GRAUPNER MC-22S, Programming Manual

Page: 100 / 180

100 Program description: Mixers
Throttle setting: “Thr setting AR”
In a competition the pilot is expected to cut the motor
completely, but for practice purposes this is certainly
not advisable. Instead set the throttle so that the mo-
tor runs at a reliable idle during auto-rotation, so that
you can open the throttle immediately to recover from
an emergency.
Tail rotor setting: “tail rotor offset AR”
For normal fl ying the tail rotor is set up in such a way
that it compensates for motor torque when the heli-
copter is hovering. This means that it already genera-
tes a certain amount of thrust even in its neutral posi-
tion. The level of thrust is then varied by the tail rotor
control system, and also by the various mixers which
provide all manner of torque compensation, while the
tail rotor trim is also used to compensate for varying
weather conditions, fl uctuations in system rotational
speed and other infl uences.
However, in an auto-rotation descent the main rotor
is not driven by the motor, and therefore there is no
torque effect for which compensation is required, i.e.
which the tail rotor would have to correct. For this re-
ason all the appropriate mixers are automatically swit-
ched off in auto-rotation mode.
However, the basic tail rotor setting must be different
for auto-rotation, as the corrective thrust described
above is no longer required.
Cut the motor and set the helicopter horizontal. With
the transmitter and receiving system switched on,
fold both tail rotor blades down and change the blade
pitch angle to zero degrees using the “Tail rotor off-
set” menu. Viewed from the tail, the tail rotor blades
should now be parallel to each other. Depending on
the friction and running resistance of the gearbox, you
may still fi nd that the fuselage has a slight yawing ten-
dency in an auto-rotation descent. The relatively small
torque which causes this effect must then be correc-
ted if necessary by adjusting the tail rotor blade pitch
angle. This value will always be a small fi gure bet-
ween zero degrees and a pitch angle opposed to the
direction of tail rotor pitch required for normal fl ight.