Why are'nt there any carbon fibre fuselages ?

[Gray E Fowler]

Hitesh...

There are! Aeroslave has delivered about 20 full CF fuselages(Aries and 
Entropy's). Check www.aeroslave.com for pictures. The reasons they are not 
so popular are several.
First-The newer, wider designs require an "A" sandwich construction to be 
stiff (no -not strength) enough. This mean two fabric layers separated by 
a core. Unlike fiberglass, CF  only comes in limited configurations. For 
RC planes two main tow (yarn) weights are of interest, "T-300" 1K and 3K. 
1K tow =1000 filaments, 3K=3000 filaments. When woven into a "tight" 
fabric, the 1K fabric =3.7oz/yd and the 3K fabric = 5.7oz/yd. When fibers volumes are equal, you can expect a 3X increase in 
modulus when using CF instead of glass.  The problems arise because the 
new planes such as the Symphony have a huge fuselage area. The "A" 
sandwich construction uses a 3.2oz glass fabric, AND take less resin to wet out, resulting in a lighter 
weight fuselage that is "Stiff Enough". So CF fuselage is not really 
needed.

Second-Fiberglass costs about $6/yd, 1K CF costs $75/yd, and 3K costs 
about $50 yd.

Third-There does seem to be a small amount RF interference requiring the 
the antenna to exit the fuse. To many pattern flyers, seeing an antenna 
outside the fuse is akin to seeing a plumber's butt crack....equally 
embarrising. BTW-my antenna hangs out......

Fourth-Most pattern flyers really do not understand composites and the use 
and advantages of CF, therefore they are not real concerned (other than 
being forced to route the antenna ouside-so they only see negatives).

At Aeroslave, we have confined the expensive use of CF to areas that have 
the biggest bang for the buck, the Nose of the fuse, the Chin cowl and the 
Canopy. The 3X stifness of CF allows us to build the Canopy and Chin cowl 
as solid laminates and still exhibit stiffnes and integrity, The use of an 
A sandwich design on such parts is possible, but much more fragile than a 
solid laminate. Solid laminates do not soak up fuel nor dent, nor damage 
easily. We also use a specialty unidiectional CF that has the stiffness of 
steel. We place this and the rear of the wing root, eliminating the need 
for a former. This unidirectional CF  is 3X stiffer than the lower cost 
"T-300" CF mentioned above and about 10X stiffer than fiberglass. 

Hopefully this answers your questions. 



Gray Fowler
Principal Chemical Engineer
Composites Engineering




"Hitesh Gajjar" <hitesh at salt.ac.za>
Sent by: discussion-request at nsrca.org
03/23/2005 07:41 AM
Please respond to discussion

 
        To:     "NSRCA" <discussion at nsrca.org>
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        Subject:        Why are'nt there any carbon fibre fuselages ?



Hi,

I'm wondering why there aren't any full carbon fibre fuselages - is the
reason weight, strength or radio interference ? If it's radio 
interference,
would putting the aerial in the wing not solve it, and then making it
pluggable. Just wondering.

Cheers,
Hitesh

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