X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 25 Feb 2009 08:11:45 -0500 Message-ID: X-Original-Return-Path: Received: from [64.12.143.101] (HELO imo-m13.mail.aol.com) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTP id 3513373 for lml@lancaironline.net; Tue, 24 Feb 2009 09:24:17 -0500 Received: from VTAILJEFF@aol.com by imo-m13.mx.aol.com (mail_out_v39.1.) id q.c0d.4a586e56 (34991) for ; Tue, 24 Feb 2009 09:24:13 -0500 (EST) Received: from smtprly-da01.mx.aol.com (smtprly-da01.mx.aol.com [205.188.249.144]) by cia-db01.mx.aol.com (v123.3) with ESMTP id MAILCIADB014-5bad49a403063d9; Tue, 24 Feb 2009 09:24:14 -0500 Received: from WEBMAIL-DY08 (webmail-dy08.sim.aol.com [205.188.185.143]) by smtprly-da01.mx.aol.com (v121_r5.5) with ESMTP id MAILSMTPRLYDA014-5bad49a403063d9; Tue, 24 Feb 2009 09:24:06 -0500 References: X-Original-To: lml@lancaironline.net Subject: Re: [LML] Re: FW: 360 in a small-tail LNC2? X-Original-Date: Tue, 24 Feb 2009 09:24:06 -0500 X-AOL-IP: 76.215.111.197 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: vtailjeff@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8CB64A2AF413B76_1C68_44A7_WEBMAIL-DY08.sysops.aol.com" X-Mailer: AOL Webmail 41421-STANDARD Received: from 76.215.111.197 by WEBMAIL-DY08.sysops.aol.com (205.188.185.143) with HTTP (WebMailUI); Tue, 24 Feb 2009 09:24:06 -0500 X-Original-Message-Id: <8CB64A2AF249F86-1C68-219C@WEBMAIL-DY08.sysops.aol.com> X-Spam-Flag:NO ----------MB_8CB64A2AF413B76_1C68_44A7_WEBMAIL-DY08.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii" thanks Chris! -----Original Message----- From: Chris Zavatson To: lml@lancaironline.net Sent: Mon, 23 Feb 2009 5:16 pm Subject: [LML] Re: FW: 360 in a small-tail LNC2? Come on guys, the relative angles of wing and stab (with or w/o elevator deflection) do not drive longitudinal stability.? That angle simply determines the trim airspeed for the configuration.? Note that stick forces should not be confused with stability.? Stick forces can be made light or heavy independent of stability.? Testing of stability is actually done stick free - i.e. no hands on the controls. Driving parameters for static stability are?primarily:? Lengths of the mean aerodynamic chords for the wing and stab, their relative distance to each other, the location of the CG relative to the MAC.? To?actually determine the proper stab angle.? You also need pitching moment data for the airfoil sections, lift slope curves,?your desired trim airspeed, and?the wing down wash angle. Dynamic stability gets a lot more complicated in a hurry.? Items such as aircraft mass moments of inertia are needed. The overall?recipe for best speed is to set the angle of the stab such that no elevator deflection is needed at the target speed.??Set the CG aft until either stability becomes and issue or the tail is flying at zero angle of attack.? Since we have all glued our stabs in place at one angle or another, the drag of counter weights sticking out in the airstream is pitted against trying?to decrease the down force on the tail.? Flap position has a big influence on pitching moment of the section (especially our NLF section) and therefore determines how much work needs to be done by the tail.? ? Chris Zavatson N91CZ??? L360std www.N91CZ.com ? ----------MB_8CB64A2AF413B76_1C68_44A7_WEBMAIL-DY08.sysops.aol.com Content-Transfer-Encoding: 7bit Content-Type: text/html; charset="us-ascii" thanks Chris!


-----Original Message-----
From: Chris Zavatson <chris_zavatson@yahoo.com>
To: lml@lancaironline.net
Sent: Mon, 23 Feb 2009 5:16 pm
Subject: [LML] Re: FW: 360 in a small-tail LNC2?

Come on guys, the relative angles of wing and stab (with or w/o elevator deflection) do not drive longitudinal stability.  That angle simply determines the trim airspeed for the configuration.  Note that stick forces should not be confused with stability.  Stick forces can be made light or heavy independent of stability.  Testing of stability is actually done stick free - i.e. no hands on the controls.
Driving parameters for static stability are primarily:  Lengths of the mean aerodynamic chords for the wing and stab, their relative distance to each other, the location of the CG relative to the MAC.  To actually determine the proper stab angle.  You also need pitching moment data for the airfoil sections, lift slope curves, your desired trim airspeed, and the wing down wash angle.
Dynamic stability gets a lot more complicated in a hurry.  Items such as aircraft mass moments of inertia are needed.
The overall recipe for best speed is to set the angle of the stab such that no elevator deflection is needed at the target speed.  Set the CG aft until either stability becomes and issue or the tail is flying at zero angle of attack.  Since we have all glued our stabs in place at one angle or another, the drag of counter weights sticking out in the airstream is pitted against trying to decrease the down force on the tail.  Flap position has a big influence on pitching moment of the section (especially our NLF section) and therefore determines how much work needs to be done by the tail. 
 
Chris Zavatson
N91CZ   
L360std

 

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