<HTML><FONT FACE=arial,helvetica><FONT SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">In a message dated 11/25/2003 1:12:08 PM Eastern Standard Time, geobet@gis.net writes:<BR>
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<BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Subj:<B>Re: CTE </B><BR>
Date:11/25/2003 1:12:08 PM Eastern Standard Time<BR>
From:<A HREF="mailto:geobet@gis.net">geobet@gis.net</A><BR>
Reply-to:<A HREF="mailto:discussion@nsrca.org">discussion@nsrca.org</A><BR>
To:<A HREF="mailto:discussion@nsrca.org">discussion@nsrca.org</A><BR>
<I>Sent from the Internet </I><BR>
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Sorry to disagree here, but it would appear that the conclusion being drawn by the respondants is that the pushrod expansion and contraction is the major cause of the problem. Not so, in my experience! Going to pull-pull cables, whether they be steel or kevlar thread will not get rid of the elevator trim change under consideration here.The coefficient of thermal expansion between the cables, which is very small, and the balsa in the fuse, which is significantly greater(glass too) will generate a differential of sufficient magnitude that the "devil" will still attack you when you least expect it. <BR>
The best solution that I have observed is to put the servos in the stabs. Short of this, I have been using servos mounted just at the L.E. of the stab and using a very short pushrod(approx. 6"). My current thinking is that I will still mount the servo in the same area and go with cables.Very light and direct. As regards Kevlar, I currently have a pattern practise ship that I do almost all of my flying with that has kevlar on the rudder and it has two years of mucho sequences to it's credit with no apparent wear or abrasions to the thread. At this point in time I have still not acquired the necessary intestinal fortitude to use kevlar on the elevator. <BR>
Georgie Amir Neshati wrote: <BR>
<BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px">Pull-pull will eliminate the trim change...</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> </FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">Amir</FONT><FONT COLOR="#000000" style="BACKGROUND-COLOR: #ffffff" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"> </BLOCKQUOTE><BR>
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Georgie,<BR>
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Don't fret it. I have used Kevlar every where in the tail without problems at all. <BR>
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BTW Kevlar has a negative CTE, that is it gets shorter as temp increases. Kevlar cables actually get a little tighter in summer and looser in Winter, or opposite what you would expect. I have never had a set-up that retained it's trim as well <BR>
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All, I still have a quantity of 40 pound test and 80 pound testTeflon coated Kevlar for sale. These are the smallest profiles around, for all you discriminating modelers. The teflon coating eliminates the chafe on composite fuse sides. Contact me directly please<BR>
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Matt K</FONT></HTML>