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 5.3.1) with ESMTP id 4085897 for flyrotary@lancaironline.net; Sun, 17 Jan 2010 15:22:24 -0500 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 8AA9F173836 for ; Mon, 18 Jan 2010 04:21:47 +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 0A6D3BEC02C for ; Mon, 18 Jan 2010 04:21:32 +0800 (WST) Message-ID: From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Inclined Radiators was : [FlyRotary] Re: Scoops Date: Mon, 18 Jan 2010 06:21:31 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000F_01CA9806.79CD64D0" 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 100117-1, 01/17/2010), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_000F_01CA9806.79CD64D0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Tracy, Thanks for the feed back. Your right the wedge shape isn't as good as = the bell shape and I can well understand the time you spent on the = design.=20 This gives me some things to consider and I'm glad it's working well for = you, that's good info as well. George ( down under)=20 Two points,=20 Air does not care which tilt axis we are talking about so that is not = a factor. Mine was tilted on the horizontal axis if it helps envision = it. A 'wedge' duct does not preclude a 'bell shaped' duct. The bell shape = DOES become distorted to the point of not being recognizable but it = still functions as one. I spent several days sculpting mine. Wouldn't = have spent that time if a simple wedge would be as good. Tracy On Sat, Jan 16, 2010 at 10:56 PM, George Lendich = wrote: Tracy, Ed &Al, I don't know if we are all talking about the same thing so to = clarify in my own mind, I would like to say my opinion on these notes I = have, suggest to me that the 55 degrees, is from the direction of the = air flow i.e. 55 degrees from the horizon or X axis. That would be only = 35 degrees from the Y axis or vertical. So 35 degrees inclined vertical = isn't too bad - in a bell shaped duct. However I could be wrong and the = original reference could have been 55 degrees inclined from vertical, = which also sounds plausible, seeing their talking inclined, one might = think inclined from vertical. Al what's your thoughts on this. However I believe Tracy, you are saying 80 degrees from vertical and = I believe he must be referring to a wedge shaped duct, as I don't think = you could fabricate a bell shaped duct to cope with that degree to the = duct walls. This brings me to the question on what angle is desirable in a wedge = shaped duct, if your unable to fit in a bell shaped duct or should I = merely be considering the size of the inlet opening. I believe I = remember in wedge shaped ducts they should be as high or as wide as the = Rad, considering the placement of rad i.e. under engine or side of cowl = with appropriate depth of the inlet opening. Comments please. George ( down under) =20 Well the basic idea has validity because I carried it to an = extream. My rad is inclined about 80 degrees to the 5" duct so flow = axis is almost perpendicular to the duct. A 5" rad would never cool = that 20B so inclining it radically was the only answer in my = configuration. Water cooling has never been my problem. Oil cooling is = working pretty good with the new oil cooler. It was the "30 row oil = cooler" from CXracing if anyone is curious. Tracy On Sat, Jan 16, 2010 at 4:18 PM, George Lendich = wrote: Ed,=20 I would like to see that again, as I believe would others, like = Al and Thomas. I'm hoping someone tries it in an aircraft to test the = theory. TIA George ( down under) I recall an article on some experiments done on inclined = radiators in race cars.=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. For example take a duct that is 24=94 wide (X) and 12=94 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). The source indicated that up to 30Deg the drag increases and = heat transfer goes down due to uneven air flow distribution and = disturbances =96 apparently above that angle this adverse effect = decreases and of course you have the much larger frontal area.. At least that is what I recall. If anyone is interested = I=92ll see if I can find the article in my files 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 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%. George; do you have the source for that info? It may be a good = idea to verify this information. I don=92t 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=92t = remember what the factors were; maybe something about the configuration = of the core. Or maybe my memory just isn=92t 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_000F_01CA9806.79CD64D0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
Tracy,
Thanks for the feed back. Your = right the=20 wedge shape isn't as good as the bell shape and I can well understand = the time=20 you spent on the design. 
This gives me some things to consider = and I'm glad=20 it's working well for you, that's good info as well.
George ( down under) 
 
Two points,
  Air does not care which tilt axis we are = talking=20 about so that is not a factor.  Mine was tilted on the horizontal = axis if=20 it helps envision it.

A 'wedge' duct does not  preclude a = 'bell=20 shaped' duct.   The bell shape DOES become distorted to the = point of=20 not being recognizable but it still functions as one.  I spent = several days=20 sculpting mine.  Wouldn't have spent that time if a simple wedge = would be=20 as good.

Tracy

On Sat, Jan 16, 2010 at 10:56 PM, George = Lendich <lendich@aanet.com.au> wrote:
Tracy, Ed &Al,
I don't know if we are all talking = about the=20 same thing so to clarify in my own mind,  I would like to say = my=20 opinion on these notes I have, suggest to me that the 55 degrees, is = from=20 the direction of the air flow i.e. 55 degrees from the horizon or X = axis.=20 That would be only 35 degrees from the Y axis or  vertical. So = 35=20 degrees inclined vertical isn't too bad - in a bell shaped duct. = However I=20 could be wrong and the original reference could have been 55 degrees = inclined from vertical, which also sounds plausible, seeing their = talking=20 inclined, one might think inclined from vertical.  Al what's = your=20 thoughts on this.
 
However I believe Tracy, you are = saying 80=20 degrees from vertical and  I believe he must be referring to a = wedge=20 shaped duct, as I don't think you could fabricate a bell shaped duct = to cope=20 with that degree to the duct walls.
 
This brings me to the question on = what angle is=20 desirable in a wedge shaped duct, if your unable to fit in a bell = shaped=20 duct or should I merely be considering the size of the inlet = opening. I=20 believe I remember in wedge shaped ducts they should be as high or = as wide=20 as the Rad, considering the placement of rad i.e. under = engine or=20 side of cowl with appropriate depth of the inlet = opening.
Comments please.
George ( down = under)  

Well the basic idea has validity because I carried it to an=20 extream.  My rad is inclined about 80 degrees to the 5" duct = so flow=20 axis is almost perpendicular to the duct.  A 5" rad would = never cool=20 that 20B so inclining it radically was the only answer in my=20 configuration.  Water cooling has never been my = problem.  Oil=20 cooling is working pretty good with the new oil cooler.  It = was the=20 "30 row oil cooler" from CXracing if anyone is=20 curious.

Tracy

On Sat, Jan 16, 2010 at 4:18 PM, George = Lendich=20 <lendich@aanet.com.au> wrote:
Ed,
I would like to see that again, = as I=20 believe would others,  like Al and Thomas. I'm hoping = someone tries=20 it in an aircraft to test the theory.
TIA
George ( down = under)

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

 

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

 

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

 

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

 

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

http://www.flyrotary.com/

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

http://www.rotaryaviation.com/Rotorhead%20Truth.htm

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


To: = Rotary=20 motors in aircraft
Subject: [FlyRotary] = Re:=20 Scoops

 

 

Thomas,

Nice=20 research.

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

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

2. Over 30*=20 things improve.

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

and drag is=20 less by 20%.

 

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

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

All



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

The message was checked by ESET NOD32=20 Antivirus.

http://www.eset.com


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