Basic Tuning; Advanced Tuning For 3D Pilots - Skookum SK720 User Manual

16 Basic Tuning

Definitions:
Tail gain adjusts the holding ability of the gyro in yaw (rudder).
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Cyclic gain adjusts the stability and holding ability of the gyro for
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aileron (roll) / elevator (pitch).
Note: The Tail Gain and Cyclic Gain values are overall gains, which are
multiplied by the Base Gains which can be set by advanced users.
Follow these steps:
1) As a starting point, for most helis adjust the gains for the SK720 to about
50% for the Cyclic gain and 50% for the tail gain. But for very small
helis, start with 40% for the Cyclic gain, and 30% for the tail gain.
2) Lift the helicopter off into a hover and try some small elevator and aileron
motions. If it oscillates or does anything violent as you spool up, email
Skookum Robotics technical support for help before flying again.
3) Incrementally adjust the tail gain to the maximum value possible without
seeing any oscillation during hover or after sharp stick motions.
4) If the helicopter doesn't hold well in pitch or roll or "slides" to the side, turn
the Cyclic gain up a small amount. If the helicopter oscillates while
hovering, turn the Cyclic gain down slightly. Repeat until you get the best
gain.
5) Try some forward flight. If the helicopter oscillates in roll at high speed, turn
the Cyclic gain down a small amount. If it doesn't hold well, turn the Cyclic
gain up.
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 significantly.
7) After tuning your SK720, use the PC setup software to save a copy of your
setup to your computer's hard drive. Save your setup using the Save Setup
option in the File menu.
No further tuning should be required for most users. If the maximum aileron and
elevator motion of the helicopter is not fast enough for you however, or for other
advanced tuning, see Sections 17 and 19.1 of this manual.
©2010 Skookum Robotics, Ltd

17 Advanced Tuning for 3D Pilots

If you are a 3D pilot, some extra tuning is required for good performance during
piros and fast collective changes.
1) The helicopter's centre of gravity should be directly under the main shaft.
Check by putting the blades at right angles to the fuselage and pick the
helicopter up with your fingers under the blade-grips. The helicopter should
hang with the main shaft straight up and down.
2) Ensure that the swash motion is even throughout its range.
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35 ©2010 Skookum Robotics, Ltd
Put the SK720 into setup mode and set collective pitch to zero. The
swash should be level. Adjust the individual servo centers or the
linkages as required.
Set the collective pitch to maximum positive. The swash should still be
level. If not, adjust the servo travels for one or two of the swash servos
on the Swash Servos tab in the SK720's setup software. (See Figure 17.1
below)
Do the same for max negative pitch, using servo travels for the other
direction.
Figure 17.1 – Swash Servo Travel Adjustment Settings
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