face. It is not necessary to use dual rates if you set some exponential into the ailerons and ele-
vators.
Ailerons:
10mm ‘up’ and 8mm ‘down’. Set about 40% exponential in the ailerons, as they
seem to get quite sensitive at slow speeds when the nose is raised for landing.
Elevators:
10mm ‘up’ and 10mm ‘down’. We also recommend about 30 - 40% exponential
on the elevators.
Rudder:
15mm ‘left’ and ‘right’.
Flaps:
About 10 degrees down for take-off, but not critical at all. For landing 45 degrees
is enough and if you use more it slows down very quickly indeed.
No gyro is needed, but of course it’s always nice to have one on the rudder and nose-steering for
cross-wind take-offs and landings.
Ground angle:
With the main and noseleg lengths shown in the manual, and same diameter wheels, the Sabre
should have the correct angle of incidence when sitting on the ground.
For nice smooth takeoffs, and landings that bounce-free landings, you can fine tune the main
and/or nosegear landing gear leg lengths a little if necessary to set the wing incidence at the root
to about +1 degree - and then the tips will have almost zero incidence, due to the wash-out in the
wing.
Flying the Sabre
It’s always a good idea to have an experienced jet pilot friend standing by your side for the first
flight. He can act as your timer, advise you when to land due to fuel, and watch for other traffic in
the circuit or hazards on the runway during landing - generally reducing your workload during the
test flight.
I use a little flap for take-off, about 10 degrees maximum, but it is not really necessary. Accelerate
slowly, keep it straight, and let it roll a long way for the first take-off. Lift off will be very smooth if
you have set the ground incidence angle as stated above. After lift-off, keep the motor at full power
for 5 - 10 seconds, retract the landing gear, and climb to get some height. Reduce to about half
power, turn down wind and check that the flaps are up. make some gentle , level, circuits and trim
the plane out on the elevator and ailerons. When it’s trimmed, get some more height, reduce power
to just above idle, and extend the flaps to landing position (45 °) to check that there is no induced
roll. The flaps are quite powerful and push the nose up a little, so you may need to hold in a bit of
‘down’ elevator, and then apply this as a mix with the flaps after your first flight.
The Sabre is quite fast, even without gear doors, and has a good glide - useful to know if you have
a flame-out ! I always do my low passes, long rolls and knife-edge passes in a ‘down-wind’
direction, so that if the turbine stops I only have to make a 180 ° turn to get back to the runway
and land into the wind. Although this was very important in the old ‘Ducted-fan’ days, it is still a wise
precaution, especially during first flights with a new model.
Don’t flare out too much for landing. Just make a very gentle low pass with about 30 - 40 degree
flap, cut the throttle to high idle, and let it settle on the main gear. In strong winds you wont’ need
to use the flaps at all. Later on, with more experience of the model, you can make short, steep land-
ings - but if you use lots of flap then the Sabre slows down really quickly and you will definitely need
to hold in a bit of ‘down’ elevator and keep some power on all the way to the threshold. At high an-
Fox Composites Co., Ltd.
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