shaking on g570

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cc1975
Posts: 22
Joined: Thu 24. May 2018 9:04:13

hello, i have a question.
my g570 sport works very fine with spirit pro. i only have shaking on the head when i do tictocs or hard rainbows, when turning from positive to negative pitch.
does anyone can help me which value i have to change?

as in attaches setup B1 one is with 2100 headspeed and B2 with 2400.
i dont load up B0, cause this is with 1700 RPM and only for starting and landing.

hope you can help me out.
greetings christian
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ZeXx86
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Joined: Mon 29. Apr 2013 16:06:44
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Hello,

we have found that this problem is occurring only with BK servos due to a certain interference issues. Unfortunately it is basically not possible to solve it in any settings in the unit. But I dont know which servos you are using. With any other this should not be case.

Otherwise this problem could happen if Geometry 6° is configured too high (not configured precisely).

Also I recommend to verify the following:
1. Toggle the Servos/Subtrim (tuning) menu
2. And then verify if all servo arms are at the center as close as possible and at the same time there is 0° between main blades (you can fold ends of the blades to stay together - they should be at the same level).

Cyclic Gain is OK, so there should not be any other issue.
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cc1975
Posts: 22
Joined: Thu 24. May 2018 9:04:13

I have KST MS815HV on Swashplate, running on 7,6V from Hobbywing 120V4.
Servotrim is perfect, also geometry exactly on 6 degrees. also the swashplate is exactly levelled with 0 Pitch, all arms are correct in the middle.

here is a video from third flight. you cannot see the shaking there but you see that all runs good.....

https://www.youtube.com/watch?v=31sculOkCVc
ZeXx86
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Thank you for the message.

As far as I know the KST MS series require slightly lower gain (especially when used on rudder). So you could try to set for example Cyclic Gain at 45 - 50% and see if it will help.
But even flying with the lowest cyclic gain is still safe, so you do not have to worry about stability.
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cc1975
Posts: 22
Joined: Thu 24. May 2018 9:04:13

on tail i have futaba 256HV, working fine as you can see in the video.
i have cyclic gain on 45% only at 1700rpm, cause if i get higher the heli is shaking slowly while hoovering.

but i will try with 50% at 2100 and 2400 rpm later and see if it gets better
ZeXx86
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The most helicopters should fly with no issue with Cyclic Gain up to 65%, but from our team pilot who is flying for KST we know that gains with magnetic sensors must be decreased.

It is hard to guess why the problem you described is occuring, but you might try to increase Advanced/Elevator Filter which will help with possible bouncing. If there is elevator bouncing it could affect also aileron. So I recommend value 3.
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ZeXx86
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You can also decrease Cyclic Ring - Aileron / Elevator range little bit - this is for safety reasons as configured 13° is already quite high. But for hard 3D and higher RPM it is OK.
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cc1975
Posts: 22
Joined: Thu 24. May 2018 9:04:13

so i will try 55% cyclic gain and set elevator filter on 3.
cc1975
Posts: 22
Joined: Thu 24. May 2018 9:04:13

so yesterday i tried cyclic gain from 65 down to 45% and set elevator filter on 3 and 4; no change. was even no more precise to fly and unstable at 45% cyclic........
ZeXx86
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Hmm, that is strange.

Could you verify that there is nothing that could touch the unit when flying? For example a connectors, canopy, cables.
The only thing that could cause it normally is imprecisely configured Geometry 6°, but you are saying it is correct.

What you could try is to remove all blades and run the motor. Then observe the swashplate when motor is running if there is no strange behavior such as a random jittering. Was this helicopter flying previously well (with these servos)?
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