The rudder
is a sandwich of two skins. They are very thin at .020 and are about
the only major piece that is pre-punched. Extreme care has to be taken
in handling these skins. It is VERY easy to crimp these skins
accidentally and ruin them.
Rudder Stiffeners
The first
step in rudder construction is to gather up the stiffeners made of .025
formed angle. You have to mark about 1/4 inch on either side of the
outermost holes on the inside of the rudder skins, and cut each piece
of angle to match that size. After I used my band saw to cut the
stiffeners down to size, I used my break to bevel one end and
taper the other. I measured and cut the first stiffener, then
subsequently used that piece for a stencil to mark and cut the others.
As part of
this process, I numbered and marked arrows on the stiffeners and
the skins to make sure I got the orientation of
the stiffener/angles correct. These pieces end up being nested
together inside the closed rudder "sandwich" and the stiffeners on one
skin have to form a sort of a box with the stiffener on the other skin.
So they have to be riveted in opposite orientation.
The bold line on the right is where the spar
sits. The arrow at the bottom shows where the "open" side of the
stiffeners will sit. I marked 1/4 inch on either side of the outer
holes and cut all the pieces to length. The layout shows the
approximate position of the stiffeners. I don't know what the 38 is at
the bottom. Something the Czechs wrote on there.
The stiffeners have to be marked for drilling. They
are to be drilled 5/16 from the back of the flange, not the edge. I
used a green Ultra Fine Sharpie for this. Since you have to back-drill
the stiffeners using the pre-punched skin as a guide, you also have to
mark the position of the first hole on the stiffener. You could measure
that, but I eyeballed it, having positioned the stiffeners and choosing
the best fit of the stiffeners between the end holes. I used a
red ultra fine Sharpie
to cross mark the location of the end hole. That way, I can see
the green line through the holes on the skin, and I also know the end
hole drill point has a red hash mark on it. It's very easy to see
the red and green through the tiny holes.
The way I drilled the holes in the
stiffener/angles was pretty much per plans. I used a pair of clamped
1x2's to hold the stiffeners. I stuck the tapered side of the stiffener
down in the crack between the boards, and laid the skin over the top.
I then positioned the red cross mark under the end hole and drilled it
through into the board @ #40. I clekoed that hole and then made sure
the green line was visible int he holes and drilled the other end and
clekoed it. Then I drilled all the holes in between. There are 7
stiffeners on each skin. And you have to be very careful to orient the
skins and the stiffeners properly. The red cross mark always goes on
the spar end, forward.
Notice in the pic above how the taper is to the
doubler (aft) side of the skin. Also notice that the "open" side of the
stiffener faces the same direction as the arrow. Just for good measure,
I put numbers and arrows on the stiffeners and near the line of
holes they will be attached to. It's VERY easy to get confused.
Another note: I used several 1x2's to lay under
and support each skin as I was drilling them. They are very flimsy in
their natural state, and having the boards keep everything at the same
level is essential.
You can see the upper skin in the pic above has just
the vellum removed from around the holes. I did this with a pencil
soldering iron. This stuff is really thin and easy to remove.
One the inside of the skins, I could care less what
they look like, so it was easiest just to go ahead and remove ALL the
vellum (plastic protective film).
Now I am ready to debur and dimple these parts prior
to riveting! At this point I was working on all 6 empennage control
surface skins in a big batch. The processes and tools are the same, so
it's fewer steps to get these parts all "stiffened" together.
Deburring the Rudder skin was easy. Dimpling was
scary at first, but turned out to be a simple affair. I did all the
empennage control surface skins and stiffeners in one big lot. That did
save me a little time. And once you establish a good rhythm, you can
make pretty good time on one of these repetitive processed. It was
FUN!
I used 3-3.5 rivets and a 3x gun to attach the
stiffeners to the Rudder skin. That process was also fun. I used that
3M/Scotch tape to hold an entire row of rivets in place, flipped the
piece over (very carefully!) and oriented the stiffener over the
rivets. No clekos this time. I found that when I pressed the stiffener
down over the rivets that the pieces sat very nicely in position.
Theoretically, I should have started in the middle of the stiffeners, I
supposed, but I didn't. I went from end to end. Carefully making sure I
didn't go off the end of the back plate. Another good thing to do is
bop the gun down on the rivet before hitting the trigger. You get that
good metallic sound and a solid stop, and you know you can have at it!
