Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2891565 for flyrotary@lancaironline.net; Mon, 15 Dec 2003 09:24:21 -0500 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-03-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id hBFEO9ow019987 for ; Mon, 15 Dec 2003 09:24:11 -0500 (EST) Message-ID: <000b01c3c316$af7ff000$1702a8c0@WorkGroup> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: evap core versus radiator Date: Mon, 15 Dec 2003 09:21:09 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0008_01C3C2EC.C64E5A80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0008_01C3C2EC.C64E5A80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I agree with Al, Evaporator cores are not designed for the flow of = water. Its hard to beat a custom built exchanger provided it is well = designed for the proper conditions. On the other hand for $5-$15 from = your local junk yard and a few more $ for welding/brazing on fittings = the evaporator cores are hard to beat cost effective wise compared to = what you might spend for a custom radiator. Several folks have done flow = tests that indicate while they do drop a bit more pressure than a car = type radiator normally would, that they still permit plenty of coolant = flow. I fly with two in series and have more than adquate cooling for most = regimes of flight. A steep full power climbout on a hot day will push = the system to its limits, but otherwise they work just fine for the = power an NA 13B is likely to produce. Now if you are going turbo or = otherwise intend to produce over 200HP for extended periods (perhaps = using the 2.85 redrive and running 7000 rpm) or going with a 3 rotor, = then you need to carefully analyze your cooling needs and indeed the = cores may not be up to the job. So if you want the utlimate in a taylored designed cooling system and = feel it is needed then a custom radiator by a reputuably (meaning they = understand cooling) builder is the way to go. On the other hand, there = are enough aircraft flying with the evaportor cores to show that they = will normally do the job for your typical NA 13B installation. Ed Anderson Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Monday, December 15, 2003 1:37 AM Subject: [FlyRotary] Re: evap core versus radiator Be aware that AC evaporators are designed for much lower flow rate of = a completely different fluid. It is fortunate that some cores make = relatively effective coolant radiators. But before using one you (or = someone) should check the pressure drop with the fluid we use; either = water of or 50/50 water/EG, at the flow rate you need. Be particular = careful about connecting 2 units in series. A 5/8" dia provides only about 1/3 sq in of x-sectional area for flow. = On a 2-rotor you'll want flow capability of at least 25 gpm. In a 5/8 = dia opening this is a flow velocity of about 25 ft/sec. That is high, = and results in significant pressure drop. The pressure drop in an AC = core can also be high depending on the design. =20 Connecting 2 of these in parallel can work, a la Tracy Crook et. al. = Putting all the flow through one (and one that no one has tried before), = or two in series is not a good idea, certainly not without doing some = flow testing first. Go to Griffin, or other custom radiator vendor with your heat load, = coolant and air flow rates, and configuration constraints and have them = quote you a radiator. =20 Just my opinion, of course. Al Subject: [FlyRotary] Re: evap core versus radiator Tracy and I are using 5/8" inlets and 3/4" outlets. 4 1/2" is about 1" thicker than what we use. Finn sqpilot@earthlink wrote: Hi, fellow rotary enthusiasts.....I am confused regarding radiator = versus evaporator cores. Ed Klepeis can make a radiator for me that = measures overall 16 x 10 x 4 1/2, by sandwiching two 2 1/4" thick cores = together. Unfortunately, there are two 2" wide tanks on each end, which = reduces the cooling fin area to 12" x 10" x 4 1/2". I calculate that to = a total area of around 540. I have found an evap. core that measures 9 x 13 1/2 x 4 5/8" = thick. I believe that comes out to a total area of around 561. That = would fit perfectly in the cowling with even less modifications to = inlets, etc. (Read that as less work for me). I have heard on this = forum that evap. cores are a good choice for cooling, as they can take = high pressures. Is there anything else I should consider regarding = radiator versus evap core for cooling? Inlet and outlet tubes look to be = around 5/8". The core looks just like one from a GM Safari or Astro Van = except for the size difference. I don't know if the 5/8" inlet/outlet = tubes would be too restrictive to flow compared to a radiator that would = be made with 1" NPT inlet/outlets? My guess is that once the water gets = inside either the evap core or the radiator, flow is going to be = restricted by the tubing sizes inside the cooling device regardless of = the inlet/outlet sizes? I know that Ed Anderson, Tracy and others have = had success with evap cores. Any possible pros and cons would be much = appreciated. Thank you for your time and opinions. Paul Conner ------=_NextPart_000_0008_01C3C2EC.C64E5A80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I agree with Al, Evaporator cores are = not designed=20 for the flow of water. Its hard to beat a custom built exchanger = provided=20 it is well designed for the proper conditions.  On the other hand = for=20 $5-$15 from your local junk yard and a few more $ for welding/brazing on = fittings the evaporator cores are hard to beat cost effective wise = compared=20 to what you might spend for a custom radiator. Several folks have done = flow=20 tests that indicate while they do drop a bit more pressure than a car = type=20 radiator normally would, that they still permit plenty of coolant=20 flow.
 
