GRAUPNER mx-20 Hott Programming Manual page 148

Mixer functions
The individual options on the "Wing mixers" menu
option are discussed below, separately for single-, dual-
and multi-fl ap models. Before we start, a number of
remarks on the differentials for ailerons and fl aps:
Aile. diff. or Diff. ( Aileron differential)
WING MIXERS
Brake settings
Aile.diff.
AI RU
EL AI 0%
Normal
AI +100%
AiI-tr +100%
Diff.
fl.pos
Normal
AILE
For aerodynamic reasons, the drag generated on
an aileron oriented downwards is greater than that
generated by the same aileron when it is oriented
upwards by the same amount. One effect of this unequal
distribution of drag produces is a yawing motion around
the vertical axis and, accordingly, a "turning away"
from the intended direction of fl ight, which is why this
undesirable side effect is also termed "adverse yaw".
This effect is naturally greater on the comparably long
aerofoils possessed by model gliders, compared to e. g.
powered aircraft models, which generally have relatively
short moment arms. For the former, it must normally
be compensated for by making a simultaneous rudder
defl ection in the opposite direction. However, this rudder
148 Detail program description - Control adjust
defl ection also generates drag and therefore further
reduces the aircraft's effi ciency.
If, on the other hand, a differential is applied to the
aileron orientations, by giving the aileron oriented
downwards a smaller defl ection than the aileron
oriented upwards, the (undesirable) adverse yaw can
be reduced – and possibly entirely negated. However,
the basic precondition for this is that each aileron must
have its own servo present, which can therefore also
be embedded straight into the aerofoils. In addition, the
0%
shorter linkage paths produce an additional benefi t:
0% –––
reproducible aileron confi gurations that also exhibit less
0% –––
"play".
0%
0%
Unlike mechanical solutions, which not only commonly
need to be designed and built in when constructing
the model but also produce a slightly increased "play"
in the control system for strong differentials, the
transmitter-based differential typically used today offers
considerable benefi ts.
The degree of differential can be changed at any
time, for example, and, in extreme circumstances, the
downward defl ection of an aileron – in what is termed
a "split" position – can be suppressed entirely. This
approach not only reduces or even suppresses "adverse
yaw", but can, in certain circumstances, even generate
a positive yaw: in such cases, an aileron command will
generate a yaw about the vertical axis in the direction
of the turn. For large glider models in particular, this
approach lets such aircraft fl y "clean" turns using just
the ailerons, which is not otherwise possible unaided.
The adjustment range of -100% to +100% makes it
possible to set a differential appropriate for each side,
regardless of the direction of rotation of the aileron
servos. While "0%" corresponds to a normal linkage, i. e.
no differential, "-100%" or "+100%" represents the "split"
function.
For aerobatic fl ying, low absolute values are required to
ensure the model rotates exactly along its longitudinal
axis when an aileron command is given. Values near
0% (normal)
to the center (-50% or +50%) are typical for facilitating
turns in thermals. The split setting (-100%, +100%) is
popular with slope fl yers, where ailerons alone are often
50% (differential)
used for turning the model.
If you tap the  or  keys on the right touch
pad (CLEAR) at the same time, this will reset values
100% (split)
changed in the active (highlighted) fi eld back to 0%.
Note:
Negative values are not usually necessary if channels
are assigned properly.