X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 30 Mar 2009 21:13:28 -0400 Message-ID: X-Original-Return-Path: Received: from bay0-omc3-s16.bay0.hotmail.com ([65.54.246.216] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3564435 for lml@lancaironline.net; Mon, 30 Mar 2009 11:31:03 -0400 Received-SPF: pass receiver=logan.com; client-ip=65.54.246.216; envelope-from=gt_phantom@hotmail.com Received: from hotmail.com ([10.12.232.158]) by bay0-omc3-s16.bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.3959); Mon, 30 Mar 2009 08:30:26 -0700 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Mon, 30 Mar 2009 08:30:05 -0700 X-Original-Message-ID: Received: from 68.211.168.165 by COL0-DAV20.phx.gbl with DAV; Mon, 30 Mar 2009 15:30:03 +0000 X-Originating-IP: [68.211.168.165] X-Originating-Email: [gt_phantom@hotmail.com] X-Sender: gt_phantom@hotmail.com X-Original-Message-ID: <49D0E57A.6010500@hotmail.com> X-Original-Date: Mon, 30 Mar 2009 11:30:02 -0400 From: GT Phantom Reply-To: gt_phantom@hotmail.com Organization: None User-Agent: Thunderbird 2.0.0.21 (Windows/20090302) MIME-Version: 1.0 X-Original-To: lml@lancaironline.net Subject: Re: RE: [LML] Re: Poor Slow-flight Cooling References: In-Reply-To: Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 30 Mar 2009 15:30:05.0669 (UTC) FILETIME=[66C69150:01C9B14C] X-Original-Return-Path: gt_phantom@hotmail.com Thanks Bill & Chris,

I don't have the equipment handy to measure pressures, but this gives me a good idea.  I don't live in Vegas like the original owner did - I can simply try sealing the NACA duct.  That may resolve the issue.

Thanks to all who responded,

Bill Reister
N351E


Bill Bradburry wrote:

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