Why are'nt there any carbon fibre fuselages ?

[Rcmaster199 at aol.com]

Hitesh, a couple years ago, the boys at Aeroslave had built an all carbon  
fuse of one of their models. The fuse was extremely stiff and light. Don't know  
if they ever flew it tho.
 
There are some radio links available now that are not as bullet proof as  
desired and an all carbon fuse could cause a problem, if the antenna is embedded  
in the fuse. Running the antenna out to a wing tip is not a good idea because 
 then it would fly normal to the flight line. For maximum effectiveness, the  
airborne antenna should fly parallel the flight line.
 
Kevlar is substantially less expensive than carbon cloth. Kevlar has a much  
lower modulus than carbon, which means it will not be as stiff (about a  
five-fold difference, depending on grades). But it is far tougher in impact  which 
means it can take alot more abuse (equal thickness sections) than carbon  
before cracking. Both materials in combination produce the better composite  since 
it would be a better compromise of properties.
 
Kevlar absorbs vibration better than carbon does but carbon will stiffen  
areas like fuse tails far better.
 
 
For stiffness and lightness, it's hard to beat a total area vacuum sandwich  
(TAVS) construction. A little thicker foam component as  Piedomnt used in 
their Temptation fuse, is better than the extremely  thin layer that CARF uses in 
their IMPACT models. If they used lightweight  Kevlar cloth as the outside 
skin of the TAVS, it would produce a very good  composite that would be nearly 
bullet proof
 
MattK

 
 
In a message dated 3/23/2005 9:08:08 AM Eastern Standard Time,  
hitesh at salt.ac.za writes:

Hi,

I'm pretty sure that carbon fibre is cheaper or at least as  expensive as the
kevlar used in latest designs. From my current fus, I can  tell that the
kevlar sections are alot more flexible than the carbon fibre  parts which are
really stiff. Is the inherent flexibility a good thing and  part of the
design ?

Cheers,
Hitesh


 
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