X-Virus-Scanned: clean according to Sophos on Logan.com X-PolluStop-Diagnostic: (direct reply)\eX-PolluStop-Score: 0.00\eX-PolluStop: Scanned with Niversoft PolluStop 2.1 RC1, http://www.niversoft.com/pollustop Return-Path: Received: from imf17aec.mail.bellsouth.net ([205.152.59.65] verified) by logan.com (CommuniGate Pro SMTP 4.3c4) with ESMTP id 865629 for flyrotary@lancaironline.net; Mon, 11 Apr 2005 21:50:03 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.65; envelope-from=ceengland@bellsouth.net Received: from [209.215.63.151] by imf17aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20050412014913.KRJJ4997.imf17aec.mail.bellsouth.net@[209.215.63.151]> for ; Mon, 11 Apr 2005 21:49:13 -0400 Message-ID: <425B2919.9050401@bellsouth.net> Date: Mon, 11 Apr 2005 20:49:13 -0500 From: Charlie England User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: RV10 Cowl References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit echristley wrote: >>On Sun, 10 Apr 2005 21:43:53 -0600 Jarrett & Heidi Johnson >> >> > wrote. > > >>I've actually done a >>smiley face induction on a previous model [ I think I modified this current >> >> > > > >>model to the new profile] but was told that it would work better w/ a more >>seperate induction with a sorta boundry layer splitter [Picture k of that >>same report] I didn't totally agree with it at the time on the principle >>that the boundry layer there is... 0.0001 thick or so.. [ just an >>un-educated guess] It would be an easy fix to make it w/out the boundry >>seperator or.. not.. which ever. >> >> > >You should have went with your first instinct in my opinion. Like you said, >the boundary layer at that point does not exist in any measurable thickness, >and your going to get increased drag from the vortices created in the >intersecting surfaces. > My take was a bit different. Note that there is a 'dam' between the spinner & the intake. The text says that it's there so that the boundary layer can be forced into the inlet. In other words, a brute force method of dealing with the boundary layer. If you look at a standard Van's cowl & then look at a Sam James cowl or at one of loPresti's cowls, you will see that the aftermarket cowls have 'boundary layer splitters' & Van's does not. The Sam James cowl is faster than Van's. Even more significant to me in that paper are the exit techniques. Both the extractor bump & the 'internal cowl flap' look like they deserve attention. Charlie