Adjusting The Throttle And Collective Pitch Curves - GRAUPNER mx-16 ifs Programming Manual

Adjusting the throttle and collective pitch curves

A practical procedure
Although the throttle and collective pitch control systems
are based on separate servos, they are always operated
in parallel by the throttle / collective pitch stick (except
when auto-rotation is invoked). The Helicopter program
automatically couples the functions in the required way.
mx
In the -16iFS program the trim lever of control func-
tion 1 only affects the throttle servo, i. e. it acts as idle
trim (see "Digital trims" on page 34).
The process of adjusting "throttle" and collective pitch
correctly, i. e. setting the motor's power curve to match
the collective pitch setting of the main rotor blades,
is the most important aspect of setting up any model
mx
helicopter. The program of the -16iFS provides inde-
pendent adjustment facilities for the throttle, collective
pitch and torque compensation curves.
These curves can be defi ned using a maximum of fi ve
reference points. To defi ne the control curves all you
have to do is set individual values for these fi ve points in
order to determine each control curve.
However, before you set up the throttle / collective pitch
function it is important to adjust the mechanical linkages
to all the servos accurately, in accordance with the set-
up notes provided by the helicopter manufacturer.
Note:
The hover point should always be set to the centre
position of the throttle / collective pitch stick.
Idle setting and throttle curve
Note:
Since electric power systems by their nature require no
idle setting, it is not necessary to adjust the idle value.
However, the matching of the throttle and collective pitch
curve(s) must still be carried out as described here, in a
similar way to a glow-powered helicopter.
The idle setting is adjusted solely using the trim lever
of the Ch 1 function, with the throttle limiter closed, as
described in detail on pages 63 and 64. Reference point
1 of the throttle curve defi nes the throttle setting when
the helicopter is in a descent, but without affecting the
hover setting.
This is a case where you can exploit fl ight phase pro-
gramming to use different throttle curves. An increased
system rotational speed below the hover point proves to
be useful in certain circumstances; for example, for fast,
steep landing approaches with greatly reduced collective
pitch, and for aerobatics.
+100%
The diagram shows a curve with
a slightly altered throttle setting
below the hover point at the centre -100%
of stick travel.
Different throttle curves are programmed for each fl ight
phase, so that you can use the optimum set-up both for
hovering and aerobatics:
• Low system rotational speed with smooth, gentle
control response and low noise at the hover.
• Higher speed for aerobatics with motor power settings
close to maximum. In this case the throttle curve also
has to be adjusted in the hover range.
The basic set-up procedure
mx
Although the
range of adjustment for the collective pitch and throt-
tle curves, it is essential that you fi rst adjust all the
mechanical linkages in the model according to the
information supplied by the helicopter manufacturer, i. e.
all the system linkages should already be approximately
correct in mechanical terms. If you are not sure of this,
any experienced helicopter pilot will be glad to help you
with this basic set-up.
The throttle linkage must be adjusted in such a way
that the throttle is just at the "fully open" position at the
full-throttle setting, or the speed controller or an electric
helicopter is set to full-power. When the throttle limiter
is at the idle position, the Ch 1 trim lever should just be
able to close the throttle completely, without the servo
striking its mechanical end-stop (quick throttle adjust-
ment using the "digital trim": see page 34). With an
electric helicopter the motor should stop reliably when
the throttle limiter is closed.
Take your time, and carry out these adjustments very
carefully by adjusting the mechanical linkage and / or
changing the linkage point on the servo output arm or
the throttle lever. Only when you are confi dent that all is
well should you think about optimising and fi ne-tuning
1 2 3 4 5
Control travel
the throttle servo using the transmitter's electronic facili-
ties.
Caution:
Read all you can about motors and helicopters, so
that you are aware of the inherent dangers and the
cautionary measures required before you attempt to
start the motor for the fi rst time!
Program description: helicopter mixers – model helicopter
-16iFS transmitter provides a broad
83