CTE

[Jeff Hughes]

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
>  
>  
>  
> 
> 

-- 
CoreComm Webmail. 
http://home.core.com

=====================================
# To be removed from this list, send a message to 
# discussion-request at nsrca.org
# and put leave discussion on the first line of the body.
#