Seat Bulkhead
The
width of my bulkhead is a bit wider than the Plan's dimension - mine is
~18". I used a carpenter's contouring tool to determine the profile of the
fuselage where the bulkhead meets. Then I transferred the profile to a 3/8" PVC
foam. After minor shaping and sanding, the bulkhead fits against the fuselage
sides nicely. Note the profile of the foam?
According
to the Plan, the rear thigh support follows the same curvature as the front.
However, if you check the dimension closely, you'll find that the ribs (for the
thigh support) are shorter in the rear than the front. Therefore, the thigh
support curvature is steeper for the rear. In addition, the Plan does not call
out any supporting ribs for the rear seats. According to the archives, no
one seems to know why either.
I
made a set of 3" wide hinges and embedded half of the hinges in the top of
the foam. I also drilled a couple of 3/8" diameter holes through the hinges
for flox anchor.
To
be more precise with the curvature, I decided to make a set of ribs to help
shape the rear thigh curvature. This time the thigh supports rest on top of
the bulkhead (instead of level to the IP edge in the front). Once the ribs were made,
I hot glued them in place such that I could make the thigh supports to the
appropriate curvature. I lanced the thigh support foam per Plan. I added an
extra lance at about 1/2" from the front most edge. I also rounded the
front most edge for a smoother transition. 
I
glassed both sides of the bulkhead with 1 ply BID. I used a laser to determine the
slot location on the armrest where the bulkhead protrudes through (as shown).
With the slot cut, I hot glued them in place first, such that I could establish
the hinge positions for the back seat.
Here's
a picture of the completed thigh support. I have yet to glass the second half of
the hinge to the fuselage bottom.
The
seat backs are pretty straight forward - a 12" x 18" flat piece. Again, I embedded
the hinges in the foam with flox and glassed as before. I hot-glued a 3"
board between the two seat backs to keep them straight and parallel to each
other. Then I lined them up in position per plan and floxed the hinges in
place with 4 layers of BID.