User manual

203Program description - Helicopter mixer / Auto-rotation setting
Tail rotor AR
In normal flight, the tail rotor is set so that it compen-
sates for motor torque while the model is hovering. It
therefore generates some a certain amount of thrust
even in its normal position. 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, fluctua-
tions in system rotational speed and other influences.
For auto-rotation, however, the main rotor is not driv-
en by the motor, but by the “windmill” principle. Since
this, in turn, does not generate any torque for which
the tail rotor must compensate, all corresponding mix-
ers are switched off automatically.
Since the absence of torque in auto-rotation also
means the above-mentioned thrust is superfluous,
however, a different tail rotor configuration is also
required:
Cut the motor and place the helicopter on the ground
in a level attitude. With the transmitter and receiving
system switched on, select the flight phase “Auto-
rotation” and then fold the tail rotor blades down. Now
change the value on the “Tail rotor” line until the tail
rotor blade angle of attack is zero degrees. Viewed
from the tail, the tail rotor blades should be parallel to
one another.
Depending on the friction and running resistance
of the gearbox, the fuselage may still yaw slightly,
however. This relatively slight torque must then be
corrected if necessary by adjusting the tail rotor blade
pitch angle. This value will always be a figure between
zero degrees and a pitch angle opposed to the pitch
angle in normal flight.