X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 31 May 2007 08:48:52 -0400 Message-ID: X-Original-Return-Path: Received: from smtp106.sbc.mail.re2.yahoo.com ([68.142.229.99] verified) by logan.com (CommuniGate Pro SMTP 5.1.9) with SMTP id 2076251 for lml@lancaironline.net; Thu, 31 May 2007 04:05:36 -0400 Received-SPF: none receiver=logan.com; client-ip=68.142.229.99; envelope-from=gbfitz@swbell.net Received: (qmail 13957 invoked from network); 31 May 2007 08:04:54 -0000 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=swbell.net; h=Received:X-YMail-OSG:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=Ul81T4mNnsqJm84hZtK/sTtSZ5BPfAaJ2HGk7hapDfGV0iGUgltYfoORY4v+HcVBfXanB8PO+4Eb+bFrUbm81sI5v0F+iouteBSfhkXz21BQUNL1Mr+Q0ZZj5hIwgpeoLrbnktEiotPGZdjGfRFnVy0WUjbrkxXC5IsP1Xp9D38= ; Received: from unknown (HELO eaglenest61) (gbfitz@swbell.net@70.130.160.190 with login) by smtp106.sbc.mail.re2.yahoo.com with SMTP; 31 May 2007 08:04:53 -0000 X-YMail-OSG: gEPtkcAVM1m_6LAtNQwmrHfkfgGY19yk2Iii2inQJLbUB6Y6n.JQXfBjx.8kEcKvXcunxQz9rVtggtrDXOhRothtz6lsM6aUqfhOs2pC9.lBvowBfigO_Q-- X-Original-Message-ID: <005f01c7a35a$33ebbd20$4001a8c0@eaglenest61> From: "Gary Fitzgerald" X-Original-To: "Lancair Mailing List" References: Subject: [LML] Re: Tru Trak ADI vs. Standard AI X-Original-Date: Thu, 31 May 2007 03:02:13 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_005C_01C7A330.166B7FD0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1807 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1896 This is a multi-part message in MIME format. ------=_NextPart_000_005C_01C7A330.166B7FD0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Getting back to the original topic for a moment -=20 One factor that hasn't yet been discussed is whether or not you require = your backup to use a different sensing method than your primary = instruments. The Trutrak appears to use a solid-state gyro, which the = Chelton also appears to use. Therefore, an external anomaly (static, EM = interference, vibrations at a certain frequency (actually happened, = though not to a Chelton), alien death rays while flying over New = Mexico, whatever) that compromises the sensing element of your primary = display will also compromise your backup. An AI's display is based on a spinning rotor - pretty hard to get any = more basic than that. Not exactly high tech, but we know pretty well = what can cause them to provide misleading information (that whole = accelerating/decelerating/climbing/descending stuff from the instrument = rating test). Provide power, the rotor spins, you know which way is up. Personally - and I have absolutely no data to back this up - I don't = think we've found all of the failure modes of these solid-state gyros = yet (although from what I read, the experimental community is finding a = lot of them). I tried in vain to convince a pair of builders at my = local EAA chapter that backing up one EFIS with another solves one = particular failure mode but leaves you vulnerable to a bunch of other = ones, especially if the backup EFIS is a lower priced one from the same = vendor. Maybe it's just me... A few years ago, I got to see the cockpit of an F/A-18, and there among = the million or so of dollars of redundant display screens was a gyro AI = and airspeed and altitude steam gauges. Just one of those things that = make you go, "Hmmmmm...." Gary Fitzgerald LNC2 standard build ~70% steam gauges + AOA Engine: TBD St. Charles, MO I spoke to the Tru Trak representative at Sun n Fun and he stated that = there are stall warnings built in to the system and that I could = "retrain" myself to interpret the ADI properly. Nevertheless, I am = concerned that in a difficult situation, I would interpret the Tru Trak = in the way I would a standard AI. Your thoughts and advice? D. Brunner Legacy N241DB hoping to fly in June ------=_NextPart_000_005C_01C7A330.166B7FD0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Getting back to the original topic for = a moment -=20
 
One factor that hasn't yet been = discussed is=20 whether or not you require your backup to use a different sensing = method=20 than your primary instruments.  The Trutrak appears to use a = solid-state=20 gyro, which the Chelton also appears to use.  Therefore, an = external=20 anomaly (static, EM interference, vibrations at a certain=20 frequency (actually happened, though not to a = Chelton),  alien=20 death rays while flying over New Mexico, whatever) that compromises the = sensing=20 element of your primary display will also compromise your = backup.
 
An AI's display is based on a=20 spinning rotor - pretty hard to get any more basic than that.  = Not=20 exactly high tech, but we know pretty well what can cause them to = provide=20 misleading information (that whole = accelerating/decelerating/climbing/descending=20 stuff from the instrument rating test).  Provide power, the rotor = spins,=20 you know which way is up.
 
Personally - and I have absolutely no = data to back=20 this up - I don't think we've found all of the failure modes of these=20 solid-state gyros yet (although from what I read, the experimental = community is=20 finding a lot of them).  I tried in vain to convince a pair of = builders at=20 my local EAA chapter that backing up one EFIS with another solves one = particular=20 failure mode but leaves you vulnerable to a bunch of other ones, = especially if=20 the backup EFIS is a lower priced one from the same vendor.  Maybe = it's=20 just me...
 
A few years ago, I got to see the = cockpit of an=20 F/A-18, and there among the million or so of dollars of redundant = display=20 screens was a gyro AI and airspeed and altitude steam gauges.  Just = one of=20 those things that make you go, "Hmmmmm...."
 
Gary Fitzgerald
LNC2 standard build=20 ~70%
steam gauges + AOA
Engine: = TBD
St. Charles,=20 MO
 
I spoke to the Tru Trak = representative at Sun n=20 Fun and he stated that there are stall warnings built in to the system = and=20 that I could "retrain" myself to interpret the ADI properly. =20 Nevertheless, I am concerned that in a difficult situation, I would = interpret=20 the Tru Trak in the way I would a standard AI.  Your thoughts and = advice?
 
D. Brunner
Legacy N241DB
hoping to fly in=20 June
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