X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from nlpi053.prodigy.net ([207.115.36.82] verified) by logan.com (CommuniGate Pro SMTP 5.2.2) with ESMTP id 2880892 for flyrotary@lancaironline.net; Thu, 01 May 2008 20:19:18 -0400 Received-SPF: none receiver=logan.com; client-ip=207.115.36.82; envelope-from=panzera@experimental-aviation.com Received: from cdibmpat2 (adsl-76-250-177-126.dsl.frs2ca.sbcglobal.net [76.250.177.126]) (authenticated bits=0) by nlpi053.prodigy.net (8.13.8 smtpauth/dk/8.13.8) with ESMTP id m420IZ0w014767 for ; Thu, 1 May 2008 19:18:39 -0500 From: "Patrick Panzera" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: radiator orientation? Date: Thu, 1 May 2008 17:18:37 -0700 Message-ID: <037101c8abea$111317a0$1801a8c0@cd.constructiondesigns.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0372_01C8ABAF.64B43FA0" X-Mailer: Microsoft Office Outlook 11 In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 Thread-Index: Acir6C1AIKSvO7EiRliA4PZP0ID54wAAMosg This is a multi-part message in MIME format. ------=_NextPart_000_0372_01C8ABAF.64B43FA0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit You are correct, Mark, Minimizing or eliminating laminar flow next to metal - in other words causing the laminar flow in the boundary layer to become turbulence does promote heat transfer. It also increase skin friction and drag. However, if the turbulence gets to the point of causing air flow separation then that hurts both cooling and the drag factor. So like most other things involving aircraft - compromise is called for. My cores are slanted - but, only because I could not fit them in the space I had allocated for them any other way. Otherwise they would be perpendicular to the air flow. Clearly slanted cores do work and most of the time we install them in that orientation due to space constraints or aesthetics as Pat Panzera indicated in his response. Paul Lipps has seen great performance gains with his unique propeller design when bolted to his Lancair 235 and the Phantom Biplane, both of which have very streamlined cowls. When he tried it on a stock RV6, it seems that too much of the cowl frontal area blocked thrust from the propeller. It's like if you had a 60" diameter prop bolted to a 72" diameter radial engine. If you are not familiar with Paul, his plane or his prop, here's an electronic copy of an issue CONTACT! Magazine that has the information. http://www.contactmagazine.com/Issue79/Issue79.pdf Pat ------=_NextPart_000_0372_01C8ABAF.64B43FA0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

 

You are correct, Mark, Minimizing or eliminating laminar flow next to metal - in other words causing the = laminar flow in the boundary layer to become turbulence does promote heat transfer.  It also increase skin friction and drag.  However, = if the turbulence gets to the point of causing air flow separation then that = hurts both cooling and the drag factor.  So like most other things = involving aircraft - compromise is called for.

 

My cores are = slanted - but, only because I could not fit them in the space I had allocated for = them any other way.  Otherwise they would be perpendicular to the air flow.  Clearly slanted cores do work and most of the time we = install them in that orientation due to space constraints or aesthetics as Pat = Panzera indicated in his response.

 

Paul Lipps has seen great = performance gains with his unique propeller design when bolted to his Lancair 235 = and the Phantom Biplane, both of which have very streamlined = cowls.

When he tried it on a stock RV6, it = seems that too much of the cowl frontal area blocked thrust from the = propeller.

 

It’s like if you had a = 60” diameter prop bolted to a 72” diameter radial engine. =

 

If you are not familiar with Paul, = his plane or his prop, here’s an electronic copy of an issue CONTACT! Magazine that has the information.

http://www.co= ntactmagazine.com/Issue79/Issue79.pdf

 

Pat

 

=

 

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