GRAUPNER MC-22S, Programming Manual

Page: 98 / 180

98 Program description: Mixers
Once the model descends reliably as described, ad-
just the value for “Throttle low (L)” so that system ro-
tational speed neither increases nor declines during
the descent. This completes the set-up procedure for
throttle and collective pitch.
Final important notes
Before you start the motor, check carefully that the
throttle limiter is completely closed, so that the throttle
can be controlled by the trim lever alone. If the thrott-
le is too far open when you switch the transmitter on,
you will see and hear a warning. If you ignore this and
start the motor with the throttle too far advanced, the-
re is a danger that the motor will immediately run up
to speed after starting, and the centrifugal clutch will
engage at once. For this reason you should
always grasp the rotor head
fi rmly when starting the motor.
However, if you accidentally start the motor with the
throttle open, the rule is this:
Don’t panic!
Hang on to the rotor head regardless!
Don’t let go!
Immediately close the throttle, even though there may
be a risk of damaging the helicopter’s drive train, be-
cause:
YOU must ensure that the helicopter
cannot possibly move off by itself
in an uncontrolled manner.
The cost of repairing a clutch or even the motor itself
is negligible compared to the damage which a model
helicopter can cause if its spinning rotor blades are
allowed to wreak havoc.
Make sure that nobody else
is standing in the primary hazard zone
around the helicopter.
It is important never to switch abruptly from idle to the
fl ight setting by suddenly increasing system rotational
speed. This would cause the rotor to accelerate quik-
kly, resulting in premature wear of the clutch and gear
train. The main rotor blades are generally free to swi-
vel, and they often cannot keep pace with such swift
acceleration; they may respond by swinging far out
of their normal position, perhaps resulting in a boom
strike.
Once the motor is running you should slowly increa-
se system rotational speed using the
throttle limiter ;
if you have assigned an external switch for the thrott-
le limiter, we strongly recommend that you program a
time constant of about fi ve seconds for running up the
system rotational speed (opening the throttle limiter),
but
zero time delay for closing the throttle limiter. The-
se values are set in the » Control adjust « menu; see
page 62.
Now bring the model back to the hover, which again
should coincide with the mid-point of the Ch1 stick. If
you fi nd that the collective pitch stick now has to be
moved from the mid-point in the “higher” direction,
then you should correct this deviation by increasing
the collective pitch angle at the hover until the model
again remains stationary at stick centre. Conversely, if
the model hovers below the mid-point, correct this by
reducing pitch angle again. You may fi nd that it is also
necessary to correct the throttle opening at the hover
point.
Continue adjusting these settings until you really do
achieve a constant rotational speed over the full ran-
ge between hover and climb.
The descent setting
The descent adjustment should now be carried out by
placing the model in a descent from forward fl ight at
a safe height by fully reducing collective pitch; adjust
the collective pitch minimum value (“Collective pitch
low”) so that the model descends at an angle of 60°
… 80°.
- +
1
10
0
L H
Hover
point
Stick travel
OUTPUT
This diagram only shows the changes to
the collective pitch maximum value “H”.
-
+
10
0
L H
1
1
OUTPUT
Stick travel
This diagram only shows the change in
the hover point, i.e. collective pitch mini-
mum and maximum have been left at
-100% and +100% respectively.
This diagram only shows the changes to
the collective pitch minimum value “L”.
-
+
1
10
0
L H
Hover
point
Stick travel
OUTPUT