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 4080513 for lml@lancaironline.net; Tue, 12 Jan 2010 19:19:14 -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=fLuM78UsAAAA:8 a=pGLkceISAAAA:8 a=cqNLozs3X_v3bhpQoEwA:9 a=ekjvXXHUXeLPCf96DWEA:7 a=QIUbjPVOIL8qrw1RPmTnEtaKUOsA:4 a=3jk_M6PjnjYA:10 a=MSl-tDqOz04A:10 a=Ia-xEzejAAAA:8 a=898rrfZ5j80kF1EHNnMA:9 a=XFfOcHsoe9XfnAe9oDoA:7 a=Pxz_FbDmgqMJmUd73LM8WifWJtYA:4 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:4631] helo=micomxp) by hrndva-oedge02.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id C5/B7-17464-E511D4B4; Wed, 13 Jan 2010 00:18:38 +0000 X-Original-Message-ID: <000a01ca93e5$f1407e50$6401a8c0@micomxp> From: "Wolfgang" X-Original-To: Subject: Re: Measured Stall Angle of Attack X-Original-Date: Tue, 12 Jan 2010 19:18:33 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01CA93BC.082C82F0" 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_0007_01CA93BC.082C82F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable You can count on about 4 degrees lower AoA for a wing of about 15% = thickness and full flaps. As much as 6 degrees lower for a 20% wing and as little as 2 degrees = lower for a 10% wing. Your airfoil milage may vary. Wolfgang =20 From: marv@lancair.net=20 Subject: Re: Measured Stall Angle of Attack=20 Date: Tue, 12 Jan 2010 08:01:26 -0500=20 To: lml=20 =20 =20 =20 Posted for Jeff Peterson : LML: =20 Would it be possible for some one (or several pilots) with a = flying 360 to measure the actual stall angle of attack for a few flap settings? =20 I am tinkering on the bench with AOA circuits and considering = adding an offset for as a function of flaps up versus down. But, I would = like to know if this really is needed. After all, many thousands of = airplanes do have stall warnings that do not include flap input. =20 If my 360 was flying here is how I would make the measurement. attach an "angle locator" to the arcraft, aligned with a = longeron. rig a video camera to record the locator. =20 Fly a few stalls, but be sure to hold altitude in the lead up to = the stall. =20 Then review the tape on the ground. =20 Perhaps someone out there already knows the answer to my question: by how many degrees does stall angle of attack shift? --=20 Jeff Peterson L 360, buiding the panel [This has all been done, it's already on the market in the form of = the Advanced Flight Systems (used to be Proprietary Software) AOA = instruments. Those instruments assume that you have a new airfoil the = instant you add flaps. That's why there are two databases, one for = flaps up, one for flaps down. Different folks trigger the flaps down at = different amounts of flap deployment, although "any" flaps is = sufficiently different from "no" flaps to trigger the change in = database. As there are an infinite number of flap settings, the = decision to handle this info in this manner was taken to avoid = information overload and unnecessary complexity. ]=20 ------=_NextPart_000_0007_01CA93BC.082C82F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
You can count on about 4 degrees lower AoA for a wing of about 15%=20 thickness and full flaps.
As much as 6 degrees lower for a 20% wing and as = little as 2=20 degrees lower for a 10% wing.
Your airfoil milage may vary.
 
Wolfgang
 
From: marv@lancair.net
Subject: Re: Measured Stall Angle of=20 Attack
Date: Tue, 12 Jan 2010 08:01:26 = -0500
To: lml

 
Posted for Jeff Peterson=20 = <jeffreyb.peterson@gmail.com>:

 LML:
 
 = ;Would=20 it be possible for some one (or several pilots) with a flying 360=20 to
 measure the actual stall angle of attack for a few = flap=20 settings?
 
 I am tinkering on the bench with AOA = circuits=20 and considering adding an
 offset for as a function of = flaps up=20 versus down.  But, I would like
 to know if this = really=20 is needed.  After all, many thousands of airplanes=20 do
 have stall
 warnings that do not include flap=20 input.
 
 If my 360 was flying here is how I would = make=20 the measurement.
 attach an "angle locator" to the = arcraft,=20 aligned with a longeron.
 rig a video camera to record the = locator.
 
Fly a few stalls, but be sure to hold = altitude in=20 the lead up to the stall.
 
 Then review the tape = on the=20 ground.
 
 Perhaps someone out there already knows = the=20 answer to my
 question: by how many degrees does stall = angle of=20 attack shift?

 --
 Jeff Peterson
 L=20 360,  buiding the panel

[This has all been done, = it's=20 already on the market in the form of the Advanced Flight Systems = (used to=20 be Proprietary Software) AOA instruments.  Those instruments = assume=20 that you have a new airfoil the instant you add flaps.  = That's why=20 there are two databases, one for flaps up, one for flaps = down. =20 Different folks trigger the flaps down at different amounts of = flap=20 deployment, although  "any" flaps is sufficiently different = from "no"=20 flaps to trigger the change in database.  As there are an = infinite=20 number of flap settings, the decision to handle this info in this = manner=20 was taken to avoid information overload and unnecessary = complexity. =20 <Marv>   = ]
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