X-Virus-Scanned: clean according to Sophos on Logan.com
X-SpamCatcher-Score:   2 [X]
Return-Path: <Grant.Schemmel@Aeroflex.com>
Received: from [12.10.147.52] (HELO utmcmail.utmc.com)
  by logan.com (CommuniGate Pro SMTP 5.1.7)
  with ESMTP id 1874571 for flyrotary@lancaironline.net; Wed, 28 Feb 2007 15:00:54 -0500
Received-SPF: none
 receiver=logan.com; client-ip=12.10.147.52; envelope-from=Grant.Schemmel@Aeroflex.com
Received: from pony.utmc.utc.com ([172.24.100.19] RDNS failed) by utmcmail.utmc.com with Microsoft SMTPSVC(6.0.3790.211);
	 Wed, 28 Feb 2007 12:58:51 -0700
Received: by pony.utmc.utc.com with Internet Mail Service (5.5.2655.55)
	id <CSPGJ95M>; Wed, 28 Feb 2007 12:57:46 -0700
Message-ID: <B31F84BBE80CD411A4BC00A0C9EC0F2503C35827@pony.utmc.utc.com>
From: "Schemmel, Grant" <Grant.Schemmel@Aeroflex.com>
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Re: Pinched ducts was : [FlyRotary] Re: cowl open
	ings for water radiators
Date: Wed, 28 Feb 2007 12:57:43 -0700
MIME-Version: 1.0
X-Mailer: Internet Mail Service (5.5.2655.55)
Content-Type: multipart/alternative;
	boundary="----_=_NextPart_001_01C75B72.B55777DA"
Return-Path: Grant.Schemmel@Aeroflex.com
X-OriginalArrivalTime: 28 Feb 2007 19:58:51.0446 (UTC) FILETIME=[DE211D60:01C75B72]

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.

------_=_NextPart_001_01C75B72.B55777DA
Content-Type: text/plain

Joe,  I too would like a copy if possible.  Send it to n602gs@yahoo.com <mailto:n602gs@yahoo.com>  if you would.
 
Otherwise, I think posting it on the website is a good idea too.
 
Thanks!
 
Grant Schemmel

  _____  

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of H & J Johnson
Sent: Wednesday, February 28, 2007 12:55 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Pinched ducts was : [FlyRotary] Re: cowl openings for water radiators



Joe, I'd love a copy. I've a 100mb inbox so no worries. Maybe Marv would like to put it on the web and save having to email it to several people. Whoever wants a copy can just download it..

Jarrett

 

----- Original Message -----

From: Joe Ewen <jewen@comporium.net> 

Date: Wednesday, February 28, 2007 12:57 pm 

Subject: [FlyRotary] Re: Pinched ducts was : [FlyRotary] Re: cowl openings for water radiators 

