Great Planes Piper J-3 Cub 20 Kit - GPMA0158 - Manual (Page 36)

Special Notes For Covering The Cub 20 Fuselage:
The idea is to make the Great Planes Cub 20 appear to
have an "open structure" like the full-size Piper Cub
Therefore, the covering is not bonded to, or touching much
of the fuselage structure On the fuselage sides, the only
areas where the covering is bonded to the frame are along
the bottom edge, the side stringer and pushrod exits, from
the fuselage front to about 1/2" aft, stringers on the
turtledeck, wing saddle, cabin window frame corners, tail
fairing block, a 1/4" wide strip along the bottom of the
stabilizer and the fuselage rear Bond the MonoKote film to
these areas but use a heat gun to shrink the covering over
the rest of the structure Use a piece of masking tape to lift
the covering anywhere it was accidentally stuck down
The covering on the fuselage should be bonded to the
entire fuselage bottom and upper front deck Be sure
to use a Hot Sock when ironing down the covering to
sheeted surfaces
Recommended Covering Sequence:
1 TE surfaces of wing
2 Bottom of left wing panel
3 Bottom of right wing panel
4 Top of left wing panel (overlap covering 1/4" at wing LE
and wing centerline)
5 Top of right wing panel (overlap covering 1/4" at the LE
and wing centerline)
6 Tail Junction Strips as described above
7 Stab bottom
8 Stab top
9 Fin left and right side
10 Fuse bottom
11 Fuse sides
12 Fuse top
13 Rudder left and right side
14 Bottom of elevators
15 Top of elevators
16 Die-cut landing gear fairing
17 Ends of ailerons
18 Bottom of ailerons
19 Top of ailerons
20 Wing struts
Paints Used On The Prototype:
There are several parts on the Cub 20 that require painting
Two-part epoxy paints such as K&B or Hobbypoxy are
highly recommended where durability and fuel resistance
are important On the Cub 20 we used an airbrush to apply
Hobbypoxy primer and Hobbypoxy Cub Yellow on the cowl,
hub caps, windshield and fuel cap We brush painted the
cabin interior with the same paint We used Testers chrome
and black to paint the dummy engine, then fuelproofed it
with Hobbypoxy clear Testors paint was also used on the
pilot figure An alternative to Hobbypoxy is Top Flite
LustreKote - available in aerosol cans LustreKote is
fuelproof and is a perfect color match to MonoKote film
Surface Preparation:
Degrease and clean all plastic parts with rubbing alcohol,
then allow to dry before proceeding Mask off the area on
the windshield that will not be painted with masking tape.
Examine the photos on the box to determine which portions
of the windshield are to be painted Lightly sand the area
with 400-gnt sandpaper and wipe clean Spray the cowl,
windshield and hubcaps with a thin coat of primer The
primer provides a good base coat for the paint to adhere to
It's best to allow the primer to dry overnight before sanding
Wet sand the primer with 320 and 400-gnt sandpaper using
a block where possible.
Color Application:
Two-part epoxy paints are not difficult to use if you have
spray equipment or an airbrush Use equal parts of the
mixed color paint (Part A) and gloss hardener (Part B), then
stir well Use about 1/3rd of the total volume of parts A and
B combined, of Hobbypoxy thinner Remember to use an
approved respirator or mask, and spray paint in a well
ventilated area.
D 1 Fuelproof the firewall We recommend brushing on
one of the following 30-minute epoxy thinned with a little
alcohol, polyester resin, or fuelproof paint or dope.
D 2. Fuelproof any external wood that is exposed
D 1. Our prototype Cub 20 uses a 4 oz. Great Planes fuel
tank with the right-angle fuel supply nipple to avoid kinking
the fuel tube Attach 1/2" foam rubber on top, bottom and
sides of the tank Mount the foam rubber to the tank floors
and fuselage sides with double-sided tape to make sliding
the fuel tank in and out easier Also, attach a piece of foam
rubber to the front of the fuel tank to prevent it from hitting
the firewall Cut two 8" pieces of medium fuel tubing Mark
a "P" on both ends of one piece of fuel tubing and a "V" on
both ends of the other fuel tubing Insert the fuel tubing
through the holes in the firewall Set the fuel tank in the
fuselage Connect the fuel tubing marked "P" on the fuel
pickup nipple and the tubing marked "V" on the vent nipple
Slide the fuel tank into the fuel tank compartment while
carefully pulling the fuel tubing out the front of the firewall
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