X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 13 Jan 2010 08:19:05 -0500 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.123] verified) by logan.com (CommuniGate Pro SMTP 5.3.1) with ESMTP id 4080547 for lml@lancaironline.net; Tue, 12 Jan 2010 19:44:26 -0500 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=1.0 c=1 a=50vDblQ1AAAA:8 a=dOoDZmAWAAAA:8 a=Ia-xEzejAAAA:8 a=Mp8n5W5ZTFAVCzn4yusA:9 a=KNtQFbXuCY3ra0VLz-T9MmQKV1QA:4 a=XY96fHeFyScA:10 a=f-MNE9I93sYA:10 a=EzXvWhQp4_cA:10 a=bs_X3xL0fNKb228qQ5AA:9 a=PaxlZsUZiuTSPqXX5uQA:7 a=nJT7pD_-BQSObK0dWQRqO438200A:4 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:4765] helo=micomxp) by hrndva-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 5E/25-18377-6471D4B4; Wed, 13 Jan 2010 00:43:50 +0000 X-Original-Message-ID: <000b01ca93e9$769acd00$6401a8c0@micomxp> From: "Wolfgang" X-Original-To: Subject: Re: [LML] Do-it-yourself AOA Project X-Original-Date: Tue, 12 Jan 2010 19:43:45 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0008_01CA93BF.8D8B8C90" 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_0008_01CA93BF.8D8B8C90 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable The home made AoA indicator from BarkerAircraft.com has a 5V regulator. = With that running the electronics and a 2.2V typical forward V @ 10ma on = the LED's, that leaves 2.8V at 100ma total dissipated by the chip with = all LED's illuminated. The total dissipation of the chip comes out to = about 0.28W. I don't see that raising the chip temperature to any where = neat a 100C limit. Wolfgang -------------------------------------------------------------------------= ------- From: Hamid Wasti =20 Sender: =20 Subject: Re: [LML] Do-it-yourself AOA Project=20 Date: Mon, 11 Jan 2010 19:41:18 -0500=20 To: lml@lancaironline.net=20 =20 =20 =20 It is an interesting product with some clever ideas, but a very = poor implementation. It is unlikely that it will keep working reliably = for long in the real-world/real-aircraft environment. The system does not take into account flap deployment. Anyone here = use flaps? The "normal" position of the probe is with the Hall sensor at the = zero point of the magnet. Anyone concerned about the fact that the = system could report "normal" output if the probe or the magnet falls = off? Even the most rudimentary analysis of the Hall sensor's output as = its temperature varies from -20C to +50C would reveal a potential for = some worrisome inaccuracies. You could stall several LEDs before you = expect to, or you could be several LEDs away from a stall when the = system says you should be stalling. Would you be more or less likely to = actually stall in these situations? The design does not take into account the fact that each LED that = is on will cause the main IC's temperature to rise by about 15C. A = little slow flight practice with a 6 LEDs on and the IC is well past its = 100C limit, generating a burning smell and possibly smoke. Same would = happen after an engine out as you glide down at best glide speed. Can = you think of a worse time to find smoke in the cockpit? This is just a partial list of issues, but I think it gets the = picture across. The only thing worse than not having something is having = something that is not reliable. Regards, Hamid Gary Fitzgerald wrote: He has an article on this project in the Dec. 2008 edition of = Sport Aviation. Interesting use of a Hall Effect sensor.=20 ------=_NextPart_000_0008_01CA93BF.8D8B8C90 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
The home made AoA indicator from = BarkerAircraft.com=20 has a 5V regulator. With that running the electronics and a 2.2V typical = forward=20 V @ 10ma on the LED's, that leaves 2.8V at 100ma total dissipated by the = chip=20 with all LED's illuminated. The total dissipation of the chip comes out = to about=20 0.28W. I don't see that raising the chip temperature to any where neat a = 100C=20 limit.
 
Wolfgang
lml@lancaironline.net
From: Hamid Wasti=20 <hwasti@lm50.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Do-it-yourself AOA=20 Project
Date: Mon, 11 Jan 2010 19:41:18 = -0500
To:


 
It is an interesting product with some = clever=20 ideas, but a very poor implementation. It is unlikely that it will = keep=20 working reliably for long in the real-world/real-aircraft=20 environment.

The system does not take into account flap = deployment.=20 Anyone here use flaps?

The "normal" position of the probe = is with=20 the Hall sensor at the zero point of the magnet. Anyone concerned = about=20 the fact that the system could report "normal" output if the probe = or the=20 magnet falls off?

Even the most rudimentary analysis of the = Hall=20 sensor's output as its temperature varies from -20C to +50C would = reveal a=20 potential for some worrisome inaccuracies. You could stall several = LEDs=20 before you expect to, or you could be several LEDs away from a = stall when=20 the system says you should be stalling. Would you be more or less = likely=20 to actually stall in these situations?

The design does not = take=20 into account the fact that each LED that is on will cause the main = IC's=20 temperature to rise by about 15C. A little slow flight practice = with a 6=20 LEDs on and the IC is well past its 100C limit, generating a = burning smell=20 and possibly smoke. Same would happen after an engine out as you = glide=20 down at best glide speed. Can you think of a worse time to find = smoke in=20 the cockpit?

This is just a partial list of issues, but I = think it=20 gets the picture across. The only thing worse than not having = something is=20 having something that is not=20 reliable.

Regards,

Hamid

Gary Fitzgerald = wrote:
He has an article on this project in the Dec. 2008=20 edition of Sport
Aviation. Interesting use of a Hall Effect=20 = sensor.
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