CTE

[Jeff Hughes]

Easy enough to check. Tonight I'll measure one click on a typical 
futaba set up. (I know it will also depends on arm orientation (servo 
motion is rotational converted to linear) and arm length). But at 
least it will be a ball park.


> That would depend on if you had a low cost Futaba(w/slide trim) vs. 
a high
> end JR(w/digital trims)
> 
> Wayne G.
> 
> ----- Original Message ----- 
> From: "george kennie" <geobet at gis.net>
> To: <discussion at nsrca.org>
> Sent: Monday, December 01, 2003 1:11 PM
> Subject: Re: CTE
> 
> 
> > If a digital servo moves one increment of it's total resolution 
with each
> > click of the trim lever, then .013 is equal to about 39 clicks of 
your
> > trim. Maybe enough to do a big loop?
> > Probably no where near the realityof the actual, but I'll still 
bet there
> > are a lot of clicks involved to move your elevator .013 ( I'm 
betting more
> > than 10 and probably close to 20). I'm assuming, of course, that 
you have
> > your trim rate adjusted to it's smallest value.
> > G.
> >
> > Jeff Hughes wrote:
> >
> > > I stayed out of this thread earlier. But if you run the numbers 
for a
> > > 50 degree temp swing, your only talking 0.013" of differential. I
> > > doubt if someone is noticing that. Probably the horsepower 
difference
> > > over a 50 degree swing makes more difference in how the plane is
> > > flying.
> > >
> > > > Nat
> > > >
> > > > I was gone last week....The CTE for balsa will change with the
> > > density of
> > > > the balsa it self, but as you have noted, humidity plays a 
larger
> > > part
> > > > here in expansion and contraction. This is not a factor with 
the
> > > composite
> > > > pushrods.
> > > >
> > > > I am not as inclined as Jason was to read all those emails 
while I
> > > was
> > > > gone, but in short CTE is not so much a problem as is the mis
> > > matched CTE,
> > > > in this case the carbon fiber pushrod vs. the fiberglass 
fuselage. I
> > > have
> > > > not run the calculations but anyone interested assume the CF 
rod to
> > > have a
> > > > CTE of zero, then the fuselage to have a CTE of 6.5 X 10-6 
in/in F.
> > > I
> > > > would imagine that if you set your trim at 100F then flew in
> > > December at
> > > > 50F you may have one or two clicks of trim to compensate.  The
> > > original
> > > > post asked about storage down to zero F. In reality the servo 
arm or
> > > > elevator would just move with the cold contraction.
> > > >
> > > >
> > > >
> > > > Gray Fowler
> > > > Principal Chemical Engineer
> > > > Composites Engineering
> > > >
> > > >
> > > >
> > > >
> > > > "Nat Penton" <natpenton at centurytel.net>
> > > > Sent by: discussion-request at nsrca.org
> > > > 11/24/2003 09:24 PM
> > > > Please respond to discussion
> > > >
> > > >
> > > >         To:     <discussion at nsrca.org>
> > > >         cc:
> > > >         Subject:        CTE
> > > >
> > > >
> > > > 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
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
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> > > http://home.core.com
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> >
> 
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