X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 16 Jul 2010 12:28:21 -0400 Message-ID: X-Original-Return-Path: Received: from hrndva-omtalb.mail.rr.com ([71.74.56.124] verified) by logan.com (CommuniGate Pro SMTP 5.3.8) with ESMTP id 4395521 for lml@lancaironline.net; Fri, 16 Jul 2010 11:30:32 -0400 Received-SPF: none receiver=logan.com; client-ip=71.74.56.124; envelope-from=Wolfgang@MiCom.net X-Original-Return-Path: X-Authority-Analysis: v=1.1 cv=Wd4F0Mu8V05kqqt67pyjJbbzQCzSsR+BbLtAgo88TiY= c=1 sm=0 a=QYLDXIQEIe4A:10 a=0qYQvVkOOIcA:10 a=MHZY6FYWMEQOp7S43i2QIw==:17 a=CjxXgO3LAAAA:8 a=Ia-xEzejAAAA:8 a=ndVRne3UAAAA:8 a=158TOEoEP4W5igIE564A:9 a=BUKwygvP-KODFNswHkEA:7 a=EXc2vpaa65ZWKsGRDfWgMvLxfVwA:4 a=wPNLvfGTeEIA:10 a=rC2wZJ5BpNYA:10 a=EzXvWhQp4_cA:10 a=PXfdplBk1JVtYvAu:21 a=UgHsHkUW4-TpufiQ:21 a=NIOBAoonrgqsll6a0rsA:9 a=3xEAv4I79HNOQaG4iaUA:7 a=eC8pnMfAmQ0whOmVEPw5BV3ruGgA:4 a=MHZY6FYWMEQOp7S43i2QIw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.218.201.50 Received: from [74.218.201.50] ([74.218.201.50:1371] helo=Lobo) by hrndva-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id 98/8D-25499-4FA704C4; Fri, 16 Jul 2010 15:29:56 +0000 X-Original-Message-ID: <004d01cb24fb$b9abb3e0$6401a8c0@Lobo> From: "Wolfgang" X-Original-To: Subject: Re: [LML] Re: Small tail, MK II tail, CG range X-Original-Date: Fri, 16 Jul 2010 11:29:47 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_004A_01CB24DA.3259AF80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_004A_01CB24DA.3259AF80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable CG location and stability is what it's all about. The CG is a physical = space within which the designer wants you to stay. But little if = anything is divulged about where that space's definition came from. Saying the CG is 15% to 30% of the MAC is interesting but not conclusive = without some assumptions of what the C in MAC stands for. If a reference is given to a percent of MAC where C =3D Chord, then all = is well and easily determined. However if C is intended to be Center = then all bets are off without being given the location of that point by = the aircraft designer. The Mean Aerodynamic Chord is a geometric calculation and is not = influenced by flight forces. The Mean Aerodynamic Center of a wing is a point on the wing chord which = results in a constant moment when the wing angle of attack is changed. = If the cg is at the ac, the forces on the tail will be minimized. Now keep in mind that MAC (chord) will give, well gee, the chord of the = wing and then saying the CG is a % of MAC actually means something but = using MAC (center) fails to give a usable reference for the purposes of = CG determination. So . . . I think we have to assume we're talking about MAC where C =3D = chord Wolfgang -------------------------------------------------------------------------= ------- From: Chris Zavatson =20 Sender: =20 Subject: Re: [LML] Re: Small tail, MK II tail, CG = range=20 Date: Fri, 16 Jul 2010 05:57:11 -0400=20 To: lml@lancaironline.net=20 =20 =20 There appear to be different definitions for MAC out there. I am = more familiar with MAC being used for "mean aerodynamic center". I = suppose MAC could also refer to "mean aerodynamic chord", as you point = out. My text on stability and control (Etkin) uses =AFc (with the bar = over the c) for "mean aerodynamic chord". It is easy to tell which = definition is meant in diagrams or equations. It is definitely not as = clear in textual form. I suppose it is best to spell out the intended = definition. Chris Zavatson N91CZ 360std www.N91CZ.com=20 ------=_NextPart_000_004A_01CB24DA.3259AF80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
CG location and stability is what it's = all about.=20 The CG is a physical space within which the designer wants you to stay. = But=20 little if anything is divulged about where that space's definition came=20 from.
 
Saying the CG is 15% to 30% of the MAC is = interesting but=20 not conclusive without some assumptions of what the C in MAC stands=20 for.
 
If a reference is given to a percent of = MAC where C=20 =3D Chord, then all is well and easily determined. However if C is = intended to be=20 Center then all bets are off without being given the location of that = point by=20 the aircraft designer.
 
The Mean Aerodynamic = Chord is a=20 geometric calculation and is not influenced by flight forces.

The = Mean=20 Aerodynamic Center of a wing is a point on the = wing chord=20 which results in a constant moment when the wing angle of attack is = changed. If=20 the cg is at the ac, the forces on the tail will be = minimized.

Now keep=20 in mind that MAC (chord) will give, well gee, the chord of the wing and = then=20 saying the CG is a % of MAC actually means something but using MAC = (center)=20 fails to give a usable reference for the purposes of CG=20 determination.
 
So . . . I think we have to assume we're talking = about MAC=20 where C =3D chord
 
Wolfgang
lml@lancaironline.net
From: Chris Zavatson=20 <chris_zavatson@yahoo.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Small tail, MK = II tail,=20 CG range
Date: Fri, 16 Jul 2010 05:57:11 = -0400
To:
There appear to be different = definitions=20 for MAC out there.  I am more familiar with MAC being used=20 for "mean aerodynamic center".  I suppose MAC could=20 also refer to "mean aerodynamic chord", as you point = out. =20 My text on stability and control (Etkin) uses =AFc = (with the=20 bar over the c) for "mean aerodynamic chord".  It is easy to = tell=20 which definition is meant in diagrams or equations.  It = is=20 definitely not as clear in textual form.  I suppose it is = best to=20 spell out the intended definition.
 
Chris Zavatson
N91CZ
360std
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