Top Flite TOPA0400 - Manual (Page 47)

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2. Cut hatch guides from leftover 1/4" x 1/4"
balsa stringers. Use thin CA to glue the guides
between the hatch blocks, flush with the bottom of
the wing skin.
NOTE: Unless you have a reverse throw servo,
you will need to mount the flap servos in an
asymmetrical manner as shown on the wing plan
to have them both move in the same direction.
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3. Tape the hatches in place and drill 1/16" pilot
holes at the punch marks on the hatches and into
the hatch blocks. Remove the hatches and enlarge
the holes in them to 3/32". Countersink the holes
in the hatches to accept the #2 x 3/8" flat head
screws. Secure the hatches to the hatch blocks
with the #2 x 3/8" flat head screws.
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4. Remove the servo hatches from the wing.
Apply a drop of thin CA to each hole in the hatch
blocks to harden the threads.
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5. Position the servos on the hatches so that
the servo arms are centered in the hatch openings.
Use 30-minute epoxy to glue 5/16" x 3/4" x 7/8"
basswood servo mounting blocks to the
servo hatches.
NOTE: Secure the servo mounting blocks by first
drilling several 1/16" holes about 3/16" deep into the
gluing surface of the basswood blocks. Roughen
the servo hatch where the epoxy will be applied.
Pack epoxy into the 1/16" holes before clamping the
blocks in position.
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6. After the epoxy has fully cured, insert a 1/32"
or 1/16" temporary shim between the servo and the
plywood hatch. Drill 1/16" pilot holes and mount the
servos to the mounting blocks. Remove the shims.
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7. If you are using a four arm “cross” servo
horn, trim off three of the four arms. Reinstall the
servo hatches in the wing.
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8. Thread a 4-40 nut onto each of four 4-40 x
12" threaded rods. Slide a silicone clevis retainer
onto each rod followed by a 4-40 threaded metal
clevis threaded on at least 14 turns.
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9. Attach a heavy-duty control horn (not
included) to each clevis. With the pushrods aligned
with the servo arms, position the control horns on
the ailerons and flaps so that the clevis holes are
aligned with the LE of the control surfaces. Mark the
control horn mounting holes. Depending on the type
of control horns used, drill the proper size pilot holes
at the marks and mount the control horns to the
control surfaces with 1/2" long wood screws (not
included). Be careful not to drill through the top skin.
Remove the control horns and prick a few holes into
the wood under the control horn. Apply several
drops of thin CA to the pin holes to strengthen the
balsa. After the CA cures, sand smooth and
reattach the control horns.
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10. Attach solder clevises to the outermost hole
in the servo arms. Center the servo arms, ailerons
and flaps. Cut the pushrods to the appropriate
length. Remove the pushrods and solder clevises
from the wing. Solder the clevises onto one
end of each pushrod. Silver solder is highly
recommended. Slide a silicone retainer over the
solder clevises and reinstall the pushrods on the
servo arms and control horns.
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