Composite-ARF SuperXtra 330L
(3.1m span)
Cowling
Finished in 2 hours
Attaching the 2 piece cowling is quite easy, as it is already
cut and trimmed at the factory, and should need almost no
adjustment for a perfect fit.
Sand the inside surface of both side (horizontal) flanges to
ensure a good gluing surface, and glue the 8 small pieces
(size 10 x 20mm) of 3mm milled plywood onto the flanges
of the bottom part of the cowling (4 each side), spaced
equally from the back to the front (see photos). The front
edge of the front piece should be 35mm (1.5”) from the
front of the cowl to clear the end of the mounting flange.
You can tack them in place with thick CA, and then rein-
force with 30 minute epoxy and microballoons mix.
Then take the bottom half and drill 3mm holes through the
dimple in either side, which match up with the dimple on the
fuselage, which also need to be drilled 3mm Ø. Do the
same by drilling the 2 holes in the back edges of the top half
of the cowling also, in the marks/dimples that are moulded
in. Temporarily bolt the bottom and top halves in place on
the fuselage with two M3 bolts and blind nuts on the inside
(inverted), and check for good fit. Tape the rest of the bot-
tom and top halves firmly in place, ensuring a flush fit with
the fuselage, and no gaps. If necessary you can sand the
inside back edges of both halves of the cowling to have a
perfect flush fit with the fuselage.
Now check the fit of the overlaps of the 2 halves of the
cowling, and sand the inside edges a little if needed for a
flush fit. When happy, tape together firmly and drill through
the joining flanges into the 8 plywood pieces, and secure
with 2.2mm ø x 10mm sheetmetal screws provided. The
holes for these small screws should be exactly 5mm from
the bottom edge of the top half of the cowling. The rearmost
2 screws will need to be shortened after fitting, otherwise
they will touch the motor dome. Just cut them off flush with
the inside of the plywood pieces.
The cowling is retained on the fuselage with 9 bolts M3 x
12mm and blind nuts. Drill one 3mm diameter hole at the
top/centreline of the cowl, approx. 10mm from the back
edge of the cowling, and insert an M3 x 12mm bolt and then
glue an M3 blind nut inside the fuselage with one drop of
thick CA glue. Don’t forget to rough up the area inside the
fuselage with coarse sandpaper first to ensure a good glue
bond. Note that the blind nuts are fitted
reversed
, with the
spikes pointing inwards! Check alignment again, and then
drill and fit the other 6 bolts in the same way, securing the
blind nuts to the inside of the fuselage with a single drop of
thick CA. Don’t forget to wax, or oil, the M3 bolts first, to
15
(above and below) Drill the
moulded-in marks in the fuselage
and both cowling halves and retain
with M3 bolts to ensure perfect
alignment.
