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PostPosted: Fri 03. Sep 2021 18:19:31 
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Joined: Mon 23. Aug 2021 22:21:16
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Hello Spirit-users!
My helicopter drags counter clockwise during positive pitch pump.
The setup is Trex500x with Spirit2 fbl and ESC Hobbywing v3 100A. Rotor rotates clockwise. Governor is set in the ESC (not in Spirit2 because I was never able to make Spirit2 lock to rpm-signal from ESC)
The counter clockwise drag is more extreme with less gyro gain in Spirit2 and decreases with more gyro gain. Even with 100% gyro gain there is still a drag counter clockwise.
When common ruddergain is set to 1.5 the gyro gain can be set to max 60% before the tail starts to ocillate violently, but even then I just can’t get ridd of the counter clockwise drag. What other parameters affect this unwanted behavior?

Anyone with experience on this topic?


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PostPosted: Fri 03. Sep 2021 21:46:48 
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Joined: Mon 29. Apr 2013 16:06:44
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Hello,

please take a here:
http://manual.spirit-system.com/index.p ... ning_Guide

Probably you will need to set Pirouette consistency and rudder delay properly.

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PostPosted: Sat 04. Sep 2021 8:54:33 
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Wow, thanks ZeXx86 for quick response.
Will go to the field and try out as soon as possible…


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PostPosted: Sat 04. Sep 2021 16:20:06 
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Hi ZeXx86.
Back from the field, and here are the values I ended up with:

Heli size: trex500x
ESC Hobbywing v3 100A: Gove Store on throttle flat 65
Common rudder gain: 1,5
Gyro gain: head lock 63 (starts oscillate at 65)
Rotation rate: 15 (enjoy fast rotation)
Rudder delay: 2 (servo DS535M)
Piro Consistensy: 220 (starts overshoot at 230)

Much better, but tail is still not rock solid during pitch pumps hard up/down. Results are outside your recomendations. Should I look at the servo limmits maybe? Find it hard to adjust limmits correctly in head lock mode. Can limmits be veryfied in yaw rate mode (negative gyro values) and then switching to head lock mode (positive gyro values) afterwards?

Or is there still something I may have missed?


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PostPosted: Sun 03. Apr 2022 9:26:46 
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Hi again.

Have unfortunately not solved the issue yet. Have same behavior on two different helis with two different FBLs (Spirit2 and Microbeast Plus). Got better results after tightening the tailbelt to avoid «belt jumps». Also got better results by tuning the tail gyro gain when spinning up on ground to easier find the point where tail starts to shake rapidly. Will next explore revomix that I believe is compensation of tail rotor torque as result of variable main rotor torque. Will also look for Youtube-videos to see if anyone explains tail parameter setup.
Does anyone have a good solution for this (I believe) common issue?


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PostPosted: Mon 11. Apr 2022 21:59:22 
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Hi again.
Have figured out at least one potential mistake that I do consequently: I use to center the tail rotor by setting the servo arm 90 deg. to the tail push rod, then adjusting the length of the tail push rod until tail blades are perfectly in parallell, which I have now read is not the way to do it. It is the push slider on the tail shaft that should be centered, making the tail blades stand in an angle to each other to compensate main rotor counter clockwise torque. This angle can be calibrated by hovering when tail gyro set to rate mode (not head lock mode). If heli rotates when stick is centered then adjust the length of the tail push rod until heli does not rotate any more. I have misunderstood the function of tail gyro head lock mode as I thought the electronics kept the head locked anyway because it actually do. But when the gyro already compensates what should be compensated by correct mechanical adjustment in fore hand it may not deal perfectly with even more compensation during pitch pumps? Have not tried out the theory in real life yet, but will try within one to two weeks.

Does this make sence to any of you?

Best regards.


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PostPosted: Sun 17. Apr 2022 13:49:02 
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Joined: Thu 05. Oct 2017 20:06:35
Posts: 246
It's the heli, not the fbl. The 500x needs crazy headspeed to hold the tail.
Check out the 500x forum on helifreak.


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PostPosted: Mon 18. Apr 2022 16:28:51 
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Hi jjuk.
Thanx alot for the update. Will definetly check out that forum. Tried with relatively high headspeed today but need to balance the rotors more precisely first to avoid the whole plane shaking apart. Will post updates here as I unveil the secrets of kicking tailrotors


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PostPosted: Tue 24. May 2022 14:53:14 
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SOLVED:
It seems that my trex 500x has tail kickouts simply because the tail rotor does not push enough air when needed. The reason seems to be slippery belt gears, inadequate drive gear ratio and too small tail rotor blades, which in sum lead to tail kick during pitch pump. The drive gear ratio between the pinion gear, main gear/tail pulley and tail shaft gear is factory default and hence difficult to change. The fix for me was instead to tighten the belt as much as possible and replace the trex 500x 78mm tail blades with trex 550x 85mm tail blades. Bigger and heavier blades push more air, have relatively less difference in weight (which lead to remarkably less vibrations) and responded more to tail gyro gain. In total the fixes gave me a way better flying experience.


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PostPosted: Sat 02. Jul 2022 20:25:08 
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After changing the tail blades, what were your fbl settings?
I've ordered some 550 blades.


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