X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 50 [XX] (51%) URL: contains host with port number (-49%) URL: weird port adjustment Return-Path: Received: from imo-m28.mx.aol.com ([64.12.137.9] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2024186 for flyrotary@lancaironline.net; Thu, 03 May 2007 16:45:33 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.9; envelope-from=BMears9413@aol.com Received: from BMears9413@aol.com by imo-m28.mx.aol.com (mail_out_v38_r9.2.) id q.ce0.10ab4050 (52825) for ; Thu, 3 May 2007 16:44:26 -0400 (EDT) Received: from mblk-r37 (mblk-r37.mblk.aol.com [152.163.179.36]) by cia-m01.mx.aol.com (v115.11) with ESMTP id MAILCIAM011-ce59463a49aa165; Thu, 03 May 2007 16:44:26 -0400 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: Cooling area drag Date: Thu, 03 May 2007 16:44:26 -0400 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: bmears9413@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8C95BDAF954A731_1FBC_1B437_mblk-r37.sysops.aol.com" X-Mailer: AOL WebMail 25698 Received: from 65.182.71.8 by mblk-r37.sysops.aol.com (152.163.179.36) with HTTP (WebMailUI); Thu, 03 May 2007 16:44:26 -0400 Message-Id: <8C95BDAF954A731-1FBC-E77F@mblk-r37.sysops.aol.com> X-AOL-IP: 152.163.179.36 X-Spam-Flag: NO ----------MB_8C95BDAF954A731_1FBC_1B437_mblk-r37.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" That looks like the way to go, if the rad will fit. unfortunatly I didnt think of that when I ordered the $500.00 radiator. I'll have to see if it will fit. I was worried about, and still concerned about, mounting the rad that low and supporting it. Bob Mears Supermarine Spitfire -----Original Message----- From: blake.lewis@gmail.com To: flyrotary@lancaironline.net Sent: Thu, 3 May 2007 3:32 PM Subject: [FlyRotary] Re: Cooling area drag If the scoop is big enough to contain the radiator, you could do a Kays and London Wedge. The kind that the police tried treat as a bomb on top of Paul's van when he was testing it. Here is a rough sketch. Blake On 5/3/07, bmears9413@aol.com wrote: Ed, Give me some pointers on my cooling system before I get started. You surely will save me some mistakes. My air intake will be below and behind my radiator. I imagined just building some deflectors to "s" the air up to the radiator. Aft of the radiator the air will exit out the back half of the air scoop. the radiator will be laying flat, under the motormount. the oil coolers are under each wing...as it should be in s spitfire. Thanks, Bob Mears Supermarine Spitfire -----Original Message----- From: eanderson@carolina.rr.com To: flyrotary@lancaironline.net Sent: Thu, 3 May 2007 11:49 AM Subject: [FlyRotary] Re: Cooling area drag Actually, Mark, I started pulling together what I believed to be the major factors without getting too down in the weeds about rotary cooling, a couple of years ago with the intention of publishing an e book (pamphlet more likely) . Then I ran into the problem that the seemingly best diffuser (Streamline duct) was simply too long (in its optimum configuration) for most of our needs. Yes, you can shorten it but then you incur more drag. So I scratched my head about that for a while until the light bulb came on. After experimenting with a number of duct shapes and reading more, I came to the conclusion that if my understanding about what killed effective cooling was correct then I should be able to achieve my cooling/drag goals with the "Pinched" duct. But, what I wanted to do and never took the time to do was to go back with Mr. Bernoulli and calculate the air velocity along each segment of the streamline duct and then do the same for my "pinched" duct to see if there was any similarity. Also, I have not paid much attention to the exiting duct - simply because I don't have room for one. I tired one back almost 8 years ago and decided the