Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.1.6) with ESMTP id 2706711 for flyrotary@lancaironline.net; Sun, 02 Nov 2003 10:27:12 -0500 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id hA2FQuQU005802 for ; Sun, 2 Nov 2003 10:27:06 -0500 (EST) Message-ID: <000801c3a155$41e62600$1702a8c0@WorkGroup> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: radiator at cowl outlet? Date: Sun, 2 Nov 2003 10:23:16 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0005_01C3A12B.540E6100" 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_0005_01C3A12B.540E6100 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message =20 ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Sunday, November 02, 2003 10:03 AM Subject: [FlyRotary] Re: radiator at cowl outlet? I would think baffling that channels some air over the pipes and turbo = and out the cowling around the radiators would be another solution. =20 Hi Marko. I've been thinking about that option as well. Since the = turbo will account for most of the unwanted heating, it certainly makes = sense to try to duct as much of that heat out of the cowl as possible. = Another thing that I'll add to the new cowl is a small hatch directly = above the turbo. This will be something that can be opened after = shutdown, to allow the heat to escape. =20 Rusty HI Rusty, Been think (always a bad idea in my case) about your concern of = heating the air before the radiator (if installed in the outflow area). = While there is no question there would be some heating by such things as = the turbo, etc. I am not certain that it would significantly effect the = air temperature, particularly in flight. Heres what my rational is based on. A single GM evaporator core that = we use calculates out to having approx 7000 square inches (actually a = bit more) of surface area (fins and tubes) thats approx 48 square feet = of surface area for one core. From whats been reported the air temp = rise through a core is approx 20-30F getting rid of all the coolant = heat the engine needs to have rejected Now you wouldn't want air 30F higher than ambient going into your rear = mounted radiator, but I'll bet if you estimated the surface area of your = turbo and other significant heat generators that you won't come up with = anywhere near 48 square feet. Furthermore if you shield the worst heat = producer (your turbo and exhaust), I would imagine you might find your = air temp not increasing that much before it reaches your radiator. =20 I intitially was concerned about the same type of thing. I felt that = if I ducted the rear of my radiators to my side louvers that would keep = the hot air from "reheating" the engine. Well, it seemd to actually = make matters worst (I suspect the ducts were restricting the expanding = hot air coming out of the radiators). Tracy Crook convinced me that the = additional heat content (as opposed to temperature) blowing over the = engine was insignificant in adding to the heat load. Removed the outlet = ducts and overall cooling improved. So if you do add ducts to get the air from your inlet to the rear, = just try to make certain that the ducts help rather than hurt. No calculations, just a gut feeling which of course could be = incorrect. Ed Anderson ------=_NextPart_000_0005_01C3A12B.540E6100 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
 
 
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Sunday, November 02, 2003 = 10:03=20 AM
Subject: [FlyRotary] Re: = radiator at cowl=20 outlet?

I would=20 think baffling that channels some air over the pipes and turbo and out = the=20 cowling around the radiators would be another solution.  
 
Hi = Marko.  I've been=20 thinking about that option as well.  Since the turbo will = account=20 for most of the unwanted heating, it certainly makes sense = to try to=20 duct as much of that heat out of the cowl as = possible.  Another=20 thing that I'll add to the new cowl is a small hatch directly above = the=20 turbo.  This will be something that can be opened after shutdown, = to=20 allow the heat to = escape.  
 
Rusty
 
HI Rusty,
 
    Been think (always a bad = idea in=20 my case) about your concern of heating the air before the radiator (if = installed in the outflow area).  While there is no question there = would=20 be some heating by such things as the turbo, etc.  I am not = certain that=20 it would significantly effect the air temperature, particularly in=20 flight.
 
Heres what my rational is based on.  A = single GM=20 evaporator core that we use calculates out to having approx 7000 = square inches=20 (actually a bit more) of surface area (fins and tubes) thats = approx =20 48 square feet of surface area for one core.  From whats been = reported=20 the air temp rise  through a core is approx 20-30F getting = rid of=20 all the coolant heat the engine needs to have=20 rejected
 
Now you wouldn't want air 30F higher than = ambient=20 going into your rear mounted radiator, but I'll bet if you estimated = the=20 surface area of your turbo and other significant heat generators that = you=20 won't come up with anywhere near 48 square feet.  Furthermore if = you=20 shield the worst heat producer (your turbo and exhaust), I would = imagine you=20 might find your air temp not increasing that much before it reaches = your=20 radiator. 
 
I intitially was concerned about the same = type of=20 thing.  I felt that if I ducted the rear of my radiators to my = side=20 louvers that would keep the hot air from "reheating" the engine.  = Well,=20 it seemd to actually make matters worst (I suspect the ducts were = restricting=20 the expanding hot air coming out of the radiators).  Tracy Crook=20 convinced me that the additional heat content (as opposed to = temperature)=20 blowing over the engine was insignificant in adding to the heat = load. =20 Removed the outlet ducts and overall cooling=20 improved.
 
So if you do add ducts to get the air from = your inlet=20 to the rear, just try to make certain that the ducts help rather than=20 hurt.
 
No calculations, just a gut feeling which = of course=20 could be incorrect.
 
Ed=20 Anderson
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