User's Manual

146
Programming example - fi xed-wing model
“Ail/Flap” line, and “none (/inv) in the “Motor at Ch 1” line.
Of particular interest at the moment are “AIL-Diff.”
(aileron differential) and the “AIL ¼ RUD” (aileron ¼
rudder) mixer, sometimes known as a combi-switch,
and perhaps the mixers “Brake ¼ AIL” and “Brake ¼
FLAP”.
As already described in detail on pages 89 and 90, the
purpose of “AIL-Diff.” (aileron differential) is to eliminate
adverse yaw.
When a model aircraft turns, the down-going aileron
produces more drag than the up-going one if both move
through the same angle, and this causes the model to
yaw in the opposite direction to the turn. This can be
eliminated by setting differential aileron travel. A value
between 20% and 40% is usually a good starting point,
but the “perfect” setting nearly always has to be estab-
lished by practical testing.
The same applies to the “FL-Diff.” (fl ap differential)
option if your model also features two camber-changing
fl ap servos, assuming that the fl aps are also to be used
as ailerons, e. g. using the “AIL ¼ FL” mixer.
The “AIL ¼ RUD” (aileron ¼ rudder) mixer serves a
similar purpose, but also makes many models generally
easier to handle when turning. A value of around 50%
is usually a practical starting point. However, it is advis-
able to be able to switch this function off, particularly if
you have ambitions as an aerobatic pilot; this is done by
assigning a physical switch to the mixer (for example,
the writer switches this mixer off “automatically” when he
switches into the “Speed” fl ight phase, simply by assign-
ing the same switch to both options).
It is usually only necessary to set up a “Brake ¼ ELE”
(brake ¼ elevator) mixer if your model suffers an
excessive change of speed when you deploy the brak-
ing system. The danger is that you might need to retract
the brakes again on the landing approach when you
realise the model will “land short”; if its airspeed is too
low when you retract the brakes, the model will just fall
to the ground at that point. If you set up such a mixer it is
important to test the setting at a safe height, and adjust
the trim compensation if necessary.
If you have selected “2AIL” or “2AIL 2FL” in the “Aileron /
Flap” line of the “Basic settings” menu …
stick mode
motor on C1
1
no
tail type normal
CH8 delay
aile/flap 2aile
yes
… and if you wish to be able to defl ect both ailerons up
using the throttle / brake stick (Ch 1), then a suitable
value should be entered in the “Brake ¼ AIL” line.
0%
0%
0%
0%
–––
–––
–––
–––
–––0%
ail
diff aile.
rudd
brak
brak
elev
aile
elev aile
In principle the same applies to the “Brake ¼ FL” line,
which also becomes available if you have selected “2AIL
2FL”, although the set value should cause the fl aps to
defl ect as far as possible in the downward direction
when the brake stick is operated. It is important to en-
sure that the servos do not strike their mechanical end-
stops. To achieve this, you may need to limit the servo
travel(s) for the servos concerned using the “TRAVEL-”
or “TRAVEL+” line on the “RX SERVO” display page of
the “Telemetry” menu.
If the ailerons are set up to act as simple brakes, as de-
scribed previously, or as part of the braking arrangement
in a butterfl y (crow) system, then you should always
enter a value for “Diff.-Red.” (“differential reduction” -
see page 93) - selecting 100% is the safe option here!
Differential reduction means that aileron differential is
suppressed proportionally only when you operate the
airbrake stick. The purpose of this is to increase the
down-going aileron travel on the landing approach, with
the aim of improving aileron response.
If the wing is equipped with two camber-changing fl ap
servos in addition to two separately actuated ailerons,
then the “AIL ¼ FL” (aileron ¼ fl ap) mixer transfers
the aileron movements to the fl aps; we suggest that the
fl aps should not follow the movement of the ailerons to a
greater extent than about 50%.
Note:
If you have only installed one fl ap servo, you should
leave this mixer at 0%.
The “FL ¼ AIL” (fl ap ¼ aileron) mixer works in the
opposite direction; depending on the layout of the model
we suggest values between about 50% and 100% for
this option. The fl aps are controlled using the transmitter
control or switch assigned to the input “E6”. Preferably,
however, one of the rotary proportional controls (CTRL 6
… 8) should be used for this.
Note:
We strongly recommend that you reduce the travel of
the fl aps to about 25% in the “Transmitter control
settings” menu, as this gives fi ner control of the fl ap
positions using the selected transmitter control.