X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 29 Aug 2010 15:22:14 -0400 Message-ID: X-Original-Return-Path: Received: from imr-db01.mx.aol.com ([205.188.91.95] verified) by logan.com (CommuniGate Pro SMTP 5.3.8) with ESMTP id 4447223 for lml@lancaironline.net; Sat, 28 Aug 2010 21:22:26 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.91.95; envelope-from=Sky2high@aol.com Received: from imo-ma03.mx.aol.com (imo-ma03.mx.aol.com [64.12.78.138]) by imr-db01.mx.aol.com (8.14.1/8.14.1) with ESMTP id o7T1Lfq6003876 for ; Sat, 28 Aug 2010 21:21:41 -0400 Received: from Sky2high@aol.com by imo-ma03.mx.aol.com (mail_out_v42.9.) id q.ec4.1401d05 (43955) for ; Sat, 28 Aug 2010 21:21:37 -0400 (EDT) Received: from magic-m18.mail.aol.com (magic-m18.mail.aol.com [172.21.136.206]) by cia-dd01.mx.aol.com (v129.4) with ESMTP id MAILCIADD014-abb34c79b621c3; Sat, 28 Aug 2010 21:21:37 -0400 From: Sky2high@aol.com X-Original-Message-ID: <6043c.7e8d0c49.39ab1021@aol.com> X-Original-Date: Sat, 28 Aug 2010 21:21:37 EDT Subject: Re: [LML] Re: Pitot tube and AoA X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_6043c.7e8d0c49.39ab1021_boundary" X-Mailer: AOL 9.5 sub 155 X-AOL-IP: 24.15.17.119 X-Spam-Flag:NO X-AOL-SENDER: Sky2high@aol.com --part1_6043c.7e8d0c49.39ab1021_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Aye there Rob, I'll be watch'n my P&Qs. The devil with what's outside the winder............. Grayhawk In a message dated 8/28/2010 5:24:38 P.M. Central Daylight Time, rwolf99@aol.com writes: John - The Jim Frantz AoA system (now sold by, I think, Advanced Flight Systems) uses pitot and static information, so you would get erroneous AoA readings with a plugged pitot tube. Specifically, the system depends on the relationship between the differential pressure across the wing from top to bottom (lets call that DeltaP) and the dynamic pressure which we recall is the difference between pitot and static pressure (lets call that Q). It turns out that the quotient DeltaP/Q is proportional to angle of attack if you pick the right point along the chord (which is why the instructions tell you to put the pressure ports in certain places). Therefore, if your pitot tube is plugged, DeltaP/Q will be off and so will the alpha readout. Now, if you're using a different system such as a Dynon, all bets are off. I don't know how that is mechanized. - Rob Wolf --part1_6043c.7e8d0c49.39ab1021_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Aye there Rob, I'll be watch'n my P&Qs. The devil with what's out= side=20 the winder.............

Grayhawk

In a message dated 8/28/2010 5:24:38 P.M. Central Daylight Time,=20 rwolf99@aol.com writes:

John -

The Jim Frantz AoA system (now sold by, I think, Advanced Flight Sy= stems)=20 uses pitot and static information, so you would get erroneous AoA readin= gs=20 with a plugged pitot tube.

Specifically, the system depends on the relationship between the=20 differential pressure across the wing from top to bottom (lets call that= =20 DeltaP) and the dynamic pressure which we recall is the difference betwe= en=20 pitot and static pressure (lets call that Q). It turns out that th= e=20 quotient DeltaP/Q is proportional to angle of attack if you pick the rig= ht=20 point along the chord (which is why the instructions tell you to put the= =20 pressure ports in certain places). Therefore, if your pitot tube= is=20 plugged, DeltaP/Q will be off and so will the alpha readout.

Now, if you're using a different system such as a Dynon, all bets= are=20 off. I don't know how that is mechanized.

- Rob=20 Wolf

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