REFLECTOR: Pitch servo installation

[Mike Dawson]

If you hook it up directly with no spring and the servo should freeze you will be SOL. If the servo or the actuator freeze the spring can be overidden by the stick. 
Mike
N104DD



On Saturday, November 16, 2013 8:25 AM, Dennis King <kitfox94 at comcast.net> wrote:
 
Peter,
Some autopilots have a separate output to control the pitch trim actuator so that the system can automatically adjust the trim while flying with the autopilot engaged to minimize loads on the pitch control servo.  In that case a separate trim actuator is still used but wired to the autopilot.  Is it possible that is the type of system you have?  An autopilot that allows you to adjust pitch trim using a single actuator would have to use a servo that is actively controlling pitch all the time.  It would also need a clutch with a high break-away torque, so it would need to be connected through the pitch trim spring to allow you to move the elevator independently from servo position.  Otherwise the servo would need an internal spring, or some type of variable torque control that electronically simulates a trim spring.  I don't know if those types of systems exist, but I'm only familiar with the type I have (Trio).

If you decide you do need both actuators with your system, I can post a picture of the pitch servo/trim actuator installation that I have in my 173RG.


Dennis King


________________________________
From: "Peter Braswell" <peter.braswell at gmail.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Friday, November 15, 2013 4:44:03 PM
Subject: Re: REFLECTOR: Pitch servo installation


John,
Right.  That's with the pitch actuator attached though.  With a servo, when there's no power to it, it rotates freely.  That's why I'm thinking the spring is not necessary.  But again, I might be wrong.  

-Peter


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On Fri, Nov 15, 2013 at 4:10 PM, John Dibble <aminetech at bluefrog.com> wrote:

I mentioned this a few weeks ago.  You need the spring so you will be able to move the stick and manually control pitch.
>
>John
>
>
>On 11/15/2013 2:56 PM, Peter Braswell wrote:
>
>All, 
>>I'm getting ready to install my pitch servo and I was wondering if anybody on the list has pictures on how they may have gone about this.  I'm going to leave off the pitch actuator as I don't need it.  My AP servo does double duty and adjusts the trim as well.  I was going to modify the pitch actuator install but have been scratching my head.  The pitch actuator pivots and is connected to the spring.  I think it pivots because it's a linear actuation.  I'm wondering if I can just eliminate the pitch actuator and attach my pitch servo directly to the pitch spring?  Obviously it's impractical to have the pitch servo pivot.Do I even need the spring at all or can there be something rigid instead that comes off the elevator, projects up and attaches directly to the servo rod end?
>>
>>
>>TIA,
>>Peter
>>
>>
>>------------------------------------------------------------------------ 
>>SUDO Labs | Zuluworks.com | ThreePoint.io 
>>
>>"It's a Jungle Up There": www.zuluworks.com
>>Cell: 804.690.5896
>>
>>------------------------------------------------------------------------
>>
>>
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