Return-Path: Received: from [65.33.162.59] (account marv@lancaironline.net) by logan.com (CommuniGate Pro WebUser 4.2b8) with HTTP id 322554 for flyrotary@lancaironline.net; Thu, 15 Jul 2004 11:49:19 -0400 From: "Marvin Kaye" Subject: Re: [FlyRotary] Re: New Scoop To: "Rotary motors in aircraft" X-Mailer: CommuniGate Pro WebUser Interface v.4.2b8 Date: Thu, 15 Jul 2004 11:49:19 -0400 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format="flowed" Content-Transfer-Encoding: 8bit "Al Gietzen" : """ Typically we would like the radiator area to at least 3-4 times the inlet area to slow the air to recover pressure and reduce drop across the core. We'd then like to accelerate the air again before it exits; at something near the free-stream velocity. Because of other losses, like sudden expansions at rad exit, or whatever; we don't have good enough conservation of energy to get back up to full speed, so we need exit area greater than 1.12 time the inlet. A rough rule of thumb might be a ratio of about 1.5. And, of course, be sure to include all the inlet and outlet areas. """ When I was building the cowl for the Eagle540 I was a bit concerned about intake area vs outlet area. We've got 2 scoops (small one above the prop for the third intercooler and a large one below for the 3 oil coolers) and 2 large NACA ducts (for the primary intercoolers) feeding air into the cowling. The only outlets were the areas surrounding the exhaust stacks, and calculations said we had a 1:1 inlet/outlet area. This concerned me greatly, as the number I remembered as optimal for that ratio was 1:1.7... please don't ask me where I remembered it from, as I'm not sure... although I suspect it's from early discussions with Fred Moreno. Anyway, we added louvers to both sides of the cowl to get up to that ratio. We should be flying within the month, I'll let you know if the cooling is up to snuff. FWIW.