Carf-Models Ultra Flash, Instruction Manual

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tral fin, as shown, to allow extra cooling air to enter the outer
thrust tube - and this is especially important if you fly in high
ambient temperatures. They should be approx. 60mm long
and 30mm wide. On both prototypes, with these intakes, the
fuselage did not get warm - even after 2 or 3 minutes of
engine idling in ambient temperatures of around 30° C. See
template at end of Manual for shape.
Engine and Bypass/Inlet Joiner Installation
Turbine installation is extremely simple with easy access
thru’ the large wing opening. It is a fully-bypassed system,
using a new carbon composite bypass duct, and a sepa-
rate fibreglass joiner to connect the bypass to the inlet
ducts that are already installed for you at the factory.
We recommend a turbine of 8 - 12kg thrust, and the proto-
types have been flown extensively with both Jetcat P70
and P120. Both give more than adequate performance,
and take-off from grass is only about 75metres with the
P70 - and any similar turbine in this thrust range will be
suitable. The bypass duct is 135mm diameter, which suits
installation of turbines up to a maximum of 116mm max.
diameter. With the recommended receiver and turbine bat-
teries positioned in the pockets either side of the nosegear,
you will find that Centre of Gravity is easily set without
adding any additional weight in the nose.
IMPORTANT: Please note that the Flash is designed for a
maximum turbine thrust of 1
4
kg (1
4
0 Newtons) and this
must not be exceeded. All the photos in this section show
a JetCat P1
2
0 installed.
Large engine mounting:
If fitting a ‘standard-sized’ 116mm diameter turbine (eg:
Jetcat P80 or P120) secure the engine mount to the motor
with the glowplug (or kerosene start) orientated as shown
(see photo P6).
Most brands of turbine have slightly offset mounting brack-
ets (eg: JetCat), and in this case you should pack them off
the ply mounting rails with plywood spacers to get the tur-
bine in the precise vertical centre of the bypass, which is
very important for the best performance and cooling of the
motor and thrust tube. For Jetcat P80 or P120 this spacer
should be 5mm thick. Cut the spacers from the 3mm x
12
(above) Glue spacers onto the
factory-installed engine mounting
rails to centre your turbine in the
bypass as necessary.
(above) Inlet ducts are factory-
installed and painted for you.
(below) General view of P120
installed in carbon bypass duct.