> Thomas, 
> Please confirm that you want me to send it, it is a big file - 
> 68MB.  Might bog you down a bit if you do not have a broad band 
> connection.Joe 
>  ----- Original Message ----- 
>  From: Thomas y Reina Jakits 
>  To: Rotary motors in aircraft 
>  Sent: Wednesday, February 28, 2007 1:12 PM 
>  Subject: [FlyRotary] Re: Pinched ducts was : [FlyRotary] Re: 
> cowl openings for water radiators 
> 
> 
>  Yes, please send me that one or post if anyone else is interested! 
>  However the real interesting thing would be to proof Ed's system 
> as an alternative for a clean K&N if space is at a premium. 
> 
>  For me the whole project (still in the dream fase) is more about 
> the modifications, building, discussions, etc. Flying the finished 
> product is 2nd to everything else. 
>  I make a living (more or less) flying the most fantastic 
> invention ever (helicopters) in a beautiful country, so getting in 
> the air is not the prime factor for planning an Experimental 
> Project... 
>  Thomas 
>    ----- Original Message ----- 
>    From: Joe Ewen 
>    To: Rotary motors in aircraft 
>    Sent: Wednesday, February 28, 2007 1:04 PM 
>    Subject: [FlyRotary] Re: Pinched ducts was : [FlyRotary] Re: 
> cowl openings for water radiators 
> 
> 
>    I have a pdf of the K & W if you need it.  I found the Excel 
> sheet Ed made reduced the K&W info into a manageable form. 
>    Joe 
> 
> 
>    ----- Original Message ----- 
>      From: Ed Anderson 
>      To: Rotary motors in aircraft 
>      Sent: Tuesday, February 27, 2007 7:46 AM 
>      Subject: [FlyRotary] Re: Pinched ducts was : [FlyRotary] Re: 
> cowl openings for water radiators 
> 
> 
>      Thomas is right, Joe. 
> 
>       Lots of good stuff on cooling on Paul's site - if you want 
> your own copy of K&W they are long out of print.  However, there 
> was (may still be there) a place in the Philippines that would 
> make you a bound Xerox copy of the book for somewhere around $30.  
> Unless you like pouring over a lot of math thought it makes for 
> heavy reading {:>).  
> 
>      Ed 
>        ----- Original Message ----- 
>        From: Thomas y Reina Jakits 
>        To: Rotary motors in aircraft 
>        Sent: Monday, February 26, 2007 10:46 PM 
>        Subject: [FlyRotary] Re: Pinched ducts was : [FlyRotary] 
> Re: cowl openings for water radiators 
> 
> 
>        Joe, 
> 
>        I hate to do that, but if you need even more study stuff, 
> go to Paul Lamar's site and read up on the cooling chapter. He put 
> an impressive collection of data there and a lot of ideas - at 
> your own risk. There some ways that work well too (obviously, as 
> they are used...), but you will not find it on his site, as these 
> ideas do not agree with his findings. 
>        If you need something like Ed has, then you will get a lot 
> of info here: http://www.rotaryeng.net/cooling.html 
> 
>        (The quoted site belongs to Paul Lamar, all info on it was 
> collected by him and is provid to the public by him. Where 
> applicable Paul Lamar holds copyrights as noted on his site...) 
> 
>        Best Regards, 
>        Thomas Jakits, 
>        "Slim ball parasite and low life jerk" 
> 
>        PS: Whatever one thinks about him, he does have an 
> impressive collection of info! 
> 
> 
>          ----- Original Message ----- 
>          From: Ed Anderson 
>          To: Rotary motors in aircraft 
>          Sent: Monday, February 26, 2007 9:38 PM 
>          Subject: [FlyRotary] Pinched ducts was : [FlyRotary] Re: 
> cowl openings for water radiators 
> 
> 
>          Actually, there is, Joe.  But, you are going to be sorry 
> you asked {:>). 
> 
>            I spent quite a hit of time studying a tome (Kuchuman 
> and Weber better know as K&W)  on air cooling of liquid cooled 
> engines written back in the hey day of high speed mustangs 
> lightenings, spitfires, etc. Sort of the liquid cooling bible.   
> Chapter 12 (the one of most interest to us) showed a duct that 
> reportedly had the best pressure recovery (84% or thereabouts) 
> around for a subsonic duct that they had found.  It was called a 
> "StreamLine Duct" (See attached graph - the graph a of the top 
> graph shows the shape of the duct (or at least 1/2 around the 
> center line - sorry for the poor quality).  
> 
>           After quite a bit of studying and thinking about what I 
> had read about cooling ducts, it finally became clear to me that 
> the perhaps top thing that is clearly detrimental to good cooling 
> is having flow separation in the duct.   Most of the old drawings 
> of a cooling duct shape followed a sinusoidal shape - rapid 
> expansion right after the opening.  It turns out that 
> "traditional" shape is probably one of the worst shapes for a 
> cooling duct (the story why is too long to get into here). 
> 
>          Anyhow,  Flow separation leads to eddies and turbulence 
> which casts a "shadow" of turbulent air on the cooling core.  Like 
> a shadow, the further away from the core the separation occurs 
> (like near the entrance of the duct) the larger the shadow it 
> casts on the core area.  This "shadow"  adversely interferes with 
> the flow of air through the core and reduces the effectiveness of 
> the core. 
> 
>            What causes this separation is that as pressure is 
> recovered by the expansion of the duct, the build up of the very 
