SIG Four-Star 20EP, Instruction Manual, Page: 17 / 26

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i. The rudder is hinged in the same manner as the other parts, but it is easier to install AFTER the fin has been glued onto
the fuselage. For now, go ahead and cut the slots for the hinges in the fin and rudder, but do not glue them. Set them
aside until later.
VERY IMPORTANT: It's critical that you only make one application of glue to each side of the hinges. If you apply
additional glue to the hinge after the first application of glue is already dry, the second application of glue will merely
puddle in the hinge gap and make the hinge too stiff to operate properly. The excess glue can also weaken the hinge!
When properly glued, the portion of the hinge that you see in the hinge gap should have a dry appearance, not wet. A dry
appearance indicates that almost all of the glue has properly soaked into the hinge and wood. A wet appearance indicates
that excess glue is puddled in the hinge gap. Excess glue can become brittle with age and cut the hinge. Also, NEVER
USE CA ACCELERATOR (KICKER) ON CA HINGES!
FINAL ASSEMBLY
57a.
Install the wing on the fuselage.
b.
Mark a centerline on top of the stabilizer, making sure that the centerline is
perpendicular to the trailing edge of the stabilizer. Then pin the stabilizer in place
on the fuselage. Carefully measure from the trailing edge of the wing to the
trailing edge of stabilizer. Both measurements should be the same. If there is any
difference rotate the stabilizer until the measurements are identical.
c.
Also check the alignment of the stabilizer to the wing in the front view. The
stabilizer should be level with the wing. If it is not, alter the stab mount platform of
the fuselage as needed.
d.
When satisfied with the alignment, use a fine-line felt-tip pen to draw lines on the bottom of the stabilizer along the
fuselage sides. Then remove the stabilizer from the fuselage and cut away the covering material between the lines, where
the stabilizer will be glued to the fuselage, exposing the bare wood underneath.
Cut just inside the marked lines with a sharp knife. Try not to cut into the balsa wood.
e.
Glue the stabilizer permanently onto the fuselage. Recheck the alignment and adjust as necessary before the glue dries.
58a.
Test fit the fin in place on top of the fuselage, inserting the bottom of the fin
trailing edge between the fuselage sides. Use a felt tip pen to mark the position of
the fin on top of the stabilizer.
b.
Carefully remove the covering material from the the top of the stabilizer where the
fin will attach. The covering should be trimmed away 1/16" inside the drawn lines.
It is extremely important that you cut the covering only and not the balsa
underneath. Do not cut into the balsa.
c.
Permanently glue the fin in place. Use a triangle to check that the fin is square
with the top of the stabilizer. Let dry.