Rudder Skeleton
Now it's time to go back and make the rudder skeleton.
I hadn't enough coffee in my system at 7 am when I started looking at
this part of the plans, but I finally figured it out... I think!
I gathered up the parts and laid them out. I set the
exploded view in front of me, and then read the first few pages of the
rudder skeleton part of the plans. I was a little confused about using
a shim to square the rudder horn. Then I figured out that the formed
bottom rib of the rudder fits between the rudder horn and the
spar. A shim is necessary on the back of the rudder horn
below the rib to complete the "sandwich" of parts. This keeps all the
thicknesses the same and ensures that everything is flat. "Square"?
OK... I guess...
Plans call for a 3/8 bolt to hold parts together. I
decided to just use the control rod ends supplied with the kit. You
simply line all the parts of the sandwich together and tighten the
"bolt". At the bottom of the rudder, I used a flat plate to make sure
everything was "square". Lining these parts up is a snap once you get
the idea. The pics in the plans are very helpful.
I didn't tighten the control rod end that much. I
decided to clamp everything, using the rod end to make sure the big
hole was centered well enough. After clamping, I drilled everything,
including the .032 shim I made from floor panel scrap, using a #40
bit and clekoed as I went.
The bottom of the rudder has a doubler that goes on
the outside, opposite the rudder horn/rib/shim sandwich. The
doublers at the middle and top of the rib go in the inside, which is to
say the aft side, of the spar. I used my rod end and my fingers to line
everything up and hold the parts in position. I then drilled
#40 through all of the pre-punched holes and clekoed as I went.
This was easy peasy.
I drilled the two flat doublers to the spar and
drilled them @ #40. Then clekoed and drilled up to #30. Deburred and
then riveted using 4-5 (and longer) universal (regular?) rivets. This
was pretty fun. I had to turn the pressure up on my 4x gun to 40 pounds
to get a good fast buck on these rivets.
The big job was the assembly at the south end of the
rudder. I first drilled all the parts (without the R-010 rudder horn
bracket in place) up to #30 and deburred them. I riveted the top row of
rivets on the doubler to get it in place. Then I riveted the k1000-6
nutplate, which hold the 3/8 inch rod end. I then used 4-9 rivets on
the
thickest sandwich of parts.
Having riveted the major parts of the rudder spar, I
moved on to the counterweight/top assembly. Basically, you trim the
small "rib" to 5/8 inch and rivet it to the big top rib back to back.
The smaller part has a joggle in it that I will drill to the R-002 spar
(already assembled) later on. Waiting for verification of what angle I am
supposed to use to help support this counterweight/rib assembly.
Just for funsies, I put the R-010 under the spar and
lined up the pre-drilled holes on the rudder horn. I went ahead and
confirmed that the Spar/counterweight assembly measures to the nominal
47.5 inches. I kind of set all the skeleton parts together on the bench
to better understand the creation of this assembly. It really makes
beautiful sense once the light comes on!
The counterweight skin was the next task. I wasn't
sure if I had the correct piece, but guessed at the U-shaped piece
bundled with the elevator counterweight skins. Guess they forgot to
mark this one.
The c/w skin is bent pretty close to shape, but I had
to coax the bends a bit to form around the corners at the leading edge.
There was quite a gap at the corners, and of course the skin needed to
be more or less flush with the r31 assy. It only took about 10 minutes
to bend/re-bend the piece until it sat rather passively on the rudder.
As the plans say, you can't use too many clamps on
this part. I used all 10 of my little cleko clamps and a couple longer
cleko clamps. I measured for the flange centers, marked the skin
appropriately, measured for the rivet holes and drilled everything @
#40, clekoing each hole as I went along.
I went ahead and clekoed the rudder skeleton parts
together. It's a nice piece. I'm starting to understand how this stuff
all works, and I'm amazed at the design that these parts have
undergone. Very nice.
I was on a roll this night, so I grabbed a rudder skin
and the doubler that goes at the trailing edge. I lined the bottom edge
with the edge of the skins and carefully clamped the very outer edge.
