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Noisy Hitec Servo on Flaps of Futura - 10/8/2012 5:43 PM   
mun_iz


 

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Status: offline 		Hi all,

Need some advice.

I was fixing the flap servos on my Futura 1.9m tonight. I am using a Hitec HS 7985MG on 6V.

When i powered up the servo, there was a lot of loud buzzing and clicking. The clicking is accompanied by vibrations on the control surface.

The same phenomenon is observed when I switched the servo to a HS7955TG. I also tried increasing the dead band width of the servos (up to 4). Although the clicking noise is reduced (it did not go away), I noticed the servo "over-travels" at this setting.

The servos were connected to a Futaba R6014HS RX for the tests.

In the video, the servo is the 7955TG. There is a bit of binding when the flap is fully up but none whatsoever when the flap is deployed.

Is the chatter normal for Hitec servos... I am not so worried about the noise the servos are producing but it is the vibration that is making me uncomfortable.

Would appreciate any advice.

Thanks.

Isaac

http://www.youtube.com/watch?v=P36Z8sEVXYw&feature=youtu.be



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RE: Noisy Hitec Servo on Flaps of Futura - 10/8/2012 6:55 PM   
Jame


 

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Status: offline 		Ive used the 7955TG all round on my Flash and they have a similar buzzing noise on each of the surfaces, especially the Flaps and Ailerons as they are having to hold the weight of quite a large surface, it sounds like there is maybe a small amount of binding when the Flap is in the Up position, I would maybe check this with an In Line amperage meter to ensure the correct amount of Current Draw in the different positions. Ive never noticed any vibrating of the surfaces on our models though, only ever on a customers CARF Eurosport (with Hangar 9 3D style Control Arms causing the Servo to try and over center) but this was cured by an adjustment of the dead band width and he was advised to make sure the setting was good for him before flying the model.

If its the slight buzzing your concerned about, other than in the Up position, I wouldnt worry, Ive had over 100 flights on my flights on my Flash and its worked flawlessly but I would maybe just check for any unwanted binding.

Hope this helps.

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RE: Noisy Hitec Servo on Flaps of Futura - 10/8/2012 7:07 PM   
basimpsn


 

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Status: offline 		Sounds normal to me


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RE: Noisy Hitec Servo on Flaps of Futura - 10/9/2012 12:51 AM   
mun_iz


 

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Status: offline 		Hi all,

Thanks for the advise... The vibrations that i mentioned in my post are actually jitters.

Found a better word while searching for a solution online.

It jitters and clicks (not continuous hum) at takeoff and landing flap positions.

Not sure if it would quiet down once under constant Loading while flying. I think I will set the deadband to 3 and re-test.

Isaac

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RE: Noisy Hitec Servo on Flaps of Futura - 10/9/2012 5:58 PM   
Meesh



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Status: offline 		I'm assuming the plane is being worked on and your transmitter is very close to the plane.

Try backing away a little and see if the jitter subsides.

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RE: Noisy Hitec Servo on Flaps of Futura - 10/9/2012 7:23 PM   
joeflyer



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Status: offline 		That's why I don't use digital servos on flaps.  Digitals always hunt for center and the weight of the flap and/or slight binding in the up position will make them buzz and vibrate.  Replace them with a set of HS645MG's (or comparable analogs) and your problems will go away.
 
Joe

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RE: Noisy Hitec Servo on Flaps of Futura - 10/9/2012 7:25 PM   
Meesh



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Status: offline 		I'm with Joe. Hitec 645MG on all flaps.

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RE: Noisy Hitec Servo on Flaps of Futura - 10/9/2012 9:41 PM   
k12rc



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quote:

ORIGINAL: Meesh

I'm with Joe. Hitec 645MG on all flaps.


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RE: Noisy Hitec Servo on Flaps of Futura - 10/10/2012 3:36 AM   
mun_iz


 

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Status: offline 		Hi all,

Thanks for the replies.

Yes, my tx was placed within a metre of the rx when I did those test. Will try moving it further and re-test.

Also found another possible solution online which was to damp the control horn movement by sandwiching a piece of Velcro (soft side) between the servo casing and the servo horn. Will also try that and feedback should someone else be interested.

If all attempts fail... I will replace with an analogue servo as recommended. Just want to try to resolve the digital "clicking" as I might face the same issue if I mount them elsewhere.

Isaac

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RE: Noisy Hitec Servo on Flaps of Futura - 10/11/2012 12:21 AM   
Nhalyn



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Status: offline 		A thing you have to think of, if your Futura is your fisrt full composite bird (don't know for th emoment), is that this wing is a real resonator chamber !

The same servo (7955TG) on the same wing but constituted of plain foam + obeshi would produce less noise or un-noticeable noise...

Looking at your video, the "noise" seems also normal to me. I use this servo on the flaps of a propelled plane and all work flawlessly for 3 years now... I use also the same servo on the horizontal (full moving) stabilizer of a 1/3 scale Ka6E gliser, and it work flawlessly since first flights a year ago.

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RE: Noisy Hitec Servo on Flaps of Futura - 10/11/2012 11:22 AM   
mun_iz


 

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Status: offline 		Hi,

Yes I think you were right about sounds being amplified by the futura wing... I encountered the same in another plane that I assembled sometime back... It is the jitters that i am encountering in the current setup that had me concerned.

I did the tx position and Velcro trick... The Velcro does help to some extent but I am going to change out the servo with a 645mg that I have in my box spares. Will save the digital servo for other applications.

I have a video of the result of applying the Velcro which I would post later when I get on a PC.

Thanks again for the suggestions.

Isaac

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RE: Noisy Hitec Servo on Flaps of Futura - 10/11/2012 12:47 PM   
mun_iz


 

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Status: offline 		The video of my velcro test. I don't encounter jitters and clicking when the flap is deployed anymore but when I raise the flap, it comes back.

The photo shows the placement of the velcro.



Attachments
Click to see fullsize image.
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RE: Noisy Hitec Servo on Flaps of Futura - 10/11/2012 3:38 PM   
jetpilot



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Status: offline 		I always use digitals on flaps. Usually 8711's.
I try not to have a metal arm on a metal clevis.
Scott

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RE: Noisy Hitec Servo on Flaps of Futura - 10/13/2012 8:44 AM   
mun_iz


 

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Status: offline 		Hi Scott,

Thanks for voicing out the concern with regards to metal clevis to metal horn contacts. It shouldn't be a problem for mine as my clevises are kept tight on the horn with the use of washers as spacers to prevent slack and therefore excessive rubbing.

I am actually more worried about plastic servo horns not up to the task and stripping its spines during flight as several people had encountered in this forum.

Isaac

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RE: Noisy Hitec Servo on Flaps of Futura - 10/13/2012 9:37 AM   
Ali



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Status: online 		First video looks fine and sounds fine to me. Not sure I am too keen on the Velcro idea as this is Putting a constant load onto the servo through friction. Domt forget as soon as you are doing 1mph upwards there will be some form of load on that surface anyway. Adding more to me seems like a great way of burning a servo. I know the Velcro trick from the aerobatic guys who put it on surfaces to stop a servo that fails to centre each time, but in this application I see it as more of a hindrance than a help.
Relax and go fly.
I am with Scott on the plastic arms. If the correct ones are used then I actually prefer them over metal.
Regards Al


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RE: Noisy Hitec Servo on Flaps of Futura - 10/15/2012 2:08 AM   
mun_iz


 

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Status: offline 		Hi Ali,

Thanks for the advice and reassurance.

Isaac

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