zigs and zags it had to avoid engine/motormount, etc impeded airflow more than helped it. But, alas, just as I was recently about to go to publication, the new "bible" of cooling was published - so how could I possibly compete {:>). I may still do it as if it passes the gauntlet of folks on this list (or errors if any {:>)) are corrected,as it may be useful to some. Ed ----- Original Message ----- From: Mark Steitle To: Rotary motors in aircraft Sent: Thursday, May 03, 2007 12:34 PM Subject: [FlyRotary] Re: Cooling area drag ED, So, tell us, when is your book on cooling going to be available? Mark On 5/3/07, Ed Anderson wrote: Less we forget how important drag is in our hobby, I took a formula for calculating drag at different airspeeds and the Hp required to push the given frontal area along at the stated airspeed. This is for two of our traditional GM evaporator cores using their combined frontal area of 180 sq inch or 1.25 sq feet. This assumes that airspeed shown represents the velocity through the cooling core (which is not really likely to reach speeds above 80 mph if you have any sort of ducting), but that is an assumption on my part since as Bill keeps reminding me I have not instrumented my ducts {:>) Air Speed (MPH) HP 400.533333 601.80 804.27 12014.40 14022.87 16034.13 18048.60 20066.67 Clearly the faster your cruise speed the more important it is to minimize cooling drag. Of course the airspeed the core sees should normally not be over 10% of your cruise speed or 30% of your climb speed (According to Horners rule of thumb). So slowing down your cooling airflow to lessen drag is one reason for paying some attention to your ducting. However, cooling again depends on many other variables, for instance accepting a high velocity airflow through your core may permit you to use a smaller frontal area core thereby offsetting to some extent the higher drag. In fact, space constraints may force you to his configuration regardless. Another factor to consider is trade off between frontal area drag and thermal transfer efficiency. A large thin radiator is theoretical the most efficient due to that factor. However, it disturbs a larger segment of air (resulting in higher drag) - not really important in an auto at 60 mph but very important in a Cozy at 200+ MPH. A thicker core with smaller frontal area disturbs less air and while it has more skin drag that is small compared to the frontal area drag. Tracy refers to the approach of thicker cores as "... getting the most cooling possible for the smallest column of air disturbed". So while theoretically the thicker core is less thermodynamic efficient - it turns out with sufficient dynamic pressure available it provides definite benefits in our application. The average thickness of NASCAR radiators is 3" and up to 7" for the longer high speed tracts. Since they operate in speed regimes close to what most of us fly - they just might know what they are doing given the $$ they will spend for even a slight speed advantage. Ok, back to creating a company - boy, a lot to learn Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html AOL now offers free email to everyone. Find out more about what's free from AOL at AOL.com . -- Blake C. Lewis -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html [Image Removed] ________________________________________________________________________ AOL now offers free email to everyone. Find out more about what's free from AOL at AOL.com. ----------MB_8C95BDAF954A731_1FBC_1B437_mblk-r37.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/html; charset="us-ascii"
That looks like the way to go, if the rad will fit. unfortunatly I didnt think of that when I ordered the $500.00 radiator. I'll have to see if it will fit. I was worried about, and still concerned about, mounting the rad that low and supporting it.
 
