X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 02 Mar 2006 00:48:12 -0500 Message-ID: X-Original-Return-Path: Received: from wind.imbris.com ([216.18.130.7] verified) by logan.com (CommuniGate Pro SMTP 5.0.8) with ESMTPS id 1002439 for lml@lancaironline.net; Wed, 01 Mar 2006 12:56:29 -0500 Received-SPF: none receiver=logan.com; client-ip=216.18.130.7; envelope-from=brent@regandesigns.com Received: from [192.168.1.100] (wireless-216-18-135-19.imbris.com [216.18.135.19]) (authenticated bits=0) by wind.imbris.com (8.12.11/8.12.11.S) with ESMTP id k21HtT7L060442 for ; Wed, 1 Mar 2006 09:55:35 -0800 (PST) (envelope-from brent@regandesigns.com) X-Original-Message-ID: <4405E00F.4060606@regandesigns.com> X-Original-Date: Wed, 01 Mar 2006 09:55:27 -0800 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: AHRS -- Crossbow responds Content-Type: multipart/alternative; boundary="------------090109050201070907010008" This is a multi-part message in MIME format. --------------090109050201070907010008 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Brent, would you opt to stay with the X-bow 425 or go with the Pinpoint unit? Chat Daniel Chat, My advice here is the same as it is for any avionics decision, "wait as long as you can before making a decision". 425 users are in the rare position of having BOTH the equipment manufacturer (X-bow) and the dealer (D2) offering to support or replace the product. If you are in a position to do so, then you may want to wait and see if X-bow really does have the problem fixed. According to the web site the Pinpoint GADAHRS has an integrated air data computer (ADC) and a remote magnetometer. The 425 has an integrated magnetometer and no air data computer. Both have integrated GPS. While not mentioned, if the Pinpoint unit has an ADC then it must also have an outside air temperature probe (OAT), which is need to calculate TAS. These differences would translate to some amount of work to accommodate the change. I currently have an X-bow 500 in my plane. No matter what path you take, be sure to get a reasonable amount of flight testing in before you launch into actual. During flight testing of Fosset's GlobalFlyer there was a failure of both the attitude and air data systems that were part of the installed Chelton EFIS. As it turned out it wasn't a "failure" at all, but an expected, if undesirable, system interaction. It seems the Shaden ADC and its OAT probe were certified to the -55 celsius (-67F) DO160 limit. The Shaden engineers assumed that if the OAT was reporting a temperature outside this lower limit then there must be a failure of the OAT system and the accuracy of the TAS was in doubt. When the GlobalFlyer was tested in the flight levels above 350 the actual OAT fell below the "failed" threshold causing the ADC to report "failed" causing the AHRS to loose aiding and also report "failed". Given that nothing had actually failed the fix was simple, above FL180 if the OAT fails out of range then use the ICAO Standard Atmosphere to calculate air data. The point is that even when using certified components there are challenges at the system integration level that only testing will uncover. Regards Brent Regan --------------090109050201070907010008 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Brent,
<snip> would you opt to stay with the X-bow 425 or go with the Pinpoint unit?
Chat Daniel

Chat,

My advice here is the same as it is for any avionics decision, "wait as long as you can before making a decision". 425 users are in the rare position of having BOTH the equipment manufacturer (X-bow) and the dealer (D2) offering to support or replace the product. If you are in a position to do so, then you may want to wait and see if X-bow really does have the problem fixed.

According to the web site the Pinpoint GADAHRS has an integrated air data computer (ADC) and a remote magnetometer. The 425 has an integrated magnetometer and no air data computer. Both have integrated GPS. While not mentioned, if the Pinpoint unit has an ADC then it must also have an outside air temperature probe (OAT), which is need to calculate TAS. These differences would translate to some amount of work to accommodate the change. I currently have an X-bow 500 in my plane.

No matter what path you take, be sure to get a reasonable amount of flight testing in before you launch into actual.

During flight testing of Fosset's GlobalFlyer there was a failure of both the attitude and air data systems that were part of the installed Chelton EFIS. As it turned out it wasn't a "failure" at all, but an expected, if undesirable, system interaction. It seems the Shaden ADC and its OAT probe were certified to the -55 celsius (-67F) DO160 limit. The Shaden engineers assumed that if the OAT was reporting a temperature outside this lower limit then there must be a failure of the OAT system and the accuracy of the TAS was in doubt. When the GlobalFlyer was tested in the flight levels above 350 the actual OAT fell below the "failed" threshold causing the ADC to report "failed" causing the AHRS to loose aiding and also report "failed". Given that nothing had actually failed the fix was simple, above FL180 if the OAT fails out of range then use the ICAO Standard Atmosphere to calculate air data.

The point is that even when using certified components there are challenges at the system integration level that only testing will uncover.

Regards
Brent Regan

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