Aft Upper Skin or Turtle Deck
Timing for final
installation of the aft upper skin is
important. You can
and fit everything any time. But
you are finished with everything inside the tail before you rivet the
on. I didn’t have
this option. I had
to move and needed to make the fuselage
secure with the canopy installed before I moved.
So I installed the aft upper skin a lot
earlier than I wanted to. This
spent a lot of time lying on the wood braces inside the tail. This was not fun!
plans show you how to make some
plywood boards to set on
the lower longerons.
ended up with a
few changes to the boards as parts were installed.
The plans made no provision for the elevator
So I cut
out well as I used
that small piece of plywood often across the floor ribs in the main
as I was working there.
Tie Down Holders
I made my tie down
holders out of
scraps of aluminum. This
is lighter then steel nuts, and since I
had the parts handy, was easier too.
couple of rivets hold each to the F-869 gussets.
F-882 Canopy Rail Receptacle
had a hard time
riveting the bottom
three rivets on the
F-882, because I riveted them after I had riveted the sides. I would suggest starting
by riveting the
F-882 to the F-807B bulkhead with the bottom three rivets. This will let you bend the
F-882 out of the
way a little to get a bucking bar or the head of the squeezer in there. After these three are
finished, cleco the
rest of the F-882 to the F-807B bulkhead and finish riveting.
Make sure the flanges on
bulkheads match perfectly with
the inside of the F-825 aft upper skin—don’t leave any gaps.
If the fit isn’t good, the
thinner skin will get pulled to the bulkhead when you rivet.
This will cause the skin to have a wavy
line. The rivets
will be sitting lower
and the skin between them will bump out.
This meant I had to cleco
on, mark the flanges that
needed tweaking, remove the skin, and bend the flanges.
Then repeat the entire process.
Yes, it took a long time and a lot of
installing and removing. But
finish is worth it. Any
bumps in the
smooth curve across the back of your plane will be very conspicuous.
I also made some thin
shims to fill
the space, caused by the
lower skins, between the F-805 skin and the bulkheads just above the
upper longeron. I
didn’t want the side
of the plane to have a bend inward just above the F-887. I used a piece of scrap
aluminum that was thick
enough to fill the gap at the bottom, usually .032.
I cut it about two to three inches long, and
wide enough to sit across the bulkhead.
Then I filed it into a wedge shape so it would
on the bottom
and taper off at the top. Then
I bent it
to fit the curve of the bulkhead and fit it in the space. If it was too big, I cut
it shorter or filed
it thinner as required until it neatly filled the void.
I left the shim long enough to stop half way
between rivets. I
then drilled and
dimpled holes through the shim to match the holes in the skin and
bulkhead. When I
riveted the skin on, I
had to use rivets a little longer than the call out for the first few
I drilled and screwed the
completely on at this
point. Then when I
had finished the
canopy installation, I found that the anchor pin on the canopy frame
into the C-806 anchor block scraped the top of the rail. So I had to remove it and
grind down the top
just a little. If I
were doing it again,
I would only put in a few of the screws that hold the rail in place,
easier to remove later if needed.
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