X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 21 Jul 2007 06:08:41 -0400 Message-ID: X-Original-Return-Path: Received: from wind.imbris.com ([216.18.130.7] verified) by logan.com (CommuniGate Pro SMTP 5.1.10) with ESMTPS id 2190362 for lml@lancaironline.net; Fri, 20 Jul 2007 20:58:21 -0400 Received-SPF: none receiver=logan.com; client-ip=216.18.130.7; envelope-from=brent@regandesigns.com Received: from [192.168.1.100] (cbl-238-80.conceptcable.com [207.170.238.80] (may be forged)) (authenticated bits=0) by wind.imbris.com (8.12.11/8.12.11.S) with ESMTP id l6L0vgtO048701 for ; Fri, 20 Jul 2007 17:57:43 -0700 (PDT) (envelope-from brent@regandesigns.com) X-Original-Message-ID: <46A15A02.4060907@regandesigns.com> X-Original-Date: Fri, 20 Jul 2007 17:57:38 -0700 From: Brent Regan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 X-Original-To: Lancair Mailing List Subject: Re: Watson AHRS Content-Type: multipart/alternative; boundary="------------060205080602090900090100" This is a multi-part message in MIME format. --------------060205080602090900090100 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit John asks: <<<<<" Is anybody on the list using the Watson AHRS with their Chelton/Sierra Flight Systems EFIS? I have a Chelton EFIS-SV and Watson but have not installed it yet. I'd be interested in your comments on the Watson unit? Are you still using it or have you upgraded to Crossbow or Pinpoint? " >>>>> The CSF software supports the Watson but I would not recommend using the Watson as it is based on older technology and is relatively easy to confuse. I used to have a Watson in my IV-P until it developed the nasty habit of doing aileron rolls every time I encountered some P-Static. I replaced it with a XBow-500, which has a habit of "seeking" +- 4 degrees in yaw. I sold the Watson on ebay for about 10 Franklins. You can sell anything on ebay. I plan to sell the Xbow 500 when I get around to installing a Chelton GADAHRS. "Brent, you still running a 500?" "Yep, the cobbler's kids don't have shoes." All MEMSs based AHRS (Watson, XBow 425 and 500, Dynon, BM, OP (XBow), and Garmin 1000) can be "confused" with certain flight maneuvers (e.g. slow climbing sliding turn) resulting in anything from a few degrees of offset in yaw, pitch or roll to the aforementioned aileron rolls. One dealer reports that he has the goods on every AHRS tested with the exception of the Chelton ADAHRS. The Chelton ADAHRS, so far, is the only system that has proven resistant to users finding its "secret handshake" that would cause a perturbation of more than 3 degrees for more than 90 seconds. When someone does, I'd like to hear about it. IMHO a reliability and performance ranking, based on anecdotal data and direct experience, would put the Watson and XBow 425 near the bottom. Step up to the XBow 500 and Garmin G900x. Another step would get you the Chelton ADAHRS and the Rockwell Collins AHRS (The RC does not have an integral Air Data Computer). The last step takes you out of the MEMs box and into the Fiber Optic Gyro (FOG) platforms like Litef. What should you use? I couldn't say. What is your tolerance for spinning displays when you are wings level? The next question is "How old are, and what is the update status of your IDUs?". If your system is old enough to have a Watson then it predates most of the hardware upgrades necessary to run the latest version of the CFS software. Upgrades include Encoders, RAM, CPU and Hard Drive. Talk to Chelton if you are unsure. The good news is that any IDU-I can be updated to the latest performance specs. Regards Brent Regan --------------060205080602090900090100 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit John asks:

<<<<<" Is anybody on the list using the Watson AHRS with their Chelton/Sierra Flight Systems EFIS?
I have a Chelton EFIS-SV and Watson but have not installed it yet.

I'd be interested in your comments on the Watson unit?  Are you still using it or have you upgraded to Crossbow or Pinpoint? "
>>>>>

The CSF software supports the Watson but I would not recommend using the Watson as it  is based on older technology and is relatively easy to confuse.  I used to have a Watson in my IV-P until  it developed the nasty habit of doing  aileron rolls every time I encountered some P-Static. I replaced it with a XBow-500, which has a habit of "seeking" +- 4 degrees in yaw.  I sold the Watson on ebay for about 10 Franklins. You can sell anything on ebay. I plan to sell the Xbow 500 when I get around to installing a Chelton GADAHRS.

"Brent, you still running a 500?"
"Yep, the cobbler's kids don't have shoes."

All MEMSs based AHRS (Watson, XBow 425 and 500, Dynon, BM, OP (XBow), and Garmin 1000) can be "confused" with certain flight maneuvers (e.g. slow climbing sliding turn) resulting in anything from a few degrees of offset in yaw, pitch or roll to the aforementioned aileron rolls. One dealer reports that he has the goods on every AHRS tested with the exception of the Chelton ADAHRS. The Chelton ADAHRS, so far, is the only  system that has proven resistant  to users finding its "secret handshake" that would cause a perturbation of more than 3 degrees for more than 90 seconds.  When someone does, I'd like to hear about it.

IMHO a reliability and performance ranking, based on anecdotal data and direct experience, would put the Watson and XBow 425 near the bottom. Step up to the XBow 500 and Garmin G900x. Another step would get you the Chelton ADAHRS and the Rockwell Collins AHRS (The RC does not have an integral Air Data Computer). The last step takes you out of the MEMs box and into the Fiber Optic Gyro (FOG) platforms like Litef.

What should you use? I couldn't say. What is your tolerance for spinning displays when you are wings level?

The next question is "How old are, and what is the update status of your IDUs?". If your system is old enough to have a Watson then it predates most of the hardware upgrades necessary to run the latest version of the CFS software.  Upgrades include Encoders, RAM, CPU and Hard Drive. Talk to Chelton if you are unsure.  The good news is that any IDU-I can be updated to the latest performance specs.

Regards
Brent  Regan
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