I have the same tail issues on all three of my helis and never have been able to tune this undesirable kick on pitch pumps out despite trying all things recommended.

Been flying my O4 lately and flying it harder than I have before after a ton of winter sim 3D progression. This tail kick is really cramping my style.

I was set at 86% gain with a 1.3x common gain. I have never got a wag in a hover but flying fast and banking hard will initiate a tail shudder throughout the bank. I’ve dropped the gain down to 75% and no longer get the tail shuddering in most banked turns but every so often, when flying hard backwards, I enter a really big tail wag that starts small and works itself really big (20 degrees or so) that lasts until I slow the heli down. Really chaotic and unnerving.

I noticed I can induce the same “wag of death” when stopping hard during fast piros. The stop will cause this wag and it’ll persist for a few seconds, violently.

I’ve reduced my rudder dynamic from 8 to 5 in hopes to fix it and it’s better but not gone and my piro stops are now softer than I’d like.

I’m not sure if there is something else going on that’s getting in the way of cranking my gain higher to deal with the tail kick. Or is it all related?

All three heli’s have the tail kick but only seen the “wag of death” on my O4. My Logo 600 still shakes through banked turns occasionally.

All helis have butter smooth tails mechanically and setup with 3-4° of pitch at the neutral position.

Any ideas to figure this all out?


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After reading many threads over the months on tail kicks, I’m wondering if Spirits “piro consistency” is the same as I gain that iKon users speak of?

What about D gain?


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Hello,

first from all you should change servo arm to a longer, because tail limits are way too big. This mean that for Spirit this mechanical tail gain is not optimal.

Pirouette Consistency is also too big for the model. I recommend to reduce it to 170. Yes, it is more like I-gain. For each model the value is different, but same models have usually same value.
Then you will be able to set higher tail gain without any oscillations.

To improve the performance, try to set Revomix to a value of 3-4.

These changes will make the tail much better.

_________________
Spirit System developer

Piro Consistency was recently bumped from around 170 to 185 last weekend as a means of seeing if it had an effect on the "wag of death." I'll return it there but the wag was still very much present with ~170 set.

Some follow up questions...

1. I'll refer to the Oxy 4 manual when I get home but I think the servo arm length is exactly per the Oxy manual. Should that be ignored and let the Spirit tail limits dictate the servo length for this and all my models over the heli manual recommendations? That's fine, just making sure I understand correctly.

2. Can a 0 setting of Rudder Delay on this KST 565X servo be causing any unwanted wag behavior? Should that be bumped up? I started in the 2-5 range, but tried the 0 setting. I only ask because I've never noticed a wag before last weekend on hard rudder stops from a fast piro before.

3. Is the wag in FFF (specifically tail first) and hard rudder stops most likely a P gain thing or something else?

4. Would disabling the Spirit gov be wise while I attempt to diagnose and tune the tail better?

Thanks Tomas.

Update:

I changed the ball distance on the tail servo 1 hole further out.

It’s given me tail endpoints of 133 & 133.

While that lowered the endpoints in Spirit by almost 60, it’s also bowed the tail push rod which might introduce new issues because the tail rod guide is offset on the boom??



I dropped the piro consistency to 170 again and raised the rudder delay to 5.

Hopefully I can test it this weekend and will report back.




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Hello,

these are good adjustments, but I am afraid the push rod can't touch the guide at all. If it is touching it in any way it will degrade the performance noticeable.

The KST servos are little bit different from others because they offer very big travel resolution. So the settings must be also different to compensate this.

I would leave Rudder Delay at 0.

_________________
Spirit System developer

So my options are to remove the pushrod guide or return the ball to the hole it started out in resulting in those high endpoints of 190. Guessing you're recommending the pushrod guide to be removed over going back to the original ball position?

Also, could those 190 tail endpoints be the reason for the violent wag on hard rudder stops or is that related to piro consistency value or gain most likely?

Can a mis-set Rudder Delay value have any negative impact or will it just not allow optimal performance?

Got to the flying field after work and am pleased to report my tail issues have improved dramatically after moving the servo ball out a hole.

The stops are equal on both sides, I can’t induce that death wag on the hard piro stops any more.

Add in a better tuned governor after forgetting to change the gear ratio after the pinion swap, the heli is performing in the ballpark of how I hoped it would.

I dropped the tailrod guide and that hasn’t made a noticeable difference at my 3100rpm flying moderately aggressively.

I added a value of 3 to the precomp and that’s made my tail pretty much rock solid on punch outs.

I’m was getting a wag at high speeds on hard banked corners and hurricanes, but dropped the gain multiplier from 1.3 to 1.2 and it resolved that. Will slowly raise gain until I see those high speed wags in hurricanes and settle in just below that.

Is a high speed wag like that always P Gain or could it be something else that I’m solving indirectly with rudder gain?

Thanks Tomas! So much better already!


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Very well,

the violent tail wag is induced almost always by high Pirouette Consistency. I do not recommend to use value higher than 175, but not lower than 160.

_________________
Spirit System developer

Sounds good. Again, thank you. Slept like a baby last night knowing my heli is now tuned better than any heli I've owned before.