Top Flite J-3 Piper Cub - Manual (Page 9)

10. NOTE: This step assumes that you will be mounting your
engine to the right side as shown on the plans.
Carefully cut-out the firewall template provided on plan
sheet No. 2 and lightly glue it to the 1/4" plywood firewall.
Drill four 3/16" diameter holes in the firewall using the tem-
plate as a guide. Using the No. 4-40 x 5/8" bolts and the
No. 4-40 blind mounting nuts provided, install the motor
mount to the firewall. Tighten the bolts enough to force the
blind nuts into the back of the firewall. Carefully remove
the bolts and epoxy the blind nuts to the back of the fire-
wall — DO NOT get any epoxy into the holes of the nuts but
apply epoxy around the edges to retain them in place.
Epoxy both F-12 (PLY) forward landing gear block supports
in place on the inside of the fuselage. Also epoxy both F-13
(PLY) rear supports in place.
Using two 5" lengths of the 1/4" x 3" x 24" balsa provided,
cover the bottom of the nose area from the forward landing
gear block to firewall — see side view. Trim the excess flush
with the outer fuselage sides.
With the 3/32" sheet provided, plank the top nose area from
F-3 forward to firewall. This is done with two pieces with
the joining seam on top of the 1/8" x 1/4" balsa stringer.
Sand flush with rear face of F-3 and front of firewall.
MOTOR MOUNT
Trial-fit the firewall into the nose of the fuselage. You will
note that it will be necessary to slightly relieve the top fuselage
cross-brace and the face of F-1 to allow the firewall to fit
flush. It may also be necessary to trim the firewall slightly to
fit properly.
Using the remainder of the 1/8" sheeting used for the fuse-
lage sides, cut, trim and fit two pieces of this stock, cross-
grained as shown on the plans, to become the fuel tank tray.
This is most easily done by making one piece to fit ahead of
F-10 (PLY) and a second to fit behind it. DO NOT cut into
F-10 (PLY) to fit these pieces. Work around it. Glue the
tank tray pieces in place on the 1/8" x 1/4" supports.
Epoxy firewall in place against uprights, cross-braces, F-1 and
tank tray.
11. Fit and glue 1/4" die-cut bottom nose sheet F-18 in place.
This part fits flush with the bottom longerons. With the re-
maining 1/8" sheet balsa, fill in the bottom of the fuselage.
cross-grained, from the back of F-18 to the front landing
gear block, between the front and rear landing gear blocks
and from the rear landing gear block to the first 1/4" square
bottom cross-brace. This sheeting fits flush with the bottom
longerons.
12. Carefully remove the two plywood cabin frames, F-14 (PLY)
and F-15 (PLY), from their die-cut sheets. Remove the
window cut-outs from the frames. Note that F-14 (PLY) is
the right side cabin frame as it contains the upper door half.
Remove this door section from F-14 (PLY) and set it aside
along with the window cut-outs. Clean-up all of the inside
window frame edges with a sanding block as required.
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