Tail Servo Arm / Gyro / End-Points - RC Groups
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Sep 28, 2012, 02:00 AM
Registered User

Tail Servo Arm / Gyro / End-Points

I'm having trouble getting my head around the issue of TX setup for the tail servo, as it relates to the location of the ball on the servo arm.

I'm using a Align 750 gryo which, when I set the left and right yaw maximums in the gyro, these limits I think are only applicable for when the gyro issues a correction command. Is that true or am I confused?

When I command rudder on the TX, I think this over-rules the gyro limits. I'm thinking this is why some posts I've read talk about setting the servo travel end-points on the rudder, so that the TX will not over drive servo causing binding. Again, am I confused or on track?

So then the question on the ball location on the servo arm, do I want the ball closer to the pivot so that I need more "swing" with the end-points further apart, or further out on the servo arm and the end-points closer together?

You can see I'm lost here. Maybe I'm over-thinking this. Thanks for reading this long post and helping get me back on track.
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Sep 28, 2012, 08:28 AM
Zippy Puffer
2Doggs's Avatar
I think most gyros work the same way - so although I don't have any experience with the 750, I used several other gyros.

You set the tail slider travel by adjusting the gyro limits. All but the lowest end gyros will have a separate left and right limit, so you set them to ensure that there is no binding in the tail rotor at full left or full right rudder.

If you can't get the tail slider to reach the mechanical limits on one or both sides, it means you need to use a longer servo arm - i.e. move the linkage ball out on the servo arm.

Conversely, if the limits have to be set at say around 50% to prevent binding, you need to move the linkage ball in on the servo arm.

The ATV or End Point settings in the TX will affect the piro rate - and have no effect on the tail limits. That seems counter-intuitive, since most of the time, adjusting the TX ATV's will affect the servo travel.

You normally use the rudder ATV's to equalise the left and right piro rates, and that's most easily done on a Lazy Susan test stand, though you can also do it, less conveniently, by test flying the heli. A small change in the TX ATV value can make a big difference.

Hope that helps, and good luck with your tail!

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