Top Flite TOPA0500 - Manual (Page 35)

❏ R20. Fit but do not glue the bottom spar and all the
ribs of the center section to the center spar web (with
the 1/16" spar web doubler facing aft). Join the wing bolt
plate and the center TE spar (not shown in this photo) to
the ribs. Make sure your
center W1 is in the center of
the spar and make sure the W1 and the W2 with the
die-cut lines you filled in with glue are on the left side of
the center section. Use ribs W3 and W3A to hold the
outer sections of the center web in position and make
sure the right side of the center web and the
corresponding right section of the center web are on the
right side of the plan. Finally, join the top spar to the
assembly using the centerline you marked for alignment
(no gluing yet!) .
❏ 22. Position the center section assembly over the
plan. Use T-pins to hold the ribs down to your building
board over their locations on the plan, or use balsa jig
sticks leftover from building the tail to hold the ribs over
the plan the same way you did for the stab. Make sure
the wing bolt plate is centered between the W1 ribs and
all the jig tabs are contacting your building board. If
you’re installing retracts, make sure the outer portions of
the spar web are centered between the top and bottom
spars and that the W3 and W3A ribs are aligned with
their location indicated on the plan.
❏ 23. Glue the spar web to the bottom spar and glue all
the ribs to the spar web. Pull the TE spar up to fit into the
ribs. Glue the center TE spar to the ribs, then glue the
wing bolt plate to the center TE spar. Temporarily remove
the top spar and apply a bead of thick or medium CA on
the top of the spar web. Join the top spar.
❏ 24. Glue both die-cut 1/8" plywood doublers W1D to
the wing bolt plate and the W1 ribs where shown on
the plan.
❏ R25. Glue the 5-3/8" long air cylinder mounting rails
you cut earlier to ribs W2 and W3 where shown on
the plan.
❏ R26. On the left side of the center section, cut notches
in the outer W3 and W3A ribs to accommodate two 1/16"
plywood spar braces. On the right side of the center
section, cut a notch in the innermost W3 rib on both sides
of the top spar the same way. From a 1/16" x 1/4" x 10"
ply strip, cut two braces to a length of 3-5/8" for the left
side. From another ply strip, cut two more braces to a
length of 5". Test fit the spar braces. Use 30-minute
epoxy to glue the four spar braces to the front and back of
the top spar on both ends of the center section. The photo
shows the left side of the center section.
Refer to this photo for the next four steps.
❏ 27. Glue both die-cut 1/8" plywood aft dowel braces to
the W1 ribs where shown on the plan. Make sure the holes
in the dowel braces are nearest the bottom and align with
the plan.
❏ 28. Locate both die-cut 1/8" plywood forward dowel
braces. Trim one of the forward dowel braces to the length
of the front forward dowel brace shown on the plan. Glue
both forward dowel braces together so the holes align.
❏ 29. Glue the forward dowel brace, centered vertically, to
the W1 ribs.
❏ 30. Cut two 4-1/4" shaped LE’s from the 14-7/8" long
shaped balsa LE stick. Notch the aft edge of the LE’s to
accommodate the ply center LE you’ve already glued in
place. Glue the shaped balsa LE’s to W2 and the center LE
but not to rib W3.
❏ 31. Remove the center section from plan. Turn it over
and cut the jig tabs from the bottom of the ribs. Sand the
forward dowel braces and the LE’s so they match the cross
section on the plan and blend them to the ribs. Sand the
center TE spar even with the top and bottom of the ribs.
That’s all we can do on the center section until we join it to
the outer panels so set the center section aside for now.
DC-3 Fact
The DC-3 was not only larger than the DC-2, but
also much easier and safer to fly. An automatic
pilot was installed as standard equipment. The
overall design of the DC-3 was so successful that
its basic specifications were never changed. Once
the first DC-3's entered service, the speed at
which the entire industry converted over was
limited only by the rate at which Douglas could
produce them.
❏ F21. Fit but do not glue the bottom spar and all the
ribs of the center section to the center spar web (with
the 1/16" spar web doubler facing aft). Join the wing
bolt plate and the center TE spar to the ribs. Make
sure your
center W1 is in the center of the spar. Join
the top spar to the assembly using the centerline you
marked for alignment
(no gluing yet!) .
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