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Surface Preparation
No matter what brand of covering you decide to use, the surface of your
uncovered model directly affects what the covering job will look like when you
are done. Poor workmanship will show right through. Now is the time to carefully
inspect the surface of the entire model. Carefully sand any mis-matched
sheeting joints smooth and use a good quality, light weight filler to take care of
any dents, nicks or dings. The entire model should be final sanded with 220 grit
sandpaper, progressing to 360 grit. The surfaces to be covered must be clean,
dry and dust-free. Use a good quality tack rag and/or compressed air to make
sure the model is completely dusted. We would also suggest that you make sure
the physical area where you will be covering the model is as clean and dust-free
as possible.
BUILDERS TIP: We suggest that you DO NOT seal the inside of the tank
compartment before you cover the fuselage. Applying a sealer of any kind
(epoxy resin, etc.) to the inside surface of the wood prevents heat from
passing through it and can cause bubbling. Even though it is a bit more
difficult, seal the tank area after the fuselage is covered.
BUILDERS TIP: The #1 reason for
sagging covering, even after
shrinking with heat, is internally
trapped air. In the case of this
particular design, where all of the
control surfaces, including the
stabilizer and fin are lightened with
cut-outs, this can be an annoying
problem. The answer is to ventilate
each of the lightening hole bays in
each part. This is quickly done using
a hand-held twist drill with a 1/16"
drill bit installed.Simply drill a 1/16"
dia. hole through the trailing edge of
the stab and fin, into each lightening
hole - carefully centering the bit as
you go. Starting at the leading
edges, do the same thing to the
rudder, elevators and both ailerons.
When covering these surfaces, start
with the bottoms of each. Once the
covering is on and wrapped around
the leading and trailing edges, use
the sharpened end of a piece of
1/16" music wire to poke through
each of these now-covered vent
holes. Cover the tops of these
surfaces and again poke through the
drilled vent holes. Now when you use
an iron or a heat gun to shrink these
covered but ventilated surfaces, the
covering will shrink tight and stay
that way.
The canopy/hatch (without the canopy in place),rudder, elevators and ailerons
should all be covered separately and installed only after the entire model is
covered. Once the control surfaces have been covered, the previously cut hinge
slots should be located and opened with your hobby knife and a #11 blade.
A two-color trim scheme, such as the model shown on the cover of this kit, is
fairly easy to accomplish. In the case of the wing panels, stabilizer and fin, we
used the plans themselves to develop the color separation lines (patterns). These
patterns were drawn on drafting vellum, directly over the plans, taking care to
keep the color seams over solid wood. The pattern was then taped over both
colors of covering film (one underneath the other) and cut using a metal straight
edge and a hobby knife with a sharp #11 blade. This technique provides perfectly
matched pieces of covering. The rear piece is applied first, followed by the
forward piece with an overlap of approximately 3/16". Working in this manner,
using the plans as a pattern guide, practically insures a well matched,
symmetrical covering job.
Once the model is covered, take a little time to carefully go back over all of your
work. Make sure all the seams are attached and adhered and that there is no
loose covering. Next, use a sharp #11 blade to open up all of the holes and slots
that have been covered; hinge slots, hardpoint holes in the stab, fin and fuselage,
hardpoint hole in the canopy hatch, bolt holes in the landing gear block, etc. The
two J-hooks can now be screwed in place into the W-1 wing root ribs. Use epoxy
to glue the 3/16" dia. x4-1/4" rear wing locating dowel in place into the fuselage
and up against the bottom of the servo tray, leaving 1/2" of its length exposed on
each side of the fuselage.
BUILDERS TIP: An alternative method to use when opening small round holes beneath covering film, is to briefly
heat the tip of a small diameter Phillips screwdriver with a butane torch. Then simply press the tip of the
screwdriver to the covering film, directly over the hole. The covering will melt around the edge of the hole, sealing it
and leaving a perfectly round opening.
The engine compartment (firewall, fuselage sides and bottom sheeting) must now be sealed. We used SIG Polyester
Finishing Resin (SIGFR001) to completely seal the wood in this area. Brush resin just over the edges of the trimmed
covering material to seal it as well. Allow the resin to cure and sand it lightly. You can now paint the engine compartment
with a complimentary color for your covering scheme or simply use flat black or white SIG Butyrate Dope.
Your kit is supplied with a sheet of SOMETHIN EXTRA logo transfers in both black and white. This allows you to use the
white logo against a dark background or the black logo against a light background, depending upon your choice of color
schemes. These self-stick transfers are not die-cut so you must cut them from the sheet. We suggest using a sharp #11
blade and a straightedge to do this. Once the transfer is cut out, spray a little glass cleaner onto the area where it is to be
applied and carefully lay the transfer in place. The glass cleaner allows you to position the transfer accurately.