Great Planes PT-40 MkII Kit - GPMA0118 - Manual (Page 31)

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1. Use epoxy to glue the front center rib 1A between the
LEJ and FJ. Make sure it is equally centered in each wing
half and the front is centered on the leading edge. Hint: If
you are building the bolt-on wing, insert the 1/4" dowel
through the hole in the leading edge and into the center rib.
This will help you align the center rib. Remove the dowel
before the epoxy cures.
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2. Use medium CA to glue the rear center rib 1-C on
the centerline of the wing between the AJ and the TEJ.
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3. Glue the 3/16" x 3/16" bottom forward spars to the
notches in the ribs of both wing halves. Cut the ends so
they are flush with the tips.
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1. Use a straightedge and a new #11 blade to cut one of
the 3" x 30" balsa sheets into two 1-1/2" wide sheets. If
needed, true one edge of the sheets you just cut by
trimming them with your hobby knife and straightedge.
Sheet the Wing
EXPERT TIP EXPERT TIP EXPERT TIP
C. Remove the dowel and rib doublers. Lightly coat both
sides of the center rib and only one side of each rib
doubler with epoxy. Reposition the doublers on the
center ribs and clamp them until the epoxy cures. You will
be instr ucted to glue the dowel in after the wing
is sheeted. Prepare the Wing for Sheeting
31
A. Chamfer one end of the dowel you cut earlier. This
end will be the front.
C. Put the sealed bags into the tube socks, then tie a
knot in the socks to prevent them from leaking all over
your bench.
HOW TO MAKE “SOFT WEIGHTS”
Weights are needed for a variety of purposes during the
model building process, especially when setting the wing
washout in the following steps or if you need an extra
pair of hands to hold the wing. We made some 2 and 3
pound “soft weights” as follows:
A. Obtain four small, but sturdy plastic bags (freezer
bags wor k well), four old tube socks (preferably
laundered), and 10 pounds of buck shot, available at
sporting goods or gun stores. Sand may also be used,
but the weights become pretty bulky.
B. Use a scale to measure out two 2 pound bags and two
3 pound bags of shot (or sand). Seal the bags with
masking tape, without compressing the contents. Soft
weights work best if they are floppy like bean bags.
B. Test fit the dowel through the leading edge and fully
into the slot in the front center 1A rib assembly. With the
dowel in the center rib, test fit the die-cut plywood 1B
center rib doublers to the sides of the balsa center ribs.