Carf-Models Composite-ARF Yak-55 SP Instruction Manual page 36

Composite-ARF Yak-55 SP (2.6m span)
Fuel tank
The fuel tank is held to the tank base with 3 large cable-ties
(see photo on page 30). We used a Dubro #690 tank, but
depending on your choice, you might need to make some
extra notches in the fuel tank base for the cables ties, as
shown in the photo here.
Drill a hole in the motor firewall where necessary for the fuel
feed tube from the tank to the carburettor, and protect it
where it passes through the hole using a rubber grommet
or similar. Make sure there are no loose fuel tubes that can
come in contact with the hot motor, headers or exhaust sys-
tem.
Fit the correct stopper to the fuel tank for the fuel type used.
(If using Dubro tank the gasoline stopper has a small 'O' moulded in the top of it). We use the
excellent 'Tygon' brand of fuel tubing for all our models. It is totally gasoline and kerosene-proof,
and does not go hard and crack with age. Secure the feed tube inside the tank to the clunk with
a small cable tie.
If the tube is even a little loose on the brass tubes though the stopper, you can be absolutely
sure it will come off at precisely the wrong moment and your engine will quit ! Therefore please
solder some small rings onto both ends of the brass tubing (easily made from the soft wire of a
paperclip wrapped around a small screwdriver) and also secure with a fuel-line clamp or cable-
tie. Dubro Fuel barbs are an excellent alternative, but becoming more difficult to obtain now.
Don't miss this small detail - it could cost you your plane !
We use the normal 3 tube plumbing system, one from the clunk to feed the motor, one out of the
bottom of the plane (vent/overflow - leave open) and one at the top for filling (close for flight).
Final check
Now check that you have fixed all components securely. Keep in mind that all the components
inside the aircraft are loaded with the same G's as the wing and the wing spar during aerobatic
maneouvres. Check engine, cowling, wing and stab mounts carefully again.
Are all extension leads, cables and fuel tubes securely fixed to the side of the fuselage
and cannot come loose when subjected to high 'G' forces during flight.
Are all tubes and wires protected from chafing where they pass thru' the holes in fibre
glass parts or bulkheads with rubber grommets, or short lengths of split silicone tubing?
Especially if you have installed the internal mini-pipe set-up, you also must make sure
that no fuel tubing or wires can come into contact the exhausts. Use the plastic spiral-
wrap to tidy up groups of cables and make sure that they cannot move around in the
plane under high 'G' manouevres by fixing them to the sides with small cable ties. If using
the easily-available cable-tie plastic fixing plates, please do not trust the double-sided
tape that they usually have on them which can fail under vibrations. Peel it off, rough up
the back face with coarse sandpaper and glue to the fuselage sides with 30min. epoxy.
Did you fit small Tygon or silicone tube pieces over all the quick-links?
Did you tighten the M3 locknuts against all the quicklinks to make sure they cannot turn?
techsupport@composite-arf.com
(above) Make sure that the fuel
feed tubes cannot come off in
flight by using Dubro fuel line
barbs, or making your own with a
small ring of soft wire soldered on.
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