Gyro System
SRVS G490T
SRVS gyro system, Order No. 5137
7
channel used for adjusting gyro gain; the area around the centre of its travel is used for this.
In the simplest case a slider or rotary control is employed on the transmitter, providing control
over the full range of this channel (100% - 0 – 100%). If this transmitter control is moved in
the one direction from centre, gyro gain increases in "normal" mode; if it is moved in the other
direction from centre, gyro gain increases in "heading lock" mode.
Since it is not normally necessary or sensible to switch between normal and heading lock
modes, wherever possible you should completely suppress the mode you do not wish to use,
and expand the adjustment range of gyro gain over the full travel of the transmitter control;
this is very simple to achieve, especially with sophisticated computer radio control systems
such as the mc-22, mx-22 and mc-24. Simply reduce the effect of the transmitter control to
about 40% and offset the centre by 60% in the appropriate direction; if necessary the
direction of effect of the transmitter control can then be reversed so that it works in the way
you wish.
In heading lock mode all mixers which affect the tail rotor must be switched off. Since the two
operational modes "normal" and "heading lock" require very different support in terms of
transmitter mixers, you should only ever switch modes by switching flight phases, so that
these requirements are taken into account automatically. However, a degree of instability is
inevitable when you switch between normal and heading lock mode, and this means that it is
essential to carry out a "hard" (sudden) switch between flight phases, i.e. without any time
delay. To date only the mc-24’s latest software solves this problem completely, as it is ca-
pable of switching individual channels "abruptly" when a "soft" flight phase switch is carried
out.
Note: when the model is on the ground, the neutral position of the servo in "heading lock"
mode may differ from the neutral position in "normal" mode. You may also find that the servo
does not return to centre in this situation after giving a control command. This is completely
normal and only ever occurs on the ground - never in flight.
Typical programming procedure with the mc-24 and PROFI-ROM:
The required end-result is (typically) two flight phases: Phase 1 ("Acro") in "normal" mode, and
Phase 2 ("Acro 3-D") in "heading lock" mode.
•
Assign the flight phase switch and phase names as described in the mc-24 manual.
•
In the "Transmitter control setup" menu for control 7 (gyro gain and normal / heading-lock
switch) assign slider 7 for both flight phases.
•
"Transmitter control setup" menu for input 7:
Flight phase "Acro":
Travel "SYM" to +40% Offset to +60%
Flight phase "Acro 3-D":
Travel "SYM" to -40% Offset to -60%
•
In the "Non-delayed channels" menu set channel 7 to "no delay".
•
For the "Acro " phase all the mixers in the "Heli mixers" menu which affect the tail rotor - roll -
> tail rotor, pitch-axis -> tail rotor, Ch1 -> tail rotor - can be used normally.
•
For the "Acro 3-D" phase switch off all the mixers in the "Heli mixers" menu which affect the
tail rotor: roll -> tail rotor, pitch-axis -> tail rotor, Ch1 -> tail rotor (in this case set all curve
points to "0" to produce a horizontal line).
•
Be sure to use the phase trims to store the tail rotor trim in both phases – don’t use the
global trim memory.
