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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>If a counter balance is a “trick”
Then full scale aerodynamic/structure engineers have been doing a poor job for
years! I would say it is a cure not a patch or trick. If you need to stiffen
your structure and or control system you will most likely add weight to the aft
end of the airplane. If you “spend” the same weight to add mass
ahead of the hinge line and the same effort aft of the hinge line to remove weight
you make flutter impossible regardless of your stiff control system or lack of
it. Dick Hanson proved this long ago. He also showed less stress on servos and a
lighter plane overall. If an ounce or two on a under weight pattern ship cost
the airframe and gear with in it, it is a rather false economy. If you
eliminate the possibility of divergence via surface balance you will not have flutter
occur. If you have a component fail in a stiff ( but unbalanced) system
and the surface gets “loose” then you have the flutter get you…if
its balanced it can’t. Of course none of us have any thing fail on
us do we :>) <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Regards<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Bill <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'> <st1:PersonName
w:st="on">discussion-request@nsrca.org</st1:PersonName> [mailto:<st1:PersonName
w:st="on">discussion-request@nsrca.org</st1:PersonName>] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Gray E Fowler<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, April 28, 2005
10:09 AM<br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on">discussion@nsrca.org</st1:PersonName><br>
<b><span style='font-weight:bold'>Subject:</span></b> RE: Rudder counterbalance
?</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><br>
</span></font><font size=2 face="Courier New"><span style='font-size:10.0pt;
font-family:"Courier New"'>"Why not mass balance for flutter elimination.
When most full scale aircraft<br>
get painted they have to check balance of the surface ( ie Piper<br>
Cherokee's). <br>
<br>
Bill "</span></font> <br>
<br>
<br>
<font size=2 face=sans-serif><span style='font-size:10.0pt;font-family:sans-serif'>Because
most spend hundreds of dollars removing ounces of weight.</span></font> <br>
<br>
<font size=2 face=sans-serif><span style='font-size:10.0pt;font-family:sans-serif'>Flutter
is natural frequency-speed driven. If you have flutter it is usually an
indication of a serious stiffness problem, either in the set up or the
structure itself. Instead of counter balances and otehr tricks, just increase
the stiffness. That will be the biggest bang for the weight buck.<br>
<br>
<br>
<br>
Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</span></font><o:p></o:p></p>
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