I lined up the top end of the parts and clamped them. I used at least
6 clamps to hold these parts tightly and carefully together. I ended up
with about 1/32 of the doubler exposed. I used a #40 and drilled
through the doubler using the pre-punched holes in the skin, starting
in
the middle and clekoing every third hole. Then I swapped skins and
back-drilled through the pre-punched holes using the doubler as a
guide.
This process was easy enough to be "cathartic" or "therapeutic"!
Rudder Jig
(Fixture)
Now it's time to construct a wooden fixture to
assemble the skin and skeleton of the rudder.
I searched and searched and searched for the right
pieces of wood to make the fixtures. I couldn't find anything
dimensionally stable enough for the exacting dimensions call for in the
plans. Well, OK, I lied. I used scrap particle board shelves I took out
of my office about 10 years ago. This is the GOOD stuff. Probably about
30 - 40 years old. Dense. FREE! I thought it might fall apart,
but amazingly, it is no where near the crap they sell today.
I laid out the dimensions on the boards and drilled
holes in the lower corners. Used a hand saw to cut the long center cuts
and planed on using a jig saw to cut across the bottom. No blades in
the jig... all broken... duh. So I used a coping saw instead. And a
rasp and file.
The important thing to remember here is that the
location of the kerf at the bottom of the "slot" and the width at the
top opening of the "slot" are the important dimensions. Then, as long
as the boards of the fixture are square and plumb, you got no problems.
I mounted the boards on my handy beam that I used
earlier in the construction of the HS and VF. I put the boards
PERFECTLY (hah!) along one edge and marked on the beam 41 inches
on center. I used a speed square to make sure the boards stayed square
when screwing down the boards with shelf angle brackets. I then
verified that I had 41 inches along both sides of the fixture between
the boards.
On nice thing about using this shelving is that it is
so square on the ends that the boards stand straight up on
their ends without support. It makes locating the angle brackets VERY
easy.
Rudder Skins
At this point I deviated from the plans a bit. I
already had the skins clekoed with the trailing edge doubler in between.
Rather than take this all apart and clamp the skins to
the skeleton, I just put the skins int he fixture, and then dropped in
the skeleton. It WANTS to go right to place! SWEET!
Another deviation from the plans: Don't bother
finding the centerline of the lower rib. The spar is 5/8 wide and the
rib is 3/4. The pre-punched holes are centered on 5/8 on the skins, so
drawing the lines on the rib was a waste. Instead, I am just going to
clamp the rib flush along the bottom edge of the skin. Easy peasy!
I double checked the dimensions of the fixture and I
used a straight edge to check the trailing edge for
straightness. I used a #40 bit and drilled the skins to the
skeleton after lining up the flange centers with the pre-punched skin
holes. I clekoed every 2nd or 3rd hole as I went along.
I removed the rudder assembly from the fixture and set
it on my work table, still all clekoed together. I marked the extra
rivet line on the counterbalance weight, mimicking the pre-punched
holes
directly above.
The rudder assembly is now ready to D&D and then
rivet together. COOL!
I dimpled and deburred the skins and skeleton. I did
not use the C-frame at all on the skeleton, but of course did use it on
the skins. This was a fun little process. I had to hand squeeze a few
places and countersink others.
Before final assembly I made up some replacements
"skirts" to replace the R-022 doublers. These pieces are used to attach
the fiberglass fairing. Unfortunately, they do not close the ugly hole
around the rudder horn. I chose to make a set of "extended" r-22's that
completely close in this area. It will not be flush with the
fiberglass, but will only block the hole.
I scotchbrited the inside of the skins and all the
parts. I primed them with self etching primer prior to assembly.
Before clekoing the entire skin/skeleton it is
necessary to rivet 8 holes on each side of the counterbalance skin on
the top of the rudder. You cannot get access to this area after the
skins are closed onto the skeleton, so you have to rivet this area
before all others. I back-riveted these holes on my bench.
Before re-clekoing the parts, you have to re-bend the
corners of the counterbalance. Then cleko these REAL tight. I riveted
this area first, from the leading edge back. Then I put the assembly in
the wood fixture and riveted along the spar. Then back on the bench, I
inserted the R22 skirts and riveted along that side.
