Sender: <marv@lancaironline.net>
To:  lml@lancaironline.net
Date: Tue, 31 May 2011 08:16:54 -0400
Message-ID: <redirect-4998979@logan.com>
Received-SPF: pass
 receiver=logan.com; client-ip=75.180.132.120; envelope-from=super_chipmunk@roadrunner.com
From: "Bill Wade" <super_chipmunk@roadrunner.com>
References: <list-4997680@logan.com>
In-Reply-To: <list-4997680@logan.com>
Subject: Re: [LML] Re: Change the speed of the ROC servo  for trim
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----=_NextPart_000_01F1_01CC1EAC.A7337F80"
Importance: Normal

This is a multi-part message in MIME format.

------=_NextPart_000_01F1_01CC1EAC.A7337F80
Content-Type: text/plain;
	charset="Windows-1252"
Content-Transfer-Encoding: quoted-printable

  Does the plane need full trim travel or is it usually a matter of a =
small correction?

  Would it work to reduce the speed mechanically by using an idler arm =
that pivoted at one end, had the servo attached at the other, and the =
trim tab link at an intermediate point? That would slow the movement and =
increase thrust at the cost of reduced travel. Looking at my IV-P =
elevator it seems there might be room enough to do something. Not in the =
aileron though.  -Bill Wade

From: paul miller=20
Sent: Sunday, May 29, 2011 4:47 PM
To: lml@lancaironline.net=20
Subject: [LML] Re: Change the speed of the ROC servo for trim

Jim, I had that issue.  Lancair avionics put a 200k pot in series in the =
original installation back in 2004.   I have a 28v airplane driving the =
12v Ray Allen servo.  You might have something different?  I thought it =
never worked because 98% of the pot travel results in the pitch trim =
being fully off.   But I found that there is a very small range where =
there is speed control so that's where I'm at now (about 25% of the =
original speed).   It takes a few seconds to trim out pitch now--before =
it was the "bump".  The autopilot behaves much differently now without =
huge bumps as it captures an altitude (Tru-Trak).=20

If I get the chance later, I will probably swap out the 200k for a fixed =
value and I'm guessing it should be something in the order of a few =
ohms.   It will be important for you to test any lower voltage setting =
at altitude and have the ability to recover from a bad setting.   If you =
drive the trim at a lower voltage than rated it can work on the ground =
but might not be sufficient to work in the flight levels leaving you =
with no electric pitch trim.  Best way to start is time the full up to =
full down time trim speed and work from there.  I went from 6 seconds to =
about 25 seconds.

Some day I'll add the pitot switch to further numb the trim speed at =
cruise and wick it up a bit for approach.  Ultimately, a PWM setup is =
best and then there are no altitude concerns.

Paul=20
Legacy=20


On 2011-05-29, at 8:32 AM, Jim Nordin wrote:


  I know this has been discussed before and I=92ve given a cursory look =
on the archives. But is there a simple way of adjusting / changing the =
speed of the servo to slow it down some for pitch trim in a 4PT? The =
pitch change is too fast at speed where just a small bump has too much =
effect.
  Jim

------=_NextPart_000_01F1_01CC1EAC.A7337F80
Content-Type: text/html;
	charset="Windows-1252"
Content-Transfer-Encoding: quoted-printable

<HTML><HEAD></HEAD>
<BODY=20
style=3D"WORD-WRAP: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space"=20
dir=3Dltr>
<DIV dir=3Dltr>
<DIV style=3D"FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: 12pt">
<DIV>&nbsp; Does the plane need full trim travel or is it usually a =
matter of a=20
small correction?</DIV>
<DIV>&nbsp;</DIV>
<DIV>&nbsp; Would it work to reduce the speed mechanically by using an =
idler arm=20
that pivoted at one end, had the servo attached at the other, and the =
trim tab=20
link at an intermediate point? That would slow the movement and increase =
thrust=20
at the cost of reduced travel. Looking at my IV-P elevator it seems =
there might=20
be room enough to do something. Not in the aileron though.&nbsp; -Bill=20
Wade</DIV>
<DIV=20
style=3D"FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; =
COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: =
none">
<DIV style=3D"FONT: 10pt tahoma">
<DIV>&nbsp;</DIV>
<DIV style=3D"BACKGROUND: #f5f5f5">
<DIV style=3D"font-color: black"><B>From:</B> <A title=3Dpaul@tbm700.com =

