Optimal Head Dampening?

[curmudgeon]

The stock head damper configuration is 80D orange on inside and 90D black on outside.  I assume other damper combinations would be 90D black on inside with 80D orange on outside, all 4 dampers 80D orange, or all 4 dampers 90D black.

Since the 766 can be configured to swing 716mm (light), 766mm, and 806mm (heavy) blades at low or high head speeds, how does one determine what head damper combination is optimal?  How does blade size and/or head speed affect choice of damper hardness.  How does too soft dampening manifest?  How does too hard dampening manifest?

[Kevin Feil]

If your going to fly as a 766 mild to hard 3D , fly the head with 90/90 configuration, all black dampeners and shim accordingly. 😉


K

[Chris Sexton]

I built mine with the black harder dampers inside and softer outside. I wanted a little softer off center. Im no hard 3D pilot though. But my rotor is butter smooth from 1300-1960 and everywhere in between.

The harder flyer for sure should consider harder setups like Kevin suggested.


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[curmudgeon]

I built mine with the black harder dampers inside and softer outside. I wanted a little softer off center. Im no hard 3D pilot though. But my rotor is butter smooth from 1300-1960 and everywhere in between.

What difference does it make inserting the black inside and orange outside vs orange inside and black outside?

[Chris Sexton]

Well I don't know the actual differences. But my thought process was the outer dampers flex first as the spindle has to deflect farther before the inner dampers flex too much. So I think with orange on the outside the over all damping is softer.
It might all be in my head but that's my thought.


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[curmudgeon]

That logic makes sense.  Thanks.

Follow up question:

page 57 of the manual states:

"The standard configuration consists of (2) 90 durometer and (2) 80 durometer dampers suitable for 766mm blades running at an optimum head speed of 1950rpm."

Then it states:

"Note: Lower RPM may require softer damping and higher RPM may require stiffer damping."

I am planning on spinning at head speeds between 1600rpm and 1800rpm (low head speed by that definition), but swinging larger and heavier 806mm blades.  If a combination of one orange and one black is optimal for swinging 766mm blades at 1950rpm, what would be optimal for swinging larger and heavier 806mm blades at lower 1600rpm to 1800rpm doing mostly sports flying and mild 3D?  I mean, should I do the black on inside and orange on outside or should I just use all orange?[/font]

The reason why I make a big deal about this is because I have a pretty bad skid side to side shake at 1750rpm that tends to stabilize at around 1600rpm using the orange damper on the inside and the black damper on the outside.  I am trying to determine my options to make that side to side shake/wobble go away.  I don't know what else to do other than optimizing the dampers.   

[Chris Sexton]

Well it could be something mechanical  or setup related too. I run my 806 at 1660/1750/1850. No issues with wobbles.




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[Matt Botos]

I give tons of options on Synergy models because most advanced modelers prefer these options. Each modeler has their own opinion of what flight characteristics they like best. You have probably noticed other manufacturers give you no options at all which leaves you are stuck with the machine exactly how it comes out of the box. I like to provide the parts/options for each pilot to figure out what he or she likes the best. Nothing is set in stone when it comes to the damping of the head, tail ratios, and main gear ratios, it is all personal preference. The statements in the manual are nothing more than guidelines and should not be considered gospel.

As far as a side to side wobble, the first thing you need to do is fly the 766 for around 20-30 flight so the dampers have a chance to break in. Of course make sure the head axle and dampers are greased so everything can find its happy spot.

If you still have a wobble after the break in period, there are a few other things that you will find online that cause cause this.

1. Bad FBL sensor
2. Servo centering problem
3. Vibration (usually high frequency, check motor first)
4. Blades too tight

Beyond the dampers, very rarely is this a cause of the helicopter mechanics.

Let us know how it goes! Thanks!

Matt