X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 32 [X] Return-Path: Received: from nf-out-0910.google.com ([64.233.182.186] verified) by logan.com (CommuniGate Pro SMTP 5.1.5) with ESMTP id 1799981 for flyrotary@lancaironline.net; Tue, 30 Jan 2007 15:23:04 -0500 Received-SPF: pass receiver=logan.com; client-ip=64.233.182.186; envelope-from=wdleonard@gmail.com Received: by nf-out-0910.google.com with SMTP id c29so313571nfb for ; Tue, 30 Jan 2007 12:22:15 -0800 (PST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=Yth9TMKWIXy4vXd/CeRyCTLW3sQ5xzoNB9tEiZS8eYQDtP0JQyMZNU8LZz2Mm+3xHmx657ym6YaVYDmBbBYhx1RObhDQyFTgu1vfH6aMV3IAXiKJJAEuMcAC0ComgBnw0DX8pNiHOEIfNMTD4bI48NbvqOLGEdHeAK+qQ9IYB04= Received: by 10.49.29.3 with SMTP id g3mr1386379nfj.1170188534793; Tue, 30 Jan 2007 12:22:14 -0800 (PST) Received: by 10.49.35.19 with HTTP; Tue, 30 Jan 2007 12:22:14 -0800 (PST) Message-ID: <1c23473f0701301222r5784613fu1b38007674ac28da@mail.gmail.com> Date: Tue, 30 Jan 2007 12:22:14 -0800 From: "David Leonard" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: New Cowl Contest In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_15715_11603325.1170188534537" References: ------=_Part_15715_11603325.1170188534537 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Todd, if it aint broke dont fix it!!!! You are right about the boundry layer. But you can make up for that with a little extra size or maybe moving closer to the prop (eg P-40). Also, Doug dempsy has been telling me how Chuck Dunlap had a real problem with a duct that was away from the boundry layer, but fixed his issue when he make it bigger and more like the smile. The smile votes seem to have it so far... Dave Leonard On 1/30/07, Todd Bartrim wrote: > > I was thinking that the "oh cowl" would be better at excluding the > boundary layer, which would be better for cooling. This is just based on > comments I've read on the list during previous ducting discussions. Based on > this info, I felt my oil cooler duct was less than optimal (even though > temps are good), so I figured I could reduce the size of my inlet if I > eliminated the boundary air layer. As your "smile" duct is similar (see > attached pic) I figured this would be applicable. I hope I'm wrong and you > prove it before I change my cowl. > > Todd (building Electric Bob's Audio Isolator Amplifier today) > > On 1/30/07, Ernest Christley wrote: > > > > David Leonard wrote: > > > > > I call them the "Oh Cowl" and the "Smiley Cowl..."his > > > > Go with the smile, but put a raised ledge on the cowl side just behind > > the spinner to accelerate the air and thin the boundary layer. Reduces > > the ingestion of turbulent air. Check the CAFE Foundation's drag > > reduction report. They have a picture of what it looks like on a > > production aircraft. I have a link to it at home, but not here. > > > > -- > > ,|"|"|, Ernest Christley | > > ----===<{{(oQo)}}>===---- Dyke Delta Builder | > > o| d |o http://ernest.isa-geek.org | > > > > -- > > Homepage: http://www.flyrotary.com/ > > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ > > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ > > > > -- David Leonard Turbo Rotary RV-6 N4VY My websites at: http://members.aol.com/_ht_a/rotaryroster/index.html http://members.aol.com/_ht_a/vp4skydoc/index.html http://leonardiniraq.blogspot.com ------=_Part_15715_11603325.1170188534537 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline
Todd, if it aint broke dont fix it!!!!
 
You are right about the boundry layer.  But you can make up for that with a little extra size or maybe moving closer to the prop (eg P-40).
 
Also, Doug dempsy has been telling me how Chuck Dunlap had a real problem with a duct that was away from the boundry layer, but fixed his issue when he make it bigger and more like the smile.
 
The smile votes seem to have it so far...
 
Dave Leonard

 
On 1/30/07, Todd Bartrim <bartrim@gmail.com> wrote:
I was thinking that the "oh cowl" would be better at excluding the boundary layer, which would be better for cooling. This is just based on comments I've read on the list during previous ducting discussions. Based on this info, I felt my oil cooler duct was less than optimal (even though temps are good), so I figured I could reduce the size of my inlet if I eliminated the boundary air layer. As your "smile" duct is similar (see attached pic) I figured this would be applicable. I hope I'm wrong and you prove it before I change my cowl.

Todd    (building Electric Bob's Audio Isolator Amplifier today)

On 1/30/07, Ernest Christley < echristley@nc.rr.com > wrote:
David Leonard wrote:

> I call them the "Oh Cowl" and the "Smiley Cowl..."his

Go with the smile, but put a raised ledge on the cowl side just behind
the spinner to accelerate the air and thin the boundary layer.  Reduces
the ingestion of turbulent air.  Check the CAFE Foundation's drag
reduction report.  They have a picture of what it looks like on a
production aircraft.  I have a link to it at home, but not here.

--
         ,|"|"|,              Ernest Christley       |
----===<{{(oQo)}}>===----    Dyke Delta Builder      |
        o|  d  |o        http://ernest.isa-geek.org  |

--
Homepage:   http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/


--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/






--
David Leonard

Turbo Rotary RV-6 N4VY
My websites at:
http://members.aol.com/_ht_a/rotaryroster/index.html
http://members.aol.com/_ht_a/vp4skydoc/index.html
http://leonardiniraq.blogspot.com ------=_Part_15715_11603325.1170188534537--