GRAUPNER mx-16 ifs, Programming Manual

Page: 81 / 132

81 Program description: helicopter mixers – model helicopter
When you select auto-rotation, the mixer automati-
cally switches the value to a variable pre-set value;
see the section starting on page 86.
Helicopter with speed GOVERNOR (REGULATOR)
In contrast to speed controllers , which simply adjust
power output in the same way as a carburettor, speed
governors maintain a constant rotational speed in the
system which they regulate; they accomplish this by
adjusting the power output as required. In the case of a
glow-powered helicopter the governor automatically con-
trols the throttle servo; in an electric-powered machine
the governor does the same with the speed controller.
For this reason speed governors do not require a classic
throttle curve; they just need a pre-set rotational speed.
Once this is set, the system rotational speed does not
alter unless the system requires more power from the
motor than is available.
In most cases a speed
governor is connected to receiver
output 8; see receiver socket sequence on page 41. If
this socket is already in use, then the throttle limiter func-
tion is not used, since this only affects output 6 – which is
now not occupied – via the “Ch 1
¼
throttle” mixer.
However, if you wish to be able to exploit the conven-
ience and safety features of the throttle limiter, the speed
governor should be connected to receiver output 6 – in
contrast to the usual socket sequence – and the throttle
curve adjusted so that it can simply assume the role of
the “usual” transmitter control.
In this case the “throttle curve” only determines the
nominal rotational speed of the speed controller, and this
nominal value is required to remain constant over the full
range of collective pitch; for this reason a horizontal line
should be set in the “Ch 1
¼
throttle” mixer, i. e. every
(collective pitch) input value results in the same (“throt-
tle”) output value. The “height” of the line in the graph
determines the nominal system rotational speed.
Initially, then, reference point “3” should be erased, and
reference points “1” (input = -100%) and “5” (input =
+100%) set to the
same value; for example:
1
–100%
+ 30%
+ 30%
ch1 thro
input
output
point
normal
The value to be set varies according to the speed gov-
ernor you are using, and also to the desired nominal
rotational speed; you may wish to vary it, of course, in the
various fl ight phases.
When you select auto-rotation, the mixer automati-
cally switches the value to a variable pre-set value;
see the section starting on page 86.
ch1
¼
tail (static torque compensation)
3
0%
0%
0%
tail ch1
input
output
point
normal
The default setting is a torque compensation curve with a
uniform linear mixer input of 0%, as is required for a gyro
sensor operating in “heading lock mode”; see illustration
above.
Important note:
It is absolutely essential to read and observe the set-
up instructions supplied with your gyro before enter-
ing any settings at this point, as a mistake here could
render your helicopter completely uncontrollable.
If you use your gyro sensor in “normal” operating mode,
or if the gyro only offers “normal mode”, then you should
set up the mixer as follows:
The tail rotor control curve can be defi ned using up to
fi ve points, in a similar way to the collective pitch curve
(see previous page). You can therefore modify the mixer
at any time when required, and enter symmetrical or
asymmetrical mixer inputs both above and below the
hover point. However, please ensure at the outset that
you have entered the correct direction of main rotor rota-
tion in the »
base sett. « menu.
3
0%
0%
0%
tail ch1
input
output
point
normal
Starting from -30% at Point 1 and +30% at Point 5, this
mixer should be set up in such a way that the helicopter
does not rotate around the vertical (yaw) axis (i. e. does
not deviate from the hover heading) during a long vertical
climb or descent, due to the change in torque of the main
rotor. At the hover the yaw trim should be set using the
(digital) tail rotor trim lever only.
For a reliable torque compensation setting it is essential
that the collective pitch and throttle curves have been set
up correctly, i. e. that main rotor speed remains constant
over the full range of collective pitch.
When you select auto-rotation, this mixer is auto-
matically switched off.