Return-Path: Received: from relay02.roc.ny.frontiernet.net ([66.133.131.35] verified) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2753222 for flyrotary@lancaironline.net; Thu, 20 Nov 2003 10:42:10 -0500 Received: (qmail 1331 invoked from network); 20 Nov 2003 15:42:09 -0000 Received: from unknown (HELO frontiernet.net) ([170.215.97.8]) (envelope-sender ) by relay02.roc.ny.frontiernet.net (FrontierMTA 2.3.6) with SMTP for ; 20 Nov 2003 15:42:09 -0000 Message-ID: <3FBCE0F7.8DA9F93D@frontiernet.net> Date: Thu, 20 Nov 2003 09:42:47 -0600 From: Jim Sower X-Mailer: Mozilla 4.77 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Core vs Radistor was Re: [FlyRotary] radiator References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit NACA duct has to be done right. They're like the little girl with the curl "... when they are good, they are very very good, but ..." You can't make significant (much less radical) departures from the optimum design or you get very bad results. Vortex generators will get back most of the performance of minor excursions from optimum design specs, but don't make large departures from the straight and narrow. At least that's what I've been told ... Jim S. james coffman wrote: > Watch out for naca ducting for cooling. they have a > reputation for not working. Having said that, look at > an article in this months Sport Aviation. I forgot the > plane type, but using the naca duct on an IO-540. It > completely failed in several positions until he added > difusers (sp) in front. Now works fine. There are > pictures. Interesting! Jim Coffman > --- "sqpilot@earthlink" wrote: > > Message