X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail16.syd.optusnet.com.au ([211.29.132.197] verified) by logan.com (CommuniGate Pro SMTP 5.2.2) with ESMTPS id 2881140 for flyrotary@lancaironline.net; Fri, 02 May 2008 00:05:53 -0400 Received-SPF: pass receiver=logan.com; client-ip=211.29.132.197; envelope-from=lendich@optusnet.com.au Received: from george (d220-237-232-70.dsl.nsw.optusnet.com.au [220.237.232.70]) by mail16.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id m42456wT006824 for ; Fri, 2 May 2008 14:05:07 +1000 Message-ID: <002801c8ac09$b9a0b7a0$6400a8c0@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: radiator orientation? Date: Fri, 2 May 2008 14:05:12 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0025_01C8AC5D.8A1929A0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0025_01C8AC5D.8A1929A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Pat, I e-mail Paul Lipps a couple of years ago ( well it seems like a couple = of years ) and put to him my understanding of his prop design - he = suggested that I was the only one to ( that) date that had worked it out = - he may have been pulling my leg! Basically he's just spreading the work load of the prop and minimizing = trip drag. Where the prop is not performing as it could be (at a desired = RPM)he makes it wider and thinning the tip speaks for itself, at higher = speeds. He sent me some old photo's where this had been done in the early days. Something that was old is new again. George ( down under) 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. =20 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. =20 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. =20 It's like if you had a 60" diameter prop bolted to a 72" diameter = radial engine.=20 =20 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 =20 Pat =20 =20 -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG.=20 Version: 7.5.524 / Virus Database: 269.23.7 - Release Date: 30/04/2008 = 12:00 AM ------=_NextPart_000_0025_01C8AC5D.8A1929A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Pat,

I e-mail Paul Lipps a couple of years = ago ( well it=20 seems like a couple of years ) and put to him my understanding of = his prop=20 design - he suggested that I was the only one to ( that) date = that had=20 worked it out - he may have been pulling my leg!

Basically he's just spreading the work = load of the=20 prop and minimizing trip drag. Where the prop is not performing as it = could be=20 (at a desired RPM)he makes it wider and thinning the tip speaks for = itself, at=20 higher speeds.

He sent me some old photo's where this = had been=20 done in the early days.

Something that was old is new = again.

George ( down under)

You are = correct, Mark,=20 Minimizing or eliminating laminar flow next to metal - in other words = causing=20 the laminar flow in the boundary layer to become turbulence does = promote heat=20 transfer. It also increase skin friction and drag. = However, if the=20 turbulence gets to the point of causing air flow separation then that = hurts=20 both cooling and the drag factor. So like most other things = involving=20 aircraft - compromise is called for.

My cores are slanted - but, = only because=20 I could not fit them in the space I had allocated for them any other=20 way. Otherwise they would be perpendicular to the air = flow. =20 Clearly slanted cores do work and most of the time we install them in = that=20 orientation due to space constraints or aesthetics as Pat Panzera = indicated in=20 his response.

Paul Lipps = has seen=20 great performance gains with his unique propeller design when bolted = to his=20 Lancair 235 and the Phantom Biplane, both of which have very = streamlined=20 cowls.

When he = tried it on a=20 stock RV6, it seems that too much of the cowl frontal area blocked = thrust from=20 the propeller.

It=92s like = if you had=20 a 60=94 diameter prop bolted to a 72=94 diameter radial engine.=20

If you are = not=20 familiar with Paul, his plane or his prop, here=92s an electronic copy = of an=20 issue CONTACT! Magazine that has the = information.

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

Pat

No virus found in this incoming message.
Checked by AVG.=20
Version: 7.5.524 / Virus Database: 269.23.7 - Release Date: = 30/04/2008=20 12:00 AM
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