Top Flite TOPA0400 - Manual (Page 21)

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9. Cut one 3/32" x 3" x 30" balsa sheet in half
(two 15" lengths). Make four wing skins by edge
gluing three 3/32" x 3" x 42" balsa sheets, one
3/32" x 3" x 30" balsa sheet and the previously cut
3/32" x 3" x 15" balsa sheet allowing a 1/4" off-set
at the end of each sheet. Cut off the corner of the
30" sheet and glue it as shown in the sketch.
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10. Lightly sand both sides of the wing skins with
a long sanding bar and fresh 220-grit sandpaper.
NOTE: The steps below show sheeting the flaps
with a separate piece of sheeting. This orients the
grain more parallel with the flap span and makes it
easier to fit.
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11. Tape a wing skin to the bottom of the wing
structure, aligning it with the LE and the center of
the wing. Mark the location of the outer side of rib
W-12, the gap between the wing TE spar and the
flap LE and the aileron TE assembly. You will need
to cut out around the radiator frame. We usually
leave about 3/8" overhang where possible. Use a
piece of the sheeting you trimmed off to fill in the
angled area along the LE.
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12. Trace the shape of the skin onto the other
bottom skin and the two top skins. It is not an exact
match, but this will offer an excellent starting point.
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13. Position the wing upside down on the jig
blocks. You may want to tack glue the jig to the
building surface to keep it from moving.
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14. Position the front of the sheet against the
LE. Glue it in position with thin CA.
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15. Carefully lift the wing skin away from the
ribs. Apply a bead of thick CA to the top of the ribs,
the main spar, the edge of the center sheeting,
aileron wing TE assembly and the wing TE spar.
Do not glue the wing skin to the flap LE. Press the
wing skin down and hold it in position with weights
or masking tape until the CA cures.
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16. Repeat the process to install the second
bottom wing skin.
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17. Turn the wing over and check all the glue
joints applying CA where needed.
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18. Trim the bottom skins along the gap
between the wing TE spar and the flap LE.
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19. From 3/32" balsa sheeting remaining from
the stab and shear webs, sheet the area along the
side of the radiator frame.
NOTE: Leave the wing on the jig blocks until you
are ready to sheet the top of the wing. This allows
less time for moisture and stress to twist the wing.
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