Handleiding Robbe Futaba FX-40 (pagina 94 van 105) (Engels)

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Model menu

Collective pitch -> needle valve

Collective pitch -> tail rotor

FX-40

19.7 COLLECTIVE PITCH -> NEEDLE VALVE MIXER

This function is used to program an automatic needle valve

djustment which follows the movement of the collective pitch

stick. It enables you to set the optimum fuel mixture at the car-

burettor (by adjusting the needle valve) whenever the load on

the motor alters due to changes in the pitch angle of the rotor

blades. An acceleration option can also be programmed to

optimise this function.

With the ‘Helicopter’ type already selected, mark this option in

the Model menu. The screen display now looks like this:

The first step is to activate this mixer in the standard manner:

simply mark the Status field, and the label in the field changes

from ‘INA’ to ‘ON’ or ‘OFF’, according to the physical position

of the switch. Define a switch and its direction of operation in

the standard way, using the ‘Switch’ column. The default set-

ting is ‘NONE’, i.e. the mixer is always switched on. The

effects and method of setting the ‘Glob’ or ‘Sepa’ mode have

already been described; the function is programmed in the

appropriate switch field.

An acceleration function can be programmed in a separate

frame. This function is described in full in Section 19.3 on page

88. You can enter a separate percentage value (Rate) for each

mixer, for both maximum travels of the collective pitch stick

(Min. and Max.): mark the field and enter the values required

using the arrow buttons. The setting is displayed in the field as

a percentage value. It is also possible to enter a percentage

value in the ‘Damping’ field; this determines how long the

function is to remain active once the change in setting has

been carried out.

In the bottom line you can define a point for both sides which

represents the position from which the function is to take

effect: move the transmitter stick to the desired position, and

mark the associated field. The software stores the trigger value

and the field displays the position.

The mixer function is actually set up with the help of the asso-

ciated curve using the familiar method. First define the curve

type, then program the curve using the standard procedure:

the first step is to select the curve type, then enter the curve

points separately for the left side (Rate A) and the right side

(Rate B). The method of programming a mixer curve is exactly

as described in Section 17.2 on page 58; please refer back to

that section if you are not sure.

The screen shot below shows an example of a programmed

‘Collective pitch -> needle valve’ curve.

19.8 COLLECTIVE PITCH -> TAIL ROTOR MIXER

(REVOLUTION MIXER)

The purpose of this function is to detect torque fluctuations at

the main r

otor, caused by changes to the throttle or collective

pitch settings, and pass that information to a mixer which con-

trols the tail servo, so that the tail rotor always generates the

appropriate corrective torque, thereby more or less eliminating

unwanted moments around the vertical (yaw) axis. If this mixer

is set up accurately, it greatly eases the task of the tail rotor

gyro system. However, an incorrectly set mixer of this type

(also known as a Revo mixer) will interfere with the gyro’s pro-

per function. For this reason it is particularly important to set

up this mixer accurately. An acceleration function can be pro-

grammed to optimise this function.

If a modern gyro is installed, and operated in heading-hold /

AVCS mode, the revolution mixer must always be switched off.

With the ‘Helicopter’ model type already selected, mark the

Revolution mixer (Collective pitch -> tail rotor) in the Model

menu. The screen now looks like this:

The first step is to activate the mixer in the usual way: simply

mark the Status field, and the label in the field changes from

‘INA’ to ‘ON’. The effects and method of setting the ‘Glob’ or

‘Sepa’ mode have already been described; the function is pro-

grammed in the appropriate switch field.

An acceleration function can also be programmed in a sepa-

rate frame. This function is described in full in Section 19.3

(Acceleration) on page 88. You can enter a separate percen-

tage value (Rate) for both maximum deflections of the collec-

tive pitch stick (Min. and Max.): mark the field and enter the

values required using the arrow buttons. The setting is dis-

played in the field as a percentage value. You can also enter a

percentage value in the ‘Damping’ field to indicate a time; this

determines how long the function is to remain active once the

change in setting has been carried out. In the bottom line you

can define a point for both sides which represents the position

from which the function is to take effect: move the transmitter

stick to the desired position, and mark the associated field.

The software stores the trigger position, and displays it in the

field.

The mixer function is actually set up with the help of the asso-

ciated curve in the usual way: first define the curve type, then

enter the curve points separately for the left side (Rate A) and

the right side (Rate B). The method of programming a mixer

curve is exactly as described in Section 17.2 on page 58; refer

back to that section if you are not sure.

Please be extremely cautious when making these adjust-

ments, and carry out any changes in small steps. Check all the

settings very carefully before eventually moving on to very

careful test-flights. From a stable hover the helicopter should

exhibit no tendency to rotate around the vertical (yaw) axis

when you open the throttle or increase the collective pitch set-

Robbe Futaba FX-40 Handleiding

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