Return-Path: Received: from [65.33.163.115] (account ) by logan.com (CommuniGate Pro WebUser 4.1b2) with HTTP id 2114239 for ; Fri, 11 Apr 2003 18:58:02 -0400 From: "Marvin Kaye" Subject: Re: [FlyRotary] Re: radiators To: flyrotary X-Mailer: CommuniGate Pro WebUser Interface v.4.1b2 Date: Fri, 11 Apr 2003 18:58:02 -0400 Message-ID: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format="flowed" Content-Transfer-Encoding: 8bit Posted for "Tracy Crook" : Bill Schertz & Frank have already done a good job of explaining this so I'll just add a couple of thoughts to what Frank said. The heating due to pressure recovery is small and is unavoidable. The alternative (no pressure recovery) means no cooling at all so this factor must be ignored in practical systems. The best analysis I've seen on the P51 cooling system showed that it reduced cooling drag to about a 40 HP loss, an astonishingly low value for a 2000 HP aircraft. A net gain (thrust) from the cooling system is a theoretical possibility but still a pipe dream in actual systems. Tracy Crook