Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Fri, 26 Sep 2003 11:23:13 -0400 Message-ID: X-Original-Return-Path: Received: from smtp01.mrf.mail.rcn.net ([207.172.4.60] verified) by logan.com (CommuniGate Pro SMTP 4.1.4) with ESMTP id 2604882 for lml@lancaironline.net; Fri, 26 Sep 2003 10:57:02 -0400 Received: from 208-59-159-157.s411.tnt2.frdb.va.dialup.rcn.com ([208.59.159.157] helo=OFFICE) by smtp01.mrf.mail.rcn.net with smtp (Exim 3.35 #4) id 1A2u1c-0006eA-00 for lml@lancaironline.net; Fri, 26 Sep 2003 10:56:53 -0400 X-Original-Message-ID: <038a01c3843e$773b2730$b89e3bd0@OFFICE> From: "Bill & Sue" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: Gain a couple of knots X-Original-Date: Fri, 26 Sep 2003 10:57:10 -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 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Good discussion Eric, Larry & others. There is one point that I haven't seen mentioned in this whole drag reduction thread though. Yes, the tail plane produces a downward force (necessary for stability) and of course, things can be tweeked to minimize the drag that the tail plane produces. The missing point is that the "weight" of the tail down force must be lifted by the main wing. It is here, in the wing, that you would see the most drag reduction from minimizing tail down force. Moving the CG forward requires more tail down force to balance. The additional tail down force must be lifted by the wing exactly as if it were "real" weight. At a given airspeed and weight, the aircraft with a more forward CG will be flying at a higher angle of attack and producing more induced drag. Conversely, moving the CG aft will reduce the required tail down force, lower the total lift requirement of the wing and allow it to fly at the same airspeed with a lower angle of attack and therefore less induced drag. Remember day one of primary ground school? In unaccelerated flight lift = weight? Ain't so (unless you define "lift" as the net lift of the wing minus the tailplane). Lift, as produced by the wing, is greater than weight by an amount exactly equal to the tail down force. Bill harrelson@erols.com N5ZQ LNC2 O-320 VA42 Fredericksburg, VA