User manual

127Program description - Control adjust | Helicopter models
just imagine what could happen if, while carrying the
helicopter to the take-off site with the motor running,
the C1 stick were to be inadvertently operated …
If the carburetor or speed controller is open too far
when the transmitter is switched on, an audible warn-
ing will be sounded and the basic display will show
the message:
Thr
too
high!
Tip:
Take advantage of the »Servo display« to observe
the influence of the throttle limit control. The »Servo
display« screen can be reached from almost any
menu position with a simultaneous tap on the  se-
lection keys of the left four-way button, Bear in mind
that servo output 6 controls the throttle servo on the
mc-16 HoTT and mc-20 HoTT transmitters!
Basic idle setting
Put the throttle limit into its “full throttle” position by
pushing the throttle limit regulator – by default, the
right side proportional slider Lv2 – all the way to its
forward position limit. Set the throttle/pitch stick to the
maximum pitch position and also check the sub-menu
“C1  Throttle” of the menu …
»Helicopter mixer« (beginning page 188)
… to ensure that a standard throttle curve is active. If,
for example, the standard throttle curve has already
been changed following the initialization of a model
memory then this must be at least temporarily reset
to the values “Point L = -0 %”, “Point 1 = +50 %” and
“Point H = +100 %”:
“Lim.”
The proportional slider Lv2, mounted on the right
side of the transmitter, is assigned by default to input
“Lim.”:
In5
offset
Thro
Gyro
Lim.
–––
–––
–––
Lv2
0%
0%
0%
0%
GL
GL
GL
GL
typ
fr
fr
fr
–––
SEL
This pre-assignment makes it unnecessary to pro-
gram the two flight phases as may be familiar from
use of other remote control systems – one “with idle-
up” and one “without idle-up” – because the given op-
tions of the transmitters mc-16 HoTT and mc-20
HoTT offers a much more flexible approach to fine-
tuning and optimizing increases to system rotational
speed below the hover point than the so-called “idle-
up”. If it is nevertheless preferable for the helicopter
to be programmed “with idle-up”, then deactivate the
“throttle limit” function described below by setting
input “Lim.” to “fr”.
Meaning and application of “throttle limit”
As already mentioned under “Throttle”, and in con-
trast to fixed-wing models, the power output of a
helicopter’s drive system is not controlled directly with
the C1 stick, but only indirectly via the throttle curve
settings in the »Helicopter mixer« menu or – if the
model features a speed controller – via that mecha-
nism.
Note:
Of course for different flight phases, flight phase
programming can be used to set individual throttle
curves.
Nevertheless, both methods of output control de facto
result in the helicopter carburetor never approaching
anything near its idle speed under “normal” flight con-
Throttle limit function
ditions, and that the motor can therefore neither be
started or stopped cleanly without some other means
of intervention.
The “throttle limit” feature resolves this problem ele-
gantly by using a separate transmitter control – by
default the Lv2 proportional slider mounted on the
right side of the transmitter – to limit the throttle servo
or the output level of a speed controller. In this way,
it is possible to “throttle back” with the throttle limit
control, even as far as the idle setting, at which point
the trim control for the throttle/pitch stick takes over
or directly shuts off an electric drive. Conversely, the
throttle servo or speed controller can only open up to
its full-throttle position if the throttle limit control has
also released the full servo travel path.
The value set on the (right-hand) plus side of the
“travel” column must therefore always be set high
enough to ensure that the maximum setting of the
throttle limit control never restricts the full-throttle
position achievable with throttle curve settings – which
typically means setting a value in the range +100 % to
125 %.
– travel +
+100%
+100%
+100%
Gyro
Lim.
+100%
+100%
+100%
+100%
normal
+125%
In5
Thro
The value on the (left-hand) minus side of the “travel”
column should be set so that the throttle limit control
can safely cut off an electric drive or close a carbure-
tor sufficiently to cut off a combustion motor in con-
junction with – digital – C1 trim. Because of this, leave
this value (initially) at +100 %.
Furthermore, this variable “limitation” of throttle travel
not only provides a convenient means to start and
stop the motor but may also prove to be more than
an insignificant safety improvement! For example,