href=3D"mailto:paul@tbm700.com">paul miller</A> </DIV>
<DIV><B>Sent:</B> Sunday, May 29, 2011 4:47 PM</DIV>
<DIV><B>To:</B> <A title=3Dlml@lancaironline.net=20
href=3D"mailto:lml@lancaironline.net">lml@lancaironline.net</A> </DIV>
<DIV><B>Subject:</B> [LML] Re: Change the speed of the ROC servo for=20
trim</DIV></DIV></DIV>
<DIV>&nbsp;</DIV></DIV>
<DIV=20
style=3D"FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; =
COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: =
none">Jim,=20
I had that issue.&nbsp; Lancair avionics put a 200k pot in series in the =

original installation back in 2004.&nbsp;&nbsp; I have a 28v airplane =
driving=20
the 12v Ray Allen servo.&nbsp; You might have something different?&nbsp; =
I=20
thought it never worked because 98% of the pot travel results in the =
pitch trim=20
being fully off.&nbsp;&nbsp; But I found that there is a very small =
range where=20
there is speed control so that's where I'm at now (about 25% of the =
original=20
speed).&nbsp;&nbsp; It takes a few seconds to trim out pitch now--before =
it was=20
the "bump".&nbsp; The autopilot behaves much differently now without =
huge bumps=20
as it captures an altitude (Tru-Trak).=20
<DIV>&nbsp;</DIV>
<DIV>If I get the chance later, I will probably swap out the 200k for a =
fixed=20
value and I'm guessing it should be something in the order of a few=20
ohms.&nbsp;&nbsp; It will be important for you to test any lower voltage =
setting=20
at altitude and have the ability to recover from a bad =
setting.&nbsp;&nbsp; If=20
you drive the trim at a lower voltage than rated it can work on the =
ground but=20
might not be sufficient to work in the flight levels leaving you with no =

electric pitch trim.&nbsp; Best way to start is time the full up to full =
down=20
time trim speed and work from there.&nbsp; I went from 6 seconds to =
about 25=20
seconds.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Some day I'll add the pitot switch to further numb the trim speed =
at cruise=20
and wick it up a bit for approach.&nbsp; Ultimately, a PWM setup is best =
and=20
then there are no altitude concerns.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Paul </DIV>
<DIV>Legacy </DIV>
<DIV>&nbsp;</DIV>
<DIV>
<DIV>&nbsp;</DIV>
<DIV>
<DIV>On 2011-05-29, at 8:32 AM, Jim Nordin wrote:</DIV><BR=20
class=3DApple-interchange-newline>
<BLOCKQUOTE type=3D"cite"><SPAN=20
  style=3D"WIDOWS: 2; TEXT-TRANSFORM: none; TEXT-INDENT: 0px; =
LETTER-SPACING: normal; BORDER-COLLAPSE: separate; FONT: medium =
helvetica; WHITE-SPACE: normal; ORPHANS: 2; WORD-SPACING: 0px; =
-webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: =
0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: =
auto; -webkit-text-stroke-width: 0px"=20
  class=3DApple-style-span>
  <DIV lang=3DEN-US vlink=3D"#FF0D00" link=3D"blue">
  <DIV style=3D"page: section1" class=3DSection1>
  <DIV=20
  style=3D"MARGIN: 0in 0in 0pt; FONT-FAMILY: 'Comic Sans MS'; FONT-SIZE: =
14pt"><FONT=20
  size=3D4 face=3D"Comic Sans MS"><SPAN style=3D"FONT-SIZE: 14pt">I know =
this has been=20
  discussed before and I=92ve given a cursory look on the archives. But =
is there a=20
  simple way of adjusting / changing the speed of the servo to slow it =
down some=20
  for pitch trim in a 4PT? The pitch change is too fast at speed where =
just a=20
  small bump has too much=20
effect.<BR>Jim</SPAN></FONT></DIV></DIV></DIV></SPAN></BLOCKQUOTE></DIV>
<DIV>&nbsp;</DIV></DIV></DIV></DIV></DIV></BODY></HTML>

------=_NextPart_000_01F1_01CC1EAC.A7337F80--