The final closure of the skin is at the trailing edge
doubler. I clekoed every other hole and placed universal rivets (3-4)
in every hole. I then checked alignment of the trailing edge with my 4
foot metal ruler. I had to coax the edge a bit, then got out the
pneumatic squeezer and put in two cup sets for the #3 rivets. The
double cup sets makes for a nice round edge on the shop head of these
rivets.
I tried to completely round the rivet heads and ran
into two problems. One, the smaller the shop head is squeezed, the more
it wants to deform the skin around the rivet. It kinda tries to bunch
out the metal, roll it away from the rivet, and opening the skin away
from the doubler. Not good. Second, the cup set would dig into the
metal and make an ugly smiley. So I abandoned this process and was
content with normal sized shop heads with nice rounded edges that won't
catch clothing, sponges or wash cloths.
Roll The Rudder Leading
Edge
After closing the trailing edge of the rudder, the
next step is to round the spar side so it can swing around the aft end
of the VF. That's the next chore. Time to take a break and regroup!
The rudder and VF have been sitting around for about a
month, waiting for construction of their sibling control surfaces.
I have rough cut the top part of the skin to allow for the
counterbalance to swing though and have the VF primed. As far as metal
work goes, all I needed to do on the rudder was roll the leading
edges of the skin to curve at the hinges.
Rolling the skins is pretty simple, really. I used a
3/4 copper pipe and drilled it to the pre-punched holes in the skins
with a #40. I clekoed every hole in one skin segment at a time
and used vice grips to twist down the skins. That starts the roll.
It's surprising how much work it is to get the roll to stay put.
Once the skins are preliminarily rolled, I went back
and coaxed the skins to nearly closed, i.e. the holes in the flanged
skin are visible directly under the holes in the straight skin.
Well, I couldn't quite get them to overlap nicely like I did the two
elevators, but I got them pretty close.
When getting ready to rivet the rolls closed, I
decided to cleko every other hole. Once clekoed, I drilled every other
hole up to #30. I got out the 117 AVEX blind rivets supplied with the
kit, and my Stanley pop rivet gun, and started popping them in from the
centers out. This all went pretty quick. Second phase, pull the rivets,
drill the remaining holes to #30 and pop those puppies. Easy.
Rudder End Caps
I dug out the fiberglass tips and started doing some
preliminary shaping just to get an idea of what's ahead. Boy, am I
depressed now!
I started whittling on the rudder cap with a big hand
file and my dremel. I really don't like the way this thing sits in
here. It was hard to determine whether to set the glass inside the
rudder, or mate it with doubler/flanges edge to edge like the plans. I
decided to go with the plans, but modified to my own technique. I
intend to screw on all the fiberglass parts, so I'll make
doubler/flanges to set the top cap in place.
At the same time, I'm going back and forth from the
top to the bottom caps. Trimming the bottom cap was tricky around the
rudder horn, but at least the metal doublers are already in place. I
just have to line up the finish edge and that part is ready to screw
down. I'll need to determine what to do with the tail light pretty
soon, though.
I ended up trimming down the top cap on the rudder
about an inch shorter than the plans. I just didn't like how tall it
was. It didn't look right. So my cap is under 4 inches at the leading
edge and the trailing edge is about 3 inches.
The only problem with this is that now the VF cap,
which was cut nearly to the exact size (big DUH) is going to be too
short fore and aft. I had to shorten it height-wise about 1 1/4 inch to
match it to the rudder. Since that piece has a curve off of the leading
edge to the top at an angle, as you shorten it, it also becomes
narrower. Now I'm going to have to glass about 1 inch onto the back end
of this cap to match it to the rudder cap.
Scrap from my HS skins worked nicely for flanges on
the rudder cap. These pieces are a little over 18 inches. Inside the
counterbalance, the flanges of the skeleton are about 5/8 down from the
top edge of the skin, so the flanges on my rudder cap have to be this
long or a little less.
I measured and drew a 5/8 line to mark the edge
of the fiberglass. I then drew a line at 3/8 above that
line and drilled #30 holes in the doubler/flange every 3 inches
along this , starting just about 1/4 inch front the LE, planning
to set the metal just behind the leading edge curve of the
fiberglass. I placed the 5/8 line along the edge of the fiberglass and
drilled the #30 holes through the glass by just sighting the holes in
the doubler. I clekoed the end holes.
