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<DIV><FONT face=Arial size=2>Wayne, if I'm envisioning your set up
correctly, the bellcrank is taking the changes in CTE there.</FONT></DIV>
<DIV><FONT face=Arial size=2>Without the bellcrank, running a straight shot
pushrod will still cause changes in trim....</FONT></DIV>
<DIV><FONT face=Arial size=2>I'm sure you Texans are at least </FONT><FONT
face=Arial size=2>as smart as us camel jockies to figure this one out
;-)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Amir</FONT></DIV>
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<DIV><FONT face=Arial size=2></FONT><FONT face=Arial size=2></FONT><BR></DIV>
<DIV><FONT face=Arial size=2>I am running an MK bellcrank and c.f.
pushrod in my carbon fiber/coremat fuse Aries. Titanium ends and
ball links hooking it all up except for the control horn I used Du-bro nylon
clevis. I don't remember but maybe a flight or two that I had to
change the elevator trim even a click. Not only is the c.f fuse
dimensionally stable but I have no formers in it outside of the two rails for
the rudder and elevator servo. I have replaced the nylon control horns
once due to wear (MK ballbearing clevis would eliminate this problem) but
other then that it has worked fine and with hardly any trim
problems</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Wayne G.</FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=amirneshati@earthlink.net
href="mailto:amirneshati@earthlink.net">Amir Neshati</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, November 25, 2003 2:18
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: CTE</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Both sides of a the cable will expand or
contract the same, so the trim will still not change due to different
CTEs</FONT></DIV>
<DIV><FONT face=Arial size=2>They may </FONT><FONT face=Arial size=2>get
tighter or looser, but still no trim change.....I flew a few hundred flights
on a glass fuse. with a carbon</FONT></DIV>
<DIV><FONT face=Arial size=2>pushrod, had the trim sensitivity set to 20%
and would take as much as 6 of these little clicks to trim each
flight.</FONT></DIV>
<DIV><FONT face=Arial size=2>As it got warmer, the problem I encountered was
that I would take off, on the trim pass the plane would head for the
ground,</FONT></DIV>
<DIV><FONT face=Arial size=2>so I would start adding the up trims....about a
minute in the flight the fuselage would cool and now the fuselage
would</FONT></DIV>
<DIV><FONT face=Arial size=2>contract a bit, so comes in a click or two of
down trim now, but noticed the rudder pull-pull would never change
trim with</FONT></DIV>
<DIV><FONT face=Arial size=2>any changes in temps ..so, I gave
pull-pull a try on the elev. and after 400 flights in temps. ranging from 50
to 100 degrees</FONT></DIV>
<DIV><FONT face=Arial size=2>it still worked great. I tightened the cables
only one time after the first day or two of flying and didn't touch them
again.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The only thing I can see here is that due
changes in air density (the CTE for those tiny molecules of
air)</FONT></DIV>
<DIV><FONT face=Arial size=2>a tiny bit of elevator change may be
experienced, and one may change the trim by a tiny click and be
done.</FONT></DIV>
<DIV><FONT face=Arial size=2>Where as with a pushrod, I had to change elev.
trim by 4~6 clicks at first, then after a minute or so into the
flight</FONT></DIV>
<DIV><FONT face=Arial size=2>as the fuselage temps. stabilized due to the
cooling air flowing over it, would have to re-trim
again...</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I weighed a carbon pushrod once that was ready
to install and weighed around 1.5 ounces and I believe the </FONT></DIV>
<DIV><FONT face=Arial size=2>40 lbs. coated fishing line stuff weighed
only a few grams...Kevlar would probably weigh only a couple of
grams.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Have fun,</FONT></DIV>
<DIV><FONT face=Arial size=2>Amir</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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<DIV><FONT face=Arial size=2></FONT><BR></DIV>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
<P>Amir Neshati wrote:
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<FONT face=Arial><FONT size=-1>Pull-pull will eliminate the trim
change...</FONT></FONT> <FONT face=Arial><FONT
size=-1>Amir</FONT></FONT>
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<DIV style="FONT: 10pt arial">----- Original Message -----</DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=natpenton@centurytel.net
href="mailto:natpenton@centurytel.net">Nat Penton</A></DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A></DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, November 24, 2003
7:24 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> CTE</DIV> <FONT
face=Arial><FONT size=-1>Gray what is the CTI for balsa ? I have
carbon push rods / balsa fuse and my elev trim moves around
considerably. I suppose it is because of humidity variation between
the shop and outdoors ?? The pushrods are 50"
long.
NatPenton</FONT></FONT> </BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>