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15 Advanced Tuning Options
The helicopter can be tuned in a more detailed way using the settings on the
Advanced
tab of the USB interface program:
Maximum Rate:
The desired roll or pitch rate of the heli at maximum cyclic stick
deflection. Equivalent to the area of a flybar’s paddles. If increased, Bell gain
will also need to be increased slightly.
Bell Gain:
Amount of motion of the swashplate in response to cyclic stick
deflection. Normally set by a gain dial on the gyro’s case, that dial can be
disabled to lock the bell gain to a specific value.
When the gain dial is used, it will set the elevator bell gain, but the aileron
bell gain will be a fraction of that, by the ratio set here. Example: The
Advanced Tab shows Bell gains of 20% elevator and 10% aileron, and the gain
dial is not disabled. Then if the gain dial is set to 50%, the elevator bell gain
will be 50% and the aileron bell gain will be 25%.
Hiller Gains:
Similar to “heading hold” on a yaw gyro. Higher Hiller Gain is
equivalent to increasing the weight of a flybar’s paddles, and adds stability and
resistance to wind gusts. This feature gives the heli a “locked-in” feel. Slop-free
linkages, rigid rotorhead mechanics, stronger servos, and stiff blades allow
higher gains here.
The Hiller gain dial is used to set the elevator and aileron hiller gains in the
same manner as described above for the Bell gain dial.
Damping Gains:
Roll and pitch rate motion damping. Higher gain is equivalent to
having heavier rotor blades or a higher head speed, and helps with stability
during forward flight and pyros. Fast digital servos allow higher gain here. The
default gains are best for analog servos, but can be set to 20/16 for digital
servos. Appropriate Damping gains are normally about 1/3 as large as the Hiller
gains.
Tail Drag Compensation:
All helis have uneven drag on their airframes,
especially the tail.
For better piros and tick-tocks
, this feature lets you trim
out the effects that has during hard collective pitch use. To use this feature,
follow these three steps:
1)
Make sure your heli’s balance point is under the main shaft, or slightly
nose-heavy.
2)
Check that your swash is level at min, zero, and max collective pitch while
in Setup mode. On the servo tab, first adjust the swash to be level at zero
pitch using the trims, then use the servo travels to make sure the swash is
level at min and max collective. This is needed because servos are not all
identical; the pots that measure their position can vary by 10% or more.
3)
If the heli tends to nose-up when max collective is applied quickly from a
hover, subtract one from elevator tail comp. If the heli goes right, subtract
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one from aileron tail comp. Add one to the fields if it noses down, or goes
left.
Hiller Decay:
Causes accumulated Hiller response to decay back to neutral, to
make the gyro more forgiving of insults. If you watch a heli with a flybar in
hover, after a sharp control input you’ll see the flybar’s disk offset for a
moment, then drift back to level. This provides the same effect.
A value of 100% here can help smooth out rapid tic-tocks, piros, or other 3D
maneuvers, especially repeated ones. However, high values for Hiller Decay
will also limit the gyro’s ability to hold steady in gusty wind, or trim the heli
perfectly in hover.
Disable Gain Dials:
If enabled, the gain dials on the gyro itself will have no effect.
The gains will be taken straight from those entered in the gains setup tab.
Hiller Dial Also Scales Damping Gain:
If enabled, then the Hiller gain dial will
also adjust the damping gains, by the ratio of the Hiller Dial setting vs. the
elevator Hiller gain in the setup.
For example, if Elevator Hiller gain is 50% on the Advanced tab, the Hiller
Dial is set to 100%, and Damping is set to 20% for elevator on the Advanced
tab, the resulting damping gain would be 100/50*20 = 40%.
This can make it easier to re-tune the gyro when mechanical changes are
made that will affect the gains, such as to cyclic pitch or head speed.
Show Actual Gains:
Brings up a table of the actual gains the SK360 will use in
flight. These gains are based on the settings on the Advanced tab, modified by
the Bell and Hiller dial’s settings. This feature can help you understand how
the gain dials and base-gains work together.
Default Gains:
Resets all of the settings on the Advanced tab to those in the
Default setup file. Does not effect any settings on the other tabs.