I countersunk the #30 holes in the fiberglass and
rounded up some #3-4 flush SOFT rivets. I squeezed these
beginning in the middle holes and working my way out to the ends. I
used a flat/thin nosed yoke to get into the deep taper at the TE.
When I gather up some courage, I'll mark a 3/8 inch
line on the CB skins and mark holes every 3 inches, probably very
symmetrical to the rivets in the cap. I plan on using the nifty little
#4 nutplates and screw I got from Cleveland Tool. But I'm going to do
some more finishing on these parts before I jump ahead to attaching
them to the rudder.
Now I have a VF cap that has a short side at the
trailing edge. I went to the crap pile behind my 3in1 break and got an
appropriate piece of metal. This one just happened to still have the
vellum on it. Good. Hope epoxy doesn't stick to it. Even if it does, at
least I'll be able to separate the metal.
I took my trusty glue gun and sealed down the strip of
metal on the aft edge of my VF cap. I opened my virgin can of West
System epoxy and grabbed a cup, brush, and aluminum foil. The metal
went onto the outside of the cap hoping that I would get a relatively
smooth surface.
I cut two pieces of Bi cloth for the "extension". One
was exactly the width, and one was about double that width. Set the
wide piece down and filled it with epoxy. Then I set the narrow piece
on top of that and wet it, "squeegy" off the excess as I went. I wet
the piece (already roughened) where the extension was to go. I cut the
foil and took the whole (minor) mess and reversed it. That way, I could
mash, er..., place the glass precisely where it needed to go in the
INSIDE of the VF cap.
Four tongue blades (Ahhhh sticks) made good retainers
for the edges of the foil, which I folded over the edge of the cap. I
used some nifty spring clamps to hold them all down and hopefully keep
the glass from sliding too much.
I don't have much experience with this stuff, so I
hope it works. After it hardens, I plan to put two or three layers on
the outside of the extension for strength and adhesion. Then I'll grind
the inside as necessary. I hope the piece doesn't end up too heavy.
There was already about a 1/2 inch pool of hardened epoxy inside the
curve of the piece, so it's already hefty. If I wasn't so lazy, I would
have dremeled that out. We'll see what happens. I may be calling
Brian to buy new parts.
Both extensions worked well, and I'll need to
reinforce them, as well as extend the other side of the rudder tail
cone. That West System is pretty nice! Virtually no smell. But
the slow set is TOO slow for my taste with little projects like this.
So I ordered a quart of fast catalyst. And on the tail cone extension I
used 1:1.5 (pumps) resin to catalyst, and it seemed to turn out
fine.
Now I need to reinforce them and get them finished
out. I need to get that rudder and VF off my table so I can do the same
thing on the HS and elevator tips. Still have a ways to go, though.
My lead counterweights came from Van's. The rudder
requires 830 grams. The E-614-020 weights are precisely 830 grams.
Without the hardware. One weight in the C/B of the Rudder should be
sufficient.
I ordered 6 of the weights. 5 of them go in the
elevators. You're supposed to split one in two and stack a half
weight on top of the other pair. The half weight goes outboard of
course, under the fiberglass cap. I'll just use hardware bolts and
fender washers to retain all these weights.
Hang the Rudder
The fuselage came down off my table and put the cherry picker away. I
had to scoot the whole project forward about 2 feet just to have a
chance to start hanging the feathers. As it is, my work table is in the
way. I'm going to have to figure something out there, or just climb
around a lot more....
I gathered up the rudder and wiggled the rod ends into the VF brackets.
I just dropped some spar AN3 bolts through and viola! Looks pretty good
with the rudder in place I must say.
The manual calls for "30 degrees R/L" Now I'm stupid, and I don't
know if that means 15 each way or 30 each way. I looked in chapter one
and it says the same thing. Since the other control surfaces move 25+
degrees for the most part, I'll ASSume that I am supposed to be able to
crank that rudder 30 each way.
You have to trim a bunch of skin off the emp to let the rudder swing on
the hinges. I went through about 4 dremel discs figuring out the
first side, then measured it and went to town on the other side.
Sorry, but my new camera SUCKS. I need to go back to the old Mavica. It
takes pretty pictures and stays in focus with less flash and better
color.... but I digress.
