REFLECTOR:Slipping Aileron trim

KeithHallsten reflector@tvbf.org
Mon, 13 Oct 2003 22:46:48 -0700


Tony,

Both the original "string" system and the various versions of the
MAC-servo-driven aileron trim systems just bias the centering springs on the
control stick torque tube bellcrank.  An autopilot servo would require a
much more direct connection to the aileron push-pull cables (either in the
back of the cabin or under the cowling at one of the aileron bellcranks).
So there is no obvious compatability issue.

However, some autopilots also drive the trim servos, so that the autopilot
servo doesn't have to push so hard and so there is no major "out of trim"
condition upon autopilot disconnect.  There might be some potential for
incompatibility between the autopilot trim drive circuitry and some types of
trim motors.

Keith Hallsten

----- Original Message ----- 
From: "Tony Babb" <tonybabb@alejandra.net>
To: <reflector@tvbf.org>
Sent: Monday, October 13, 2003 10:17 PM
Subject: Re: REFLECTOR:Slipping Aileron trim


> Sorry if this seems like a (couple of) dumb questions but....
>
> What's the advantage of the Mac servo over the factory supplied unit - it
> certainly looks better but is there a functional/ reliability/ maintenance
> advantage?
>
> If I were to install an autopilot (eventually) would they all work with a
> Mac servo or do A/Ps have a separate servo - reason I ask is that a vendor
> (I forget which) at OSH was trying to get me to order his servos so they'd
> be compatible with his A/P (his argument was it's easier to install when
> you're building than to retrofit - probably true but could that lock me in
> to his A/P) . Sooo... if they are a separate servo are they proprietary to
> the A/P or is there a common standard.that works with most A/Ps.
>
> Thanks
>
>
> ----- Original Message -----
> From: "Dave Black" <dvblack@comcast.net>
> To: <reflector@tvbf.org>
> Sent: Monday, October 06, 2003 8:42 PM
> Subject: Re: REFLECTOR:Slipping Aileron trim
>
>
> > Keith,
> >
> > > Ahh!  I see that the servo slides the long angle "rack" back and
forth,
> and
> > > the "rack" carries the supports for the outer ends of the springs with
> it,
> > > thereby shifting the neutral point for the bellcrank.
> >
> > You got it!!
> >
> > Basically I replaced the copier motor with the Mac servo, and the slip
> string
> > with the aluminum rack (made from scrap parts). It's a drop-in
> replacement.
> >
>
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