GRAUPNER MC-22S, Programming Manual

Page: 105 / 180

105 Program description: Mixers
shown on page 102: this is the elevator trim mixer „6
EL“, to which switch 6 has been assigned:
L i n e a r M I X 1 6 E L 6 o f f = >
L i n e a r M I X 2 ? ? ? ? - - - -
L i n e a r M I X 3 ? ? ? ? - - - -
L i n e a r M I X 4 ? ? ? ? - - - -
t y p e f r o m t o A d j u s t
S E L
t
S E L S E L
Use the rotary control to move the inverse video fi eld
to the bottom line and onto the arrow:
. A brief
press on the rotary control now switches to the se-
cond screen page:
L i n e a r - M I X 1 6 E L
o f f
If this display does appear, you have not activated the
mixer by operating the assigned external switch – in
this case “6”.
To correct this, operate the switch:
L i n e a r - M I X 1 6 E L
M i x i n p u t O f f s e t
+ 0 % + 0 % 0 %
®
O
U
T
P
U
T
-
+
10
0
S T O A S Y S Y M C L R
The solid vertical line in the graph represents the cur-
rent position of the transmitter control assigned to in-
put 6. The solid horizontal line shows the mixer ra-
tio, which currently has the value “zero” over the who-
le stick travel; this means that the elevator will not “fol-
low” when the fl aps are operated.
The fi rst step is to defi ne the offset ( mixer neutral
point ):
The dotted vertical line indicates the position of the
mixer neutral point (“offset”), i.e. that point along the
control travel at which the mixer has
no infl uence on
the channel connected to its output. As standard this
point is set to the centre position.
In our example the neutral position of the fl aps is lo-
cated at the forward end-point of the slider, and for
this reason no elevator trim correction is necessa-
ry at this point; we must therefore shift the mixer neu-
tral point exactly to that point. Move control 6 in the di-
rection of +100%, select
STO using the rotary control
and press the rotary control briefl y. The dotted verti-
cal line now moves to this point – the new mixer neu-
tral point – which
always retains the “OUTPUT” value
of zero in accordance with the mixer defi nition.
As it happens, this setting is diffi cult to show in a
screen shot, so we will change the “offset” value to
just +75%.
L i n e a r - M I X 1 6 E L
M i x i n p u t O f f s e t
+ 0 % + 0 % + 7 5 %
®
O
U
T
P
U
T
-
+
10
0
S T O A S Y S Y M C L R
(You can automatically reset the mixer neutral point to
centre by selecting
CLR ).
Symmetrical mixer ratios
The next step is to defi ne the mixer values above and
below the mixer neutral point, starting from the cur-
rent position of the mixer neutral point. Select the
SYM fi eld, so that we can set the mixer value sym-
metrically relative to the offset point we have just pro-
grammed. Press the rotary control briefl y, then set the
values in the two left-hand inverse video fi elds within
the range -150% to +150%. Remember that
the set
mixer value always refers to control travels value! Set-
ting a negative mixer value reverses the direction of
the mixer, while pressing the CLEAR button erases
the mixer ratio.
The “optimum” value for our purposes will inevitab-
ly need to be established through a fl ight testing pro-
gramme.
L i n e a r - M I X 1 6 E L
M i x i n p u t O f f s e t
+ 2 0 % + 2 0 % + 7 5 %
®
O
U
T
P
U
T
-
+
10
0
S T O A S Y S Y M C L R
Since we previously set the mixer neutral point at
+75% of control travel, the elevator “EL” will alrea-
dy exhibit a (slight) down-elevator effect at the neu-
tral point of the landing fl aps, and this, of course, is
not wanted. To avoid this problem we shift the mixer
neutral point back to 100% control travel, as descri-
bed earlier.
If you were now to reset the offset from 75% to, say,
0% control travel, the screen would look like this:
L i n e a r - M I X 1 6 E L
M i x i n p u t O f f s e t
+ 2 0 % + 2 0 % 0 %
®
O
U
T
P
U
T
-
+
10
0
S T O A S Y S Y M C L R