X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from poplet2.per.eftel.com ([203.24.100.45] verified) by logan.com (CommuniGate Pro SMTP 5.3.5) with ESMTP id 4236892 for flyrotary@lancaironline.net; Tue, 27 Apr 2010 21:41:35 -0400 Received-SPF: none receiver=logan.com; client-ip=203.24.100.45; envelope-from=lendich@aanet.com.au Received: from sv1-1.aanet.com.au (mail.aanet.com.au [203.24.100.34]) by poplet2.per.eftel.com (Postfix) with ESMTP id D17C11738A7 for ; Wed, 28 Apr 2010 09:40:55 +0800 (WST) Received: from ownerf1fc517b8 (203.171.92.134.static.rev.aanet.com.au [203.171.92.134]) by sv1-1.aanet.com.au (Postfix) with SMTP id 1D0A1BEC013 for ; Wed, 28 Apr 2010 09:40:53 +0800 (WST) Message-ID: <6FEA051A20DF4451BFDF6ED76C6CFFD9@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: 20B RV-8 cooling results Date: Wed, 28 Apr 2010 11:40:56 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0007_01CAE6C7.AA2C70C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 100427-1, 04/27/2010), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0007_01CAE6C7.AA2C70C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ed/ Tracy, Can't say as I understand Tracy's set- up completely, other than it's = toward the lower end of Rad sizes. I was thinking to myself how I could = create a -ve pressure in the rad outlet to create a suction on the Rad. = We all know how the exhaust augmentation works and I was wondering why = we can't do the same thing with the rad outlets by running the rad = outlets inro a larger outlet fed by outside air. At idle the air is fed = by the prop air stream and at level fight it is fed by outside air = stream. The outside air could be could controlled by a butterfly - simple = enough. I know there emphasis on using shutter /flaps to control the = cowl outlet and I believe their good at restricting air flow, but I = don't know if this equates to a good -ve pressure behind the Rad. This = presupposes the Rads are completely enclosed for both inlet and outlet = air. George ( down under) 75% of my cooling problems were solved with the oil cooler change I = did but still needed more margin for hot weather climbs. Made the = decision to not change or enlarge the cooling outlet (that adds drag) = so went ahead and butchered the pretty inlets I made. =20 Ed Anderson's spreadsheet on BTUs & CFM cooling air required was = instrumental in deciding to go this way. It showed that without = negative pressure on the back side of the rads, there would never be = enough cfm to do the job during climb at full throttle. Negative = pressure is what I had when I flew without the cowl on but oh what a = draggy condition that was.=20 The old inlets were 4.5" diameter for the radiator and 4.125" diameter = for oil cooler. New inlets are 5.190" for the rad, and 4.875" dia for the = oil. This may not sound like a lot but it represents a 36% increase in = inlet area. Results were excellent. Oil temp went down 19 degrees at the test = speed (130) and water temp dropped 9 degrees. On 80 degree day and 500 = ft msl the oil temp maxed out at 194F at 210 mph which is way faster = than I would normally go at this altitude. Temp was around 175 at 130. = Oil Temp in climb remained below redline (210) but the temperature = lapse rate today made results not very meaningful. OAT was dropping 14 = degrees a minute at 3000 fpm climb rate.=20 now back to that nasty composite work to pretty up the inlets again. = They look like large stubby pitot tubes now. I hadn't thought of a good name for the RV-8 but a friend in = California recently came up with the winning idea which fit it well. = "Euphoriac" It's a term from a Sci Fi book (Vintage Season) meaning = something which induces euphoria. =20 ------=_NextPart_000_0007_01CAE6C7.AA2C70C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Ed/ Tracy,
Can't say as I understand Tracy's set- = up=20 completely, other than it's toward the lower end of Rad sizes. I was = thinking to=20 myself how I could create a -ve pressure in the rad outlet to = create a=20 suction on the Rad. We all know how the exhaust augmentation works and I = was=20 wondering why we can't do the same thing with the rad outlets by running = the rad=20 outlets inro a larger outlet fed by outside air. At idle the air is fed = by the=20 prop air stream and at level fight it is fed by outside air = stream.
The outside air could be could = controlled by a=20 butterfly - simple enough. I know there emphasis on using shutter /flaps = to=20 control the cowl outlet and I believe their good at restricting air = flow, but I=20 don't know if this equates to a good -ve pressure behind the Rad. This=20 presupposes the Rads are completely enclosed for both inlet and outlet=20 air.
George ( down under)
75% of my cooling problems = were solved=20 with the oil cooler change I did but still needed more margin for hot = weather=20 climbs.   Made the decision to not change or enlarge the cooling = outlet=20 (that adds drag)  so went ahead and butchered the pretty inlets I = made. 
Ed Anderson's spreadsheet on BTUs & CFM cooling = air=20 required was instrumental in deciding to go this way.   It = showed=20 that without negative pressure on the back side of the rads, there = would never=20 be enough cfm to do the job during climb at full throttle.  = Negative=20 pressure is what I had when I flew without the cowl on but oh what a = draggy=20 condition that was.

The old inlets were 4.5" diameter for the = radiator=20 and 4.125" diameter for oil cooler.
New inlets=20 are        5.190" for the = rad,  and=20   4.875" dia for the oil.

This may not sound like a lot = but it=20 represents a 36% increase in inlet area.

Results were = excellent. =20 Oil temp went down 19 degrees at the test speed (130) and water temp = dropped 9=20 degrees.  On 80 degree day and 500 ft msl the oil temp maxed out = at 194F=20 at 210 mph which is way faster than I would normally go at this=20 altitude.  Temp was around 175 at 130.    Oil Temp in = climb=20 remained below redline (210) but the temperature lapse rate today made = results=20 not very meaningful.  OAT was dropping 14 degrees a minute at = 3000 fpm=20 climb rate.

now back to that nasty composite work to pretty up = the=20 inlets again.  They look like large stubby pitot tubes = now.

I=20 hadn't thought of a good name for the RV-8 but a friend in California = recently=20 came up with the winning idea which fit it well. "Euphoriac"  It's a term from a  Sci Fi book = (Vintage=20 Season)  meaning something which induces euphoria. =20
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