GRAUPNER mx-24s, Programming Manual

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190
fl ecting the inboard control surface(s) down increa-
ses lift and produces an up-elevator effect. Defl ec-
ting them up creates the opposite effect. In contrast,
the outboard ailerons have the reverse effect: a down-
defl ection produces a down-elevator effect, and vice
versa. In this case there are really no limits to what
you can achieve with careful thought and the sophis-
ticated mixers included in the software of the
mx
-
24s. This could extend to setting up curve mixers
which pass just a small degree of up / down travel to
the outboard pair of control surfaces, and only then at
fairly extreme stick travels. For his own model this wri-
ter uses a curve mixer defi ned by a total of four refe-
rence points, i. e.:
0%
m
OU
T
P
U
T
--
+
100
1 2
EL 5
+33%
0%
Point
Curve MIX 9
Input
Curve
off
Output
In this example the two reference points 1 and 2 are
set to 0%, the left end-point to +60%, and the right
end-point to -65%; the curve is then rounded off by
pressing the
ENTER button.
Please note that you should be extremely careful
when setting differential travel with such a confi gurati-
on, regardless of the type of servo arrangement your
model employs. This is because differential travels
on a tail-less model tend to produce an asymmetrical
elevator effect rather than the desired reduction in ad-
verse yaw. For this reason it is advisable to start with
a differential setting of 0% – at least for the fi rst few
fl ights. When you are familiar with the model and feel
the need to experiment, it may then be feasible under
certain circumstances to try differential settings devia-
ting from zero.
For larger models it may be advisable to install win-
glets fi tted with rudders, i. e. small vertical surfaces
Programming examples: Fixed-wing model
at the wingtips. If these are actuated by two separa-
te servos, the rudder signal can very easily be “split”
and differential applied by using one of the mixers in
the menu ...
»Dual mixers« (page 144)
… with the second rudder servo connected to a free
receiver output. In the case of a model with the “Del-
ta / fl ying wing” tail type, this might be receiver output
“5”, which we will use in the following example:
Diff.
SEL
? ? ? ? 0%
SEL
? ? ? ? 0%
SEL
5 RU +75%
D U A L M I X E R
Mixer
Mixer
Mixer 1
2
3
The differential travel is necessary in this case , since
the outside rudder turns through a larger radius than
the inside rudder when the model is fl ying a turn; this
is broadly analogous to the effect of front wheel toe-
in on a car.
Note:
This is the only possible method of programming dif-
ferential rudder travel!
You may also want both rudders to defl ect outwards
when a braking system is operated using the C1
stick, and this can be achieved by setting up a further
“LinearMIX C1
5” mixer with a suitable travel set-
ting. The offset should be set to “forward” (+100%) or
“back” (-100%) to suit your personal preference, but
the C1 stick is usually at the forward end-point when
the airbrakes are retracted, and the winglet rudders
are required only to defl ect outwards proportionally
when the brakes are extended.
Even though the default setting of all the inputs in
the »
Transmitter control adjust « menu is “free”,
you should still move to the fl ight phase independent
menu …
»MIX-only channel« (page 142)
… and, in the interests of safety, de-couple the
“wrong” control function from the control channel to
which the second servo is connected. In our example
this means setting control channel 5 to “MIX only”:
1 2 3 5 6 7 8 9 1112 4 10
M I X O N L Y C H A N N E L
MIXonly
normal