Spirit System
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Strange behavior of the tail...
https://www.spirit-system.com/phpBB3/viewtopic.php?f=20&t=3235		 Page 1 of 2
Author:  Denndb [ Mon 25. Mar 2019 9:59:15 ]
Post subject:  Strange behavior of the tail...
Hi,

I need some more help.. I have Trex 450 Pro.

Namely I have noticed some strange problem with the tail.

I went out yesterday to try my heli for the first time since I have configured Spirit System and all the mechanics, and here's what happened:
I started to spin up the motor slowly and when it reached the default speed, right before lifting off, heli started to rotate on the ground (good that I haven't actually lifted off!), as if it wasn't in heading hold mode at all... and crashed while spinning :(

I'm not aware of any wrong setup of the tail... tail servo is working properly, servo direction is set correctly. My rudder endpoints in transmitter are trimmed so that in Spirit app diagnostic tab the range is exactly from -100 to 100. Tail servo subtrim is set in Spirit app so that in neutral position the tail blades pitch is cca 0 degrees and the tail slider is in the middle. Tail servo endpoints are also configured correctly in Spirit app, so from side to side as much as it was possible. I have set common tail gain to 1.00 and tail gain to 70, according to manual.

Now I would like to test the tail before I go try to fly, without main blades mounted, not to crash again. But it looks strange to me even when I just power the heli on with no throttle applied - tail slider tends to be too much towards the end point.

It looks as something is not configured correctly, but I don't know what?

Please help, any advice appreciated.

Thanks,
Denis
Author:  ZeXx86 [ Mon 25. Mar 2019 12:30:17 ]
Post subject:  Re: Strange behavior of the tail...
Hi,

the only issue why this is happening is some of the basic setup:
a) Servo reverse is wrong - Servo tab - CH4.
b) Position of the unit is configured incorrectly - General tab.

There are no other options if mechanics was OK.
Author:  Denndb [ Mon 25. Mar 2019 13:00:54 ]
Post subject:  Re: Strange behavior of the tail...
Thanks for you support... I will doublecheck those 2 things.

My Spirit system unit is placed horizontally as if it was 180 degrees, but connectors side is facing the tail, so I have set it as 0 degrees in config. Should be OK?

Regarding the servo reversing - I assume the following, please correct me if I'm wrong:
so I assume that in transmitter, I should not reverse any servos, all reversing is done only in Spirit app, is it correct?
Author:  ZeXx86 [ Mon 25. Mar 2019 13:06:21 ]
Post subject:  Re: Strange behavior of the tail...
Yes, position selection seems to be correct.

Servo reversing is done in the radio if stick direction is not matching with the Diagnostic tab - movement of the Rudder channel.
Then if the servo is not moving in the right direction it must reversed in the Servos tab.

Correct movement of the tail mechanics is so that the tail slider seems to be connected with the ground while you are moving with the model.
So the tail slider is going always in the opposite direction of the movement
Author:  Denndb [ Mon 25. Mar 2019 14:09:06 ]
Post subject:  Re: Strange behavior of the tail...
OK great, thanks! This could be the solution, because I did not check against directions is diagnostic tool. I will check directions for all 4 servos, to stay on the safe side.

Just to be sure before I do that - I have already adjusted servo subtrims in Spirit app so that my swash is perfectly aligned. Possible re-working servo directions for channels CH1, CH2, CH3 and CH4 does not affect these subtrim settings, is that correct?
Author:  ZeXx86 [ Tue 26. Mar 2019 14:53:21 ]
Post subject:  Re: Strange behavior of the tail...
Servo Reversing have no effect at the Subtrim settings.
So you can reverse servos as you wish.
Author:  Denndb [ Wed 27. Mar 2019 10:41:27 ]
Post subject:  Re: Strange behavior of the tail...
In the meantime, I have checked the radio stick movement direction, versus what is shown on diagnostic tab and yes - the rudder and aileron stick movement was not matching the movement direction on Diagnostic tab. So I have reversed rudder and aileron channel in the radio and then, once the diagnostic tab was showing all directions matching the stick movements, I have adjusted reversing in Spirit app so that all servos move in proper direction.

The tail now looks fine to me, for instance when I hold the heli in my hand and rotate it clockwise, tail slide compensates by moving towards the right.

Tail endpoints are adjusted as well.

Is there anything else that needs to be done/checked in radio/spirit setup in order to have the tail working properly (before I try it - I will first try to spin te motor with no main blades attached, just to see if heading hold works firmly)?
Author:  Denndb [ Fri 29. Mar 2019 11:42:39 ]
Post subject:  Re: Strange behavior of the tail...
Hi,

Today I have tried to spin the motor with no main blades attached. Before that, I have made sure that radio rudder stick movement matches the movement seen in diagnostic tab.

So when motor is running, I can confirm that tail servo direction is correct and I'm able to rotate heli the right direction using rudder stick. That seems to be fine.

The only doubt I have before I try to lift off with main blades attached is the following:
When I was testing with no main blades attached, while the motor was running, I have tried to manually slightly move the heli by rotating it left and right. While doing that, I was trying to feel with my hand how agile the tail will be in compensating that movement. It was compensating in right direction but not felt as quite agile (as for instance with my old fbl controller when this same compensation was felt as "rock solid"). Is that bad or normal behavior (note that I was testing it on the ground with no main blades attached)?

The tail servo I'm using is S9650 Digital servo.

My tail gain was on 70, should I set it higher?
Author:  ZeXx86 [ Fri 29. Mar 2019 15:11:56 ]
Post subject:  Re: Strange behavior of the tail...
Hello,

the behavior is very normal, you might just need to increase Gyro Gain. But I recommend to do this after the first hover and few rudder sticks.
It might be also due to a smaller RPM.
Author:  Denndb [ Fri 29. Mar 2019 15:32:59 ]
Post subject:  Re: Strange behavior of the tail...
OK thanks, I will try it
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