> pressure recover we want -  starts to hinder the boundary layer 
> flow near the wall of the duct.  It slows it down and causes it to 
> lose energy and attachment to the duct wall.  At a certain point 
> the flow separates and starts to tumble/rotate and depending where 
> (near the duct entrance or near the core) the flow separates, 
> determines how much of the core area is adversely affected.  So if 
> the boundary layer's energy level (air speed of its molecules) is 
> maintained at a high level separation is less likely. 
> 
>          So ideally, you would like to prevent any separation 
> during pressure recovery.  The Streamline Duct is the so called 
> "Trumpet" duct or "Bell" duct .  After the opening, there is a 
> long section of non-expanding duct followed by a rapid expansion 
> into the "bell" shape just before the core.  The long non- 
> expanding part of the duct maintains the energy (air flow) of the 
> boundary layer and separation does not occur until well into the 
> "bell" shape expansion. 
> 
>           In fact, it happens way up in the corner of the 
> bell/core interface and affects a very small area of the core. 
>          For full effectiveness the "Streamline duct" from K&W 
> needs a length of 12-17".  Well, that's way more distance than I 
> had.  So I got to thinking that if keeping the speed of the air 
> molecules near the duct wall helps prevent boundary layer 
> separation and the cooling killing eddy of turbulent air -  what 
> could I do with my short 3 - 6" (no jokes you guys).  We all know 
> from Bernoulli that if an area is squeezed down that the velocity 
> of the air flow increases - right?  
> 
>          So I decided to try to maintain or increase the energy 
> of the air by pitching down the neck just before it goes into the 
> bell shape expansions in hopes that the increased energy will help 
> the boundary layer stay adhered to the duct wall until well into 
> the corner of the bell shape.  So that's the story of the pinched 
> ducts.  There is no question in my mind that this is not as 
> effective as if I could have had the 16" to build the duct - but, 
> in this hobby, you work with what you've got - right? 
> 
>          Does it work?  Who knows - but I seem to fly with less 
> opening area than most folks and have no cooling problems.  So 
> that's my 0.02 on the topic - see told you, you would regret 
> asking {:>). 
> 
>          Ed 
> 
> 
>            ----- Original Message ----- 
>            From: John Downing 
>            To: Rotary motors in aircraft 
>            Sent: Monday, February 26, 2007 8:53 PM 
>            Subject: [FlyRotary] Re: cowl openings for water radiators 
> 
> 
>            Ed, is there some particular reason that you necked 
> the inlet down small, then enlarged it again.  Thankyou for the 
> pictures.  JohnD 
>              ----- Original Message ----- 
>              From: Ed Anderson 
>              To: Rotary motors in aircraft 
>              Sent: Monday, February 26, 2007 3:39 PM 
>              Subject: [FlyRotary] Re: cowl openings for water 
> radiators 
> 
>              John, don't know if these photos will help.  But, 
> like you I only have between 3 and 6" of duct distance on the 
> radiators.  You should do Ok with 20 sq inch on each opening with 
> a good diffuser/duct.  Attached are some photos of my current 
> ducts.  The openings are 18 sq inches each.  I have had one 
> opening down to as little as 10 square inches - but that was a bit 
> marginal - so opened it back up.  I have a generous exit area for 
> the hot air including a larger 4" x 12" bottom opening as well as 
> louvers on each side of the cowl.  So you mileage could vary - but 
> Tracy has essentially the same size opening as well as several others. 
> 
>              Ed 
>                ----- Original Message ----- 
>                From: John Downing 
>                To: Rotary motors in aircraft 
>                Sent: Monday, February 26, 2007 12:12 PM 
>                Subject: [FlyRotary] cowl openings for water radiators 
> 
> 
>                What size openings do I need for the water 
> radiators?   The Wittman Tailwind cowl I have has postal slots of 
> 3' x 7 3/4" , which is   approx. 22 1/4 sq in. on each side.  Sam 
> James for the 160 Lycoming is using 4 3/4' round holes which are 
> 17.6 sq. inches on each side.  My radiators are quite close to the 
> opening and I plan on making the diffusers trumpet shaped, will 
> the openings be large enough if I can stay over 20 sq. inches on 
> each side with a decent trumpet shape.  JohnD       hushpowere II 
> on order - hope to start in 2 weeks if weather cooperates. 
> 
> 
> ---------------------------------------------------------------- 
> 
> 
>                -- 
>                Homepage:  http://www.flyrotary.com/ 
>                Archive and UnSub:   
> http://mail.lancaironline.net/lists/flyrotary/ 
> 
> 
> ------------------------------------------------------------------ 
> 
> 
>              -- 
>              Homepage:  http://www.flyrotary.com/ 
>              Archive and UnSub:   
> http://mail.lancaironline.net/lists/flyrotary/ 
> 
> 
> ------------------------------------------------------------------- 
> --- 
> 
> 
>          -- 
>          Homepage:  http://www.flyrotary.com/ 
>          Archive and UnSub:   
> http://mail.lancaironline.net/lists/flyrotary/ 


