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Surface Preparation
A good covering job starts with good surface preparation. Regardless of what type of covering you choose, it won't hide
poor workmanship. Fill any small surface gaps or dents with a lightweight filler or spackling paste. Sand every piece of the
model; first with 220-grit sandpaper, then again with 360 or 400-grit sandpaper.
The engine compartment and the cockpit require preparation before general covering is started. Since it's too difficult to
apply covering material to the engine compartment, it must be fuel-proofed with several coats of clear dope or two coats of
polyester resin, sanding between coats. Finish off the engine area with a few coats of colored SIG SUPERCOAT Dope.
Most of the SUPERCOAT plastic iron-on films have a matching SIG SUPERCOAT Dope color.
Covering With Sig Supercoat Iron-On Plastic Film
You will need at least three rolls of SUPERCOAT to cover the Four-Star 60. If a multi-colored finish is wanted, more than
three rolls of SUPERCOAT may be needed.
Covering The Wing
Begin the wing by covering the wingtips and plywood hold-down plates. On the
wingtips, run the covering material "around the corner" 3/16" to 1/4". Later, when
the main top and bottom covering pieces are applied, there will be an overlap that
is easily trimmed and will leave a nearly invisible seam. Extend the covering
material 3/16" to 1/4" past the outside edges of the hold-down plates to provide
an area for overlap and sealing.
Cover the main portion of the wing in four pieces, starting with the bottom. Trim
the covering off at the top of the leading and trailing edges. Cover the top of the
wing last so all of the seams will be on the bottom or back edges. The top
covering should overlap the full width of the leading edge and the vertical section
of the trailing edge.
BUILDER'S TIP:
When trimming material at overlaps
be especially careful not to cut
through the layer of covering
underneath. Laying a small strip of
plastic or cardstock under the trim line
makes it much easier to trim and
eliminates the worry of cutting the
covering underneath.
Wait until both the top and bottom pieces of covering material have been sealed completely around their edges before
shrinking the large open areas between the ribs. Alternate between the top and the bottom surface to avoid uneven
shrinking which could cause a warp. Keep the heat gun moving at all times as it's possible to burn a hole in the
covering. If the covering material starts to "balloon up", put a small pin hole in the bottom of each rib bay to allow the
expanding air to escape.
After all of the covering is tight, bond the covering material to all of the spars and ribs by going over them with the
sealing iron. This will maximize the torsional stiffness of the wing.
Cut an "X" pattern at the hatch opening on the bottom of each wing panel and iron the overhanging material to the
spars and hatch rails. Trim off the excess after all edges are sealed. Don't forget to cover the plywood hatches - for a
neat looking job, wrap the covering around the edges of the hatches 3/16" to 1/4".
Covering The Fuselage
The fuselage should be covered with six pieces in the order described below:
Fuselage Bottom - 2 pieces, front and rear
Fuselage Top - 2 pieces, top deck and stringers
Fuselage Sides - 2 pieces, left and right
All seams should overlap 3/16" to 1/4". When covering solid wood surfaces like
the front of the fuselage sides, better results can be obtained by starting at the
center and working toward the outer edges. This avoids trapping air under the
covering.
The trickiest part of covering the fuselage is the stringer area behind the cockpit. Cut a piece of covering wide enough to
go completely over the top of the fuselage and long enough to overlap the headrest and the tail fairing blocks. Start by
applying one edge of the covering to one of the fuselage sides, overlapping 3/16" to 1/4" onto the sides. Drape the
material to the other fuselage side, pull tight, seal the covering to the side and trim off the excess leaving 3/16" to 1/4"
overlap.
