.
COVERING
General Instructions
All of the Wonder prototypes were covered with Sig Supercoat Iron-On Plastic Covering. Supercoat is ideal for sport
models because it's lightweight and easy to apply. One roll is plenty for a Wonder, but most modelers will want two or
more colors.
Details about colors and decal placement for specific versions of the Wonder follow. All four versions have different colors
or markings to help distinguish the top of the model from the bottom. This is very important for visibility in flight, especially
with small, fast models like the Wonder. Keep this in mind if you plan your own custom color scheme.
We recommend that you cover the wing, fuselage, tail surfaces, control surfaces, and skid all separately before hinging
and final assembly. This way the parts are much easier to handle.
The following instructions provide advice and procedures specific to the Wonder. Be sure to read the two pages of step-
by-step, photo illustrated instructions included with each roll of Supercoat. If you choose another brand of covering
material, be sure to read the manufacturer's directions (supplied with the covering) and follow them carefully.
Surface Preparation
A good covering job starts with a 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 the entire model
with 220-grit sandpaper, then again with 360 or 400-grit sandpaper.
Since it's too difficult to apply covering material to F-1 and the inside of the cowl, they must be fuel-proofed using several
coats of clear dope or two coats of polyester (glass) resin, sanded between coats. Finish off the engine area with a few
coats of colored Sig Supercoat Dope. (Most of the Sig Supercoat Plastic Covering colors have a matching Sig Supcoat
Dope color.)
Covering The Fuselage
The fuselage should be covered with four pieces of material, starting with the bottom, followed by the two sides, and
ending with the top. If you're using more than one color, it may take more pieces of material. All seams should overlap
about 1/8". When covering solid wood surfaces like the fuselage sides, better results can be obtained by starting at the
center and working toward the outer edges, allowing air to escape as you iron.
Experienced modelers know that oily engine exhaust likes to creep into every crack it can find, which means special care
must be taken to keep the hatch area as fuel-proof as possible. When you cover the hatch, be sure to cover the front and
rear edges, and wrap the material around both sides about 1/4". The covering material on the fuselage sides should wrap
around the bottom in the hatch area as well as the wing saddle area.
Covering The Wing
Begin the wing by covering the wingtips and plywood hold down plate. Cover each wingtip with two pieces of material, first
the bottom and then the top. Seal each piece securely to the capstrip and sheeting for the end rib. Later, when the main
top and bottom covering pieces are applied, they will overlap the wingtip covering on the end rib. Cover the hold-down
plate with a single piece of material, extending it about 1/8" past the outside edges of the plate to provide an area for
overlap. Cover the main portion of the wing starting with the bottom and then the top so that the seams will be on the
bottom where they will be less visible. The top covering should overlap the full width of the leading edge and trailing edge.
Wait until both the top and bottom pieces of covering material have been sealed completely around the edges before
shrinking the large open areas between the ribs. Alternate between the top and bottom surface to avoid uneven shrinking
which could cause warp. Your sealing iron or a special heat gun can be used (household blow dryers don't provide enough
heat). Keep the heat gun moving at all times or you may burn a hole in the covering. If you notice the covering material
"ballooning up", put a small pin hole in the bottom of each rib bay to allow the expending air to escape.
Covering The Sheet Balsa Parts
The stabilizer, elevator, fins, ailerons, and canopy pieces should each be covered with two pieces of material - bottom first,
then top. Iron the material from the center out to avoid trapping air bubbles.
Don't be alarmed if these small parts bow slightly after covering just one side. This is a common condition that should
correct itself after covering the second side.