Carf-Models Ultra Flash, Instruction Manual

Page: 18 / 44

Fuel System.
The standard Flash kit includes a single composite fuel
tank (2.2 litres) that installed in the fuselage above the
inlet ducts, and a hopper tank that is installed in the cock-
pit area. If you are installing a turbine of 9kg thrust or
more, you will also need to install the optional wing fuel
tank (1.4 litres) to give reasonable length flight times.
Important Note: Please wash out all fuel tanks carefully
before final assembly and installation to remove any parti-
cles from the manufacturing and joining processes.
Fuselage Tank:
The fuselage tank is pre-joined and tested at the factory
and has a central baffle installed to prevent fuel surge and
Centre of Gravity changes during aerobatic manoeuvres.
It is installed above the inlet ducts on 2 composite glass-
balsa plates that you need to fit.
Trim the flanges all around the back of the cockpit open-
ing by about 3 - 4mm so that you can push the fuel tank
into place. Don’t trim them too much - the tank should still
be a little tight to push into the fuselage at the top. Also
trim the horizontal flanges at the back of the cockpit area
for about 35mm length (behind the canopy hook slots),
which makes it easier to get the tank in and out of the
fuselage. (see photos right)
Position the front face of the fuel tank about 10mm (3/8”)
behind the back of the cockpit opening. Cut 2 strips of the
3mm thick composite balsa-fibreglass sheet provided,
both 25mm wide, to secure the back end of the tank.
Sand the surfaces of the fuselage, and glue the horizontal
strip across the fuselage first with slow epoxy. Then shape
the ‘stop’ that fits vertically behind it to match the fuselage
shape and glue it in place. Finally reinforce the glue joints
with a couple of pieces (approx. 60mm x 40mm) of the
200 gram fibreglass cloth provided and slow (24hr) lami-
nating resin.
Cut another strip of the composite balsa 152mm wide and
50mm deep, to make the front tank support. Taper the
sides a little so that it is about 148mm wide at the back to
match the shape of the fuselage. With the tank in place
against the back stop, fit this strip under the front of the
tank as shown here, with 2 scrap pieces of 3mm balsa or
plywood as temporary packers between the strip and the
bottom of the tank. These packers are important! (see
photo P8)
The front edge of the tank support should be about 5 -
16
(above) The fuselage tank com-
pleted, ready for installation.
(below) Trim the flanges of the
cockpit area as shown to fit the
the fuel tank.
(above) Rear fuel tank support
reinforced with fibreglass cloth.
(below) Tack front front tank sup-
port in place with 3mm thick
packers under the tank.