<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2800.1141" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=arial,helvetica><FONT lang=0 face=Arial size=2
FAMILY="SANSSERIF">Part of the equation that has not been considered is that
some symmetrical surfaces with a thin trailing edge have a dead band that is
avoided either by blunting, changing foil or putting a turbulator
upstream. <FONT face="Times New Roman" size=3>Selig's 8020 was an attempt
to resolved the issue in glider tails. Mark Drela suggested and uses a much more
forward point on his foils I believe as part of this. Dead band is the
equivalent of having a loose steering box in your car where you have to move the
steering wheel a measured distance before you are back at the other side
again. Are you old enough? Gets rid of all that hard work you put in
getting it tight and precise. Now you have the opportunity to chase it around
the sky with precision- not the airplane but the neutral. Nice can
of worms.</FONT></FONT></FONT></DIV>
<DIV><FONT face=arial,helvetica><FONT lang=0 face=Arial size=2
FAMILY="SANSSERIF"><FONT face="Times New Roman"
size=3></FONT></FONT></FONT> </DIV>
<DIV><FONT face=arial,helvetica><FONT lang=0 face=Arial size=2
FAMILY="SANSSERIF"><FONT face="Times New Roman"
size=3>Rick</FONT></FONT></FONT></DIV>
<DIV><FONT face=arial,helvetica><FONT lang=0 face=Arial size=2
FAMILY="SANSSERIF"><FONT face="Times New Roman"
size=3></FONT></FONT></FONT> </DIV>
<DIV><FONT face=arial,helvetica><FONT lang=0 face=Arial size=2
FAMILY="SANSSERIF"><FONT face="Times New Roman" size=3>Richard Hallett
Pittsfield ME USA</FONT></DIV></FONT></FONT></BODY></HTML>