GRAUPNER MC-22S, Programming Manual

Page: 97 / 180

97 Program description: Mixers
ting all the mechanical linkages in the model in accor-
dance with the information supplied by the helicopter
manufacturer, i.e. all the system linkages should al-
ready be as close to absolutely correct as possible in
mechanical terms. If you are not sure how to achie-
ve this, an experienced helicopter pilot will be glad to
help you with the basic mechanical set-up procedure.
The throttle linkage must be adjusted in such a way
that the carburettor is just at the “fully open” position
at the full-throttle setting. When the throttle limiter is at
the idle setting, the Ch1 trim lever should just be able
to close the carburettor barrel completely, without the
servo striking its mechanical end-stop (servo stalled).
Take your time, and carry out these adjustments very
carefully by altering the mechanical linkage and / or
changing the linkage point on the servo output arm or
the throttle lever. Only when you are confi dent that all
is well should you start optimising and fi ne-tuning the
throttle servo using the electronic facilities.
Caution:
Read all you can about motors and helicopters,
so that you are aware of the dangers inherent
in this activity, and the cautionary measures re-
quired before you attempt to start the motor for
the fi rst time!
With the basic set-up completed, it should be possib-
le to start the motor in accordance with the operating
instructions supplied with it, and to adjust the idle set-
ting using the trim lever of the throttle / collective pitch
stick. The idle position which you set is indicated in
the transmitter’s basic screen display by a horizontal
bar at the display of the Ch1 trim lever’s position. Re-
fer to page 32 of this manual for a full explanation of
the digital trims.
The following procedure assumes that you wish to set
up your helicopter “normally”, i.e. with the hover point
exactly in the centre of the stick arc. Roughly at the
mid-point of the collective pitch stick the model should
lift off the ground and hover at the rotational speed
you wish to use. If this is not the case, the settings
can be corrected as follows:
1. The model does not lift off until the collective
pitch stick is above the centre point
2. The model lifts off below the centre point
Important:
you should persevere with this adjustment until the
model hovers at the correct rotational speed at the
centre point of the throttle / collective pitch stick’s tra-
vel. All the other model settings depend upon the cor-
rect setting of this parameter!
The standard set-up
The remainder of the standard adjustment procedu-
re is completed on the basis of the fundamental set-
up which you have just carried out, i.e. the model ho-
vers in normal fl ight at the centre point of the throttle
/ collective pitch stick at the correct rotational speed.
This means that your model helicopter is capable of
hovering and also fl ying circuits in all phases whilst
maintaining a
constant system rotational speed .
The climb setting
The combination of throttle hover setting, collective
pitch setting for the hover and the maximum collecti-
ve pitch setting (“Collective pitch high”) now provides
you with a simple method of achieving constant sys-
tem rotational speed from the hover right to maximum
climb.
Start by placing the model in an extended vertical
climb, holding the collective pitch stick at its end-point:
motor speed should not alter compared with the ho-
ver setting. If motor speed falls off in the climb, when
the throttle is already fully open and no further power
increase is possible (this assumes that the motor is
correctly adjusted), then you should reduce the ma-
ximum blade pitch angle at full defl ection of the coll-
ective pitch stick, i.e. in the “collective pitch high” po-
sition. Conversely, if motor speed rises during a ver-
tical climb, you should increase the blade pitch ang-
le. This is carried out by selecting the point “H” (high)
and changing the reference point value using the ro-
tary control.
- +
10
0
L H
1
Stick travel
Hover
point
b) Rotational speed too high
Remedy: increase the bla-
de pitch value for
collecti-
ve pitch at the stick centre
setting; this is carried out
in the
“Collective pitch cur-
ve” menu.
- +
10
0
L H
1
Stick travel
Hover
point
a) Rotational speed too high
Remedy: reduce the thrott-
le opening in the
“Channel
1 throttle” mixer at the
stick centre point.
-
+
10
0
L H
1
Stick travel
Hover
point
- +
10
0
L H
1
Stick travel
Hover
point
b) Rotational speed too low
Remedy: reduce the bla-
de pitch value for
collecti-
ve pitch at the stick centre
setting; this is carried out
in the
“Collective pitch cur-
ve” menu.
a) Rotational speed too low
Remedy: increase the va-
lue for the throttle servo
parameter at the centre
point of the stick travel in
the
“Channel 1 throttle”
mixer.
OUTPUT
OUTPUT
OUTPUT
OUTPUT