Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2) with ESMTP id 352019 for flyrotary@lancaironline.net; Wed, 04 Aug 2004 12:45:55 -0400 Received-SPF: none receiver=logan.com; client-ip=24.25.9.100; envelope-from=eanderson@carolina.rr.com Received: from EDWARD (cpe-069-132-183-211.carolina.rr.com [69.132.183.211]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id i74GjMPg024182 for ; Wed, 4 Aug 2004 12:45:23 -0400 (EDT) Message-ID: <000601c47a42$6f79f3f0$2402a8c0@EDWARD> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: May not work above 8000 MSL was [FlyRotary] Date: Wed, 4 Aug 2004 12:45:22 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 X-Virus-Scanned: Symantec AntiVirus Scan Engine SNIP > > > I hear what you're sayin', but I really don't think so. How much pressure does it take to make hot oil flow through a short length of tube (or a port in the pump) at a VERY low flow rate? Very little. We're talking a few cc/min; and I'd guess even a couple of psi, would do the job nicely. And at 8000 ft we still have; what, about 11 psi. > > > > > > > > > > > > As we go to higher altitudes it is probably more likely that we'd get vapor lock upstream from the fuel pump before we stop getting oil from the metering pump. > > > > > > > > > > > > This is just off the top of my head, so, you know, maybe there is something I overlooked. The question is: what phenomenon was Atkins observing? He obviously had some reason for his statement. > > > > > > > > > > > > Al > What about the vacuum of the rotors drawing the oil into the chambers? That happens at any altitude. > Marc Wiese > You are correct, Marc. However, while the pressure differential created by the rotors may assist in getting the oil from the "injector" into the combustion chamber, I am not certain that it would affect the flow of oil from the Oil pump metering boss into the pump chamber. The oil metering pump being a positive_displacement pump is going to pump whatever oil flows into its chamber. The issue is whether the drop in ambient pressure at altitude will cause the oil flow from the front housing boss into the pump chamber to drop below some critical level. If the rotor chamber lower pressure IS "felt" throught the oil injector, its line and the pump chamber to the pump boss then it would indeed "assist" in the oil flow and signficicantly reduce or eliminate any "Altitude" effect. Ed Anderson > >> Homepage: http://www.flyrotary.com/ > >> Archive: http://lancaironline.net/lists/flyrotary/List.html