Model menu
Collective pitch curve
F X - 4 0
19.1 COLLECTIVE PITCH CURVE SETTINGS
Operating the collective pitch stick moves the collective pitch
servo or servos, but also automatically operates the throttle
servo. The match between collective pitch and throttle is very
important, and for this purpose the collective pitch function can
be assigned one of six possible curve types, each of which can
be allocated a maximum of seventeen variable points. The FX-40
also offers switchable flight modes which enable the pilot to set
up the optimum collective pitch curve for each flight mode indivi-
dually.
As soon as you select a Helicopter as the model type, the scree-
n’s basic display changes: the second stopwatch (Timer2) disap-
pears, and its place is taken by the current throttle and collective
pitch settings, reflecting the actual position of the throttle / col-
lective pitch stick. This means that you always have this impor-
tant information right in front of your eyes. The screen shot below
shows just such a display.
To move to the collective pitch curve set-up screen, mark this
option in the Model menu (‘Helicopter’ type already selected).
The screen now looks like this:
While you are programming a collective pitch curve, you may find
it helpful to display the collective pitch values as angles instead
of percentage figures. You can make this change by marking the
‘Unit’ field; the currently selected unit is always displayed in this
field. Mark this point, and the screen looks like this:
For the model helicopter application, the throttle and collective
pitch functions are always intimately connected. It therefore
makes obvious sense to have direct access to the throttle
function from the collective pitch curve set-up screen. You can
switch to AFR programming for the throttle function by mar-
king the appropriate field in the first line; the active display
always has a red background. It is possible to determine whet-
her the settings are to apply to all flight modes (Glob) or only to
the currently active flight mode (Sepa) using the ‘Glob’ or
‘Sepa’ button field. The change takes place when you confirm
the security query.
• Programming collective pitch curves
This menu is used for setting up the collective pitch curves
in the following flight modes:
Normal:
for starting and stopping the motor
Idle-up 1:
for hovering
Idle-up 2:
for circuits
Idle-up 3:
for aerobatics
Auto-rotation:
for auto-rotation landings
Flight modes 6 - 8:
for any other purpose
If you wish to set up different collective pitch curves, you must
first switch from group mode (Glob) to individual flight mode
(Sepa). You can switch between these two curves (flight
modes) by operating the switch (flight mode switch) assigned
to that mode (see Section 17.1, page 55). When you switch the
transmitter on, the Normal flight mode must be selected; if not,
the mixer alarm sounds. The RF section can only be switched
on in ‘Normal’ mode.
Collective pitch curves are programmed using the familiar pro-
cedure. First you have to define the curve type: five curve
types are available via the corresponding fields, in addition to
the standard linear curve. The values are adjusted exactly as
described for programming the Dual Rate curves; please refer
to this in Section 17.2 on page 58.
This shows a typi-
cal collective pitch
curve for the
‘NORMAL’ flight
mode; the base
curve is a linear
type. The curve
should be pro-
grammed in such
a way that motor
speed remains as nearly constant as possible over the full
range of collective pitch travel . For most applications a five-
point curve is sufficient for this purpose.
A typical curve for
the ‘Idle-up 1’
flight mode; the
base curve is a
linear type. In this
case the values
are optimised for
the hover, so that
the motor main-
tains the correct
speed for all collective pitch settings. For most applications a
three-point curve is sufficient.
A typical curve for
the ‘Idle-up 3’
flight mode; the
base curve is a
linear type. In this
case the values
are optimised for
aerobatics, so that
the motor main-
tains the correct
speed for all collective pitch settings. For most applications a
three-point curve is sufficient.
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