I fly with two in series and have more = than adquate=20 cooling for most regimes of flight.  A steep full power climbout on = a hot=20 day will push the system to its limits, but otherwise they work just = fine=20 for the power an NA 13B is likely to produce.  Now if you are = going=20 turbo or otherwise intend to produce over 200HP for extended periods = (perhaps=20 using the 2.85 redrive and running 7000 rpm) or going with a 3 rotor, = then you=20 need to carefully analyze your cooling needs and indeed the cores may = not be up=20 to the job.
 
 So if you want the utlimate in a = taylored=20 designed cooling system and feel it is needed then a custom radiator by = a=20 reputuably (meaning they understand cooling) builder is the way to go. = On the=20 other hand, there are enough aircraft flying with the evaportor cores to = show=20 that they will normally do the job for your typical NA 13B=20 installation.
 
Ed Anderson
 
 
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
From:=20 Al = Gietzen=20
Sent: Monday, December 15, 2003 = 1:37=20 AM
Subject: [FlyRotary] Re: evap = core versus=20 radiator

Be = aware that=20 AC evaporators are designed for much lower flow rate of a completely = different=20 fluid.  It is fortunate that some cores make relatively effective = coolant=20 radiators.  But before using one you (or someone) should check = the=20 pressure drop with the fluid we use; either water of or 50/50 = water/EG, at the=20 flow rate you need.  Be particular careful about connecting 2 = units in=20 series.

 

A = 5/8=94 dia=20 provides only about 1/3 sq in of x-sectional area for flow.  On a = 2-rotor=20 you=92ll want flow capability of at least 25 gpm.  In a 5/8 dia = opening=20 this is a flow velocity of about 25 ft/sec.  That is high, and = results in=20 significant pressure drop.  The pressure drop in an AC core can = also be=20 high depending on the design. 

 

Connecting 2=20 of these in parallel can work, a la Tracy=20 Crook = et.=20 al.  Putting all the flow through one (and one that no one has = tried=20 before), or two in series is not a good idea, certainly not without = doing some=20 flow testing first.

 

Go = to=20 Griffin, = or other=20 custom radiator vendor with your heat load, coolant and air flow = rates, and=20 configuration constraints and have them quote you a radiator. =20

 

Just my=20 opinion, of course.

 

Al

 

Subject: = [FlyRotary]=20 Re: evap core versus radiator

 

Tracy and I are = using 5/8"=20 inlets and 3/4" outlets.
4 1/2" is about 1" thicker than what we=20 use.

Finn

sqpilot@earthlink = wrote:

Hi, = fellow rotary=20 enthusiasts.....I am confused regarding radiator versus evaporator = cores. Ed=20 Klepeis can make a radiator for me that measures overall 16 x 10 x 4 = 1/2, by=20 sandwiching two 2 1/4" thick cores together. Unfortunately, there are = two 2"=20 wide tanks on each end, which reduces the cooling fin area to 12" = x 10" x=20 4 1/2".  I calculate that to a total area of around=20 540.

     = I have=20 found an evap. core that measures 9 x 13 1/2 x 4 5/8" thick. I = believe=20 that comes out to a total area of around 561. That would fit = perfectly=20 in the cowling with even less modifications to inlets, etc. (Read = that as=20 less work for me).  I have heard on this forum that evap. cores = are a=20 good choice for cooling, as they can take high pressures.  Is = there=20 anything else I should consider regarding radiator versus evap = core for=20 cooling? Inlet and outlet tubes look to be around 5/8". The core looks = just=20 like one from a GM Safari or Astro Van except for the size=20 difference.  I don't know if the 5/8" inlet/outlet tubes would be = too=20 restrictive to flow compared to a radiator that would be made with 1" = NPT=20 inlet/outlets?  My guess is that once the water gets inside = either the=20 evap core or the radiator, flow is going to be restricted by the = tubing=20 sizes inside the cooling device  regardless of the inlet/outlet=20 sizes? I know that Ed Anderson, = Tracy and=20 others have had success with evap cores.  Any possible pros and = cons=20 would be much appreciated.  Thank you for your time and = opinions. =20 Paul Conner

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