All tanks are leak-tested at the factory, but we
strongly recommend that you double-check them
before installing in your plane! Block one of the tubes
and blow into the other with your mouth while the
tank is under water to check for integrity. Do
not
pressurise tank with any type of air pump. Wash out
the tanks before fitting the stoppers, to make sure
there are no particles inside that could get into the
turbine fuel system. We use petrol/gasoline for
washing tanks out, and then discard it afterwards.
Make up the stoppers, bending the brass tubes as
shown. Extend the brass vent/fill tube inside the tank
with a short length of Tygon so that it reaches the
top of the tank and allows you to fill it completely.
Make sure that the clunk weights do not quite touch
the back of the tank in any position. We recommend
that you either solder on proprietary ‘fuel barbs’,
such as the Dubro ones shown, or very short lengths
of 1/8” I.D brass tubing to make sure that the fuel
tube cannot slide of the the Ø 1/8” brass feed tubes
- or have any chance of an air leak.
It is up to you whether you connect the main tanks
together in ‘series’ or ‘parallel’, but in our experience
we seem to get less air in the hopper tank when they
are connected in series. We recommend that you fit
a small ‘hopper’ tank (approx. 125cc/4 oz capacity)
between the main tanks and the turbine fuel pump to
exclude air from the system that could cause a
flame-out. It is your choice, but we have had suc-
cess using both the BVM UAT and the Intairco ‘Air-
trap’ tank (part # IAC-216R). There is plenty of space
to fit it in the back of the cockpit area,
between the stiffening rails, where it
will also be visible after each flight to
check for air.
If you have chosen to fit a turbine at
the upper end of the recommended
thrust range you may wish to install a
3rd fuel tank of about 300cc (10 fl.oz)
to give you longer flight time, and
there is plenty of space to fit this in
front of the rear cockpit bulkhead,
below the hopper tank.
In all circumstances, follow your tur-
bine manufacturers instructions and
recommendations for the fuel system
connections & installation.
Fox Composites Co., Ltd.
24
(below) Close-up of stopper assembly,
with barbs soldered onto brass tubes.
(above) Intairco ‘Air-Trap’ is an excellent
and inexpensive hopper tank (125ml).
(below) Tubes from tank can pass above
or below inlets into cockpit area. Turbine
services pass thru’ a hole in rear cockpit
bulkhead as shown here.
