X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao103.cox.net ([68.230.241.43] verified) by logan.com (CommuniGate Pro SMTP 5.3.1) with ESMTP id 4086825 for flyrotary@lancaironline.net; Mon, 18 Jan 2010 12:28:02 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.43; envelope-from=rv-4mike@cox.net Received: from fed1rmimpo03.cox.net ([70.169.32.75]) by fed1rmmtao103.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20100118172727.BPOB26337.fed1rmmtao103.cox.net@fed1rmimpo03.cox.net> for ; Mon, 18 Jan 2010 12:27:27 -0500 Received: from willsPC ([68.105.86.80]) by fed1rmimpo03.cox.net with bizsmtp id X5TR1d00J1k005Q045TSiw; Mon, 18 Jan 2010 12:27:26 -0500 X-VR-Score: 0.00 X-Authority-Analysis: v=1.1 cv=tFsbg6ins7CCNpnljIJNduQMDmn6okYQ4EWCOqLKcEg= c=1 sm=1 a=7is6ADb-yswA:10 a=XruvlouZCDbGUgEaRUiNZQ==:17 a=ayC55rCoAAAA:8 a=arxwEM4EAAAA:8 a=QdXCYpuVAAAA:8 a=7g1VtSJxAAAA:8 a=ekHE3smAAAAA:20 a=UretUmmEAAAA:8 a=Ia-xEzejAAAA:8 a=nUuTZ29dAAAA:8 a=xVhY2PgbGrTAW3uTgvAA:9 a=NaiAUBjxyStT1p-6svsA:7 a=gSn0WtUwxDhhDfegTyZ3j8rcxCUA:4 a=1vhyWl4Y8LcA:10 a=EzXvWhQp4_cA:10 a=RgKmhMJKDEmXxEWj:21 a=14TbAq7KPZE8XSLP:21 a=eIwCkTKe1vnNOXxQofoA:9 a=uXsgWOetoA9p3eOosksA:7 a=gChC2myu1jlPNh-_6GAmUAb8ryEA:4 a=FBgD1vB1trK2AY8Q:21 a=p6pLRCqYRibnebQn:21 a=XruvlouZCDbGUgEaRUiNZQ==:117 X-CM-Score: 0.00 Message-ID: <6074E2D634BD4A9EB08850A37F6F6D5C@willsPC> From: "Mike Wills" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Inclined Radiators was : [FlyRotary] Re: Scoops Date: Mon, 18 Jan 2010 09:27:24 -0800 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0197_01CA9820.71B05F40" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8089.726 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8089.726 This is a multi-part message in MIME format. ------=_NextPart_000_0197_01CA9820.71B05F40 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I'm with Ed and Tracy on this one. My rad is inclined maybe 5 degrees = from horizontal beneath the engine. There was many years ago a retired = cooling system engineer for one of the auto makers who used to inhabit = Paul's list. He had a pretty elegant software tool that could calculate = cooling effectiveness as well as aerodynamic drag for virtually any = config you'd like to try. Of course there are a lot of assumptions made = in this sort of analysis. But bottom line was that both cooling and = aerocynamics were improved dramatically as surface area of the rad went = up, more or less regardless of the orientation of the rad to the airflow = (one assumption being that you have space and skill to fabricate a duct = like Tracy's to slow the airflow so it will turn the corner). So my rad = ended up horizontal and as large as I was willing to tolerate for weight = reasons. Like Tracy, I've had zero cooling issues since first flight.=20 Mike Wills RV-4 N144MW From: Ed Anderson=20 Sent: Friday, January 15, 2010 6:05 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Inclined Radiators was : [FlyRotary] Re: Scoops I recall an article on some experiments done on inclined radiators in = race cars.=20 =20 Basically the figures that George mentioned were quoted in the source. = However (big however) what may not have been clearly pointed out was = that the major part of the reason cooling effectiveness (not efficiency) = increased was that inclining the heat exchanger permitted you to install = ever larger area cores in the same size duct. So the increase in = cooling effectiveness by inclination was in large part due to the larger = size radiator permitted by inclined placement in the duct. =20 For example take a duct that is 24" wide (X) and 12" high (Y) at zero = degree inclination. If you incline the radiator by 30 deg and then = increase its height to again fill the duct,. you can get an approx 15% = increase in the frontal size of the radiator (in the same 24x12 duct). = At 60 deg you could gain approx 100% increase in frontal size by again = increasing the height of the core to fill the duct. . Naturally that = aids in getting rid of the heat. They also point out the larger core = adds weight until you reach a point where the adverse effect of the = heavier radiator core offset its benefit (this was all addressing their = use in race cars). =20 The source indicated that up to 30Deg the drag increases and heat = transfer goes down due to uneven air flow distribution and disturbances = - apparently above that angle this adverse effect decreases and of = course you have the much larger frontal area.. =20 At least that is what I recall. If anyone is interested I'll see if I = can find the article in my files =20 Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm -------------------------------------------------------------------------= ------- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On = Behalf Of Al Gietzen Sent: Friday, January 15, 2010 1:13 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Scoops =20 =20 Thomas, Nice research. I found my notes on inclined radiators, they state 1. 0-20/30* will decrease cooling and increase drag. 2. Over 30* things improve. 3. At approx 55* cooling effectiveness is 30% greater than non-inclined = rads=20 and drag is less by 20%. =20 George; do you have the source for that info? It may be a good idea to = verify this information. I don't recall the specifics; but what I do = recall is that the conclusion was configuration dependant, and should = not be taken as generally applicable. Sorry, but I don't remember what = the factors were; maybe something about the configuration of the core. Or maybe my memory just isn't right. Worth checking. All __________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_0197_01CA9820.71B05F40 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I'm with Ed and Tracy on this one. My rad is = inclined=20 maybe 5 degrees from horizontal beneath the engine. There was many years = ago a=20 retired cooling system engineer for one of the auto makers who used to = inhabit=20 Paul's list. He had a pretty elegant software tool that could calculate = cooling=20 effectiveness as well as aerodynamic drag for virtually any config you'd = like to=20 try. Of course there are a lot of assumptions made in this sort of = analysis. But=20 bottom line was that both cooling and aerocynamics were improved = dramatically as=20 surface area of the rad went up, more or less regardless of the = orientation of=20 the rad to the airflow (one assumption being that you have space and = skill to=20 fabricate a duct like Tracy's to slow the airflow so it will turn the = corner).=20 So my rad ended up horizontal and as large as I was willing to tolerate = for=20 weight reasons. Like Tracy, I've had zero cooling issues since first=20 flight. 
 
