X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 31 May 2011 08:16:54 -0400 Message-ID: X-Original-Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4998241 for lml@lancaironline.net; Mon, 30 May 2011 09:34:16 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=super_chipmunk@roadrunner.com X-Original-Return-Path: X-Authority-Analysis: v=1.1 cv=SOlsIBN44tkg4MqIq+y2aLZdhoA3kHpmiRsLue6rfnM= c=1 sm=0 a=VHj8Vlg6hGgA:10 a=zTVDa7HKqxcA:10 a=35Tvjzvas7lBNn8+H1IYgA==:17 a=Ia-xEzejAAAA:8 a=-TabZwvoKTA8hE7f7D8A:9 a=pILNOxqGKmIA:10 a=EzXvWhQp4_cA:10 a=az2nqfWbAAAA:8 a=V7HwIEvXdE-zrsGT4VgA:9 a=TpAdzxT4iiWzwV3ExNAA:7 a=t7dr3Dmy9FQA:10 a=35Tvjzvas7lBNn8+H1IYgA==:117 X-Cloudmark-Score: 0 X-Originating-IP: 69.205.15.200 Received: from [69.205.15.200] ([69.205.15.200:63098] helo=WilliamHP) by cdptpa-oedge01.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 44/D4-15242-4BC93ED4; Mon, 30 May 2011 13:33:40 +0000 X-Original-Message-ID: From: "Bill Wade" X-Original-To: "Lancair Mailing List" References: In-Reply-To: Subject: Re: [LML] Re: Change the speed of the ROC servo for trim X-Original-Date: Mon, 30 May 2011 09:33:37 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01F1_01CC1EAC.A7337F80" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 15.4.3508.1109 X-MIMEOLE: Produced By Microsoft MimeOLE V15.4.3508.1109 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
  Does the plane need full trim travel or is it usually a = matter of a=20 small correction?
 
  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.  -Bill=20 Wade
 
Sent: Sunday, May 29, 2011 4:47 PM
Subject: [LML] Re: Change the speed of the ROC servo for=20 trim
 
Jim,=20 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=20 the 12v Ray Allen servo.  You might have something different?  = I=20 thought it never worked because 98% of the pot travel results in the = pitch trim=20 being fully off.   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).   It takes a few seconds to trim out pitch now--before = it was=20 the "bump".  The autopilot behaves much differently now without = huge bumps=20 as it captures an altitude (Tru-Trak).=20
 
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.   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.   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.  Best way to start is time the full up to full = down=20 time trim speed and work from there.  I went from 6 seconds to = about 25=20 seconds.
 
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.  Ultimately, a PWM setup is best = and=20 then there are no altitude concerns.
 
Paul
Legacy
 
 
On 2011-05-29, at 8:32 AM, Jim Nordin wrote:
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.
Jim
 
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