GRAUPNER mc-16 Programming Manual page 71

Descending Flight Setting
During the previous setting it was assumed that any
external switches possibly attached for throttle and
pitch curve change-over were in the basic position,
i.e. that for the hovering flight throttle setting "TM0"
(or without an external switch the only option
available is "TM1" which was used instead of "TM0").
This switching position is always selected when
starting the engine and the rotor. To fly you move the
switch from the start into the flight position, (throttle
preselect is switched on and the display shows
"TM1").
Before the next setting you should transfer the value
for hovering flight throttle "TM0", determined during
the preceding adjustments into "TM1". Switching
from the start to the flight position should show no
effect now.
The switch is brought to the flight position and the
rotor is started.
The descending flight setting is adjusted as follows.
Let the model, from forward flight at a reasonable
height, sink with the collective pitch stick fully back.
"PL1" (pitch minimum) should be adjusted so that
the model descends at an angle of 60 – 80°. Once
this is achieved one sets the throttle preselect value
("TL1") so that the rotor RPM neither increases or
decreases. Once this has been managed, the basic
tuning of throttle and pitch is complete.
Alternative Flight Setting
For special applications you can program an
alternative flight setting, which can be switched to
when required.
It is possible for example to set "TL2" to "0" whereby
a throttle hold results. The throttle is no longer
affected below the point of hovering flight as the
collective pitch reduces, but remains to a constant
value. Above the point of hovering flight the throttle
control takes place normally via the throttle /
collective pitch control stick.
With some model helicopters such a setting can
have advantages during aerobatics, for example with
models with four-stroke motors.
A further application possibility for this alternative
setting is the hovering flight figures of the FAI
competition program. In order to achieve the full rotor
RPM in the take-off phase, you again select "0" for
"TL2". For the normal flying operation this setting is
not recommended as during steep descending flight
the rotor RPM will increase rapidly leading to flight
instability. After the hovering flight figures are
completed you switch back to the normal flight
setting ("TM1") for the aerobatics figures.
Important Notes
Before starting the engine you should make sure that
throttle selector switch is in the start position,
otherwise after starting the engine will immediately
increase to high RPM and the centrifugal clutch will
engage.
Therefore always hold the
rotor head when starting
If the engine should be started inadvertently with
throttle pre-select switched on:
Do not panic!
Hold the rotor head rigidly!
Do not release it under any circumstances!
even if the result is that the clutch is damaged! The
repair of a clutch is negligible compared to the
damage, which uncontrolled with the rotor blades
can cause striking things around the model.
The changeover from start to flight setting should not
be done at the no load pitch position.
The rotor is accelerated suddenly which can lead to
a premature lock of clutch and transmission system.
Also the free moving main rotor blades do not
stabilise during such a jerky acceleration and can
swivel far from their normal positions, which can in
extreme cases lead to a tail boom strike.
Helicopter 71