Fuselage Skins
I made a few mistakes when dealing with the
fuselage skins of my RV-8. Here are some thoughts and
suggestions that may save you some time and hassle. These
ideas are applicable for any aluminum skinned airplane.
Drilling
the skins
Move slowly through the
process of
fitting and drilling the
skins. Follow the
directions exactly; don’t
skip ahead because you have that drill bit in the drill. If the directions say to
swap bits from a #40
to a #30 to drill one hole, then go back to a #40 to drill more, do it. Since there is no jig
holding everything
aligned, follow the instructions to ensure a true fuselage when you are
finished.
Don’t skimp on the clecos. Use them in every hole you
can. The more you
use the more sturdy and steady
your fuselage
is. This results
again in a truer finished
product. I had a
large coffee can with
silver and one with copper clecos that I drug around with me. This gave me a steady
supply when I needed
them, and also a convenient place to put the clecos as I removed them
for
drilling.
Make sure the holes align
as you
initially cleco things
together. Stick a
small punch into the
hole and wiggle it around a little to help pull the parts together and
line up
the holes if needed. It
is possible to
completely cleco a part on with it not lined up properly. If the interior parts
don’t line up with the
holes in the fuselage skins, check your fluting and straightening the
parts to
realign
the holes. You
don’t want the parts
under constant stress, trying to pull themselves apart, only being held
together by the rivets. They
should sit
naturally together and the rivets just hold them in place.
Mark everything not just
for
left/right, but forward/aft or
up/down as required. A
lot of the parts
look like they are reversible. It
is
important that they go back the same way that you drilled them to keep
everything aligned.
Because everything is
match drilled
to start with, I don’t
think you will have an issue with edge distance anywhere. But if you have drilled
the hole, and find
you don’t have the required edge distance, you can still fix it. See Edge
Distance.
Dimpling and
Countersinking
A hand held pneumatic
squeezer
made quick work of dimpling almost everything except the holes in the
middle of
the fuselage skins where it wouldn’t reach.
For
those I used the
table mounted
dimpling tool. Metal
that is .04” or thicker doesn’t dimple
well, will need to be countersink the holes in them.
If countersinking
is new,
check out my thoughts here.
Supports
I used a crate with
some foam padding
under the F-804 center
rib section when doing all the interior work on my fuselage. I then used a small
sawhorse with another pad
under the tail. This
set the fuselage at
the right height to allow me to comfortably bend over the top longeron
and
reach the interior floor.
Riveting
the Skins
Before you rivet, make
sure all the
flanges of the ribs
match up nicely with the skin. You
don’t
want them angled, or with any space.
If
they are not aligned, the thinner skin will move to meet the thicker
rib
material, and result in a dimple in the skin when viewed from the
outside. Have you
ever seen a skin that has a wave
rolling over the row of rivets, where it is higher between rivets, and
lower at
each rivet? I found
this most prevalent
on the curves on the outsides of the bottom skins, and on almost all of
the
turtle deck.
I disassembled, bent, and
reassembled
several times to get
everything pretty. There
were a couple
of spots where bending just wasn’t going to work, so I used a shim
between the
rib and the skin to keep the skin’s pretty shape.
Forward
Bottom
Skins
Before you rivet the
F-851 skins to
the assembly, check your
rudder pedal installation. If
you are
installing the ground adjustable rudder pedals, you will want to
install the attachment
angles before you rivet on the F-851L&R. Once
the fuselage skins are riveted on, you can not get
to the backside of the rivets for the rudder brackets to buck them; you
will
have to use LP-4-3 blind rivets.
If you bought the regular kit, you will need to fit
the landing gear
before you finish with the
forward bottom skins.
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