Cant shake vib E7se

[Rob_Wegryn]

Just built a brand new e7se kit, and let me first say that I'm loving this thing. I'm having issues with a vib I can't figure out. At first it started as a lower head speed thing but now is present through every head speed frm 1850 to 2050, it is much worse at the lower head speed but present and higher head speed. It only shakes when the Swash is flat if your giving a input collective/cyclic it stops shaking. I've pulled the head apart a couple times made sure everything is perfect and thrust bearings were in correct orientation and greased everything well. I'm at a loss now this kit has 6 flights on it. To me it seems like something is bent from the factory not sure. any help will be appreciated before I order parts I don't need to guess with.
Thanks
Rob

[flyalan]

What flybarless unit are you using?
Have you tried lowering your head gains?

Cheers
Alan

[Rob_Wegryn]

I'm running a v bar silverline , yes I have tried dropping the head gain there was no change.

[flyalan]

Not a VBAR guy so I will reserve any suggestions there.  Have you looked at the VBAR vibe log?
Assuming there has not been any type of crash damage hitting the tail on landing, etc?


Cheers
Alan

[Chris Sexton]

Can you post your VBAR file for me?

[Enrique Perez]

Could be several things. Need to know more details about your setup  so I can help diagnose.

Post a pic of how you have your sensor mounted.
Post the vbar config and full event log.

[Rob_Wegryn]

The Heli has never hit the ground tail included. It has around 6 flights I have the sensor mounted upside down wire toward the front on the sensor tray. I am running a scorp 4525 520, castle 160hv, bls255/256hv? Gryphon bec, rail 716 and 106 tails. Using vbar gov. I will post a log when I get home from work today I honestly don't believe it is a setup or gain issue but very well could be wrong,I wish I had a new head or shafts to try.

[Enrique Perez]

I understand and not questioning you setup , just needed to know how you have it setup.  Vibe's are not easy to figure out.

On your sensor,  what tape you using to mount it?
Have you taken the blades off and run it on the bench to see what the spectrum analyzer show's?

What will help pinpoint it fast is looking at it live while in hover,  but that would require having a vbar  Bluetooth module.

[Rob_Wegryn]

Came to the field after work dropped the cyclic gain on the vbar from 88 to 75 no change it honestly seems worse for whatever reason I'm seeing it in all head speeds now only when the Swash is flat. I ran the vib analyzer with no blades no vibes over 280. To me it seems like a bent main shaft or something screwed up in the head. Considering ordering new shafts tonight. Getting pretty frustrated this is a brand new machine!

[Rodney Kirstine]

Might be worth taking the main shaft and spindle out, real quick, and roll them on a flat surface to see if they're bent.

[Anthony Oxlade]

Is the vibration visible as the whole heli shaking? Look carefully at the skids. It sounds like your damping is too hard for your chosen head speed. As a quick check try hovering at 2100-2200 rpm. If it smooths out then you can fix the problem by reducing the thickness of  shims in the head.

[flyalan]

You mentioned the log without blades. Did you look at the log with blades on? What blades are you using? 
Agree on trying an even higher head speed. The damping is hard and as such going even higher might at least give you an idea if that is the issue. Also you can also lower the head gain even further. This will also give you an indication if you need thinner shims on the head.

Cheers
Alan

[Jean-Luc Bolduc]

Did you try straight throttle curve instead of vbar gov ? seems the cc isn't yet fully vbar compatible.

[aresti]

When setting your CC gear ratios are the values you entered matched to the E7 (116T) or the E7SE (121T)? You may be governing to a lower RPM than intended or indeed shown in the software?

[Rob_Wegryn]

I'm pretty sure I've narrowed it down to a damping issue. I turned up the hs to 2150 and everything is perfect , drop it down to 1850 it shakes. I went with a thinner .5mm shim in the head no change.  Maybe I should get a new set of dampeners ?