Mailing List lml@lancaironline.net Message #69500
From: Tom <n20087@yahoo.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Autopilot servos and L360 bobweight
Date: Wed, 19 Mar 2014 08:07:55 -0400
To: <lml@lancaironline.net>
John

As Chris points out, the servo may need a little tuning to your mechanical system. Recently while installing/testing the g3x servos I found the default gain was set too high and with a little trial and error it was not too difficult dial in.  There are more scientific methods to achieving the same result and having quite a good deal of experience at tuning control systems in a professional capacity I can say the trial and error method is probably the most efficient in this particular setting.  

I would not remove the bob weight, the 360 has lousy "feel" in pitch.  As Chris also points out the g force vs stick force curve is really horrible without it and you need the most cues at a time when you least expect it

Tom

Sent from my iPad

On Mar 18, 2014, at 3:14 PM, Chris Zavatson <chris_zavatson@yahoo.com> wrote:

John,
I think you are mixing up the counterweight and the bob-weight.  The counterweight is indeed there to prevent flutter by mass balancing the control surface.  Removing the bob-weight will reduce the stick force/g.  Lancair experimented with reducing or eliminating the bob-weight many years ago.  I don't recall the details however.
Chris Zavatson
N91CZ
360std


On Tuesday, March 18, 2014 10:33 AM, Chris Zavatson <chris_zavatson@yahoo.com> wrote:
Jack,
The bob-weight changes the slope of the stick force gradient.  It is already very shallow.  Removing the weight would make it even more so.  
What is the nature of the 'inconsistent' altitude hold, a long and slow meandering (likely a static source lag issue) or a short and quick movement (likely a gain or sensitivity issue).

Chris Zavatson
N91CZ
360std


On Tuesday, March 18, 2014 6:55 AM, Jack Dysart <jldysart1@gmail.com> wrote:
My Tru Trak autopilot altitude hold is inconsistent, and opinions are that the servo had difficulty working properly because of the mass of the bobweight on the elevator idler arm.  One possibility is to remove the weight and expect more pitch sensitivity (lighter stick force) in turns.  Has anyone found other alternatives?
What if the mass of the bobweight is reduced?
 
My servo is behind the seat and connected to a ring clamp on the elevator control tube with a smaller, roughly parallel, rod with bearing ends.
 
Jack Dysart    




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