Tail blow on logo700xxtreme

Hi,

I'm currently fighting a tail blowout problem om my logo700 xxtreme. When I'm flying a "snake" and pulling inverted pitch knife egde backward the tail flips 180°. Also other demanding figures like during a piroetting funnel it occurs regulary.
setup : kosmik160 + standard 4525 -520 ultimate motor 17T
VBAR neo and VBar ctrl
Log shows nothing irregulary, already changed the one way, bearings, tail geometry and checked the motor.
Kosmik GOV settings are Gain=4 RI = 12mOhm
105mm tails (rotortech).
1900 rpm.
fresh batteries, stock setup...

Any hints , things to try ? I'm suspecting the kosmik governor settings since this has never occured with the YGE160A ( which died )

regards,
/Kurt

I would like to know what servos you are running. I had this issue but was able to figure it out. But please let me know what servo on the tail

Hi... BLS-256HV...

Hi Kurt,

can you please also attach your setup file and three pics showing the center position of the tail rotor (right after power on) and the left/right limits?

Kind regards

Eddi

Born to fly ...
forced to work.

Hi Eddi,

attached the files. I found that there is no countertorque on the blades right after powerup. However when I center the tail pitch slider I have a few degrees as needed and equal limits 110/110

I did a tail optimize flight and get A/B values of 10/52 ,in bank one at lowest hs. 10/61 for the second bank and 15/35 al 1950 rpm in bank3

I also tried with another servo (brand new BLS 276SV ) bur same results.

my servo arm is 16mm as per manual...

Hi,

for starters, please try lowering the limits. Could be that the tail is already running into a stall.

Please also check that nothing is slipping, by holding the main rotor head and turning the tail rotor hub with quite some force (but not too much of course, no need to damage anything )

Kind regards

Eddi

Born to fly ...
forced to work.

I lowered the limits to 90. adjusted the rod for 2to 3 dregrees countertorque at startup and did an optiumizer flight. Disabled optimizer and checked. I can do a full pitch backwards loop without a problem but during piroetting funnels it flipds 180° at certain points ... So there is some improvement but it is not the tail it used to be..

I tried to turn tail rotor and main rotor and nog slipping indications occurred.

maybe it has something do do with the motor ? It is like the only part which i didn't swap yet ...

Hi Kurt,

so the limits made a difference. The tail blowing out is a tail authority thing, too little power for what you throw at it (or, as we saw, too much deflection on the tail blades _if_ thy would have the required power but run into a stall.

If you didn't change the motor, there's probably not more torque than before unless you fly harder or use more collective.

Does the pro funnel thing happen both directions?

What values does the optimizer come up with now?

From what I have seen from our team pilots, the 700 performs in all situations, but of course I do not know their particular pitch management and how well they can control it at the very limits (pretty well, obviously ). Prior to the tail flipping it usually starts to do uneven piros when countering both torque and speed, do you experience that, too?

Kind regards

Born to fly ...
forced to work.

Hi Eddi,

I did fly the heli this weekend at belgium3d F3N final competition. I only lost the tail once during piroflip in the flight to music.
As you say I think I push the collective harder and I'm surely not that good in collective management as the pro's :-) I use a rather modest 1850 rpm in which I try to fly the heli "controlled" through most figures. The uneven piros where axactly what I felt before it actually flips 180°. I might have to tweak RPM and deflection of the tailblades. I will do some testing next days and report.

Kurt

Born to fly ...
forced to work.

Tried some more defections of the tails. CCW tail is really locked CW, tail is still weak. These are the optimizer values after optimizer flight in 3 banks rpm is 1800 - 1900 - 2000. In setup, it has about 2-3° countertorque with the tail slider arm @90°. While piroetting the stops are really crisp after CCW but the tail bounces coming from CW.

limits 90/90

SIDE A Bank1-61 Bank2-75 bank3-51
SIDE B Bank1-10 Bank2-10 bank3-10

limits 100/100

SIDE A Bank1-30 Bank2-68 bank3-27
SIDE B Bank1-10 Bank2-10 bank3-10

The uneven inconsistent pirorate occurs as soon as there is load variation, ( piroetting funnel ). Mechanically everything has been changed execpt for the torque tube. I even have swapped my scorpion 4525 for a PYRO800-48L and 18T pinion. ( nothing to do with the problem but I could buy one for a really good deal and it matches the KOSMIK ESC really well imo )

Kurt

Hi Kurt,

100/100 seems to be better for Side A, Side B is OK anyway. Question is, what is weak? You most probably always feel a difference between both directions when flying hard, hard to tell how big the difference is and if it is normal or particularly different.

Hard to tell from a distance :-/

Kind regards

Eddi

Born to fly ...
forced to work.

SOLVED

Looks like I was just running too low RPM for the 3D manoevres I fly. I checked my RPM and tached at 1700 in bank 2. (must have gone wrong when I swapped to the KOSMIK ) I adjusted the ESC and have 1750/1950/2050 now !
Then did a trim flight and the tail trimmed -32. 3 turns out and I was at -8 ( fair enough ). The optimizers give now values from 26/22@1950 RPM.
This morning I did 2 testflights and all is fine now...nice locked tail !
May look silly but I didn't question the headspeed because I have flown it without problems until now, lets say with less demanding manoevres. The other side of progression.... At least the exxtreme is fully checked and in top shape now, and I'm really looking forward to ????upcoming???the successor.

We learned, thanks to your support !

Regards, Kurt

Eddi

Born to fly ...
forced to work.