Top Flite TOPA0155 - Manual (Page 19)

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5. Cut out the balsa from the ribs within the
open area of the ply doublers to accommodate the
landing gear rails.
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6. Repeat the procedure, but this time, make a set
of landing gear ribs for the left side of the center section
being certain to glue the doublers to the correct sides
of the ribs as indicated on the wing plan.
Frame the center section
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1. If building flaps, use a straightedge and a
hobby knife to cut partway through one side of die-
cut 3/32" [2.4mm] balsa wing ribs W3, W4, W5, W6,
W7 & W8 from the top of the notch to the tip as
shown. Later, the bottom of the ribs will be removed
to accommodate the flaps.
Refer to this photo for the following six steps.
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2. Cut two 1/8" x 3/8" x 36" [3.2 x 9.5 x 914mm]
basswood sticks and two 3/16" x 3/8" x 24" [4.8 x 9.5
x 610mm] balsa sticks to a length of 23-13/16"
[604.8mm]. Make a top and bottom center main
spar by gluing a basswood stick to the balsa stick.
Save the leftover basswood for the outer panels.
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3. Without using any glue until instructed to
do so, join ribs W1 through W5 to the die-cut 1/8"
[3.2mm] balsa center TE spar (CTES). Fit one of the
center main spars prepared earlier to the notches in
the bottom of the ribs. The balsa side of the center
main spar faces downward.
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4. Join the die-cut 1/8" [3.2mm] plywood forward
dowel plate (FDP) to ribs W1 & W2.
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5. Position the assembly over the plan. Pin the
center TE spar and the ribs over their locations on
the plan. Hint: Instead of directly pinning the ribs and
center TE spar to the plan, an easier and more
secure method is to place 1/2" x 1/2" [13 x 13mm] (or
similar size) balsa sticks (indicated by the small
arrows in the photo) on both sides of the ribs and
center TE spar and pin the sticks to the plan.
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6. Make shims from leftover balsa to support
bottom center main spar and push it up into the
notches in the ribs. Be certain the low-point on the
bottom of the ribs is contacting the plan. The exact
thickness of the shims may vary from kit to kit, but
the approximate thickness will be 1/8" [3.2mm].
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7. Making certain the bottom of the ribs and the aft
TE are fully contacting the plan, and that the ribs are
pushed all the way down into the notches of the
center TE spar, glue the ribs to the center TE spar. Pull
the bottom center main spar tightly up into the notches
in the ribs; then, making sure the bottom of the ribs are
contacting the plan, glue the spar to the ribs.
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8. Glue the top center main spar into position with
the balsa side up. Use a small square to make
certain the W5 ribs on both ends of the center
section are vertical.
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