Logo 700 tail lags while reversals

Hello Logo 700 owners!

I have a tail issue which I haven't solved since I bought first logo 700.
I will post a couple videos down here to visualize the problem.
I make left-pirouetted piroflips and make reversal to right-pirouetted piroflips.
While making reversals (from left piro to the right) tail has lag with sounds like "vvzhhuuuuuh". And every reversal has different lag time. This influences on accuracy cause every time you couldn't expect what time will be for this lag. Last week I had a tail failure caused by damaging bevel gears while reversals.

Yesterday I tried another heli (not mine) .The tail behaves itself perfect. Sharp stops without any sounds of "vvzhuuuuh" and fast accelerating to opposite (right) pirouette.

So that causes a fear of doing any reversals on my Logo 700.

My heli setup is:
ESC: Kontronik 160A
Motor: Kontronik Pyro 750-55
Main rotor servo: MKS HBL 960
Tail servo: MKS HBL 990
Main blades: VTX 717 (but I also tried 697. It reduced tail rotor sounds but lag remains)

My V-bar Neo tail parameters:
Tail Expert
Accel. - 80 (yes, the value is maximum but only that parameter provides fast acceleration to opposite pirouette)
P Gain - 80 (I tried it 50 increasing by 10 steps even to 90). On lower values sound of "vzhuuuuh" becomes quieter but tail lag remains with too smooth control.
I Gain - 60 (I didn't changed it. As I think, this parameter if for heading hold gain and doesn't influence on reversals)
Stop Gain A - 25
Stop Gain B - 20
D Gain - 0
I limit and I Discharge - off

Tail Optimize
TC Coll - 30 (in the beginning I tried 22 and increased to 50. Nothing happens even during sharp climbs. The tail moves CCW a little and returns to the previous position)
TC Cycl - 8 (dint change)
Zero Col. - 0
Side A - 18 (set while flying with optimizer turned on)
Side B - 26 (set while flying with optimizer turned on)
Optimizer - off

General tail rotor settings
Expo - 10 (doesn't influence)
Rate ++ - 120
Tail Gain - 60

Before I flew on flybared helis with one axis tail gyro and I didn't have any problems with reversals.

The first video recorded yesterday. You could hear the sound of "vzhuuuuh" during reversals.

https://youtu.be/b8pgLI1mq2Y

I was trying "brake dance". There reversals in this maneuver too and the same sound of "vzhuuuuh" with loading engine. I have done the same on my friends heli but there arent any tail rotor sounds, tail lags and rpm drops.

In all other cases tail behaves perfectly: hard tic-tocks,funnels, loops even during strong winds.

https://youtu.be/dFn-8kLZcEQ

The sound points me to a throw issue.

The tail seems to have too much throw, will use it for a crisp reversal but get into stall (wuuuschhh).

Could you post some pictures of the tail throws (top down on tail rotor, not fold the blades)?

regards (EN) / Gruss (DE)

Rainer Vetter

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Hello Rainer,

I think that you are right about stall.
Here is my throw but it is big enough (maximum) to provide stall effect.
But I didn't find information about maximum range for tail rotor.
I suppose it should be smaller but what exactly. Or It should be found by experimental methods?

I have vtx 717 main blades and kits standart tail blades.

Main rotor speed is 2100 rpm.

https://www.vstabi.info/en/node/842#tail

I wrote this some years ago ...

I would just lower it 5 points and try to find the sweet spot step by step.

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Für Einzelkommunikation bitte ausschließlich Email verwenden! - PN, Messenger, Chat usw. werden nicht bearbeitet.
For single user communication please send a email only! PM, Messenger, Chat etc. won't be read.