GREAT PLANES RV-4 Instruction Manual page 18

8. Draw a line the length of the aileron/flap 1/4" [6mm]
from the trailing edge of the sheeting.
9. Bevel the sheeting to match the top of the W4 ribs.
When sanded properly the bevel should meet the line you
have just drawn.
10. Locate two die-cut 1/8" [3mm] plywood control
horn plates (CHP). Glue one in the flap and one in the
aileron at the location shown on the plan.
11. Use a T-pin and punch two holes through the
flap/aileron skin between the two W4 ribs. This will identify
where to cut the flap and aileron apart in a later step.
12. Glue the remaining 3/32" x 2" x 21-3/16" [2.4 x 102
[537.8mm] balsa aileron / flap sheeting to the top of the
aileron/flap.
13. Locate the 1/4" x 3/4" x 24" [6 x 19 x 610mm] balsa
aileron/flap leading edge. Glue it in place on the front of
the aileron/flap sub leading edge.
14. Turn the aileron/flap over. Mark a line through the
pin holes that you pierced through the skin.
15. Cut the aileron and flap apart by cutting on the line
you have drawn. Now would be a good time to mark which
one is the flap and which is the aileron. Be sure to indicate
which is the top and bottom of each control surface.
Referencing the control surfaces will eliminate confusion
and insure that you install the aileron and flap properly so
that the control horn plates are located on the bottom of the
control surfaces.
16. Sand the top and bottom of the flap and aileron,
making the leading edge match the control surfaces.
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