--



Homepage:  http://www.flyrotary.com/



Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/

------_=_NextPart_001_01C75B72.B55777DA
Content-Type: text/html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=US-ASCII">


<META content="MSHTML 6.00.2900.3059" name=GENERATOR></HEAD>
<BODY>
<DIV dir=ltr align=left><SPAN class=636565719-28022007><FONT face=Arial 
color=#0000ff size=2>Joe,&nbsp; I too would like a copy if possible.&nbsp; Send 
it to <A href="mailto:n602gs@yahoo.com">n602gs@yahoo.com</A> if you 
would.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=636565719-28022007><FONT face=Arial 
color=#0000ff size=2></FONT></SPAN>&nbsp;</DIV>
<DIV dir=ltr align=left><SPAN class=636565719-28022007><FONT face=Arial 
color=#0000ff size=2>Otherwise, I think posting it on the website is a good idea 
too.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=636565719-28022007><FONT face=Arial 
color=#0000ff size=2></FONT></SPAN>&nbsp;</DIV>
<DIV dir=ltr align=left><SPAN class=636565719-28022007><FONT face=Arial 
color=#0000ff size=2>Thanks!</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=636565719-28022007></SPAN>&nbsp;</DIV>
<DIV dir=ltr align=left><SPAN class=636565719-28022007><FONT face=Arial 
color=#0000ff size=2>Grant Schemmel</FONT></SPAN></DIV><BR>
<DIV class=OutlookMessageHeader lang=en-us dir=ltr align=left>
<HR tabIndex=-1>
<FONT face=Tahoma size=2><B>From:</B> Rotary motors in aircraft 
[mailto:flyrotary@lancaironline.net] <B>On Behalf Of </B>H &amp; J 
Johnson<BR><B>Sent:</B> Wednesday, February 28, 2007 12:55 PM<BR><B>To:</B> 
Rotary motors in aircraft<BR><B>Subject:</B> [FlyRotary] Re: Pinched ducts was : 
[FlyRotary] Re: cowl openings for water radiators<BR></FONT><BR></DIV>
<DIV></DIV>
<P></P>
<P><B>Joe, I'd love a copy. I've a 100mb inbox so no worries. Maybe Marv would 
like to put it on the web and save having to email it to several people. Whoever 
wants a copy can just download it..</B></P>
<P><STRONG>Jarrett</STRONG></P>
<P><B></B>&nbsp;</P>
<P><B>----- Original Message -----</B></P>
<P></P><B>From</B>: Joe Ewen &lt;jewen@comporium.net&gt; 
<P></P><B>Date</B>: Wednesday, February 28, 2007 12:57 pm 
<P></P><B>Subject</B>: [FlyRotary] Re: Pinched ducts was : [FlyRotary] Re: cowl 
openings for water radiators 
<P></P>
<P></P>&gt; Thomas, <BR>&gt; Please confirm that you want me to send it, it is a 
big file - <BR>&gt; 68MB.&nbsp; Might bog you down a bit if you do not have a 
broad band <BR>&gt; connection.Joe <BR>&gt;&nbsp; ----- Original Message ----- 
<BR>&gt;&nbsp; From: Thomas y Reina Jakits <BR>&gt;&nbsp; To: Rotary motors in 
aircraft <BR>&gt;&nbsp; Sent: Wednesday, February 28, 2007 1:12 PM 
<BR>&gt;&nbsp; Subject: [FlyRotary] Re: Pinched ducts was : [FlyRotary] Re: 
<BR>&gt; cowl openings for water radiators <BR>&gt; <BR>&gt; <BR>&gt;&nbsp; Yes, 
please send me that one or post if anyone else is interested! <BR>&gt;&nbsp; 
However the real interesting thing would be to proof Ed's system <BR>&gt; as an 
alternative for a clean K&amp;N if space is at a premium. <BR>&gt; 
<BR>&gt;&nbsp; For me the whole project (still in the dream fase) is more about 
<BR>&gt; the modifications, building, discussions, etc. Flying the finished 
<BR>&gt; product is 2nd to everything else. <BR>&gt;&nbsp; I make a living (more 
or less) flying the most fantastic <BR>&gt; invention ever (helicopters) in a 
beautiful country, so getting in <BR>&gt; the air is not the prime factor for 
planning an Experimental <BR>&gt; Project... <BR>&gt;&nbsp; Thomas 
<BR>&gt;&nbsp;&nbsp;&nbsp; ----- Original Message ----- 
<BR>&gt;&nbsp;&nbsp;&nbsp; From: Joe Ewen <BR>&gt;&nbsp;&nbsp;&nbsp; To: Rotary 
motors in aircraft <BR>&gt;&nbsp;&nbsp;&nbsp; Sent: Wednesday, February 28, 2007 
1:04 PM <BR>&gt;&nbsp;&nbsp;&nbsp; Subject: [FlyRotary] Re: Pinched ducts was : 
[FlyRotary] Re: <BR>&gt; cowl openings for water radiators <BR>&gt; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp; I have a pdf of the K &amp; W if you need it.&nbsp; I 
found the Excel <BR>&gt; sheet Ed made reduced the K&amp;W info into a 
manageable form. <BR>&gt;&nbsp;&nbsp;&nbsp; Joe <BR>&gt; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp; ----- Original Message ----- 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; From: Ed Anderson 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; To: Rotary motors in aircraft 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Sent: Tuesday, February 27, 2007 7:46 AM 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Subject: [FlyRotary] Re: Pinched ducts 
