. I still took my time trying to minimize any scratches.
The next step was to remove the remaining vinyl from inside of skins. This was easy – but I took my time and pulled the vinyl back at a sharp angle so I would not accidentally bend the skins. It was simple but took about 10 minutes for both skins.
Fig 5-3
The last thing I did today was clean the inside skins with acetone and prime the parts. Just like before – I took a2-step process to cleaning. The first wipe was to remove the skin labeling (blue dye and any adhesive/contaminants). The second wipe was with a clean rag – for the final prep. It was probably overkill – but it did not take hardly any time. I did notice I had a light dull grey residue on the shop rag – so I must have picked up some more contaminants. The priming went easy – no surprises here.
Fig 5-4
May 1, 2005 – Back Rivet Jig & Final Prep (3 hours today – 119.5
total)
I read Van’s instructions and remembered from the SportAire workshops that back riveting was the best process for attaching the stiffener ribs. However, before I started that – I decided to build a table top jig that would support the work piece and keep the riveting plate in position. I found a piece of scrap plywood the perfect thickness and cut out a rough hole slightly larger than the plate (the cutout was positioned over the main end brace of the work bench for maximum stiffness). Next I glues & screwed a 2X4 to the underside of the plywood that would be clamped to the end of the workbench. This made a quick but sturdy riveting table.
Fig 5-5
May 2, 2005 – Final Prep for Stiffener Assembly (2 hours toady – 121.5
total)
In final preparation before attaching the rudder skins I laid out all the stiffeners and then clecoed on the forward spar to ensure adequate clearance. At the same time I also positioned the trailing edge wedge in place to make sure there was no interference. Everything looked good – but I decided to modify two stiffeners to that were a little close. By “modify” I mean that I ground the edges down a little on my belt sander, cleaned up with a scotchbrite wheel, finished with a quick scotchbrite pad rub down and finished by re-priming the exposed metal). Again – not a lot of work nor time – but I was now confident that I would not have a contact problem later on.
Fig 5-6
May 3, 2005 – Completed Stiffener assembly (2 hours today – 123.5
total)
Having completed all the preparation work – the actual riveting of the stiffeners to the skins went very quickly. The rivets were inserted one row at a time and held in place with the back-riveting tape supplied by Vans. Then, starting at the center of the rib, I worked my way to each end upsetting one rivet at a time (i.e. not skipping every other rivet). I had completed both skins and they looked great. As a side note - I decided to keep the rivet tape on for added protection. I figure I should be able to clean off any residue with acetone later. A few days later – I went back to look at the rivets… in hindsight they are probably a little “overset” because I had the regulator turned up a little high. This is not enough to worry about – but I will be more careful next time.
Fig 5-7 Fig 5-8
May 6, 2005 – Started Rudder Skeleton (2 hours today – 125.5 total)
With the rudder skins mostly completed, I started on the rudder skeleton. I took out all the parts, removed the vinyl protection where the pieces are going to be joined, and then started to prepare the individual pieces. I also rough cut the shim that goes under the lower angle.
Next, all ribs were fluted to align the holes. I was surprised how long this took. It seemed like I overshot and then had to straighten the parts – and then undershot and then had to flute deeper. After a couple of tries, I eventually got it right. Next – I clecoed the parts per the directions.
Feeling a little frustrated at how long the fluting took – I decided to call it an early night before I got upset and made a mistake.
Fig 5-9
May 8, 2005 – Continued Skeleton (1.5 hours today – 127 total)
Quitting early the previous night was a good idea. I started this evening – refreshed and eager to make more progress. So work continued on the rudder skeleton. Some of the time was spent shaping and rounding the lower angle so that it fit nicely within the bend radius of the lower rudder rib. This was not difficult and did not require much precision work. After I was comfortable with the fit - parts were located in place, clamped (remember – if you don’t want it to move – CLAMP IT!), and the necessary holes were match drilled. Lookin’ good.
Fig 5-10
May 14, 2005 – Completed Skeleton & Drilling Skin (5.5 hours today
– 132.5 total)
Today I continued to assemble the rudder skeleton – first working on the top section. I clecoed the upper & lower counterbalance ribs to the spar and then fastened the skin to the spar/ribs per Van’s directions. The appropriate holes were match drilled and then left clecoed in place.
Fig 5-11
Next I turned my attention to
fabricating the horn, which meant cutting away some material. This piece looked a lot trickier than it
really was. I had done some research on
the web and found a couple of builders trimmed too much material away and were
left with inadequate edge distance for the rivets. Having learned from their mistakes I trimmed to outside edge of the
locator holes first. I used my belt
sander to come to the final shape – and then cleaned up the sanding marks with
a scotchbrite wheel. Again, I can not
emphasize this enough – make sure you leave enough room for edge distance. I fitted the pieces together and clecoed
into place.
Fig 5-12
With most of the skeleton assembled – I attached the rudder skins. Everything aligned perfectly.
The next step was to fabricate the lower attachment strips. These are two flat strips with a corner removed to clear the lower horn. A quick measure, cut and some finishing on the scotchbrite wheel was all that was needed. The strips were aligned and clamped into place using the 1” cleco clamps. I made sure the strips are positioned close to the inside radius of the lower rib to give adequate edge distance for the rivet holes. After that, all holes were match drilled – making sure to either back up the work or that the part was adequately supported by clamps. I could not find any direction from Van’s to drill the area under the horn – but I didn’t see why it shouldn’t be done now – so I went ahead and drilled them now too.
