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HomeAircraftHelicopterMain Discussion › tail servo jitters
01-17-2009 03:02 PM  9 years agoPost 1
leadtongue

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S.Plainfield, New Jersey USA

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hi all, i recently changed out the stock eflite gyro and tail servo on my blade400 and installed the hitec 5000hg gyro and tail servo combo. i followed the directions to the t and set it up. i am now getting jitters in the tail servo at just below to just above midstick then stops as i increase the throttle. im wondering if my esc is the problem. i have your standard linear throttle and pitch curve dialed in... i have looked at my gain settings also and even changing them i still get that midstick jitter....any suggestions?

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01-17-2009 03:35 PM  9 years agoPost 2
Against Gravity

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Pottstown PA

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Jitters
You might want to try relocating your ESC, to see if you are getting electronic interference.
Play with your gain setting, see if it has any effect.
Could be some vibration in tail or head that old Gyro was not sensitive to but the new one is.
Also try different mounting foam-tape, different thicknesses and types can have a big effect on gyro.
Try putting a Velcro strap on it to help hold it, but not to tightly as this will cause vibration transfer.

Good luck, let us know how you make out.

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01-17-2009 04:06 PM  9 years agoPost 3
bigdog714

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Rochester, MN U.S.A.

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Check the tail mechanics for any binding, if your push rod flexes the gyro will be constantly trying to correct for the sudden pitch changes. It is usualy more prevalant when hovering.

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01-17-2009 06:31 PM  9 years agoPost 4
neilg.

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north of borston

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try lowering the rate?

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01-17-2009 06:39 PM  9 years agoPost 5
LaurenceGough

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UK

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What ESC are you using?

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01-17-2009 08:48 PM  9 years agoPost 6
leadtongue

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S.Plainfield, New Jersey USA

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tail jitters
there is no binding....even with tail push rod disconnected it happens...i have the stock esc from eflite....have tried lowering the rates

Installed servos on my wallet so money flys out faster!

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01-17-2009 10:03 PM  9 years agoPost 7
bigdog714

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Rochester, MN U.S.A.

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Are you sure the gyro is set for a digital servo?
Are you sure the gyro is set for your radio? Although it auto sets for the radio, sometimes it's not correct, that was an issue on a friends setup, had to be set manualy.

MD 800
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01-17-2009 10:29 PM  9 years agoPost 8
LaurenceGough

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UK

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Does it sound a bit like a glitch? Tail twitches once and a while? Can you hear the motor make a different noise (almost like it's cutting out?)

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01-17-2009 11:06 PM  9 years agoPost 9
bigdog714

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Rochester, MN U.S.A.

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That would be a battery imbalance, lipo protection kicking in on the ESC?
Its safe to assume that the gain wire is plugged in correctly or you wouldn't have been able to get into rate mode to set the tail geometry.
Not a geometry or trim issue, its not drifting.
There is a setting on the gyro for tail responce, that might be too high.
I would set a flatt line 70% throttle in Idle 1 and see if you can find a gain setting that works. Your throttle curve may have to much of a variation in head speed for the gain setting to work correctly.

MD 800
Logo 600SE
Logo 14/500 Carbon
Ballistic 700
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Avant 90E

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01-18-2009 10:23 AM  9 years agoPost 10
LaurenceGough

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UK

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I got rid of my twitches today by using a flat 95% throttle curve, before it was 95 in the middle and 100 at the ends. Seems my Align ESC doesn't like little throttle changes...

I watched it on the ground in idle up as I moved the stick, just past center stick it cut power to the motor for a ms and then went to the new 100% headspeed.

With a flat 95% curve the tail is 100% rock solid with no twitches.

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01-18-2009 04:42 PM  9 years agoPost 11
leadtongue

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S.Plainfield, New Jersey USA

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my skills are still beginner.... basically hovering...and lots of sim time...i will be in that narrow band where the twitching occurs alot of the time and dont want any surprises trying to land. i tried a futaba 3400 on the tail that i had and it did the same thing... i do have the proper servo speed selected for the type of servo...the 5083 is the first setting... used for this servo only...ive tried second and third choices for the futaba with the same results...i even calibrated my dx6i...it has a self calibrating program built in.i went over the mechanical... found that my washout base had a little binding..screws through the washout control arms were a little too tight...nice and smooth now but i still get that twitch. my esc does get pretty hot...i never paid attn to it in the past so i dont know if this was normal or signs of a bad esc. yeah i can bypass it with a strait throttle curve....but im not at that stage yet. ill try bumping up the throttle curve a little sooner and delay the pitch curve a little longer as a work around. could receiver be causing this? i have older version firmware on the 6100e ...never sent it in for update.

Installed servos on my wallet so money flys out faster!

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01-18-2009 05:41 PM  9 years agoPost 12
Against Gravity

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Pottstown PA

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Twitchy
You might want to check your motor bearings. if they are ruff or shaft is bent this could cause both problems, Hot ESC & twiching tail.
Pull the motor and spin it up out of the heli.

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01-18-2009 06:14 PM  9 years agoPost 13
bigdog714

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Rochester, MN U.S.A.

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Seems my Align ESC doesn't like little throttle changes...
When you initiate the ESC listen for the programing tones, the Align ESC sounds the program settings when you power it up, make sure that its not set for High Gain Gov. Mode, that setting causes tail twitching with a normal throttle curve.
my esc does get pretty hot...i never paid attn to it in the past so i dont know if this was normal or signs of a bad esc.
Motor timing is the ESC setting that will help control the heat, try the Low setting.

Also make sure the amps of the ESC matches the amp draw of the motor as closely as possible. If you have a 45A ESC with a 20A motor the ESC becomes a regulator which creates heat. A 45A ESC wants to deliver 45A to the motor, if the motor wont take it, the ESC must resrtict the flow, making it hot and unhappy. Throttle control from the ESC is done with pulses of varying speed and length to control the RPM of the motor, and the ESC would like to deliver the amps that it is designed for with each pulse.

This is just an easy simplified version for a basic understanding, its actualy a bit more complicated, but you can get the idea.

MD 800
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01-18-2009 06:42 PM  9 years agoPost 14
LaurenceGough

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UK

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bigdog714, it's in normal mode with soft start AFAIK, calibrated and everything.

In normal mode it doesn't twitch but in idle up with the old throttle curve (no other settings changed) it played up as above.

Very strange...

I will double check and re-calibrate tomorrow, although the problem is 100% gone now.

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01-18-2009 09:42 PM  9 years agoPost 15
bigdog714

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Rochester, MN U.S.A.

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On my electrics I fly JR 770s and they are very sensative to head speed changes, even 50rpm requires a 0.5 gain adjustment, for that reason I assign my GYRO SENS to the flight mode switch to taylor the gain for all my programed head speeds. I also use a Gov. on all my helis, nitro and electric.

MD 800
Logo 600SE
Logo 14/500 Carbon
Ballistic 700
HD 500V2
Hirobo 50E
Avant 90E

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