was : [FlyRotary] Re: <BR>&gt; cowl openings for water radiators <BR>&gt; 
<BR>&gt; <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Thomas is right, Joe. <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Lots of good stuff on cooling on 
Paul's site - if you want <BR>&gt; your own copy of K&amp;W they are long out of 
print.&nbsp; However, there <BR>&gt; was (may still be there) a place in the 
Philippines that would <BR>&gt; make you a bound Xerox copy of the book for 
somewhere around $30.&nbsp; <BR>&gt; Unless you like pouring over a lot of math 
thought it makes for <BR>&gt; heavy reading {:&gt;).&nbsp; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Ed 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ----- Original Message ----- 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; From: Thomas y Reina Jakits 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; To: Rotary motors in aircraft 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Sent: Monday, February 26, 
2007 10:46 PM <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Subject: 
[FlyRotary] Re: Pinched ducts was : [FlyRotary] <BR>&gt; Re: cowl openings for 
water radiators <BR>&gt; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Joe, <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; I hate to do that, but if you 
need even more study stuff, <BR>&gt; go to Paul Lamar's site and read up on the 
cooling chapter. He put <BR>&gt; an impressive collection of data there and a 
lot of ideas - at <BR>&gt; your own risk. There some ways that work well too 
(obviously, as <BR>&gt; they are used...), but you will not find it on his site, 
as these <BR>&gt; ideas do not agree with his findings. 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; If you need something like Ed 
has, then you will get a lot <BR>&gt; of info here: 
http://www.rotaryeng.net/cooling.html <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; (The quoted site belongs to 
Paul Lamar, all info on it was <BR>&gt; collected by him and is provid to the 
public by him. Where <BR>&gt; applicable Paul Lamar holds copyrights as noted on 
his site...) <BR>&gt; <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Best 
Regards, <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Thomas Jakits, 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; "Slim ball parasite and low 
life jerk" <BR>&gt; <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; PS: 
Whatever one thinks about him, he does have an <BR>&gt; impressive collection of 
info! <BR>&gt; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ----- Original 
Message ----- <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
From: Ed Anderson <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
To: Rotary motors in aircraft 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Sent: Monday, 
February 26, 2007 9:38 PM 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Subject: 
[FlyRotary] Pinched ducts was : [FlyRotary] Re: <BR>&gt; cowl openings for water 
radiators <BR>&gt; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Actually, there 
is, Joe.&nbsp; But, you are going to be sorry <BR>&gt; you asked {:&gt;). 
<BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; I 
spent quite a hit of time studying a tome (Kuchuman <BR>&gt; and Weber better 
know as K&amp;W)&nbsp; on air cooling of liquid cooled <BR>&gt; engines written 
back in the hey day of high speed mustangs <BR>&gt; lightenings, spitfires, etc. 
Sort of the liquid cooling bible.&nbsp;&nbsp; <BR>&gt; Chapter 12 (the one of 
most interest to us) showed a duct that <BR>&gt; reportedly had the best 
pressure recovery (84% or thereabouts) <BR>&gt; around for a subsonic duct that 
they had found.&nbsp; It was called a <BR>&gt; "StreamLine Duct" (See attached 
graph - the graph a of the top <BR>&gt; graph shows the shape of the duct (or at 
least 1/2 around the <BR>&gt; center line - sorry for the poor quality).&nbsp; 
<BR>&gt; <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
After quite a bit of studying and thinking about what I <BR>&gt; had read about 
cooling ducts, it finally became clear to me that <BR>&gt; the perhaps top thing 
