GRAUPNER mx-24s, Programming Manual

Page: 82 / 216

82
Program description: Transmitter controls
Control adjust
Throttle limit function
Throttle limit: Input 12 (throttle limit and C1 trim, throttle limit and Expo throttle limit)
The meaning and application of “Throttle limit”
In contrast to fi xed-wing models, the power output of
the motor or engine in a model helicopter is not con-
trolled directly using the C1 stick, but only indirectly
via the throttle curve settings set up in the »
Helicop-
ter mixers « menu. (For separate fl ight phases you
can set different throttle curves using fl ight phase pro-
gramming.)
Note:
In the case of a model helicopter with a speed gover-
nor (regulator), this device assumes the task of cont-
rolling motor power.
Generally speaking, for this reason the motor of a he-
licopter never even approaches idle speed in “normal”
fl ying operations; this applies whether throttle control
is by conventional means or is based on a speed go-
vernor. The net result is that the motor can neither be
started nor stopped effi ciently without some additio-
nal means of intervention.
That is why Input “12” is reserved for the “Throttle li-
mit” function in the »
Control adjust « menu of the He-
licopter program. Using a separate transmitter control
– by default the right-hand side-mounted proportional
control – the setting of the throttle servo connected to
receiver output 6 can be
limited to any level you wish,
i. e. you can use it to reduce the “throttle” setting to
idle, or alternatively even close the carburettor com-
pletely. On the other hand the throttle servo can only
follow the throttle curve and open up to its full-throttle
position if the throttle limit control has “released” the
full servo travel.
The value set on the (right-hand) “+” side of the “-tra-
vel+” column must therefore always be set to a high
level, so that the maximum setting of the throttle li-
mit control never restricts the full throttle setting which
can be obtained using the throttle curve. This usually
means a value in the range +100% to 125%:
0% +100%+100%
Thr.l +125%
offset
SEL ASY SYM ASY SYM SEL
– –time+
0%
0%
0%
+100%+100%
+100%+100%
+100%
0.0 0.0
0.0 0.0
0.0 0.0
0.0 0.0
«normal »
Input
Input
Input
Cnt. 9
free
free
free 9
10
11
12
In contrast, the value on the left-hand side of the
“-” column should be set in such a way that the
motor runs at a reliable idle when the throttle limiter is
at its rear end-point, but without preventing the (digi-
tal) C1 stick controlling it. For the time being it is safe
to leave this value at 100%.
Basic idle setting
Start by moving the throttle limiter – by default the
right-hand side-mounted proportional control – to its
forward end-point, and check that “Throttle limit” is se-
lected in the “(Collective) Pitch / throttle” line of the
menu …
»Stick mode« (page 77)
Pitch/thr
Roll
0.0s 0.0s
Pitch ax. 0.0s 0.0s
Tail rot. 0.0s 0.0s
Tr.step
SYM ASY SEL
global
global
global
Trim
4
4
4
4 0.0s 0.0s
–time+
SEL
Thr Lim
… and that a standard throttle curve is in force, as
shown in the “Channel 1
throttle” sub-menu of the
menu …
»Helicopter mixer«, (page 122)
Channel 1
Input
Curve
off 1
m
OU
T
P
U
T
-- +
1
10
0
«normal »
-100%
Output
Point
Throttle
-100%
-100%
If this is not the case, the result can be unpleasant in-
teractions between the various options which infl u-
ence the throttle servo.
Finally move the throttle / collective pitch stick trim le-
ver to centre.
Now adjust your throttle servo, preferably mechani-
cally and if necessary also using the travel adjust-
ment facility for servo 6 in the »
Servo adjustments «
menu, so that it reaches both full-throttle and idle, and
is able to stop the motor reliably when the digital trim
is operated.
To conclude this basic set-up procedure, move the
throttle limit control to the idle end-stop, and move to
the »
Transmitter control adjust « menu. Adjust the
value in the “Throttle limit 12” line on the “left-hand”
“-” side of the “-” column until the throttle limiter
no longer affects the idle range set by the C1 trim le-
ver, e. g.:
0% +100%+100%
Thr.l +125%
offset
SEL ASY SYM ASY SYM SEL
– –time+
0%
0%
0%
+100%+100%
+100%+100%
0.0 0.0
0.0 0.0
0.0 0.0
0.0 0.0
«normal »
Input
Input
Input
Cnt. 9
free
free
free
+125% +85%
9
10
11
12
Throttle limit in conjunction with the digital trim:
If you move the C1 trim in a single movement from
the established idle position of the motor to the “Motor
stopped” end-point, a marker is left at the point of the
previous idle position, and another at the end of the
trim travel – see following illustration. Starting from
this marker, a single click in the Idle direction imme-
diately restores the motor’s original idle setting; see
also page 34.
With the throttle limiter set up correctly as described,
all you have to do before you start the motor is to
move the throttle limiter in the direction of motor idle,
and set the throttle / collective pitch stick to around
centre.