Received: from logan.com (mail.logan.com[207.58.244.114]) by isp.att.net (frfwmxc09) with ESMTP id <20081017062558M09009k25me>; Fri, 17 Oct 2008 06:25:59 +0000 X-Originating-IP: [207.58.244.114] X-Virus-Scanned: clean according to Sophos on Logan.com X-ListServer: CommuniGate Pro LIST 5.2.8 List-Unsubscribe: List-ID: List-Archive: Precedence: list Message-ID: Reply-To: "Lancair Mailing List" Sender: "Lancair Mailing List" To: lml@lancaironline.net Date: Fri, 17 Oct 2008 02:25:04 -0400 X-Original-Message-ID: From: "John Huft" MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0029_01C92E99.D26FB520" Subject: [LML] Re: Blue Mountain Avionics Autopilot This is a multipart message in MIME format. ------=_NextPart_000_0029_01C92E99.D26FB520 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit One thing I do know about the S-Tec autopilot is that the pitch algorithms are extremely sensitive to any lag or delay in the static system. On certified installations the "brain box" is required to be mounted very close (3 feet or less) to the static ports, and the autopilot must have its own static ports, and not share them with any other instrument. Also not allowed are the little bottles that are supposed to catch moisture in the tubing. Pitch oscillations are the main symptoms of too much static lag. John Huft RV spy From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Wayne Bailey Sent: Sunday, October 12, 2008 6:49 PM To: lml@lancaironline.net Subject: [LML] Blue Mountain Avionics Autopilot Small tail 360 with Stec50 autopilot. AP works OK to maintaining heading - but pitch enters oscillations eventually becoming so severe requires disconnection of AP after about 30 - 40 seconds. Incredibly there is no 'gain' adjustment in the pitch axis of the STEC 50. I have read about replacing resistor on board to modify gain - but a little uncomfortable with this option. No slop in the linkage. Have not dug into the servos yet - but hoping there is a way to mechanically reduce the 'gain' by extending the servo attachment point radially outward on bellcrank - or ?? Alternatively thinking about installing BMA EFIS Gen 4 system with new servo actuators. Anyone have any experience with BMA gen 4 EFIS on a close coupled LNC2? I do know there is gain on both axis. Thanks again for the help. Wayne ------=_NextPart_000_0029_01C92E99.D26FB520 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

One thing I do know about the S-Tec autopilot is that the = pitch algorithms are extremely sensitive to any lag or delay in the static = system. On certified installations the “brain box”  is required to = be mounted very close (3 feet or less) to the static ports, and the autopilot must have its = own static ports, and not share them with any other instrument. Also not = allowed are the little bottles that are supposed to catch moisture in the = tubing.

 

Pitch oscillations are the main symptoms of too much = static lag.

 

John Huft

RV spy

 

 

 

From:= Lancair = Mailing List [mailto:lml@lancaironline.net] On Behalf Of Wayne Bailey
Sent: Sunday, October 12, 2008 6:49 PM
To: lml@lancaironline.net
Subject: [LML] Blue Mountain Avionics = Autopilot

 

Small tail 360 with Stec50 autopilot.  =

 

AP works OK to maintaining heading - but = pitch enters oscillations eventually becoming so severe requires disconnection = of AP after about 30 - 40 seconds.   Incredibly there is no 'gain' adjustment in the pitch axis of the STEC 50.  I have read about replacing resistor on board to modify gain - but a little uncomfortable with this option.  No slop in the = linkage.

 

Have not dug into the servos yet - but = hoping there is a way to mechanically reduce the 'gain' by extending the servo = attachment point radially outward on bellcrank - or ??

 

Alternatively thinking about installing BMA EFIS = Gen 4 system with new servo actuators.  Anyone have any experience with = BMA gen 4 EFIS on a close coupled LNC2? I do know there is gain on both = axis.

 

Thanks again for the help.



Wayne

 

 

 =

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