that is clearly detrimental to good cooling <BR>&gt; is having flow separation 
in the duct.&nbsp;&nbsp; Most of the old drawings <BR>&gt; of a cooling duct 
shape followed a sinusoidal shape - rapid <BR>&gt; expansion right after the 
opening.&nbsp; It turns out that <BR>&gt; "traditional" shape is probably one of 
the worst shapes for a <BR>&gt; cooling duct (the story why is too long to get 
into here). <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Anyhow,&nbsp; 
Flow separation leads to eddies and turbulence <BR>&gt; which casts a "shadow" 
of turbulent air on the cooling core.&nbsp; Like <BR>&gt; a shadow, the further 
away from the core the separation occurs <BR>&gt; (like near the entrance of the 
duct) the larger the shadow it <BR>&gt; casts on the core area.&nbsp; This 
"shadow"&nbsp; adversely interferes with <BR>&gt; the flow of air through the 
core and reduces the effectiveness of <BR>&gt; the core. <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; What 
causes this separation is that as pressure is <BR>&gt; recovered by the 
expansion of the duct, the build up of the very <BR>&gt; pressure recover we 
want -&nbsp; starts to hinder the boundary layer <BR>&gt; flow near the wall of 
the duct.&nbsp; It slows it down and causes it to <BR>&gt; lose energy and 
attachment to the duct wall.&nbsp; At a certain point <BR>&gt; the flow 
separates and starts to tumble/rotate and depending where <BR>&gt; (near the 
duct entrance or near the core) the flow separates, <BR>&gt; determines how much 
of the core area is adversely affected.&nbsp; So if <BR>&gt; the boundary 
layer's energy level (air speed of its molecules) is <BR>&gt; maintained at a 
high level separation is less likely. <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; So ideally, you 
would like to prevent any separation <BR>&gt; during pressure recovery.&nbsp; 
The Streamline Duct is the so called <BR>&gt; "Trumpet" duct or "Bell" duct 
.&nbsp; After the opening, there is a <BR>&gt; long section of non-expanding 
duct followed by a rapid expansion <BR>&gt; into the "bell" shape just before 
the core.&nbsp; The long non- <BR>&gt; expanding part of the duct maintains the 
energy (air flow) of the <BR>&gt; boundary layer and separation does not occur 
until well into the <BR>&gt; "bell" shape expansion. <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; In fact, it 
happens way up in the corner of the <BR>&gt; bell/core interface and affects a 
very small area of the core. 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; For full 
effectiveness the "Streamline duct" from K&amp;W <BR>&gt; needs a length of 
12-17".&nbsp; Well, that's way more distance than I <BR>&gt; had.&nbsp; So I got 
to thinking that if keeping the speed of the air <BR>&gt; molecules near the 
duct wall helps prevent boundary layer <BR>&gt; separation and the cooling 
killing eddy of turbulent air -&nbsp; what <BR>&gt; could I do with my short 3 - 
6" (no jokes you guys).&nbsp; We all know <BR>&gt; from Bernoulli that if an 
area is squeezed down that the velocity <BR>&gt; of the air flow increases - 
right?&nbsp; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; So I decided to 
try to maintain or increase the energy <BR>&gt; of the air by pitching down the 
neck just before it goes into the <BR>&gt; bell shape expansions in hopes that 
the increased energy will help <BR>&gt; the boundary layer stay adhered to the 
duct wall until well into <BR>&gt; the corner of the bell shape.&nbsp; So that's 
the story of the pinched <BR>&gt; ducts.&nbsp; There is no question in my mind 
that this is not as <BR>&gt; effective as if I could have had the 16" to build 
the duct - but, <BR>&gt; in this hobby, you work with what you've got - right? 
<BR>&gt; <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Does it 
work?&nbsp; Who knows - but I seem to fly with less <BR>&gt; opening area than 
most folks and have no cooling problems.&nbsp; So <BR>&gt; that's my 0.02 on the 
topic - see told you, you would regret <BR>&gt; asking {:&gt;). <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Ed <BR>&gt; 
<BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ----- 
Original Message ----- 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; From: 
John Downing 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; To: 
