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3)
Trim the swash for level hover. On a day with light wind, temporarily set the
Hiller Decay to 200%, and hover the helicopter hands-off, both nose-out and
nose-in. If it consistently drifts to its right, left, forward or back, adjust the
mechanical linkages to the swashplate to eliminate the drift. Note that the
swash will not be perfectly level as some sideways tilt is necessary to
counteract the sideways thrust of the tail rotor.
4)
Adjust the
Tail Drag Compensation
on the
Cyclic
gain banks in the PC setup
software. (See Figure 17.2 below) On a day with light wind, start from a
hover and then apply maximum positive collective. If the helicopter’s nose
goes up, lower the
Tail Drag Comp
number for
Elevator
by 1 or 2 steps. If
the nose goes down, increase the
Elevator
value by 1 or 2 steps. If the
helicopter banked the right or left, you may also have to adjust tail drag
compensation for Aileron. If it banked right, decrease the value.
NOTE
: Tail Drag Compensation is only a coarse setting; it doesn’t need to be set
precisely.
Figure 17.2 – Tail Drag Compensation setting
5)
Adjust the collective-torque compensation for the tail. (See Figure 17.3
below.) Start from a hover and then apply maximum positive collective. If
the tail goes right, increase the value for “Collective to Tail” on the Tail tab.
If it goes left, decrease that value.
Figure 17.3 – Collective-Torque Compensation setting
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6)
Turn on the
Self Tune Bell Gains
option on one or both Cyclic tuning banks.
For each of those banks, fly the helicopter as you normally would for at least
four flights. Use the SK720 setup software to disable self-tuning once the
gains stop changing much.
