X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0.4) with ESMTP id 888034 for flyrotary@lancaironline.net; Mon, 19 Dec 2005 08:28:34 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id jBJDRh4p016419 for ; Mon, 19 Dec 2005 08:27:43 -0500 (EST) Message-ID: <001301c6049f$fea47620$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Heat exchangers. Date: Mon, 19 Dec 2005 08:27:43 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0010_01C60476.156A5520" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0010_01C60476.156A5520 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Monty, a word of caution even on the GM cores. It appears that there = are considerable changes in recent years to the cores with multi pass = cores and diverters. Back many years ago there was a article in = CONTACT! mag about the difference between the GM and FORD cores with the = conclusion that the much smaller cross channels of the Ford core made it = too restrictive. However, someone on this list did a flow test and = found that the Ford core he used actually flowed more than the GM core. = So take it for what its worth. I think Steve Brooks found a diverter in = his core that impeded cooling flow. He stuck a probe down the tank = opening and found it would only go several inches. The thickness GM cores I have seen were around 3 1/2" most between 3 1/4 = - 3 3/8" thick. with 11 inches between tanks. There are smaller cores = (smaller GM cars) but all seem to have about the same thickness. Ed A ----- Original Message -----=20 From: Monty Roberts=20 To: Rotary motors in aircraft=20 Sent: Sunday, December 18, 2005 11:22 PM Subject: [FlyRotary] Heat exchangers. Monty here is my back of the envelope calculations. If you are = going to produce apporx 220HP steady State at cruise (which I assume you = are if cruising at 250MPH) then you will need to dump close to 10,000 = BTU /Min waste heat via radiators and oil coolers. My calculations = indicates that at 250 MPH cruise you will should have no problem getting = rid of that much heat with that dynamic pressure and core area(assuming = your ducts are doing their job). However, my calculations also indicate you may have to hit as much = as 150-160 MPH before your cooling is able to keep up with the heat = rejection. So don't know how long it will take you get to that speed = from take off, but better carry a bit of spray bar water. Of course, = you could pull back on the throttle and ease the heat load in a slower = climb to cruise altitude. Ed A Thanks Ed, You are the Ed I was after sorry for the confusion Ed K. I also was = not very clear about the number of heat exchangers. There would be 1 = 12X12X4 in block in each wing. We agree on the heat flow, my calcs were = somewhere around 10800 BTU/min at full tilt. 150-160 mph is fine for = climb. How long to get to that speed? Something that weighs less than = 2000 lbs and has 250 Hp gets there....quick.=20 Looks like the Ford cores will not work. I cut the end tank off one of = them this evening. It has a lot of internal baffles and is a 3 pass = design. It would probably be way too restrictive if used as a radiator. = IF not for the baffles they would be great. It is actually a much better = design for an EVAPORATOR than the GM units. Why did Ford have to pick = this particular thing to make better than GM. Just to pick on me I = guess. Anybody seen any GM cores that are 4 in thick with 9 inches between = tanks? Monty ------=_NextPart_000_0010_01C60476.156A5520 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Monty, a word of caution even on the GM = cores.  It=20 appears that there are considerable changes in recent years to the cores = with=20 multi pass cores and diverters.  Back many years ago there was = a=20 article in CONTACT! mag about the difference between the GM and FORD = cores with=20 the conclusion that the much smaller cross channels of the Ford core = made it too=20 restrictive.  However, someone on this list did  a flow test = and found=20 that the Ford core he used actually flowed more than the GM core.  = So take=20 it for what its worth.  I think Steve Brooks found a diverter in = his core=20 that impeded cooling flow.  He stuck a probe down the tank opening = and=20 found it would only go several inches.
 
The thickness GM cores I have seen were around 3 = 1/2" most=20 between 3 1/4 - 3 3/8" thick. with 11 inches between tanks.  There = are=20 smaller cores (smaller GM cars) but all seem to have about the same=20 thickness.
 
Ed A
----- Original Message -----
From:=20 Monty=20 Roberts
Sent: Sunday, December 18, 2005 = 11:22=20 PM
Subject: [FlyRotary] Heat=20 exchangers.

Monty here is my back = of the=20 envelope calculations.    If you are going to produce apporx = 220HP=20 steady State at cruise (which I assume you are if cruising at 250MPH) = then you=20 will need to dump close to 10,000 BTU /Min waste heat via radiators = and oil=20 coolers.  My calculations indicates that at 250 MPH cruise you = will=20 should have no problem getting rid of that much heat with that dynamic = pressure and core area(assuming your ducts are doing their=20  job).
 
  However, my = calculations=20 also indicate you may have to hit as much as 150-160 MPH before your = cooling=20 is able to keep up with the heat rejection.  So don't know how = long it=20 will take you get to that speed from take off, but better carry =  a bit of=20 spray bar water.  Of course, you could pull back on the throttle = and ease=20 the heat load in a slower climb to cruise altitude.
 
Ed A
 
Thanks Ed,
 
You are the Ed I was after sorry for = the=20 confusion Ed K.  I also was not very clear about the number of = heat=20 exchangers. There would be 1 12X12X4 in block in each wing. We agree = on the=20 heat flow, my calcs were somewhere around 10800 BTU/min at full = tilt.=20 150-160 mph is fine for climb. How long to get to that = speed?=20 Something that weighs less than 2000 lbs and has 250 Hp gets=20 there....quick. 
 
Looks like the Ford cores will not = work. I cut=20 the end tank off one of them this evening. It has a lot of internal = baffles=20 and is a 3 pass design. It would probably be way too restrictive if = used as a=20 radiator. IF not for the baffles they would be great. It is actually a = much=20 better design for an EVAPORATOR than the GM units. Why did Ford have = to pick=20 this particular thing to make better than GM. Just to pick on me I=20 guess.
 
Anybody seen any GM cores that are 4 = in thick=20 with 9 inches between tanks?
 
Monty
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