Graupner Hendheld RC 2.4 GHz No. of channels: 12 33124 데이터 시트

175

Practical approach

Although the throttle and collective pitch control systems 
are based on separate servos, they are always operated 
together by the throttle/collective pitch stick (except 
during auto-rotation fl ight). This coupling is performed by 
the helicopter program automatically. 
In the 

mx-20 HoTT program, the trim lever of control 

function 1 acts principally only on the throttle servo. 
However, in the "Stick mode" menu (see page 94) 
you can determine whether this should be used for idle 
trimming as part of the throttle limit function, or for idle 
trimming during the auto-rotation phase ("throttle AR").
The process of fi ne-tuning throttle and collective 
pitch, i. e. setting the motor power curve to match the 
collective blade pitch setting, is the most important 
aspect of setting up a model helicopter. The 

mx-20 

HoTT software provides for independent confi guration 
of the throttle, collective pitch and torque compensation 
curves, in addition to the C1 control curve ("Channel 1 
curve" menu, page 119). 
While these curves can be modeled using up to 
six points, fewer points are generally suffi cient. We 
recommend starting with three-point curves to begin 
with. This involves setting individual values for the center 
point and other (optional) reference points, and for the 
two end-points ("L", "low", and "H", "high") of the throttle/
collective pitch stick: together, these defi ne the control 
curves. 
Before setting the throttle and collective pitch function, 
however, you should accurately calibrate the mechanical 
linkages for all the servos, following the set-up 
instructions for the helicopter in question.

The idle setting described in detail on pages 105 to 
107 always takes place with the throttle limiter closed  –  
normally with the trim lever of the C1 function and only 
in special cases is the throttle limiter itself also utilized 
(as standard, the CTRL 6 proportional rotary control). 
The programming of a corresponding value for the "L" 
point of the throttle curve acts to set the descent speed 
of the motor, without infl uencing the hover confi guration.
Here, for example, you can use fl ight phase 
programming in order to confi gure a range of throttle 
curves. This 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. 

The screen image depicts a curve 
with a slightly changeable throttle 
setting below the hover point at 
the control center. 

Different throttle curves are programmed for each fl ight 
phase, so that you can use the optimum set-up for both 
hovering and aerobatics:

Low system rotational speed with smooth, gentle 

• 

control response and low noise when hovering
Higher rotor speed for aerobatics with motor power 

• 

set close to the maximum. In this case, the throttle 
curve must also be adjusted in the hover range. 

While the 

mx-20 HoTT transmitter permits the 

electronic confi guration of collective pitch curve and 
throttle curves to a large degree, fi rst ensure that you 
have correctly set all of the model's mechanical linkages 
as specifi ed by the helicopter manual. Experienced 
helicopter pilots will be glad to help you with this basic 
set-up.
The carburetor linkage must be set so that the throttle is 
just past the fully open setting with collective pitch set to 
maximum or, for electric helis, with the speed controller 
set to full. When the throttle limiter is closed, however, 
it must be possible to just close off the carburetor using 
the C1 trim lever (rapid throttle setting of the "digital 
trim", see page 54), without the servo mechanically 
striking its end-stop. For electric helis, it must be 
possible to cut the electric motor's speed controller 
safely with the throttle limiter closed.
Take great care when confi guring these settings, by 
adjusting the control linkage as required and/or altering 
the linkage point on the servo or carburetor lever. Only 
then should you optimize throttle servo fi ne-tuning 
electronically.