Goblin Fireball 280 (Havok) shaking

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onit12
Posts: 43
Joined: Thu 27. Sep 2018 8:07:44
Location: Tirol

I looked at the Fireball again over the winter and changed the tail servo from stock to MKS and now the tail wag is gone :D

But what I still have is when I am hovering and push the tail left and right the wobble/shaking of the whole heli. It looks like if it begins at the swashplate and is getting more and more till the whole heli shakes. I then have to land because it is totally unstable.
Can someone help me with the settings, I reduced already Cyclic gain, but nothing more.
Config-File attached.

Thanks
Tino
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Goblin_Fireball_280.4ds
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onit12
Posts: 43
Joined: Thu 27. Sep 2018 8:07:44
Location: Tirol

Really, nobody with an idea? :shock:
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Mattes61
Posts: 628
Joined: Wed 21. Dec 2016 15:13:38
Location: Germany

Hello Tino,

have you had an impact on the ground ? If yes, then maybe defective main rotorshaft or blade bearing shaft - Also it can be defective dampeners or you can try other rotor blades (other brand) ?
Have you some vibrations ? At first you have to look if mecanically is alright -
In my case it was only reducing the head gain, as said in this thread before -

Best regards
Matthias
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urgno
Posts: 274
Joined: Tue 21. Aug 2018 13:05:23
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did you grease the head dampeners ?
I always do on new built heli
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onit12
Posts: 43
Joined: Thu 27. Sep 2018 8:07:44
Location: Tirol

Mattes61 wrote:Hello Tino,

have you had an impact on the ground ? If yes, then maybe defective main rotorshaft or blade bearing shaft - Also it can be defective dampeners or you can try other rotor blades (other brand) ?
Have you some vibrations ? At first you have to look if mecanically is alright -
In my case it was only reducing the head gain, as said in this thread before -

Best regards
Matthias
Hi Matthias,

the Fireball is newly built, no crash or something so I think the components are ok, tail is also smooth. I only changed the tail servo, as mentioned, because of the tail wag. Tail wag is now gone.
I had some short test flights today and reduced head gain in 5% steps to 35 and it didn`t get better, I'm afraid it will only get worse the more I change.
I did some Vibrations tests, without main blades but tail blades on carpet floor, hope this is the way to do this!? Here are the images, "Vibrations" in the Spectrum Analyzer are, according to the real time display, ok.
fireball_x.png
fireball_y.png
fireball_z.png
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onit12
Posts: 43
Joined: Thu 27. Sep 2018 8:07:44
Location: Tirol

urgno wrote:did you grease the head dampeners ?
I always do on new built heli
Yes, did that.
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Mattes61
Posts: 628
Joined: Wed 21. Dec 2016 15:13:38
Location: Germany

Hi Tino,
can you make vibration test without tailblades ? I think 60 are high vibrations (red) -
What is this vibration at ca. 200Hz in X-Axis ? Tomas can you help please ?

Can you make a video and show us how this looks like what you are discribing ?
It is hard to discribe it only with words, I think it would help if we can look at this problem through an video -

Best regards
Matthias
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onit12
Posts: 43
Joined: Thu 27. Sep 2018 8:07:44
Location: Tirol

This is the tail rotor at 200Hz.
I will check the vibrations without tail blades and upload a video as soon as possible.

Thanks for your suggestions.

Tino
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