Rotary motors in aircraft 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Sent: 
Monday, February 26, 2007 8:53 PM 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Subject: [FlyRotary] Re: cowl openings for water radiators <BR>&gt; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Ed, 
is there some particular reason that you necked <BR>&gt; the inlet down small, 
then enlarged it again.&nbsp; Thankyou for the <BR>&gt; pictures.&nbsp; JohnD 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
----- Original Message ----- 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
From: Ed Anderson 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
To: Rotary motors in aircraft 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Sent: Monday, February 26, 2007 3:39 PM 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Subject: [FlyRotary] Re: cowl openings for water <BR>&gt; radiators <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
John, don't know if these photos will help.&nbsp; But, <BR>&gt; like you I only 
have between 3 and 6" of duct distance on the <BR>&gt; radiators.&nbsp; You 
should do Ok with 20 sq inch on each opening with <BR>&gt; a good 
diffuser/duct.&nbsp; Attached are some photos of my current <BR>&gt; 
ducts.&nbsp; The openings are 18 sq inches each.&nbsp; I have had one <BR>&gt; 
opening down to as little as 10 square inches - but that was a bit <BR>&gt; 
marginal - so opened it back up.&nbsp; I have a generous exit area for <BR>&gt; 
the hot air including a larger 4" x 12" bottom opening as well as <BR>&gt; 
louvers on each side of the cowl.&nbsp; So you mileage could vary - but <BR>&gt; 
Tracy has essentially the same size opening as well as several others. <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Ed 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
----- Original Message ----- 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
From: John Downing 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
To: Rotary motors in aircraft 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Sent: Monday, February 26, 2007 12:12 PM 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Subject: [FlyRotary] cowl openings for water radiators <BR>&gt; <BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
What size openings do I need for the water <BR>&gt; radiators?&nbsp;&nbsp; The 
Wittman Tailwind cowl I have has postal slots of <BR>&gt; 3' x 7 3/4" , which 
is&nbsp;&nbsp; approx. 22 1/4 sq in. on each side.&nbsp; Sam <BR>&gt; James for 
the 160 Lycoming is using 4 3/4' round holes which are <BR>&gt; 17.6 sq. inches 
on each side.&nbsp; My radiators are quite close to the <BR>&gt; opening and I 
plan on making the diffusers trumpet shaped, will <BR>&gt; the openings be large 
enough if I can stay over 20 sq. inches on <BR>&gt; each side with a decent 
trumpet shape.&nbsp; JohnD&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; hushpowere II 
<BR>&gt; on order - hope to start in 2 weeks if weather cooperates. <BR>&gt; 
<BR>&gt; <BR>&gt; 
---------------------------------------------------------------- <BR>&gt; 
<BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
-- 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Homepage:&nbsp; http://www.flyrotary.com/ 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Archive and UnSub:&nbsp;&nbsp; <BR>&gt; 
http://mail.lancaironline.net/lists/flyrotary/ <BR>&gt; <BR>&gt; <BR>&gt; 
------------------------------------------------------------------ <BR>&gt; 
<BR>&gt; 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
-- 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Homepage:&nbsp; http://www.flyrotary.com/ 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Archive and UnSub:&nbsp;&nbsp; <BR>&gt; 
http://mail.lancaironline.net/lists/flyrotary/ <BR>&gt; <BR>&gt; <BR>&gt; 
------------------------------------------------------------------- <BR>&gt; --- 
<BR>&gt; <BR>&gt; <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
-- <BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
Homepage:&nbsp; http://www.flyrotary.com/ 
<BR>&gt;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Archive and 
UnSub:&nbsp;&nbsp; <BR>&gt; http://mail.lancaironline.net/lists/flyrotary/ 
<P><PRE>--

Homepage:  http://www.flyrotary.com/

Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/</PRE></BODY></HTML>

------_=_NextPart_001_01C75B72.B55777DA--