Return-Path: <13brv3@bellsouth.net> Received: from imf19aec.mail.bellsouth.net ([205.152.59.67] verified) by logan.com (CommuniGate Pro SMTP 4.1.5) with ESMTP id 2645114 for flyrotary@lancaironline.net; Tue, 21 Oct 2003 09:47:41 -0400 Received: from rad ([65.80.160.144]) by imf19aec.mail.bellsouth.net (InterMail vM.5.01.05.27 201-253-122-126-127-20021220) with ESMTP id <20031021134738.UYXP1849.imf19aec.mail.bellsouth.net@rad> for ; Tue, 21 Oct 2003 09:47:38 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: temps behind radiator? Date: Tue, 21 Oct 2003 08:47:40 -0500 Message-ID: <007901c397d9$e593c530$6001a8c0@rad> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_007A_01C397AF.FCBDBD30" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 This is a multi-part message in MIME format. ------=_NextPart_000_007A_01C397AF.FCBDBD30 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Rusty, my cooling capacity model indicates that the stock Mazda cooler does not adequately cool at speeds below approx 120 MPH with high power setting (like 150-160HP or above) . Good thing I don't have a stock FC cooler :-) I have a Setrab, with a core about 9.5" x 15" x 2". Since the oil specific heat is only about 1/2 that of water, it requires approx twice the flow rate (based on that difference along) of coolant to bring the same amount of heat to the cooler. Then if the airflow through the oil cooler is impeded in any way (or you are pumping hot air into it) the situation becomes worst. There's not really much we can do about oil flow rate, short of not restricting it. Does the oil typically flow at double the rate of the coolant in the stock configuration? I've never really thought about that, but I can't see how it could. If the oil doesn't flow that much faster than water, and it has half the heat rejection of water, then do we need to size the oil cooler the same as the radiator? I've been amazed at how little radiator I need, compared to how hard it is to cool the oil, so this is starting to make sense. I'm still interested to know how much heat the air picks up when passing through a radiator. I realize that this can vary quite a bit, but I just don't have a feel for how hot the air gets. If it's 80 outside, does the air exit the back of the rad at 90, or 190, or? Someone should really make an instrument with spare temp sensors that we can use to measure these things :-) Cheers, Rusty (EWP's were in LA yesterday) ------=_NextPart_000_007A_01C397AF.FCBDBD30 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
Rusty, my=20 cooling capacity model indicates that the stock Mazda cooler does not = adequately=20 cool at speeds below approx 120 MPH with high power setting (like = 150-160HP or=20 above) . 
 
Good thing I = don't have a=20 stock FC cooler :-)  I have a Setrab, with a core about 9.5" x = 15" x=20 2".
    
Since the oil=20 specific heat is only about 1/2 that of water, it requires approx twice = the flow=20 rate (based on that difference along) of coolant to bring the same = amount of=20 heat to the cooler.   Then if the airflow through the oil = cooler is=20 impeded in any way (or you are pumping hot air into it) the situation = becomes=20 worst. 
 
There's not = really much we=20 can do about oil flow rate, short of not restricting it.  Does the = oil=20 typically flow at double the rate of the coolant in the stock=20 configuration?  I've never really thought about that, but I can't = see how=20 it could. 
 
If the oil doesn't flow that = much faster=20 than water, and it has half the heat rejection of water, then do we need = to size=20 the oil cooler the same as the radiator?  I've been amazed at how = little=20 radiator I need, compared to how hard it is to cool the oil, so this is = starting=20 to make sense. 
 
I'm still = interested to know=20 how much heat the air picks up when passing through a radiator.  I = realize=20 that this can vary quite a bit, but I just don't have a feel for = how hot=20 the air gets.  If it's 80 outside, does the air exit the back of = the rad at=20 90, or 190, or?  Someone should really make an instrument with = spare=20 temp sensors that we can use to measure these things=20 :-)
 
Cheers,
Rusty (EWP's were in LA=20 yesterday)
 
 
 
 
------=_NextPart_000_007A_01C397AF.FCBDBD30--