Great Planes Learjet 40 Kit - GPMA0439 - Manual (Page 31)

Fuelproofing may be done after covering but it is an
important step that must not be omitted.
D 1. Fuelproof the firewall and fuel tank compartment
paying special attention to the inside of the wheel well. K&B
epoxy paint or 30-minute epoxy is recommended.
D 2. Fuelproof any exposed wood.
You can practically eliminate wrinkles in the covering
caused when the model is left out in the sun or in the back
of your car by following this technique used in the Great
Planes model shop.
D 1. Cover your sealing iron with a Top Flite Hot Sock
and turn the heat about 3/4 of the way to the high setting.
D 2. Cut a piece of MonoKote film about 2" larger all
around than the surface you are going to cover Strip off the
backing and position the film. Tack the film down smack
dab in the middle of the surface.
D 1. Fill any open joints or dings (see expert tip that
follows) with HobbyLite" balsa filler, then when dry, go over
the entire airframe with progressively finer grades of
sandpaper to obtain a glass-smooth finish. We use 400-gnt
as our final grade.
D 3. Pull (as in stretch) the film toward the longest end,
sealing it to the balsa from the center outward. Work out
any wrinkles and air pockets as you proceed with a
combination of circular and back and forth motion.
Repairing Dings
Many small dings in balsa can be repaired without having
to use filler Simply moisten the area with water or rubbing
alcohol, then apply a hot sealing iron to the area. The heat
and moisture will cause the wood to swell back to its
original shape. Lightly sand off the spot to finish the repair.
Look over your work carefully with an eye to any surface
blemish that will cause problems during covering Fix the
problems before proceeding.
NOTE:The Learjet does not require much painting to
obtain the scheme shown on the box, as most of the finish
is done with Top Flite MonoKote film. The only painting
that is required are the plastic parts such as the cowl, tip
tanks, engine nacelles and canopy, but as these are
molded in white plastic they may be left unpainted if you
desire There are many other schemes used on Learjets
and two colorful ones are shown on the side of the box.
The technique we will describe here is how the model
pictured on the top of the box was finished. In general, it
involves covering most of the model with MonoKote film,
then priming and painting the cowl and surface details
Remove all dust from the structure with a Top Flite Tack
Cloth (TOPR2185) so the MonoKote film will stick well.
Make sure the MonoKote film is thoroughly stuck down
to the structure and all of the edges are sealed. Use a Top
Flite MonoKote Hot Sock'" (TOPR2175) on your covering
iron to avoid scratching the MonoKote film.
D 4. Perform the same procedure working the opposite
direction from the center.
D 5 Pull and seal diagonally toward the four corners,
always starting from the center. The trick is to shrink out
any wrinkles before you seal the film to the surface.
D 6. Use a heat gun to heat and stretch the film around
curved surfaces like the stab and rudder tips, while pulling
on the excess material. You may need to pull hard to get
out all of the wrinkles, so wear a glove to protect your hand
from the heat Follow-up the heat gun with your sealing iron
to secure the bond.
The idea behind this approach (which can be applied to any
part of the model) is to preshrink the MonoKote film as
it's applied, and remove the air pockets that can expand
later and cause the sags and wrinkles.
NOTE: When covering areas that involve sharp junctions,
like the tail section, cut narrow strips (3/8" to 1/2") and
apply them in the corners before covering the major
surfaces The larger pieces of MonoKote film will overlap
and capture these smaller pieces. This technique also
bypasses the need to cut the MonoKote film in these areas
after it has been applied. DO NOT, under any
circumstances, attempt to cut the covering material
after it has been applied to the fin and stab, except
around the leading and trailing edges and the tip.
Modelers who do this often cut through the covering and
part way into the balsa stab skin. This can weaken the stab
to the point where it may fail in flight!
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