Great Planes Learjet 40 Kit - GPMA0439 - Manual (Page 17)

D 5. Draw a horizontal line across the front of the center
leading edge block. Mark the centerline of the wing on the
front of the block. Make a mark 1-3/4" on each side of the
centerline. These marks show the position of the 1/4" wing
dowels. Drill a 17/64" hole through the block at each of
the marks.
D 6. Carve and sand the top and bottom edges of the
block to follow the airfoil contour but leave the front
surface flat.
Applying Fiberglass Cloth
A. Center one end of the fiberglass cloth on the trailing
edge of the wing, then apply several drops of thin CA to
hold it in position. Roll the loose end of the fiberglass cloth
onto a pencil, then use the pencil as a handle to stretch
the cloth over the wing toward the leading edge. Apply a
few more drops of thin CA to the LE to hold the cloth in its
"stretched tight" position.
B. Make a squeegee by wrapping a 2" wide piece of stiff
cardboard with a plastic sandwich bag or similar material.
Perform the following operation in a well ventilated
area with a fan directing air flow away from you.
C. Starting at the trailing edge, flow thin CA into the cloth.
Smooth the cloth down with the squeegee as you work
toward the leading edge. Avoid standing directly over the
work as the CA fumes can be quite irritating to your eyes
and nose.
D. Allow the CA to cure naturally without using any
accelerator. When thoroughly cured, lightly sand the
edges with 150-grit sandpaper to remove any ridges.
E. Just before you cover your model, fill the weave and
blend the edges with the wing using balsa filler. Sand the
dried filler with 220-grit sandpaper and recoat if necessary.
D 7. Round one end of each 1/4" x 4" wing dowel and
chamfer the other end (to make it easier to insert). Test fit
the dowels into the wing to be sure that they pass easily
through the leading edge block and the dihedral brace.
Glue them in place with 30-minute epoxy.
D 8. Apply 3" wide fiberglass cloth to the center joint on
the top and bottom of the wing. We prefer to adhere the
cloth with thin CA to save weight, but resin or thinned epoxy
will work just as well. Read the Expert Tip that follows
before performing step #8.
D 9. NOTE: The aileron and retract servo trays are slightly
different in size - the aileron servo tray is the smaller one.
Center the die-cut plywood aileron servo tray on top of the
wing at the marks you made in siep 5 of the previous
section (Completing the wing panels). Mark the outside
perimeter of the tray, then cut the wing sheeting from inside
the lines. Refer to the wing plan to locate the retract servo
tray opening. Mark and cut the sheeting for the retract
servo tray.
17