Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Sun, 23 Jan 2005 11:07:30 -0500 Message-ID: X-Original-Return-Path: Received: from smtpauth05.mail.atl.earthlink.net ([209.86.89.65] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 618292 for lml@lancaironline.net; Sun, 23 Jan 2005 10:55:03 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.86.89.65; envelope-from=skipslater@earthlink.net Received: from [4.61.193.2] (helo=skipslater) by smtpauth05.mail.atl.earthlink.net with asmtp (Exim 4.34) id 1Csk4P-0002XJ-EN for lml@lancaironline.net; Sun, 23 Jan 2005 10:54:33 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=simple; s=test1; d=earthlink.net; h=Message-ID:Reply-To:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE; b=qFyuYsMMVYKKg8IxSY3YptL9t2SidSA1grVDtZ4CsInhLmykEBH2CnWYvK7mSJQV; X-Original-Message-ID: <001901c50163$cf47b3a0$6401a8c0@mshome.net> Reply-To: "Skip Slater" From: "Skip Slater" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Alert. NACA 64212 X-Original-Date: Sun, 23 Jan 2005 07:54:21 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0016_01C50120.BF80D5C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-ELNK-Trace: cbee950bdf563876c8ad50643b1069f8239a348a220c2609dcdbcfb8cca8305c92123489d79d6123350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 4.61.193.2 This is a multi-part message in MIME format. ------=_NextPart_000_0016_01C50120.BF80D5C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Robert, I'm no aeronical engineer and can't read that graph with anything but = wonder, but your interpretation of it is most illuminating. It's very = believable though as once flow separates on laminar wings like ours, my = limited understanding is that AOA must be reduced beyond the separation = point before the flow reattaches. I'd love to hear some of our other = LML readers (like Gary Casey and Professor Regan) who may also be = qualified to comment on this weigh in on the subject. I have some = questions: 1. Since the ES and IV wings are so different in size and loading, is = this tip stalling effect more pronounced in one plane or the other?=20 2. Does CG have any impact on the chart or does it merely impact the = ability to reduce AOA enough to recover once the plane departs? 3. How much of the wing is considered the "tip"? Outboard of the = ailerons or including them? 4. Do the tips stall in advance of the wing root and if so, by how = much?=20 5. How much effect would some vortex generators ahead of the ailerons = have on this graph? It would seem to me that the key to avoiding this phenomina is = keeping the ailerons flying through a stall (assuming you allowed = yourself to get that far in the first place). It would appear that = Lancair Certified addressed this on the Columbia by placing leading edge = cuffs ahead of the ailerons. The effect is akin to slats on an = airliner, which keep the airflow attached to the wing longer in slow = flight regimes like takeoff and landing. On the Columbia, they keep the = part of the wing behind the cuffs (where the ailerons are) flying past = the point where the rest of it stalls, ensuring roll control throughout. = Vortex generators also delay the onset of flow separation, though = they're normally only used on STOL aircraft which often fly in that part = of the envelope. I believe our best prevention tool is giving stall = speed a very wide berth. Thanks for bringing this up. Every small morsel of information which = helps us better understand the characteristics of our machines hopefully = enhances our ability to safely fly them. Skip Slater N540ES=20 ------=_NextPart_000_0016_01C50120.BF80D5C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Robert,
   I'm no aeronical engineer = and can't=20 read that graph with anything but wonder, but your interpretation of it = is most=20 illuminating.  It's very believable though as once flow separates = on=20 laminar wings like ours, my limited understanding is that AOA = must be=20 reduced beyond the separation point before the = flow reattaches. =20 I'd love to hear some of our other LML readers (like Gary Casey and = Professor Regan) who may also be qualified to comment on this = weigh in=20 on the subject.  I have some questions:
 
1.  Since the ES and IV wings are = so different=20 in size and loading, is this tip stalling effect more pronounced in one = plane or=20 the other? 
2.  Does CG have any impact = on the chart=20 or does it merely impact the ability to reduce AOA enough to recover = once=20 the plane departs?
3.  How much of the wing is = considered=20 the "tip"?  Outboard of the ailerons or including=20 them?
4.  Do the tips = stall in advance of the wing root and if so, by how = much? 
5.  How much effect would some = vortex=20 generators ahead of the ailerons have on this graph?
 
   It would seem to me that = the key to=20 avoiding this phenomina is keeping the ailerons flying through a stall = (assuming=20 you allowed yourself to get that far in the first place).  It would = appear=20 that Lancair Certified addressed this on the Columbia by placing leading = edge=20 cuffs ahead of the ailerons.  The effect is akin to slats = on an=20 airliner, which keep the airflow attached to the wing=20 longer in slow flight regimes like takeoff and landing.  On = the=20 Columbia, they keep the part of the wing behind the cuffs (where = the=20 ailerons are) flying past the point where the rest of it stalls, = ensuring=20 roll control throughout.  Vortex generators also delay the onset of = flow=20 separation, though they're normally only used on STOL aircraft which = often fly=20 in that part of the envelope.  I believe our best prevention tool = is giving=20 stall speed a very wide berth.
   Thanks for bringing this=20 up.  Every small morsel of information which helps us = better=20 understand the characteristics of our = machines hopefully enhances our=20 ability to safely fly them.
   Skip Slater
  =20 N540ES 
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