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<DIV><FONT face=Arial size=2>Anhedral creates problems only for high yaw rate
manuevers. It is difficult to do an inverted spin - you can't get the nose up.
Proper treatment of the stab tips solves this problem,
however.
Nat</FONT></DIV>
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=jnhiller@earthlink.net href="mailto:jnhiller@earthlink.net">J N
Hiller</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, April 20, 2008 6:20
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] Annhedral
Stab</DIV>
<DIV><BR></DIV>
<DIV class=Section1>
<P class=MsoNormal><SPAN class=EmailStyle20><FONT face=Arial color=navy
size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">Thanks
Matt, as with any other design change it needs to be tried to understand the
effect. I always felt that the bottom running stab in knife-edge or the outer
stab when the fuselage is yawed is more effective than the other side and
dominate. In the old days I was able to balance knife-edge pitch by adjusting
one elevator up and the other down. When an annhedral stab is yawed it becomes
unbalanced resulting in a pitch force change towards the top of the fuselage.
If this were true it should also produce a slight roll with yaw. I will
probably never understand as much about pattern plane design as I would like,
I just try things. It either gets better or it gets worse and this is only one
of many design considerations.<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoNormal><SPAN class=EmailStyle20><FONT face=Arial color=navy
size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">OH
that rolling circle stuff makes my head hurt. An analog processor would
probably help or one about thirty years
younger.<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoNormal><SPAN class=EmailStyle20><FONT face=Arial color=navy
size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt">Jim
<o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoNormal><SPAN class=EmailStyle20><FONT face=Arial color=navy
size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial; mso-bidi-font-size: 12.0pt"><![if !supportEmptyParas]><![endif]> <o:p></o:p></SPAN></FONT></SPAN></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face=Tahoma color=black
size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: black; FONT-FAMILY: Tahoma">-----Original
Message-----<BR><B><SPAN style="FONT-WEIGHT: bold">From:</SPAN></B>
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org]<B><SPAN
style="FONT-WEIGHT: bold">On Behalf Of
</SPAN></B>rcmaster199@aol.com<BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> Sunday, April 20, 2008 12:43
PM<BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B>
nsrca-discussion@lists.nsrca.org<BR><B><SPAN
style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re: [NSRCA-discussion] Annhedral
Stab</SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
size=3><SPAN
style="FONT-SIZE: 12pt"><![if !supportEmptyParas]><![endif]> <o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black">Jim,</SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black"> </SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN style="FONT-SIZE: 12pt; COLOR: black">Most would say
that anhedral stabs are hype......</SPAN></FONT><FONT color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black"> </SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN style="FONT-SIZE: 12pt; COLOR: black">I prefer to
call them a viable option for pattern models and here're my thoughts on
the subject. First off, fundamentally, they don't change how the wing is
stabilized in pitch compared to a flat stab...same physics apply. Anhedral
area however is the resultant of two component areas, horizontal which
dominates and a vertical which adds to the already eixsting vertical
stabilizer area. It may be thought as area added to the ventral side of the
fuse without adding a subfin. This often helps settle some unwanted thrust
vector forces namely the much cussed and discussed dredded pitch to belly with
top rudder. Does it always work as prescribed? Does anything in our sport ever
always work as prescribed?</SPAN></FONT><FONT color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black"> </SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN style="FONT-SIZE: 12pt; COLOR: black">Rolling circles
may be helped with anhedral in the stab. When the anhedral angle is "just
right", there is no region during rotation (X degrees from horizontal)
that completely blanks out the stab as can happen with flat stabs. Does is do
wonders? I don't think so but it certainly does not hurt.</SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black"> </SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN style="FONT-SIZE: 12pt; COLOR: black">My new design
will have anhedral in its stab (7-8 degrees)</SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black"> </SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black">Cheers,</SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black"> </SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black">MattK</SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN style="FONT-SIZE: 12pt; COLOR: black"><![if !supportEmptyParas]><![endif]> </SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN-LEFT: 0.5in"><FONT face="Times New Roman"
color=black size=3><SPAN style="FONT-SIZE: 12pt; COLOR: black"><![if !supportEmptyParas]><![endif]> </SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal
style="MARGIN-BOTTOM: 12pt; MARGIN-LEFT: 0.5in; MARGIN-RIGHT: 0in; mso-margin-top-alt: 0in"><FONT
face="Times New Roman" color=black size=3><SPAN
style="FONT-SIZE: 12pt; COLOR: black">-----Original Message-----<BR>From: J N
Hiller <jnhiller@earthlink.net><BR>To: NSRCA Mailing List
<nsrca-discussion@lists.nsrca.org><BR>Sent: Sun, 20 Apr 2008 2:01
pm<BR>Subject: [NSRCA-discussion] Annhedral Stab</SPAN></FONT><FONT
color=black><SPAN
style="COLOR: black; mso-color-alt: windowtext"><o:p></o:p></SPAN></FONT></P><PRE style="BACKGROUND: white; MARGIN-LEFT: 0.5in"><TT><FONT face="Courier New" color=black size=2><SPAN style="FONT-SIZE: 10pt; COLOR: black">
<DIV id=AOLMsgPart_0_7ded5693-f244-4f19-bc40-e243e69250d4>Can I open a discussion on why some designs have an annhedral stab?<SPAN style="mso-spacerun: yes"> </SPAN>Was it to lower the effective flying height of the stab to reduce the wing<SPAN style="mso-spacerun: yes"> </SPAN>to stab vertical offset and knife edge belly pitch, or is there some other<SPAN style="mso-spacerun: yes"> </SPAN>reason?<SPAN style="mso-spacerun: yes"> </SPAN>Jim Hiller<SPAN style="mso-spacerun: yes"> </SPAN>_______________________________________________<SPAN style="mso-spacerun: yes"> </SPAN>NSRCA-discussion mailing list<SPAN style="mso-spacerun: yes"> </SPAN><A href="mailto:NSRCA-discussion@lists.nsrca.org">NSRCA-discussion@lists.nsrca.org</A><SPAN style="mso-spacerun: yes"> </SPAN><A href="http://lists.nsrca.org/mailman/listinfo/nsrca-discussion" target=_blank>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</A><SPAN style="mso-spacerun: yes"> </SPAN></SPAN></FONT></TT><FONT color=black size=1><SPAN style="FONT-SIZE: 9pt; COLOR: black"><o:p></o:p></SPAN></FONT></DIV></PRE></DIV>
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