X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 29 Jun 2011 15:49:43 -0400 Message-ID: X-Original-Return-Path: Received: from qmta05.emeryville.ca.mail.comcast.net ([76.96.30.48] verified) by logan.com (CommuniGate Pro SMTP 5.4.0) with ESMTP id 5037372 for lml@lancaironline.net; Wed, 29 Jun 2011 15:16:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.30.48; envelope-from=j.hafen@comcast.net Received: from omta15.emeryville.ca.mail.comcast.net ([76.96.30.71]) by qmta05.emeryville.ca.mail.comcast.net with comcast id 1vA51h0031Y3wxoA5vFdJg; Wed, 29 Jun 2011 19:15:37 +0000 Received: from [10.0.1.5] ([24.17.111.171]) by omta15.emeryville.ca.mail.comcast.net with comcast id 1vEG1h01R3hvfg88bvEKwq; Wed, 29 Jun 2011 19:14:21 +0000 From: John Hafen Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-10-355250853 Subject: Re: [LML] Airplane needs to be "fixed," Stall Speeds, Wing Cuffs, Vortex ... X-Original-Date: Wed, 29 Jun 2011 12:15:32 -0700 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1084) --Apple-Mail-10-355250853 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 Speed Saves On Jun 29, 2011, at 10:14 AM, Craig Berland. wrote: Scott, =20 Excellent post. Just a few months ago I experienced a 30 kt wind shear = at 600 AGl going into John Wayne in Santa Ana, CA. Due to the = turbulence and =93on shore=94 wind I was quite fast on final and = obviously didn=92t stall however the three passengers were quite shaken. = In this situation, I=92m not aware of any instrumentation available to = GA aircraft that would have helped. John Wayne ATIS was shortly = thereafter modified to warn pilots of the wind shear near the end of the = runway. =20 Craig Berland =20 Terrence, =20 It doesn't always take the pilot to pull the wing beyond the critical = AOA - The air is not always smooth as in a stable fluid body - = turbulence, wind shear, slow flight over different heat radiating bodies = in the summer (green fields vs black dirt), crosswinds that tumble over = trees on a strip carved out of the woods or over nearby hangars, etc. = The margin above the stall AOA may disappear in a slow highly banked = turn or even on a straight in if the air is not compliant regardless of = the trim. =20 =20 I have been impressed with our 200-300 series reflexed laminar flow wing = - have you noticed a slow down (loss of laminar flow) in turbulence? Is = that just drag or is lift also affected? Does the critical AOA change = if the laminar flow is disturbed? Is this more important when the wing = is already at a high AOA when slow and is no longer in reflex (flaps = partially deployed)? Note that if the speed changes, the trim is no = longer correct. =20 I believe that the 300 series Lancairs are unstable at low speed high = AOA because the margin may be too narrow. It may not be the pilot = unintentionally pulling past the critical AOA, but an abrupt change in = the airflow that causes the angle to be exceeded. Even though the AOA = was calibrated in clean air, the calculated margin speed above stall by = formula (1.15 x stall) may not be enough for these high performance = wings. =20 Scott Krueger =20 --Apple-Mail-10-355250853 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 Speed Saves

On Jun = 29, 2011, at 10:14 AM, Craig Berland. wrote:

Scott,

Craig = Berland

I have been impressed with our 200-300 series reflexed = laminar flow wing - have you noticed a slow down (loss of laminar = flow) in turbulence? Is that just drag or is lift also = affected? Does the critical AOA change if the laminar flow is = disturbed? Is this more important when the wing is already at a = high AOA when slow and is no longer in reflex (flaps partially = deployed)? Note that if the speed changes, the trim is no longer = correct.

Scott Krueger