X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 29 Sep 2008 13:14:00 -0400 Message-ID: X-Original-Return-Path: Received: from sj-iport-1.cisco.com ([171.71.176.70] verified) by logan.com (CommuniGate Pro SMTP 5.2.8) with ESMTPS id 3191522 for lml@lancaironline.net; Mon, 29 Sep 2008 12:34:51 -0400 Received-SPF: pass receiver=logan.com; client-ip=171.71.176.70; envelope-from=jmacknig@cisco.com X-IronPort-AV: E=Sophos;i="4.33,332,1220227200"; d="scan'208,217";a="84170144" Received: from sj-dkim-3.cisco.com ([171.71.179.195]) by sj-iport-1.cisco.com with ESMTP; 29 Sep 2008 16:34:10 +0000 Received: from sj-core-5.cisco.com (sj-core-5.cisco.com [171.71.177.238]) by sj-dkim-3.cisco.com (8.12.11/8.12.11) with ESMTP id m8TGYAeU004062; Mon, 29 Sep 2008 09:34:10 -0700 Received: from [10.21.77.76] ([10.21.77.76]) by sj-core-5.cisco.com (8.13.8/8.13.8) with ESMTP id m8TGYArN000708; Mon, 29 Sep 2008 16:34:10 GMT X-Original-Message-ID: <48E10381.8040106@cisco.com> X-Original-Date: Mon, 29 Sep 2008 09:34:09 -0700 From: Jim MacKnight Organization: ATG Hardware Engineering User-Agent: Thunderbird 2.0.0.17 (Windows/20080914) MIME-Version: 1.0 X-Original-To: Lancair Mailing List Subject: Re: [LML] Re: Small tail vs. large tail References: In-Reply-To: Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Authentication-Results: sj-dkim-3; header.From=jmacknig@cisco.com; dkim=pass ( sig from cisco.com/sjdkim3002 verified; ); Mine has long engine mount, no header & MkI tail.
Chose the long engine mount to keep CG more forward with trade off of no header tank.
Can stay within 10% of aft CG worst case (2 people [340#], 80# baggage, full fuel [42g])
jim...

Sky2high@aol.com wrote:
Chris,
 
Thanks for the explanation.  I know that there are some 360s using the long engine mount with a small tail.  I wonder if that was to correct a rearward CG issue?  Perhaps such a person could comment on how that arrangement flies.
 
Scott
 
PS - Is there a really skinny flier out there that was aloft with a heavy prop, no baggage and header fuel only?  How was the landing?  Has everyone calculated the minimum pilot weight to stay within the forward CG?
 
In a message dated 9/28/2008 12:16:46 P.M. Central Daylight Time, chris_zavatson@yahoo.com writes:
<<The Mark II tail alone exacerbates flight problems at rearward CGs since it adds such a large rearward moment.  Thus the corollary recommendation that the long engine mount be used to move the CG forward.>>
Scott,
The longer engine mounts serves to move the CG forward.  The increased surface area of the MKII tail moves the neutral point rearward.  The difference between these two defines the static margin.  As the static margin goes to zero, the aircraft becomes neutrally stable.  This means the MKII tail can handle a more rearward CG than the original for the same degree of stability or conversely, has greater pitch stability for the the same CG location.   
Two side notes:  The long engine mount is actually somewhat destabilizing in yaw and pitch due to the added surface area projected out in front of the CG.  The larger tail can also handle a more forward CG since it has more pitch authority at low speeds. 
The added area in the tail simply opens up the available CG range in both directions.  Either tail may be perfectly acceptable as long as each is kept within its individual CG capability.
Chris
 
 
 
Chris Zavatson
N91CZ
360std
 
 

 




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