X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 10 [X] Return-Path: Sender: To: lml Date: Mon, 05 Feb 2007 14:34:27 -0500 Message-ID: X-Original-Return-Path: Received: from wind.imbris.com ([216.18.130.7] verified) by logan.com (CommuniGate Pro SMTP 5.1.5) with ESMTPS id 1813114 for lml@lancaironline.net; Mon, 05 Feb 2007 13:40:45 -0500 Received-SPF: none receiver=logan.com; client-ip=216.18.130.7; envelope-from=brent@regandesigns.com Received: from [192.168.1.138] (cbl-238-80.conceptcable.com [207.170.238.80] (may be forged)) (authenticated bits=0) by wind.imbris.com (8.12.11/8.12.11.S) with ESMTP id l15IdbVe065963 for ; Mon, 5 Feb 2007 10:39:53 -0800 (PST) (envelope-from brent@regandesigns.com) X-Original-Message-ID: <45C779E8.7040009@regandesigns.com> X-Original-Date: Mon, 05 Feb 2007 10:39:36 -0800 From: Brent Regan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 X-Original-To: Lancair Mailing List Subject: Re: Wing pressure Content-Type: multipart/alternative; boundary="------------040301080101040705020402" This is a multi-part message in MIME format. --------------040301080101040705020402 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Paul Lipps writes: < the effect that creates a low pressure when a jet of fluid is forced to follow a curved surface. >> The force generated in the bent hose is due to the mass of the water inside being accelerated in a new direction, F=MA. It seems Paul is implying that an airplane is suspended in the air by the vertical component of the force used to accelerate the mass of the fluid (air) in a new direction. There is an existing vehicle that relies on this principle, it is called a "rocket". Air density at sea level is 0.076 lbs per cubic foot. If you were flying at 70 Kts (118 Ft/sec) stall at an AOA of 45 degrees (extreme example) and a projected wing / fuselage area of 100 square feet the you would be "intersecting" 11,800 cubic feet per (896 lbs) second. You would need to accelerate ALL that air at 3.35 Gs (107 ft/sec^2) vertically downward in order to produce the required 3000 lbs of force to hold your little plane in the air. This would result in a downward jet of air such that if you were holding short and a heavy landed as you were waiting then you would be buffeted by a ~50 knot blast moments after the landing airplane passed. Forget water hoses and kites, has anyone experienced a downward blast from a landing aircraft? If Paul is right and Bernoulli is wrong, how do you explain the face that the pressure in the center of a venturi is lower than the upstream pressure? Applying Coanda to a carburetor would result in air flowing into the fuel bowl rather than the opposite. Darn those pesky existence proofs. Now where did I put my copy of "Aerodynamics for Dummies"? Extraordinary claims require extraordinary proofs. Oh, the Coanda effect is the tendency of a fluid to attach to a surface and flow along it. This is the result of a pressure change, not the cause of it. From the air's perspective, the wing drags (accelerates) some of the air that comes in close proximity. This causes the static pressure to drop as the kinematic pressure increases. Bernoulli and Coanda walk hand in hand into the sunset.... disturbing image. Regards Brent Regan --------------040301080101040705020402 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Paul Lipps writes:
<<Have you seen the simple math of the force generated by water flowing through a hose when the hose is bent? Well that is how the upper-surface lift occurs. Except in this case, there is no hose bending the stream. That bending takes place because of the Coanda effect <snip> the effect that creates a low pressure when a jet of fluid is forced to follow a curved surface. >>

The force generated in the bent hose is due to the mass of the water inside being accelerated in a new direction, F=MA. It seems Paul is implying that an airplane is suspended in the air by the vertical component of the force used to accelerate the mass of the fluid (air) in a new direction. There is an existing vehicle that relies on this principle, it is called a "rocket".

Air density at sea level is 0.076 lbs per cubic foot. If you were flying at 70 Kts (118 Ft/sec) stall at an AOA of 45 degrees (extreme example) and a projected wing / fuselage area of 100 square feet the you would be "intersecting" 11,800 cubic feet per (896 lbs) second. You would need to accelerate ALL that air at 3.35 Gs (107 ft/sec^2) vertically downward in order to produce the required 3000 lbs of force to hold your little plane in the air. This would result in a downward jet of air such that if you were holding short and a heavy landed as you were waiting then you would be buffeted by a ~50 knot blast moments after the landing airplane passed. Forget water hoses and kites, has anyone experienced a downward blast from a landing aircraft?

If Paul is right and Bernoulli is wrong, how do you explain the face that the pressure in the center of a venturi is lower than the upstream pressure? Applying Coanda to a carburetor would result in air flowing into the fuel bowl rather than the opposite. Darn those pesky existence proofs. Now where did I put my copy of "Aerodynamics for Dummies"?

Extraordinary claims require extraordinary proofs.

Oh, the Coanda effect is the tendency of a fluid to attach to a surface and flow along it. This is the result of a pressure change, not the cause of it. From the air's perspective, the wing drags (accelerates) some of the air that comes in close proximity. This causes the static pressure to drop as the kinematic pressure increases. Bernoulli and Coanda walk hand in hand into the sunset.... disturbing image.

Regards
Brent Regan

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