is a pic of the rudder skins. The rudder skin is much thinner than
the skins of the horizontal and vertical stabilizer....but the biggest
difference is that it comes two pieces instead of one. If you can
image taking both ends and lifting up towards the ceiling that is
how this thing will go together.
of ribs the rudder has what are called 'stiffeners' to make it rigid.
The stiffeners are made from aluminum angle. The angle has notches
in it to tell you how to cut the thing. Note that I have drawn a line
that I will use to guide my cut. There is a taper because the rear
most part of the stiffener sits where the two halves of the rudder
come together so this taper allows the skins to meet without interference.
spent some time carefully trimming the rudder stiffeners to the proper
size and taper angle. I began by using my aviation snips to remove
the bulk then finished the job in my bench grinder with scotchbrite
is a close up of the inside of the rudder trailing edge with the stiffeners
cleco'd into place. Notice that the end of the taper is quite close
to the trailing edge of the rudder. Care needs to be taken when back-riveting
the last rivet here...you need to set the rivet enough so that it
won't hit the other skin when you do the final assembly.
are all 16 stiffeners on the workbench just ready to be primed.
hung all 16 stiffeners in my booth and primed them all at one time.
I switched to a new primer called Dupont Variprime. This stuff rocks.
It is self etching and dries very fast. All you do is clean the metal
with a degreaser then shoot the primer on. No need to scrub with scotchbrite!
It etches as it cures and it is fully dry in a few hours.
decided to build a dimple table. I got this idea from some builders
on the net and so far it is working great. Basically you just get
a flat piece of plywood, attach four legs then put adjustable levels
under each leg. In this way you can raise and lower the table height
easily and can make it flush with your C-frame tool.
another shot to show you my dimple table setup.
I am dimpling the right hand rudder skin. The rudder skin is quite
thin and it doesn't take as much force to dimple it as compared with
the HS or VS.
I have finished dimpling the left hand rudder skin.
are the rudder skins primed and ready to be back riveted to the stiffeners.
Here are the skins with the stiffeners riveted into place. Back riveting
is so much easier than "regular" riveting!
up of a typical rudder stiffener riveted into place. Notice the taper
on the trailing end to allow for the other skin to meet the edge without
is the forward spare and lower rib of the rudder skeleton. The aluminum
object at the lower end of the assembly is called the rudder horn.
Later on the control cables will attach here to pull the rudder left
is a small shim you need to construct to attach the horn to the lower
is a close up profile view of how the horn attaches to the forward
spar and the lower rib. Notice the shim that fits between the horn
and the forward spar. I thought this particular assembly was a little
hard to see in the drawing...this picture says it all.
I have fluted the top rib and the counterweight rib.
the top rib and the counterweight rib are cleco'd to the spar along
with the counterweight skin. Later a counterweight will be permanently
attached inside this assembly to help balance the rudder "feel".
I have started assembling the rudder skin and spar in preparation
to match drill the holes to final size.
the rudder is cleco'd together and match drilled to final size.
Here is the trailing edge of the rudder. Notice the wedge in place
to give the edge some support. This taper is the reason that the stiffeners
needed to be tapered in the beginning.
the horn will take the load of pushing on the rudder, it has a brace,
called cleverly enough, the horn brace. It basically attaches to the
rudder horn on one side and to the underside of the lower rib.
is another pic of the horn brace from the underside of the assembly.
I have fabricated and attached two small strips of skin to each side
of the rudder. You use the cleco clamps to hold the strips in place
and match drill with the skin holes. Later these pieces will be riveted
in place and will be used to attached the rudder bottom (fiberglass
structure, deburred and dimpled all holes except for the trailing
edge AEX wedge.
AEX wedge that fits in the trailing edge (hey, that rhymes!) is tricky
to countersink. The problem is that it is very thin, so as you countersink
the other side of the hole your bit can begin to chatter and screw
up your hole. What I did is take a scrap piece of aluminum and drill
a hole in it as shown to the left. I clamped this piece under the
hole in the wedge to act as a guide for the bit.
is what the final result looks like. The guide hole in the scrap helps
to keep the countersink cutter from chattering.
this is what the wedge looks like after countersinking. Today I also
dimpled the rudder skins.
the lower and upper ribs of the rudder. The last 3 holes in each of
these ribs on the trailing end are VERY difficult to dimple with a
standard yoke (actually, pretty impossible as the photo shows). I
had to break down and buy the vice grip dimple tool from avery tools
which worked GREAT for these hard to reach holes.
I am match drilling the counterweight to the counterweight rib.
you countersink the counterweight (see photo), and dimple the holes
in the counterweight rib. This will allow the two screws to sit flush
with the rib when you get the thing put together.
are all of the internal pieces of the rudder laid out on the table
here is everything after priming.
riveting the forward spar of the rudder today. Here is a wide angle
shot of the spar with the top and middle double plate and platenuts
riveted on. Later on the rod end bearings will screw into the platenuts
and allow the rudder to swing freely from the Vertical Stabilizer.
up of the top doubler plate.
up of the middle doubler plate.
I riveted on the lower rib assembly with the rudder horn and shim.
view of lower rib assy.
another view of the lower rib assy. Note the lower platenut for the
lowermost rod end bearing.
I have riveted on the counterweight rib to the spar.
I riveted on the counterweight skin to rib *but not the spar!*. Later
on the main rudder skin will attach to the spar as well. These rivets
were pretty hard to reach because its pretty cramped in there.
I have installed the counterweight. Notice that the screws sit flush
with the bottom of the rib.
shot of the counterweight.
I have one of the skins on and have begun to rivet the counterweight
skin and the rudder main skin together.
the counterweight skin is riveted to the spar and rudder skin.
propped up the skin so I could reach inside to set the rivets for
the horn brace.
I riveted all of the skin rivets with the exception of the trailing
edge. All of these rivets could be reached by my squeezer and no-hole
yoke except for a few on the spar that I had to buck.
the trailing edge I deviated from the plans and the results were great.
First I drilled two sides of a straight piece of angle. One side was
match drilled to every hole in the trailing edge and the other face
was drilled to every other hole.
I bought some metal epoxy from auto zone with a 30min working time,
and carefully applied it to the AEX wedge. Next I clecoe'd the assy
in every hole and let it cure for 1 day.
rivet the TE I put a rivet in every other hole and tapped them in
I flipped the thing over and cleco'd the assy in every other hole
on my trusty angle. In this way the thing is abolutely straight as
back riveted every other rivet all the way down, then un-cleco'd the
assy. I put the remaining rivets in and back riveted them all the
way down. I did not use a flush set at all (deviation from plans).
My TE is very straight and rigid. Here is a shot of what my double-flush
rivets look like.
roll the leading edge of the rudder I duct-tapped a piece of PVC to
curling the edges using the PVC and vice grips for leverage the leading
edge looks like this.
it is all cleco'd together ready to be riveted!
Rudder is Complete! Total time = 43 hours. Man this thing is constructed
completely different from the VS and HS. Quite tedious...the elevators
will be very similar in construction.