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› Tail wag on 700 size w/ Vbar blueline
11-05-2018 07:35 PM  11 days agoPost 1
Band1086

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Kennewick, Wa. USA

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What are the most common reasons for a tail wag in hover esp. on the bigger heli's?

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11-05-2018 09:41 PM  11 days agoPost 2
DemetriusUSN

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Virginia Beach, Va USA

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It would be great if we had more information, what equipment, servos and what not. So we can get a more exact picture.

Minicopter Diabolo 800, Minicopter Triabolo 700, Minicopter Diabolo 700, Minicopter Diabolo 600, Minicopter Diabolo 550, Goblin 770

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11-05-2018 11:21 PM  11 days agoPost 3
Flyin for Jesus

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Troy, IL. 62294

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Tail gain too high
Servo failing
Binding linkage
Many more possibilities.

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11-06-2018 01:57 AM  11 days agoPost 4
Band1086

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Kennewick, Wa. USA

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My tail servo is a Savox 2272MG, tail gain is set at 90, tail control rod appears to be smooth and free.

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11-06-2018 02:53 AM  11 days agoPost 5
Band1086

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Kennewick, Wa. USA

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I have a Fut BLS251 I'll try on it tomorrow. At least that will eliminate the possibility of failing servo.

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11-06-2018 03:03 AM  11 days agoPost 6
ICUR1-2

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Ottawa, Ontario

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I had a tail wag caused by bad tail rotor grip bearings.

spending time, paying attention

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11-06-2018 12:57 PM  11 days agoPost 7
DemetriusUSN

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Virginia Beach, Va USA

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Also, How far out is the ball link on the horn?

Minicopter Diabolo 800, Minicopter Triabolo 700, Minicopter Diabolo 700, Minicopter Diabolo 600, Minicopter Diabolo 550, Goblin 770

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11-06-2018 03:50 PM  11 days agoPost 8
Band1086

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Kennewick, Wa. USA

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Bearings seem to be smooth. The ball on the servo arm is at 17.5mm which is what the instructions call for. Also, on the Vbar set up, under the tail set up screen, the slider for both ways is at about 90. Should I shorten the distance the ball is set at and extend the slider to a larger number maybe?

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11-06-2018 03:53 PM  11 days agoPost 9
DemetriusUSN

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Virginia Beach, Va USA

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Move the ball in one hole and try that.

Minicopter Diabolo 800, Minicopter Triabolo 700, Minicopter Diabolo 700, Minicopter Diabolo 600, Minicopter Diabolo 550, Goblin 770

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11-08-2018 02:24 PM  9 days agoPost 10
Band1086

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Kennewick, Wa. USA

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OK, I moved the ball in one hole on the servo arm but that didn't help either. Incidentally, The ball was at 16.5mm's not 17.5. When I moved it, it was then 14mm. Also, I exchanged the Savox with a bls251 and that made no difference either. Then I tried a different gyro sensor, no difference. The only 2 other things I can think of is to secure the tail push rod with 2 guides to keep out any possible flex. And after that try a different gyro main unit, but that means I'll have to do another full Vbar set up...oh well I can't think of any other possibilities. Any more thoughts?

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11-08-2018 06:11 PM  8 days agoPost 11
Flyin for Jesus

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Troy, IL. 62294

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Hover it and let it wag for a bit, if the servo gets hot, then you have binding since you swapped servos with no change.
It may be smooth at 0RPM but not at 7000RPM.

If the servo stays cool, then maybe switch out gyro, but I find that not likely the fault.

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11-08-2018 08:54 PM  8 days agoPost 12
ICUR1-2

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Ottawa, Ontario

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I would swap out the tail rotor at this point

Might be a bearing

spending time, paying attention

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11-08-2018 09:54 PM  8 days agoPost 13
Ken Filloon

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Highland, Michigan

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Turn the gyro gain down and try it again.

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11-08-2018 11:49 PM  8 days agoPost 14
Band1086

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Kennewick, Wa. USA

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OK, I'll see if the servo gets hot. I don't have another tail assem. to switch with, but when I grab the tail grips and pull out hard on then then twist, They have no notchyness or binding, but that may not be enough of a test...Also, I did turn the gain down quite a bit and all it did was wag more out of control.

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11-09-2018 01:12 AM  8 days agoPost 15
ICUR1-2

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Ottawa, Ontario

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I know how you feel but on the plus side a spare is not a bad thing.
I tried 3 different controllers and rebuilt my tail assembly multiple times... before the tail rotor finally locked up under load.
Spent 2 seasons on and off trying to figure out my wag it was a new rotor to begin with

spending time, paying attention

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11-09-2018 03:33 AM  8 days agoPost 16
Heli Fanatix

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Fountain Valley, CA

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Let’s get back to basics, a good tail usually is under two catagory:
- Mechanical setup
- Electrical Component

If the mechanical is not good, the best Servo in the world won’t help.

Here are my suggestions
- balance main and tail blades
- main shaft, spindle, tail shaft and tail hub are “TRUE”
- make sure tail grips spins freely on tail hubs [ensure trips are not bent]
- you can remove rotor head / tail hub and hold a hex driver to the end to see if it’s bouncing [mean it’s bent]
- sometimes the pitch slider on tail shift sticks, I use a drop of dry fluid
- push rod is positioned in middle of guide, control rod has play in the guide throughout left ~ right rudder input
- make sure push rod doesn’t flex [carbon material is ideal]
- once all tail mechanism is inspected and re-assembled and perform the following:

#1 Disconnect control rod from horn
#2 Hold heli upright with tail down
#3 Control rod should drop under its own weight when you flip it tail down - tail up - tail down
#4 This lets you know everything is smooth [moving under its own weight]

As far as the electronic/component:
- follow v bar setup wizard [pay attention to tail compensation when applying pitch]
- Servo centering pulse
- Use closet servo hole to center on the horn while still achieving full travel [this ensures highest resolution]

In very rare cases, I’ve found these may cause tail wag:
- ESC [HS not holding, lacking tail authority thus tail oscillating]
- Motor [kinda like the ESC]
- Torque Tube bearing not properly spaced
- Belt missing a few teeth / tension is loose
- Plastic pulleys melted / slipping

Don’t assume anything is good
- Suspect everything until confirmed “Known Good”
- This is part of the hobby, the experiences will prove invaluable

Usual Suspects:
- Bent tail hub
- Pitch slider sticking in tail shaft [metal heats up & gets pitted ... drop of dry fluid resolves it]
- Control rod sticking/not straight

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11-13-2018 05:47 PM  3 days agoPost 17
Band1086

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Kennewick, Wa. USA

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Well, I've checked pretty much everything and even put a different Vbar on it. I'm going to secure the push rod with 2 clamps so there is absolutely no flex and after that play with the gain.

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