Bob Mears
Supermarine Spitfire
 
 
-----Original Message-----
From: blake.lewis@gmail.com
To: flyrotary@lancaironline.net
Sent: Thu, 3 May 2007 3:32 PM
Subject: [FlyRotary] Re: Cooling area drag

If the scoop is big enough to contain the radiator, you could do a Kays and London Wedge. The kind that the police tried treat as a bomb on top of Paul's van when he was testing it. Here is a rough sketch.
Blake

On 5/3/07, bmears9413@aol.com <bmears9413@aol.com> wrote:
Ed,
Give me some pointers on my cooling system before I get started. You surely will save me some mistakes. My air intake will be below and behind my radiator. I imagined just building some deflectors to "s" the air up to the radiator. Aft of the radiator the air will exit out the back half of the air scoop. the radiator will be laying flat, under the motormount. the oil coolers are under each wing...as it should be in s spitfire.
Thanks,
Bob Mears
Supermarine Spitfire
 
 
 
 
 
-----Original Message-----
From: eanderson@carolina.rr.com
To: flyrotary@lancaironline.net
Sent: Thu, 3 May 2007 11:49 AM
Subject: [FlyRotary] Re: Cooling area drag

Actually, Mark,  I started pulling together what I believed to be the major factors without getting too down in the weeds about rotary cooling, a couple of years ago with the intention of publishing an e book (pamphlet more likely) .  Then I ran into the problem that the seemingly best diffuser (Streamline duct) was simply too long (in its optimum configuration) for most of our needs.  Yes, you can shorten it but then you incur more drag.  So I scratched my head about that for a while until the light bulb came on.
 
After experimenting with a number of duct shapes and reading more, I came to the conclusion that if my understanding about what killed effective cooling was correct then I should be able to achieve my cooling/drag goals with the "Pinched" duct.  But, what I wanted to do and never took the time to do was to go back with Mr. Bernoulli and calculate the air velocity along each segment of the streamline duct and then do the same for my "pinched" duct to see if there was any similarity.   Also, I have not paid much attention to the exiting duct - simply because I don't have room for one.  I tired one back almost 8 years ago and decided the zigs and zags it had to avoid engine/motormount, etc impeded airflow more than helped it.
 
 
But, alas, just as I was recently about to go to publication, the new "bible" of cooling was published - so how could I possibly compete {:>).  I may still do it as if it passes the gauntlet of folks on this list (or errors if any {:>)) are corrected,as it may be useful to some.
 
Ed
 
 
----- Original Message -----
Sent: Thursday, May 03, 2007 12:34 PM
Subject: [FlyRotary] Re: Cooling area drag

ED,
 
So, tell us, when is your book on cooling going to be available? 
 
Mark

 
On 5/3/07, Ed Anderson <eanderson@carolina.rr.com > wrote:
Less we forget how important drag is in our hobby, I took a formula for calculating drag at different airspeeds and the Hp required to push the given frontal area along at the stated airspeed.
 
This is for two of our traditional GM evaporator cores using their combined frontal area of  180 sq inch or 1.25 sq feet.  This assumes that airspeed shown represents the velocity through the cooling core (which is not really likely to reach speeds above 80 mph if you have any sort of ducting), but that is an assumption on my part since as Bill keeps reminding me I have not instrumented my ducts {:>)
 
Air Speed (MPH)
          HP
40
0.533333
60
1.80
80
4.27
120
14.40
140
22.87
160
34.13
180
48.60
200
66.67
 
 
Clearly the faster your cruise speed the more important it is to minimize cooling drag.  Of course the airspeed the core sees should normally not be over 10% of your cruise speed or 30% of your climb speed (According to Horners rule of thumb).  So slowing down your cooling airflow to lessen drag is one reason for paying some attention to your ducting.  However, cooling again depends on many other variables, for instance accepting a high velocity airflow through your core may permit you to use a smaller frontal area  core thereby offsetting to some extent the higher drag.  In fact, space constraints may force you to his configuration regardless.
 
Another factor to consider is trade off between frontal area drag and thermal transfer efficiency.  A large thin radiator is theoretical the most efficient due to that factor.  However, it disturbs a larger segment of air (resulting in higher drag) - not really important in an auto at 60 mph but very important in a Cozy at 200+ MPH.  
 
A thicker core with smaller frontal area disturbs less air and while it has more skin drag that is small compared to the frontal area drag.  Tracy refers to the approach of thicker cores as "... getting the most cooling possible for the smallest column of air disturbed".  So while theoretically the thicker core is less thermodynamic efficient - it turns out with sufficient dynamic pressure available it provides definite benefits in our application.   The average thickness of NASCAR radiators is 3" and up to 7" for the longer high speed tracts.  Since they operate in speed regimes close to what most of us fly - they just might know what they are doing given the $$ they will spend for even a slight speed advantage.
 
Ok, back to creating a company - boy, a lot to learn
 
Ed
 
 
 
  
 
 

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