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<DIV><FONT face=Arial>You all are so fast on this stuff that by the time I read
the post the thread is old.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Ackerman exists if the rudder has control horns (as
opposed to a wheel, which is very hard to build into a rudder). The only
ideal way to have constant tension is to use a symmetrical servo arm that is
offset from its pivot (servo screw) the same amount as the rudder control horn
attachment point. This will work every time and is simple, however with a
1" thick rudder post and two 3/4" control horns you will need a 2.5" servo arm
(1.25" each side of center) and the servo throw will only be equal to your
rudder throw (maybe about 30 degrees) which gives you poor mechanical advantage
and poor use of your servo. If you use a shorter servo arm and more servo
throw the cables will go slack. The round servo wheel is a compromise by
offsetting this slack tendency and letting you get more servo throw. It's
not a perfect match but it can be very close.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Anyone that can do the math on this and present a complete
answer can get a recommendation to advance from a shade tree aerodynamicist to
an apprentice.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>--Lance</FONT></DIV>
<DIV> </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=jpavlick@idseng.com href="mailto:jpavlick@idseng.com">John
Pavlick</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">General pattern discussion</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, May 09, 2008 9:02 AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] Rudder
pull-pull</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial>Chris,</FONT></DIV>
<DIV><FONT face=Arial> The only benefit that I know of is that you don't
have to deal with the Ackerman angle like you do with arms / horns. The cable
is always the same distance from the hinge center no matter
what the angle is.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>John Pavlick<BR><A
href="http://www.idseng.com">http://www.idseng.com</A></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=cjm767driver@hotmail.com
href="mailto:cjm767driver@hotmail.com">chris moon</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-discussion@lists.nsrca.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, May 09, 2008 9:13
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] Rudder
pull-pull</DIV>
<DIV><BR></DIV>Can someone explain the benefits (real or otherwise) of the
pull-pull <BR>wheel type rudder servo arm vs. a regular servo arm? Is there
some real <BR>benefit, or is it bling?<BR>Thanks<BR><BR>Chris<BR><BR><BR>
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