Specifications
You can increase the effective resolution of the tail servo at the cost of decreasing the
travel speed which may reduce or eliminate the tail wag. To do this. you can move the
tail pitch linkage IN one hole on the tail servo arm or OUT one hole on the tail pitch
control lever.
• Tail servo may not have enough resolution
This HS-50 servo, in particular, does not work very well with a heading hold gyro due
to the servo slop.
3. Gyro or tail servo mounting problems
• Gyro not mounted securely to frame. Use only the supplied gyro tape or 1/8"
(3mm)thick 3M foam tape. Do NOT use velcro!
• Servo not mounted securely to the frame or tail boom mount.
Check for loose or stripped screws. Also, rubber servo grommets can cause wag when
used on tail servo mounts.
4. ESC with poor governor mode
• Some ESCs have a badly programmed governor mode, and the motor speed will fluc-
tuate when the governor mode is enabled.
This occurs because the gyro will apply extra tail pitch which increases the load on the
motor, which causes it to slow down. The governor mode will apply more power to the
motor, which causes the motor speed (and tail rotor speed) to increases, which causes
the tail to overshoot the proper position. The same problem occurs when the tail pitch
is decreased, and the tail overshoots the correct position again.
Basically, the ESC governor mode and heading hold gyro can go into a vicious cycle
which causes the tail to wag. This is known to happen on Align ESCs and Castle Cre-
ations ESCs with older firmware versions.
5. Other problems
• Gyro gain too high. Smaller helis usually require lower gain settings.
• Worn tail servo.
Metal geared servos tend to wear quickly when used for tail rotor pitch control.
• Gyro gain too high. Smaller helis usually require lower gain settings.
• Tail servo may be missing a tooth on a gear from previous crash damage.
• Tail servo may not have enough torque to move the tail pitch lever smoothly.
• Tail rotor may be too large (micro helis only)
This is a common problem when a GWS IPS motor with a 3x2 prop is used. Trimming
the propeller by a little may help.
26.2.4. Tail swings 30-90 degrees abruptly then corrects itself
• This could be caused by radio glitches. See Section 26.5, “Glitching”.
Troubleshooting Common Problems
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