X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 31 May 2011 08:16:53 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTP id 4998354 for lml@lancaironline.net; Mon, 30 May 2011 14:43:44 -0400 Received-SPF: none receiver=logan.com; client-ip=71.74.56.123; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=1.1 cv=u/eXSd3k4P+OuNmbl5aZU3ellt6eTxbOnGssQLT4hSY= c=1 sm=0 a=5A5HpM9lm0IA:10 a=ttCsPuSJ-FAA:10 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=Ia-xEzejAAAA:8 a=-TabZwvoKTA8hE7f7D8A:9 a=alxKonHbr3yNueEG5usA:7 a=pILNOxqGKmIA:10 a=EzXvWhQp4_cA:10 a=az2nqfWbAAAA:8 a=huPSrrWkusMnJ4cMTQEA:9 a=ihGOkDJ6LNfBQx71FLsA:7 a=t7dr3Dmy9FQA:10 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:2832] helo=Lobo) by hrndva-oedge03.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 3F/02-28963-B35E3ED4; Mon, 30 May 2011 18:43:07 +0000 X-Original-Message-ID: <001201cc1ef9$6a173ea0$6401a8c0@Lobo> From: "Wolfgang" X-Original-To: Subject: Re: [LML] Change the speed of the ROC servo for trim X-Original-Date: Mon, 30 May 2011 14:43:05 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01CC1ED7.E2D84D10" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_000F_01CC1ED7.E2D84D10 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable 200K sounds rather high for a series resistor for a motor. Having only = 2% usable range is to be expected. I'm surprised you haven't burned it = out by now.=20 I suggest you measure the current of the motor without any resistance = added, calculate the motor resistance and start with a resistor 25% of = that value and the appropriate wattage. ----- Original Message -----=20 From: paul miller=20 To: lml@lancaironline.net=20 Sent: Sunday, May 29, 2011 4:47 PM Subject: Re: [LML] 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_000F_01CC1ED7.E2D84D10 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
200K sounds rather high for a series = resistor for a=20 motor. Having only 2% usable range is to be expected. I'm surprised you = haven't=20 burned it out by now.
 
I suggest you measure the current of = the motor=20 without any resistance added, calculate the motor resistance and = start with=20 a resistor 25% of that value and the appropriate wattage.
----- Original Message -----
From:=20 paul = miller
Sent: Sunday, May 29, 2011 4:47 = PM
Subject: Re: [LML] Change the = speed of=20 the ROC servo for trim

Jim, I had that issue.  Lancair avionics put a = 200k pot in=20 series in the original installation back in 2004.   I have a 28v = airplane=20 driving the 12v Ray Allen servo.  You might have something = different?=20  I thought it never worked because 98% of the pot travel results = in the=20 pitch trim being fully off.   But I found that there is a very = small=20 range where there is speed control so that's where I'm at now (about = 25% of=20 the original speed).   It takes a few seconds to trim out pitch=20 now--before it was the "bump".  The autopilot behaves much = differently=20 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=20 value and I'm guessing it should be something in the order of a few = ohms.=20   It will be important for you to test any lower voltage setting = at=20 altitude and have the ability to recover from a bad setting.   If = you=20 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=20 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=20 cruise and wick it up a bit for approach.  Ultimately, a PWM = setup is=20 best and then there are no altitude concerns.

Paul 
Legacy 


On 2011-05-29, at 8:32 AM, Jim Nordin wrote:
I = know this has=20 been discussed before and I=92ve given a cursory look on the = archives. But is=20 there a simple way of adjusting / changing the speed of the servo to = slow it=20 down some for pitch trim in a 4PT? The pitch change is too fast at = speed=20 where just a small bump has too much=20 = effect.
Jim
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