Return-Path: Received: from fed1rmmtao07.cox.net ([68.230.241.32] verified) by logan.com (CommuniGate Pro SMTP 4.3c3) with ESMTP id 818398 for flyrotary@lancaironline.net; Thu, 24 Mar 2005 02:14:37 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.32; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao07.cox.net (InterMail vM.6.01.04.00 201-2131-118-20041027) with ESMTP id <20050324071346.HURD13104.fed1rmmtao07.cox.net@BigAl> for ; Thu, 24 Mar 2005 02:13:46 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Cooling delta T Date: Wed, 23 Mar 2005 23:14:01 -0800 Message-ID: <000001c53041$0e27e430$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 Al Gietzen wrote: > > The other point is the since the rad inlet is limited to ~210F, we > know that the larger the temperature drop, the lower the average > radiator temp (goes down by half the increase in the delta T), and the > larger the radiator core needed to dissipate the heat; a weight and > space factor. For an inlet air temp of 80F, a coolant temp drop of 50 > degrees needs about 15% more core than a 20 degree drop. Not a big > deal; but something to consider. > Al > Al, with the weight savings of the EWP (about 6lbs), you can add another GM core. In my proposed design, space won't be a factor. But wouldn't I need to then open up for more cooling air, or is that 15% figure with the same air mass? Yes; you would also need more air (=more drag) because of the smaller difference between the air temp and average rad temp. The rough 15% number assumes the same amount of heat rejected. Al