User's Manual

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Programming example - ﬁ xed-wing model

“Servo settings” menu (page 72)

rev cent

trav

100%

… ... you can set various parameters relating to the ser-

vos, i. e. “direction of rotation”, “neutral setting” and

“servo travel”, to suit the requirements of the model.

By “requirements” we mean adjustments to servo centre

and servo travel which are needed to compensate for

minor tolerances in servos and slight inaccuracies on

the model itself.

Note:

The facilities provided in this menu for setting asym-

metrical servo travels are NOT intended as a means of

setting up differential travel on ailerons and / or camber-

changing ﬂ aps. There are more suitable options for

this in the form of speciﬁ c functions in the “Fixed-wing

mixers” menu; see the ﬁ rst two options in the picture on

the right.

Once you have completed the settings described thus

far, a ﬁ xed-wing or powered model aircraft (the latter

if you enter the idle direction of the throttle stick in the

“Motor at Ch 1” line of the “Basic settings” menu) will,

in principle, ﬂ y.

However, there are no “reﬁ nements” in this set-up, and

it is the reﬁ nements which will give you more long-term

pleasure in your ﬂ ying. Assuming that you are already

capable of controlling your model safely, it’s time to get

a taste of these extra facilities; to this end we now move

on to the …

“Fixed-wing mixers” menu (pages 88 … 93)

–––

ail

diff aile.

rudd

flaps

brak

elev

flap

aile

elev

flap

aile

elev

flap

diff–red

aile

diff flaps

Note:

This men

u will show a varying range of options depend-

ing on the information you have entered in the “Basic

settings” menu. In the illustration above, the full range

is shown, as generated by the entries “2AIL 2FL” in the

“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 …

33112_mx12_HoTT_2_GB.indd Abs42:14833112_mx12_HoTT_2_GB.indd Abs42:148 06.06.2011 19:39:4606.06.2011 19:39:46