REFLECTOR:Slipping Aileron trim

John Dibble reflector@tvbf.org
Tue, 14 Oct 2003 10:05:18 -0400


I have the S-Tec 50 a/p and I consider it a "must have" nicety.  It does not control
trim and I think that roll trim is not a significant issue.  However pitch trim is
significant and the S-Tec is designed to accomodate this by having lights that
indicate when pitch is adjusting up or down.  When I note  continued adjustment in one
direction, I adjust the pitch trim until the light goes out.

John

KeithHallsten wrote:

> 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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