Carf-Models Ultra Lightning Instruction Manual page 25

We have also included 2
Festo 4mm barbed Tee's for
connecting the 2 'feed' and
'overflow' tubes from the
main tanks together, in par-
allel, as shown in the instal-
lation photos.
Connect the main tanks
together, with equal lengths
of tube (supplied), in paral-
lel, and then take a single
tube from the Festo Tee to
the 'fill' inlet at the top of the
hopper tank.
Connect the vent/overflow
tube from the Tee to a short
length of brass tube and fit
this in your chosen position in the bottom of the fuselage. You can fit this just inside the back
edge of the nosegear opening, so that is hidden in flight (and cannot get damaged) but 'overflow'
fuel comes out though the nosegear door when it is on the ground being fuelled, and also if you
put the plane on its nose for wing attachment etc. A better choice is to position the 'overflow/vent'
tube towards the back of the plane (behind the main tanks) so that no fuel leaks out when you
hold the plane on its nose during assembly and attaching the wings etc. for flight.
Important Note: Please wash out your fuel tanks carefully before final assembly and installation
in the plane to remove any particles from the manufacturing and joining processes.
Hopper Tank
Also included is a 300ml (10 ounce) hopper tank, and all the
hardware required to complete and install it in the plywood
sleeve in the bulkhead behind the cockpit, for visibility and
easy maintenance. Wrap the plywood sleeve tightly around
the hopper tank with the bubble on the tank in the 'U' shaped
cutout, and temporarily secure with a couple of rubber
bands while you join it with CA. Lightly sand the outside of
the plywood sleeve and then glue it in the circular cutout in
the top of the bulkhead just behind the cockpit with some
epoxy/micro mixture (see photo above). The 'U' shaped
cutout should be at the top (12 o'clock position). Leave the
tank in place while the glue cures to make sure you have a
tight sliding fit after afterwards. It is not necessary to secure
the tank in any other way.
Our preferred method is to have a felt clunk (eg: Webra
#1121) fixed to the end of the feed tube that goes to the fuel
pump, in the 3-dimensional centre of the fuel tank. In 'IN'
tube that goes to the top of the tank is connected to the 2
main fuel tanks, via a 'Tee' piece. If you wish you can fit a
3rd tube for filling the fuel system. Alternatively you can
install a quick-connect Festo (or similar) fitting between the
(above) Hopper tank located in
plywood sleeve.
(below) Hopper tank and sleeve
installed in bulkhead.
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