Mike Wills
RV-4 N144MW

Sent: Friday, January 15, 2010 6:05 AM
Subject: [FlyRotary] Inclined Radiators was : [FlyRotary] = Re:=20 Scoops

I recall an = article on=20 some experiments done on inclined radiators in race cars.=20

 

Basically the = figures=20 that George mentioned were quoted in the source.  However (big = however)=20 what may not have been clearly pointed out was that the major part of = the reason=20 cooling effectiveness (not efficiency) increased was that inclining the = heat=20 exchanger permitted you to install ever larger area cores in the same = size=20 duct.  So the increase in cooling effectiveness by inclination was = in large=20 part due to the larger size radiator permitted by inclined placement in = the=20 duct.

 

For example = take a duct=20 that is 24=94 wide (X) and 12=94 high (Y) at zero degree = inclination.  If you=20 incline the radiator by 30 deg and then increase its height to again = fill the=20 duct,. you can get an approx 15% increase in the frontal size of the = radiator=20 (in the same 24x12 duct).  At 60 deg you could gain approx 100% = increase in=20 frontal size by again increasing the height of the core to fill the = duct. =20 . Naturally that aids in getting rid of the heat.  They also point = out the=20 larger core adds weight until you reach a point where the adverse effect = of the=20 heavier radiator core offset its benefit (this was all addressing their = use in=20 race cars).

 

The source = indicated=20 that up to 30Deg the drag increases and heat transfer goes down due to = uneven=20 air flow distribution and disturbances =96 apparently above that angle = this=20 adverse effect decreases and of course you have the much larger frontal=20 area..

 

At least that = is what I=20 recall.  If anyone is interested I=92ll see if I can find the = article in my=20 files

 

Ed

Ed=20 Anderson

Rv-6A N494BW=20 Rotary Powered

Matthews,=20 NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm

From:=20 Rotary motors in aircraft=20 [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Al Gietzen
Sent: Friday, January 15, 2010 = 1:13=20 AM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re:=20 Scoops

 

 

Thomas,

Nice research.

I=20 found my notes on inclined radiators, they = state

1.=20 0-20/30* will decrease cooling and increase = drag.

2.=20 Over 30* things improve.

3.=20 At approx 55* cooling effectiveness is 30% greater than non-inclined = rads=20

and=20 drag is less by 20%.

 

George; do = you have=20 the source for that info? It may be a good idea to verify this = information.=20  I don=92t recall the specifics; but what I do recall is that the = conclusion=20 was configuration dependant, and should not be taken as generally=20 applicable.  Sorry, but I don=92t remember what the factors were; = maybe=20 something about the configuration of the = core.

Or maybe = my memory=20 just isn=92t right.  Worth checking.

All



__________ Information from ESET NOD32 = Antivirus, version of virus signature database 3267 (20080714)=20 __________

The message was checked by ESET NOD32 = Antivirus.

http://www.eset.com

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