Synergy 806: aileron shake at 1720rpm head speed

[DUCDOC]

In all of the Synergy crashes I have witnessed only 1 stripped an umbrella gear and that was a noobie than landed under power in wet grass and proceeded to drive the heli into the ground and the tail gears stripped out. This only happened after the tail dug a deep trench and then slowed down as the tail grips started to dig in...Pilot froze and didn't hit TH.

[Rodney Kirstine]

Originally Posted by curmudgeon

I changed the head dampers last night to all four 80D orange dampers. I verified the blade tracking and the other parameters. I currently have the collective range set to+12.7°/-12.7°, and the cyclic throw anywhere between 10.0° and 12.7°. My planned head speeds are 1870rpm, 1725rpm and 1550rpm. What is considered excessive for 806/116 blades with all four 80D head dampers?

Have you flown it since you did this?

[Dmaxison]

Originally Posted by Rodney Kirstine

Have you flown it since you did this?

He hasn't since I bought it from him

Once I get it up and running I'll let you know what I see. Setting up with Brain2, Tribunus 200, and Spin 785's for now. I'll be playing around with it as a 716 too since I've got a couple sets of VTX 717's laying around.

[Rodney Kirstine]

[Grimmy]

I PMed him about it when I saw he had it for sale and he did say that the change in dampers did get rid of the shakes.

[jhamel]

Sorry guys. I unsubscribed from this thread when I sold the heli. Yes, going with all four orange 80D dampers and lowering the head gain solved the aileron shakes at the 1730-1750rpm range. I believe there is a natural harmonic component at this rpm range. Maybe going with the shorter and lighter 716 and 766 blades may allow to fly at this 1730-1750rpm range with the black 90D dampers at higher head gains.

[Dmaxison]

This past weekend I was able to get a few flights in on her. To say I'm pleased is an understatement. I didn't have any weird tendencies using pretty much stock configs on the Brain2. I was running 1400-1800 for headspeeds. I happened to overlook the collective and cyclic setup which led to 14.5 deg pitch and 12 deg cyclic. Woops! Not such a big deal at low headspeeds, other than the tail and gov needed some work to deal with it. Man did it feel alive!

Corrected my setup to 12&10. Looking forward to some more flights this weekend to focus on some Tribunus gov tuning.

[Rodney Kirstine]

Lol, I bet it was pretty snappy with those pitch settings!

[Dmaxison]

Haha, had me checking pitch pump gain!

[GnarfleTGarthok]

Old Thread I know. But I struggled a little with the aileron wobble as well and finally understand and corrected it. Pretty much the same as everyone else. Wobbles in a hover, goes away in forward flight. Hoping this will help with anyone experiencing the same.

I was running stock setup. Black dampeners outer, orange inner. 766 rail blades with head speeds 1660, 1860, 1960. Always got a wobble that started around 1800 and got worse with increased head speed. (I almost always fly 1860rpm) I spent the weekend rebuilding the head into a few different dampener configurations and testing at different head speed.

swapping Orange Outer, Black inner. - The softer on the outer moved the harmonic up to around 1900 head speed. No wobbles below that. But wobbles above 1900.

All 4 Orange - These 80 durometer dampeners fly smooth up to 2060. No vibs, no wobbles. However, they are a little slow off center for my liking. I'm not a smack pilot by any means but I like the connected feel with the stiffer head.

Now that I finally understood what people were telling me, and understanding how stiff the head really is in the 766, I started backwards and playing with cyclic gain. In the Vbar NEO control manager, I had the following set when the dampeners were set up stock (black outer, orange inner) and wobbles.

(OLD Values)
Style 90
Agility 90
Gyro Gain 90

When setting up the cyclic gyro gain initially, I did what I always do; Slowly increase it, perform fast aileron and elevator stops and look for overshoot in the control loop by observing oscillations on the stops. The 766 basically never would do this. So I kept cranking in the gain and at some point decided that 90 was enough. The only hint Vbar manager gives you is a pointer to around 70 for a "TDR". My Logo 700Extreme used 57. (Those should have been a hint)

I want the head stiff so it performs off center, the only thing I can do is adjust the gain back down, test response, and check for wobbles. I could have left it with Orange dampeners on the outer, but decided almost everyone else is flying with the blacks outer by the manual with no issues so I would stick with that setup. I initially backed cyclic gyro gain down 10 at a time until I noticed how sloppy the heli felt on stops. This was around 50. But absolutely no wobble at any head speed with this reduced gain. The span on this setting is 40-120. So 90 down to 50 is significant. Then trial and error back up until I found the perfect match between no wobble and crisp cyclic. The value ended up being 61. ( Funny as 62 wobbles and 60 feels a little slow. It really is that close.) In order to compensate for the slightly slower loop, I increased agility a little. My final Values on the Vbar NEO are:

(New Values)
Style 90
Agility 102
Gyro Gain 61

I can't really comment on other FBL controllers. I have flown a few but only the Spartan Vortex and the VBAR NEO on the 766. Hopefully that information will help someone else that has the wobbles.