servo question

[Troy Newman]

Oh come on Jim....

For the rest of the guys...The servo moves in a  rotational motion...So the
linear distance traveled by a pushrod attached to the arm or wheel will be
greatest right off of center and will reduce the amount of linear travel of
the rod as it rotates around. A linkage not setup this will have a funny
expo like knee in it...But it will be as the arm passes through the square
position so it would be like adding expo on only one side of the servos
travel...and reverse expo on the other side of travel.......

Also it could be way up high on the travel of in a funny middle spot...and
you will get more throw one side than the other....

This sq to the pushrod also gives the servo best mechanical advantage
through the range...as the servo gets to the endpoints say full travel up
elevator..the highest force is being applied the surface...and the servo arm
is rotated in such a way to reduce the moment arm on the servo by the
pushrod pushing back.....The arm travels in an arc and the arm gets closer
to the center of the servo as it rotates off of "center"....This moment arm
is leverage for the pushrod to pushback on the servo.....So if you reduce
this distance when the forces are higher then it will make the servo have a
mechanically better shot and holding its position.

did I get it right Jim?
anything to add Jim?...I'm by far not the expert on this stuff...

Ok Still TMI....

TN



----- Original Message ----- 
From: "JOddino" <JOddino at socal.rr.com>
To: <discussion at nsrca.org>
Sent: Friday, August 01, 2003 5:29 PM
Subject: Re: servo question


> Troy,
> As you know I have been a proponent for using the full dynamic range of
the
> control system.  I crank my ATV to 140, subtrim to zero and set my AFR to
> the linear limits.  The use of programmable servos then gives me options
as
> far as the push rods go.
> I've heard this before but please explain why the servo arm should be
> perpendicular to the push rod.
> Jim
> ----- Original Message ----- 
> From: "Troy Newman" <troy_newman at msn.com>
> To: <discussion at nsrca.org>
> Sent: Friday, August 01, 2003 10:01 AM
> Subject: Re: servo question
>
>
> > Jon,
> >
> > you will be surprised at the precision you gain.....I was believe
> me....its
> > huge....60% low rates are killing the precision of your model. If you
are
> > going to try to improve your flying you need to improve your setup.
> >
> > I have been doing this a long time and been fairly successful with
> it...and
> > just this past spring I found that I was not using the equipment to its
> > potential....my answer was well I'm close and my setup is clean and
> > neat....followed all the rules about square pushrod to the servo horn
(not
> > the servo case but the arm)...and use stiff friction free
linkages....and
> so
> > on...Well my low rates that I do everything on were down in the 60-70%
> > range.
>
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