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We
will be periodically adding tips on how to get
great results in both building and flying your
airplanes.
Check back often to see what we add.
COVERING WITH
CONDENSER PAPER
To cover a lightweight indoor model’s structure with condenser paper or Japanese Tissue, it is important to pre-shrink the material before applying. These materials have a tendency to
shrink after being exposed to moisture (even
from humidity in the air). If the tissue shrinks
after it is applied to single surface covered
structures, it will warp the light framework of
your airplane and destroy its flying abilities.
To help prevent
this, lay the tissue on a piece of carpet or a
bath towel before misting. This will allow air
to surround it as it dries. Use a spray bottle
(like window cleaner comes in) to apply a mist
of water over the sheet of tissue. It should
have an even pattern of moisture droplets evenly
distributed over the tissues surface that will
soak in and cause it to look evenly damp in a
couple of minutes. When damp, it also has a
tendency to stick to itself if it becomes folded
and is somewhat difficult to pull it back apart,
so be careful. After it dries (maybe 20
minutes), mist it again.
Double shrinking
it now will cure most of the shrinkage problems
that could occur later (it can shrink as much as
1/2 across the 15 direction). When it dries,
it will look VERY WRINKLED. No problem. Use a
standard clothing iron set to a very warm
setting (cotton) and gently iron it on an
ironing board. It will now be flat but have a
slightly wrinkled, skin like texture when you
are done. This is your goal.
APPLYING
COVERING TO
SINGLE SURFACE
AIRFOILS
(cover ONLY the top
surface)
There is a grain
direction in nearly all paper that runs parallel
to the manufactured edges. In covering a wing or
horizontal stabilizer it is best for that grain
to run parallel to the leading and trailing
edges. Pre-cut the paper to be slightly larger
than the piece to be covered (maybe 1/2 on each
edge). Always cover individual sections before
assembly (i.e. if a wing has dihedral, cover
each piece with its own precut sheet). Protect
the floor with newspapers and set the component
in the middle. Using Spray Glue (such as 3M
Super 77), hold the can straight over the wing,
at least 24 away and dust on a light mist (3
seconds maximum). Move the component back to a
clean, flat surface to help prevent any warps
when applying the covering. Carefully set the
paper in place.
Caution: The covering will
immediately stick wherever it touches, so it is
a good idea to work with a partner, each holding
one side. Do not attempt to stretch the
paper, just let it comfortably lay on the
structure of the wing. Then gently pat down all
contacting surfaces to insure adhesion.
Using a new super
sharp double-edged razor blade, trim off the
excess paper all around the edges. An alternate
method of trimming excess paper is to gently
sand the outside edge (using fine sandpaper on a
sanding block). Stroke downward at about a
45-degree angle to sand through the paper only
so the excess will just drop away.
Note: For repair work
and for portions that are impractical to use
spray glue (because of the extremely sticky
overspray that may get on adjoining covering),
here is a good alternative. Mix Elmers
Carpenter Glue (or comparable aliphatic resin
glue) with rubbing alcohol. It can be diluted to
as much as 80% alcohol and 20% glue.
When thoroughly
mixed, it will have a translucent amber color.
It can be applied with a brush, a cotton swab,
or squirted out of a small applicator bottle. It
is important to work rather rapidly once the
glue is applied as it looses its adhesive
quality quickly. If covering a larger surface it
is sometimes necessary to give a quick second
coat just before applying the tissue. Allow the
moisture from the glue to completely dry before
trimming the edges as described above.
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