Top Flite TOPA0140 - Manual (Page 15)

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3. See the following photo and temporarily pin
the remainder of the 1/4" x 1/2" [6.4 x 12.7mm]
balsa stick you used for the stab hinge blocks (it
should be about 6" [150mm] long) to your building
board over the TE of the fin plan. This will help you
accurately position the fin ribs until you actually
glue the fin TE in position. Use small T-pins to pin
the fin ribs over their location on the plan so they
contact 1/4" x 1/2" [6.4 x 12.7mm] balsa stick.
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4. Use medium CA to glue the fin LE core in the
notches of the ribs.
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5. Cut 6" [150mm] from the 3/16" x 3/8" x 18"
[4.8 x 9.5 x 457mm] balsa stick for the fin LE. Trim
the fronts of the ribs at the same angle that the fin
LE will contact them. Glue the fin LE to the left side
(top) of the fin LE core so the excess extends
below rib V1 (see the following photo).
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6. Remove the 1/4" x 1/2" [6.4 x 12.7mm] balsa
stick you had pinned over the fin TE. Center the
die-cut 1/4" [6.4mm] balsa fin TE on the fin ribs
and glue it in position.
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7. Cut the fin skin for the left side of the fin from
the 1/16" x 6" x 15" [1.6 x 152 x 381mm] balsa sheet
you prepared earlier. The grain is parallel to the fin
LE and the skin should extend below rib V1 by
approximately 1/4" [6mm] to be trimmed later.
Hint: Once you make the fin skin for the left side
of the fin, use it as a template to make the skin for
the right side of the fin.
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8. Remove the T-pins and glue the fin skin to
the left side of the fin.
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9. Turn the fin over and glue the right side of
the ribs to the fin LE core, then carefully cut the jig
tabs from the bottom of the ribs.
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10. Cut three 1" [25mm] long hinge blocks
from the 1/4" x 1/2" [6.4 x 12.7mm] balsa stick you
had temporarily pinned to the plan at the fin TE.
Glue the hinge blocks to the fin TE where shown
on the plan. Trim the TE and the hinge blocks
even with the ribs and lightly sand the bumps of
the ribs left from the jig tabs.
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11. Cut another 6" [150mm] long fin LE from the
3/16" x 3/8" [4.8 x 9.5mm] balsa stick. Trim the
front of the ribs to accommodate the fin LE the
same way you did the other side. Glue the fin LE
to the fin LE core.
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12. If you haven’t already done so, cut the other
fin skin. Glue the fin skin to the right side of the fin
so the sheeting extends 1/4" [6mm] below V1.
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13. Trim the fin skins even with tip rib V4 and
the fin TE. Trim the leading edge of the fin so it is
even with the LE core, then shape the LE as
shown on the cross section of the plan.
BUILD THE RUDDER
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1. Position the die-cut 3/32" [2.4mm] balsa
rudder base over the plan and lightly mark the
location of the ribs on the base.
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2. Use a straightedge and a ballpoint pen to
mark a centerline on both sides of the die-cut 1/4"
[6.4mm] balsa rudder LE. Glue the rudder base to
the rudder LE on the centerline.
Use this photo for the next three steps.
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3. Glue the 3/8" x 3/4" x 2-3/8" [9.5 x 19.1 x
60.5mm] rudder blocks to both sides of the
bottom of the rudder base. You will shape them to
match the bottom of the rudder later.
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4. Glue a piece of leftover 1/16" [1.6mm] balsa
to one side of the die-cut 1/4" [6.4mm] balsa horn
block to increase its total thickness to 5/16"
[7.9mm]. Glue the balsa horn block to the right
side of the rudder base where shown on the plan.
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