Fig 5-13 Fig 5-14
May 19, 2005 – Prepped Parts (2.5 hours today – 135 total)
Disassembled all the parts and
started the final prep work. This means
I deburred, smoothed edges & dimpled appropriate edges. I spent a little extra time smoothing out
the horn angle and brace. When
dimpling, I used the dimple set in the Avery rivet squeezer where ever I had
enough room. In the few areas that were
really tight I used the Avery Vise grip dimpler. This worked very well.
Next came the cleaning – all
parts were washed with acetone and wiped down with clean rags. We are now ready for priming.
Fig 5-15
May 20, 2005 – Primed parts (.75 hours today – 135.75 total)
Wiped the parts down one more
time with acetone (wearing gloves) – and gave them a shot of primer. You may notice the blue painter’s tape on
the outside of the counterweight skin.
This is to make sure I don’t get any overspray on the outside (I’m still
under the delusion that I am trying to build a polished aluminum plane).
Fig 5-16 Fig 5-17
May 21, 2005 – Assembled Rudder skeleton (4 hours today – 139.75 total)
Ok – no pictures today, but I
started to assemble the Rudder skeleton following Van’s written directions. Since everything had been match-drilled it
went together as planned. All rivets
were hand squeezed with Avery’s riveter.
A little care here made every joint come out great! Now, all that’s left is to finish the
trailing edge and skinning. However, I’m
going to wait until Dad comes out in early June so he can help me with this.
Jun 5, 2005 – Skinned Rudder / Started Trailing Edge (5 hours today – 144.75
total) -
Dad came down to teach a forum
at Golden West this weekend and stayed a few days longer to help. I took a couple of days off from my real job
and we focused on finishing as much as we could on the empennage. After working on the VS, we turned our
attention to the rudder.
The first activity was to
complete the counterweight section. The
counterweight skin was “locally beveled” using a 1” belt sander and then
touched up with a scotchbrite wheel per the instructions on the plans (note
that Van’s directions did not refer to this).
The skin was then riveted to the skeleton as directed - which means not
all the way around. The rudder
counterweight was drilled out to accept the AN screws and then counterbored
using a microstop attachment in a drill press on a very slow speed. A slight interference seen between the
weight and the rivet heads was eliminated by touching up the weight on the scotchbrite
wheel.
One rudder side skin was clecoed
in place and the joint between the counterbalance skin & rudder skin was
riveted. This was delicate because it
had to be bucked from inside. The
remaining rivets on both skins were uneventful.
Fig 5-18
The Horn was riveted with blind
rivets and then the lower attachment strips were joined using a hand squeezer.
Fig 5-19
The next step was to counterbore
the wedge. We adjusted the microstop to
the correct depth - starting shallow and working deeper a small amount at a
time until it was right. Don’t go too
deep because it will create a larger diameter hole when you countersink the
opposite side.
All countersinking was done on
the edge of a scrap sheet of MDF. This
allowed the microstop to sit flat against the wedge with the lower part of the
guard extending beyond the edge of the board.
We started by drilling a #40 hole for the centering portion of the
counterbore bit. We took our time and
as a result - all counterbores came out perfect! The remaining steps were to clean the wedge with acetone and
prime.
Next came the most critical
part… and that was to prepare the surface for the trailing wedge which needs to
be ABSOLUTELY flat and straight. This
was accomplished by clamping an angle iron to the bottom of a smooth sheet of
MDF and then clamping the MDF to the work bench (with an overhang for the angle
iron to clear the bench). The final
shimming was done using small pieces of aluminum sheet between the bench and
MDF. Flatness was confirmed with the
edge of a 4’ level.
The rudder assembly was set on
the flat board and the trailing edge was drilled and clecoed to the table. This located the position of the holes for
the clecos. The clecos were taken out
and the wedge was removed. Next a very
thin coat of Pro-Seal was applied to the internal surface of both skins where
the wedge sits. The parts were
reassembled and clecoed to the table (ensuring a straight edge was
maintained). All excess Pro-Seal was
squeezed out, and the part was allowed to set overnight.
Fig 5-20
Jun 6, 2005 - Completed Rudder (3 hours today – 147.75 total)
This morning – bright &
early I removed the clecos from the trailing edge of the rudder and cleaned up
the excess Pro-Seal with acetone…… and
it came out great!! The edge is tight
and straight!!
Fig 5-21
After taking out the clecos on
the trailing edge, I noticed some
Pro-Seal in the holes, but this was easily removed with the hand deburring tool
and then running a drill bit through each hole. It was necessary to wipe the drill bit with a rag every couple of
holes. The used clecos were put into a
small container of acetone, allowed to sit for awhile and then wiped off. The
got all the Pro-Seal out of them.
The rudder was lifted off the
MDF sheet and clecos were put into every other hole.
Riveting the trailing edge went
much better than anticipated. I decided
to put the factory head on the pilot side just for matter of appearance. Then, using a pneumatic squeezer and
starting at the center rivet, I squeezing it about ½ way with the anvil
perpendicular to the rivet (not the skin!).
I squeezed rivets alternating between each side moving from the center
to the ends. Once done, I removed the
remaining clecos and repeated the process.
With all rivets squeezed ~ ½ way, I set up the back rivet jig. Then, I back riveted the entire set of
rivets with the factory head on the plate – and the shop head perpendicular to
the skin (being careful not to overdo it).
The results were excellent – it
is smooth and tight. There is a very
slight bow (<1/16”) over the entire length.
I plan
to do the same thing for my elevators trailing edges. It is a simple procedure that gives great results!
Fig 5-22