The cut mark shown above is about 7/8 in, then 2 inches up, then I just
counted rivets and made the mark. It was a pretty easy to cut, but both
sides are going to take some trimming.
At this point I don't know whether I should tweak the rod ends and pull
the rudder tighter to the VS skins or not. I have 30+ degrees of travel
each direction, but if I reposition the pivot point of the rudder, I'm
probably going to need to do a lot more massaging of the emp AND VF
skins to make it all "tight and right".
I think there is too much gap between the rudder and the VF skins. By
taking the rudder off and screwing in the rod ends, I could reduce the
gap some. However, you can still only go so far because you will
contact the skin. I guess the trick there is to reposition the rudder
toward the VF and try to reduce the gap in between as much as possible.
That's about 3/8 inch gap where the sharpie is. Sure wish I could
reduce that down. Not only for cosmetics, but for performance.
The skins on my VF aren't perfectly even on each side at the trailing
edge, so some trimming is going to be necessary just to even up the
sides. I sure hope I can reduce that ugly gap.
The 3 bearing in the rudder spar are adjustable. Initially, I had them
set per plans. But my VF skins were trimmed short before I riveted them
down. Consequently there is more gap than I would like to see between
the rudder and the VF. I removed the rudder and screwed the bearings
inward. 8 each half turns is all I could do. The big bearing at the
bottom of the rudder ran out of threads way before the smaller two
bearings in the middle and top. Well, I took what I could get. It moved
the rudder enough that I had to take my dremel and cut out 1/8 or so at
the counterweight area on top of the VF. So I didn't get very much
closure of the gap. But I wasn't going to get much more than that
because when the rudder goes full swing, it would contact the VF skin
if it stuck off the back of the VF spar too far. I wish I would have
left 1/4 inch more skin on the VF!
The bearings were binding a bit when the rudder swings. As I had left
it a long time ago, I could barely get an AN3 bolt in the VF bracket
holes. I put 2 bolts in the hung rudder bearings and observed the 3rd
bracket/bearing holes with a dental mirror and selected the hole to file
that was least offensive. What I found out was that I could twist
one bearing 1/2 turn to take out some of the binding. The middle hole
seemed the most offensive, so I took a long time filing and rehanging
the rudder. I didn't want to create too much slop in the holes. After
about 3 hours of work trying to get the rudder in closer and remove the
slight binding of the rudder movement, I'm finally happy with the
results. Now I can easily get the AN3 bolts into the holes to hang the
rudder, and the rudder is quite free to swing. Evidently I twisted
something, either constructing the rudder or constructing/mounting the
VF. Doesn't matter now, it works fine.
Rudder Stops
The rudder stops are just made with 3/4 angle. I cut 2 pieces each 3
inches long. Per the plans, I drilled out two rivets on the emp
longerons in line with the rudder arm. I drilled the stop with #40 to
match the emp factory rivet holes, then match drilled to #30 in place.
Over at my bench grinder, I rough cut the angles to clear the
rudder skin and trimmed the angle to get a square face for the stop.
The rough angle rudder stop looks like this:
The stop isn't particularly aerodynamic, so next thing is to shape it up to reduce the weight and drag.
Now if I could do something about that big assed rudder horn out there in the breeze.
The stop is supposed to be fixed to the emp with #8 hardware. I read in
passing about someone TAPPING their stops for a #8 screw. I decided to
tap the stop and the fuselage for short #8 stainless screws. I could
get a nutplate on the rear one easy enough, but I'm just tapping them.
I think I'll put some blue thread locker on the stainless screws and
call it finished.
After the elevators were hung, I attached the lead counterweights to
the elevators and the top of the rudder. I used the Vans weights that I
purchased a long time ago. the CW area of the rudder only takes one
weight and two AN3 bolts. You could mount the weight to the underside
of the rudder, but why chance it. Plus it's easier to check and service
on the top, under the fiberglass cap. Unlike the elevators, the
thinner end between the bolt holes of the lead block goes forward.
The Van's kit was pricey at $6 each block plus shipping LEAD, but it
was worth the hassle reduction. I attached the CW block with the
rudder off the ship. Time to pin it back in, and run the rudder cables
to the rudder horn. Maybe attach the tailwheel and steering link after
that.
