X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Received: from [68.202.132.19] (account marv@lancaironline.net) by logan.com (CommuniGate Pro WEBUSER 5.1.5) with HTTP id 1804859 for lml@lancaironline.net; Thu, 01 Feb 2007 15:05:13 -0500 From: "Marvin Kaye" Subject: Re: [LML] Wing positive pressure To: "Lancair Mailing List" X-Mailer: CommuniGate Pro WebUser v5.1.5 Date: Thu, 01 Feb 2007 15:05:13 -0500 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain;charset="iso-8859-1";format="flowed" Content-Transfer-Encoding: 8bit Far be it from me to take an opposing position, but how does this concept explain the operation of a propeller where we can consider the thrust it creates as simply lift in the horizontal plane? I know I've got to be missing something here. "Paul Lipps" wrote: """ A strongly held concept is that the bottom of a wing has positive pressure and the top of the wing has reduced pressure, and this is where lift comes from. Any wing with curvature on the bottom, such as the NLF1 0215F on Lancair 235,320,360 has reduced pressure both on the top and on the bottom; its just that the reduced pressure on top is lower than on the bottom, so the there is a net upward force. Since lift is a force due to a pressure difference across a surface, it may come as a shock to most of you that the pressure difference is across the top skin and the bottom skin. That's right, Ladies and germs, lift on a hollow wing is due to the air inside pushing up on the top skin and pushing down on the bottom skin, but the top skin wins, hopefully! """