GREAT PLANES Piper j-3 cub Instruction Manual page 13

9. Carefully inspect the notches in the die-cut 1/8"
balsa Outboard TE (CUB4F03). The 1/8" wide notches are
to be aligned with the #6 rib locations. Insert the tab on the
die-cut outboard TE into the slot at the aft end of the #4 rib,
with the notches facing up.
10. Place the outboard #5 rib on the spar at the proper
location and insert the aft end of the rib into the proper notch
in the outboard TE. Do not glue yet!
11. Use a straightedge to keep the outboard TE straight
as shown in the photo and glue it to the bottom TE sheeting with
thin CA. Be careful not to glue the straightedge to the sheeting.
12. Position the notched LE so the 1/8" wide notches
are near the #2, #4, #6, #6 and #7 positions. Place it on the
ribs so the ribs are centered vertically on the LE to allow for
the LE sheeting which will be installed later. Glue it in place
with thin CA.
13. Install the remaining #5 and #6 ribs. Glue them to
the LE, the spar, the outboard TE and the bottom TE
sheeting. Make sure they are centered on the LE and down
against the bottom TE sheeting.
14. Trim the bottom sheeting in the aileron area, along
the #4 rib and the outboard TE to the end of the sheet.
Maintain a straight cut past the #7 rib location. You may want
to slide a thin piece of hard plastic under the bottom sheeting
to avoid cutting into the plans when making this cut.
15. Position the #7 rib in place over the plans and onto
the tab at the end of the outboard TE. Glue the rib to the LE,
the front and top edges of the spar, the outboard TE and
the bottom TE sheeting. Trim the bottom sheeting even with
the outboard edge of the #7 rib.
16. Insert the 3/8" x 3/8" basswood Top Spar
(CUB4W09) into the notches in the ribs. Align the end of the
spar to the outboard edge of the #7 rib. Glue the spar to all
the ribs, with the spar against the front of the notch in the #7
rib. Make sure the top surface of the spar is level with the top
edges of the ribs. NOTE: Check to make sure the spar is
positioned properly to ensure a straight wing (see step 2).
17. Install a die-cut 1/8" plywood Wing Tip Brace
(CUB4W09) at the rear of the spars through the notches in
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