Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Thu, 10 Apr 2003 19:00:20 -0400 Message-ID: X-Original-Return-Path: Received: from web41302.mail.yahoo.com ([66.218.93.51] verified) by logan.com (CommuniGate Pro SMTP 4.1b2) with SMTP id 2112624 for flyrotary@lancaironline.net; Thu, 10 Apr 2003 11:09:36 -0400 X-Original-Message-ID: <20030410150933.41692.qmail@web41302.mail.yahoo.com> Received: from [67.40.183.229] by web41302.mail.yahoo.com via HTTP; Thu, 10 Apr 2003 08:09:33 PDT X-Original-Date: Thu, 10 Apr 2003 08:09:33 -0700 (PDT) From: John Overman Subject: Re: [FlyRotary] Re: radiators X-Original-To: Rotary motors in aircraft In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii > > Tracy has argued that all your cooling air comes in > at 200mph, then has to > slow down to almost 0mph to go through the radiator, > then accelerate back > to 200mph again. All that work being done on the air > costs you -- it's > drag. So he says that you want to put the minimum > amount of air through the > radiator. > > I don't know whether its significant or not, but a > couple of secondary > effects occur to me... > > 1. If the air at the radiator is compressed, it will > be able to carry more > heat away per cubic metre. So you want to maximise > the air pressure at the > radiator. But compressing air heats it. > > 2. Heating the air as it comes through the radiator > will cause it to > expand, and therefore produce thrust, which might be > useful in accelerating > the air back up to the 200mph exit speed. I vaguely > recall that the P51's > cooling system produced some thrust. > > Frank. > > Don't forget that as the air is heated it also expands and becomes less dense and therefore has less capacity to transfer the heat from the water. John __________________________________________________ Do you Yahoo!? Yahoo! Tax Center - File online, calculators, forms, and more http://tax.yahoo.com