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Aft Upper Skin or Turtle Deck

Timing for final installation of the aft upper skin is important.  You can drill, countersink and fit everything any time.  But be sure you are finished with everything inside the tail before you rivet the skin 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 meant I spent a lot of time lying on the wood braces inside the tail.  This was not fun!

Wood boards

Plywood boards for lower longerons
The plans show you how to make some plywood boards to set on the lower longerons.  I ended up with a few changes to the boards as parts were installed.  The plans made no provision for the elevator bellcrank.  So I cut the plywood down.  This worked out well as I used that small piece of plywood often across the floor ribs in the main cabin area 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.  A couple of rivets hold each to the F-869 gussets. 

Tie down holder
Tie down holder

F-882 Canopy Rail Receptacle

Rivet the bottom three firstI 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 the 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 appearance across the rivet line.  The rivets will be sitting lower and the skin between them will bump out.

This meant I had to cleco the skin 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 the final 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 F-887 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 be thicker 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 holes.

Canopy Rail

Rail with scrapeI drilled and screwed the canopy rail completely on at this point.  Then when I had finished the canopy installation, I found that the anchor pin on the canopy frame that fits 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, making it easier to remove later if needed.  

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