X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 29 Mar 2009 16:41:10 -0400 Message-ID: X-Original-Return-Path: Received: from fmailhost04.isp.att.net ([204.127.217.104] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3563225 for lml@lancaironline.net; Sat, 28 Mar 2009 22:53:32 -0400 Received-SPF: pass receiver=logan.com; client-ip=204.127.217.104; envelope-from=bbradburry@bellsouth.net Received: from desktop (adsl-146-127-125.mco.bellsouth.net[72.146.127.125]) by isp.att.net (frfwmhc04) with SMTP id <20090329025256H04009mb9oe>; Sun, 29 Mar 2009 02:52:56 +0000 X-Originating-IP: [72.146.127.125] From: "Bill Bradburry" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: RE: [LML] Re: Poor Slow-flight Cooling X-Original-Date: Sat, 28 Mar 2009 22:52:58 -0400 X-Original-Message-ID: <915D46F3258E4CAABFB71DEF3BD11917@Desktop> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001B_01C9AFF7.F1099610" X-Mailer: Microsoft Office Outlook 11 Thread-Index: AcmwDsp9UrXlh6zbQ/en+wNXBCc0pQACoYMQ X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6001.18049 This is a multi-part message in MIME format. ------=_NextPart_000_001B_01C9AFF7.F1099610 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit You could try putting a couple of vortex generators in front of the NACA scoop to trip the boundary layer. Bill B _____ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Chris Zavatson Sent: Saturday, March 28, 2009 9:36 PM To: lml@lancaironline.net Subject: [LML] Re: Poor Slow-flight Cooling Bill, -one possibility The air coming in from your 3 inch duct may actually be leaving through the NACA scoop during slow flight. NACA scoops are somewhat sensitive to orientation to the airstream and while in slow flight the orientation may be off far enough that the NACA scoop is no longer effective. Two parallel sources will fight each other if the pressures aren't well balanced. In this case, if the NACA scoop pressure drops all of a sudden, you would see a flow reversal. If you measure the pressure ahead of the cooler as you slow down, you should be able to see this transition occur. Chris Zavatson N91CZ 360std www.N91CZ.com ------=_NextPart_000_001B_01C9AFF7.F1099610 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

You could try putting a couple of vortex generators in front of = the NACA scoop to trip the boundary layer.

 

Bill B 

 

From: Lancair Mailing List = [mailto:lml@lancaironline.net] On Behalf Of Chris Zavatson
Sent: Saturday, March 28, = 2009 9:36 PM
To: = lml@lancaironline.net
Subject: [LML] Re: Poor Slow-flight Cooling

Bill,

-one possibility

The air coming in from your 3 inch duct may actually = be leaving through the NACA scoop during slow flight.  NACA scoops are somewhat sensitive to orientation to the airstream and = while in slow flight the orientation may be off far enough that the NACA scoop is = no longer effective.  Two parallel sources will fight each other if = the pressures aren't well balanced.  In this case, if the NACA scoop = pressure drops all of a sudden, you would see a flow reversal.  =

If you measure the pressure ahead of the cooler = as you slow down, you should be able to see this transition = occur.


 

Chris Zavatson

N91CZ

360std

 

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