Great Planes Ultra Sport 40 Kit - GPMA0410 - Manual (Page 9)

INSTALL THE HINGES (Do not glue)
NOTE: One-piece molded polypropylene hinges
are supplied in this kit. If you choose to use these
hinges or the "pinned"-type hinges, you may cut
the hinge slots at this time. However, if you choose
to use the one-piece hinges that are paper covered
for CA glue installation, you may wait until after
covering before cutting the hinge slots.
from your local hobby dealer). Many expert
modelers prefer to use a wing jig for high
performance airplanes, as it helps to insure a
straight, warp-free wing, especially if you do not
have a workbench or building board that is perfectly
flat. If you choose to use the Wing Jig, please read
the instructions that are included with the jig before
beginning.
1. Lay the rudder and elevators on the plan and
mark the hinge locations. Place the rudder against the
fin TE and transfer the marks over to the fin. Place the
elevators against the stab TE and transfer the marks over
to the stab.
BUILD THE WING PANELS
NOTE: It will be helpful to build the wing on a
piece of "Celotex" or other semi-soft (and flat)
surface, into which you may easily stick pins to
firmly hold down the wing parts while building, to
avoid warps.
CAUTION!!!: You must use extreme care
when cutting hinge slots with an Xacto
knife, to avoid cutting yourself! If the balsa
part breaks while you are pushing on the
knife, the blade could go into your hand
before you know it! A good precaution is to
wear leather gloves while performing the
following steps.
1. Tape the plan to your flat work surface, and
cover the wing drawing with waxed paper (so you won't
glue the wing to the plan!). NOTE: If your work space
is limited, you may cut the left and right wing half
drawings apart.
2. The shaped and notched wing leading edges
(LE) and trailing edges (TE) are fastened together by
thin strips of balsa. Separate them by folding until the
balsa breaks. Sand away the excess balsa that remains
along the edges after breaking them apart, using a T-bar
with 100-grit sandpaper.
2. Cut the hinge slots on the accurate centerlines
which you previously drew, using an Xacto knife or a
hinge slotting fork and hook. (See Step 7 on Page 17)
3. IMPORTANT! Condition or "break-in" the
hinges by folding them back and forth several times.
4. Insert the hinges into the slots and trial fit the
rudder and elevators in place on the fin and stab. Do not
glue the hinges until after you have covered the
model.
3. Before using the 1/4" x 3/8" x 27-1/4" hard balsa
spars, examine them carefully for possible imperfec-
tions. Look for knots, soft spots, diagonal grain and any
other imperfections. If possible, position each spar so the
imperfections (if any) are on the outer half of the wing
panel (toward the tip), where they will be least affected
by high stress. If the spars are warped slightly, try to
"balance them out" by installing the warped spars in
opposite directions (see sketch).
TWO WARPED SPARS INSTALLED
THIS W A Y WILL R E S U L T IN A
STRAIGHT WING
WING
NOTE: The following instructions explain how to
build the wing directly on the plans. An alternative
method is to use a Great Planes Wing Jig (available
TWO WARPED SPARS INSTALLED
THIS W A Y WILL RESULT IN A
WARPED WING
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