Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Fri, 28 Mar 2003 16:50:31 -0500 Message-ID: X-Original-Return-Path: Received: from [65.54.169.148] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.1b2) with ESMTP id 2090996 for flyrotary@lancaironline.net; Fri, 28 Mar 2003 10:58:00 -0500 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Fri, 28 Mar 2003 07:57:55 -0800 Received: from 65.137.50.129 by bay3-dav118.bay3.hotmail.com with DAV; Fri, 28 Mar 2003 15:57:55 +0000 X-Originating-IP: [65.137.50.129] X-Originating-Email: [lors01@msn.com] Reply-To: "Tracy Crook" From: "Tracy Crook" X-Original-To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Thick vs Thin X-Original-Date: Fri, 28 Mar 2003 10:58:06 -0500 Organization: Real World Solutions Inc. MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit 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-Original-Message-ID: X-OriginalArrivalTime: 28 Mar 2003 15:57:55.0697 (UTC) FILETIME=[CBE11E10:01C2F542] Subject: [FlyRotary] Re: Thick vs Thin > Posted for : > > Good point bill, there are lots of other important factors. But this > disussion is about thick vs thin. Metal, coolant, air , and fin qualities > have to be judged separately. I am assuming these qualities are the same > thick and thin. > > As far as delta T being smaller for thin rads, you miss one of the main points > in the example above. Slow down the air in the thin rad and it collects the > same amount of heat that the thick rad delivers. No matter how thin, slow > down the air enough and the delta T is the same. All factors can be set to > the same - coolant heat loss, delta Tair, mass of intake air, weight of the > radiator etc. The only major differences are speed of the air and thus the > drag of the air through the rad. > > Dave Leonard Didn't introduce this earlier because the discussion is complicated enough without adding more factors. But, this is a major factor and its time has come. The 'drag through the radiator' is caused by a very necessary factor - turbulance. Turbulance is a huge factor in how much heat will be transfered to the air from the fins. Low velocity will result in low heat transfer. Another way of putting it is that generating turbulance through the rad is the very best use of the energy in the high speed air we snagged. The energy not used by moving the air slowly through a thin rad helps in re-accelerating air at the outlet but the disadvantage of requiring a higher volume of air more than offset this small advantage. I'm sure this debate will not be settled until we can have a side by side comparison of the two approaches with all other factors being the same. You guys with the thin rads hurry up and finish your planes so we can have a "fly-off"! Tracy Crook