8411SA oscillation

[Dean Pappas]

Hello All,
There is another scenario that causes this, and it only rears its head if the cables are tight.
If one cable slackens at the extremes of travel, and both tighten near neutral, then the cable
tension will snatch the servo through neutral, and cause an oscillation.
The cure is to fix the control geometry at either the rudder or servo end.
Regards,
	Dean P.  

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com


-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of jivey61 at bellsouth.net
Sent: Monday, August 23, 2004 7:14 AM
To: discussion at nsrca.org
Subject: Re: 8411SA oscillation


 Keith
 I had the same problem last week. If you move the centering off to the rt or left and it stops oscilating, the problem more than  is likely bad gears, However if you change gears(easy to do) and that doesn't stop it then you have a worn feedback pot in the servo. (not easy to do). Send in for repair.

Jim Ivey
> 
> From: "Keith Black" <tkeithb at comcast.net>
> Date: 2004/08/23 Mon AM 12:24:21 EDT
> To: <discussion at nsrca.org>
> Subject: 8411SA oscillation
> 
> I have a new JR 8411SA on the rudder of my new plane and it frequently oscillates back and forth.
> 
> In the past I've experienced oscillation problems on the rudder using a JR 8411SA, however when this has occurred in the past (with a relatively new servo) it normally indicated that the pull-pull cables are a bit loose and tightening them will solve the problem.
> 
> However, in this case I've tightened the cables quite a bit tighter than my other plane and still have the oscillation problem even with the new servo. If I touch the rudder with my hand it will stop, and I can also stop it by moving the stick back and forth a couple of times very slowly. However, any quick moves of the rudder stick to center, or when the plane is first turned on will result in the oscillation.
> 
> As far as flying goes, I imagine that the prop wash normally stops the oscillation, much like putting my hand on the rudder, but the fact that this occurs so much and my other plane doesn't often have this problem is somewhat troubling.
> 
> Any suggestions or advice?
> 
> Thanks,
> Keith Black
> 
> 

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