X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 1 [X] Return-Path: Sender: To: lml Date: Thu, 01 Feb 2007 14:56:46 -0500 Message-ID: X-Original-Return-Path: Received: from [66.83.119.58] (HELO lucky.dts.local) by logan.com (CommuniGate Pro SMTP 5.1.5) with ESMTP id 1804809 for lml@lancaironline.net; Thu, 01 Feb 2007 14:48:23 -0500 Received-SPF: none receiver=logan.com; client-ip=66.83.119.58; envelope-from=cjensen@dts9000.com Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C74639.EFB4C912" X-MimeOLE: Produced By Microsoft Exchange V6.5.6944.0 Subject: RE: [LML] Wing positive pressure X-Original-Date: Thu, 1 Feb 2007 14:48:25 -0500 X-Original-Message-ID: <8984A39879F2F5418251CBEEC9C689B33E6A55@lucky.dts.local> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [LML] Wing positive pressure Thread-Index: AcdGMpG0pF3oee7YTgejakuXrGHNuQABLQ+Q From: "Chuck Jensen" X-Original-To: "Lancair Mailing List" This is a multi-part message in MIME format. ------_=_NextPart_001_01C74639.EFB4C912 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Paul Lipps wrote... =20 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! Unless it's not attached properly, as Steve Whitman found out. Suction is not a force; it's a human's subjective misunderstanding of things physical, such as hot and cold. Suction doesn't pull open a canopy in flight; the air in the cockpit pushes it open. Did you know that there are hundreds of pounds of pressure differential on your canopy which makes up a significant part of your aircraft's overall lift force, and slowing down the plane to close a half-latched canopy doesn't make the force go away? Please, if you can't grasp or understand this apparently un-orthodox concept that flies in the face of all you've been taught, lets not do an aerodynamic battle on these posts!=20 =20 So, let's see if I have this right..... the lift on a wing is actually the air inside the wing pushing up on the top skin of the wing (in excess of the air pushing down on the lower skin of the wing)---that is what is causing the lift. If that is so, then if we take a air tight container in the shape of a wing/airfoil, evacuate the air out of it, and position it in an airstream, that it will not generate lift because there is no air inside to push against the top skin? Mmmmmm, very interesting proposition. I'm not a betting man--usually--but I have a twenty that I'd risk! =20 Chuck ------_=_NextPart_001_01C74639.EFB4C912 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
Paul Lipps wrote...
 
 A=20 strongly held concept is that the bottom of a wing has positive pressure = and the=20 top of the wing has reduced pressure, and this is where lift comes from. = Any=20 wing with curvature on the bottom, such as the NLF1 0215F on Lancair 235,320,360 has reduced = pressure both=20 on the top and on the bottom; its just that the reduced pressure on = top is=20 lower than on the bottom, so the there is a net upward force. Since lift = is a=20 force due to a pressure difference across a surface, it may come as = a shock=20 to most of you that the pressure difference is across the top skin and = the=20 bottom skin. That's right, Ladies and germs, lift on a hollow wing is = due to the=20 air inside pushing up on the top skin = and=20 pushing down on the bottom skin, but the top skin wins, hopefully! = Unless it's=20 not attached properly, as Steve Whitman found out. Suction is not a = force; it's=20 a human's subjective misunderstanding of things physical, such as hot = and cold.=20 Suction doesn't pull open a canopy in flight; the air in the cockpit = pushes it=20 open. Did you know that there are hundreds of pounds of pressure = differential on=20 your canopy which makes up a significant part of your aircraft's overall = lift=20 force, and slowing down the plane to close a half-latched canopy doesn't = make=20 the force go away? Please, if you can't grasp or understand = this=20 apparently un-orthodox concept that flies in the face of all you've = been=20 taught, lets not do an aerodynamic battle on these posts! 
 
So,=20 let's see if I have this right..... the lift on a wing is = actually the air inside the wing pushing up on the top skin of the = wing (in=20 excess of the air pushing down on the lower skin of the wing)---that is = what is=20 causing the lift.  If that is so, then if we take a air tight=20 container in the shape of a wing/airfoil, evacuate the air out of it, = and=20 position it in an airstream, that it will not generate lift because = there is no=20 air inside to push against the top skin?   Mmmmmm, very = interesting=20 proposition.  I'm not a betting man--usually--but I have a = twenty that=20 I'd risk!
 
Chuck
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