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RUDDER SERVO FLUTTER

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RUDDER SERVO FLUTTER

Old 01-13-2012, 11:11 AM
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aframe2
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Default RUDDER SERVO FLUTTER

I have a problem with flutter in my rudder servo. It doesn't happen all of the time, mainly when I
first turn on the plane. It last for a few seconds while I move the servo back and forth. Then all
of a sudden it goes away. I thought it was the servo so I sent it in to be analyzed. No problem found
in the servo. I then thought it could be some kind of radio interference, but nothing else causes
the flutter. I will try and upload a video I made of the flutter. I will also include a picture of my
radio setup. Any advice, solutions will be
appreciated. Thanks Aframe2
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Old 01-13-2012, 11:44 AM
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jetmech05
 
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Default RE: RUDDER SERVO FLUTTER

A couple of things come to mind...1 the servo is indeed going bad.....2 the switch in the airplane could be going bad or 3 the receiver is going bad.....
If it were me...I'd swap out the servo lead for another channel...say rudder for elevator....if the problem goes to the elevator channel then it's not the receiver or the transmitter...it could be the servo or the switch.......change one if that doesn't do it then change the other......if the problem stays with the rudder channel then it could still be the switch or the receiver or transmitter......the cheapest to change is the switch....unless you have a spare receiver laying around.....
Good luck.....
Old 01-14-2012, 04:38 AM
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jaka
 
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Default RE: RUDDER SERVO FLUTTER

Hi!
Have you checked the potentiometer!? Most of the time this happens it's the pot!
Old 01-14-2012, 06:10 AM
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Rodney
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Default RE: RUDDER SERVO FLUTTER

I think you mean it has an oscillation not flutter. Flutter is the response to an out side force which can set up a self sustaining movement of a surface. If the servo is oscillating and then stopping after being exercised a bit there could be several causes. Some friction in the devices being moved causing it or it could be that the servo has a very tight dead band set up (which is not normally a bad thing) or, highly unlikely, a dirty or worn feedback potentiometer inside the servo. Do you also have the nose gear steering connected? If so, any friction or uneven strain by the nose gear could be causing this.
Old 01-14-2012, 06:25 AM
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Live Wire
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Default RE: RUDDER SERVO FLUTTER

Your battery at full charge, being 6v could cause this unti it is on for a while. Then the Tx to close to the RX can do thisl. try a range check and see what it does.
Old 01-14-2012, 09:45 AM
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bkdavy
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Default RE: RUDDER SERVO FLUTTER

Not obvious what plane the servo is mounted in, but typically this can also be caused by a large rudder and a tight deadband on the servo center. The servo hunts for the center position, but momentum of the rudder carries it through the center before it can correct it back. If the rudder has a balance tab, a small piece of self stick velcro near the leading edge will add enough friction to stop te oscillation.

This type of oscillation is not harmful, and typically goes away once there is some air moving over the rudder.

Brad
Old 01-14-2012, 10:49 AM
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speedracerntrixie
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Default RE: RUDDER SERVO FLUTTER


ORIGINAL: Live Wire

Your battery at full charge, being 6v could cause this unti it is on for a while. Then the Tx to close to the RX can do thisl. try a range check and see what it does.


This is your answer right here. This is very common with fully charged batteries and lower level servos. The other thing that concerns me is how far out you have your linkage on the servo. Not sure but the airplane looks to be some sort of warbird and does not need that kind of throw. Check your dual rates and ATV, if either is dialed down less then 75% then move the linkage in on the servo. This will further help your situation.

Old 01-14-2012, 10:53 AM
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aframe2
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Default RE: RUDDER SERVO FLUTTER

Thanks for all of your advice, The plane the servo is mounted in is the GP Waco Arf. I think you are right about oscillation not flutter.
It is a taildragger so no nose wheel to check. Please tell me what is a potentiometer and how do
I check it? I will try a range check when the weather permits, what am I looking for with that test?
thanks again. aframe2
Old 01-14-2012, 11:15 AM
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jetmech05
 
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Default RE: RUDDER SERVO FLUTTER

the pot is in the servo....you check it by 1 turn on the transmitter first...always turn on the transmitter first and turn off the transmitter last....then 2 walk away a few feet and see if the servo always returns to the same spot with no oscillation.....You are doing all of this with a charged battery correct?

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