Carbon fibre

In article <1992May14.090440.25137@aber.ac.uk>, puc@aber.ac.uk (Paul Crowley) writes:
|>Can anyone explain the difference between the carbon fibre tubes available?
|>For instance, Phantoms can be supplied with "AFC" or "Beman" and I've seen 
|>that TOTL can sell a custom spinoff with "Easton" framing. 

AFC and Beman are both companies who manufacture mostly graphite
arrows. They've found that their seconds make good kite spars. They
also sell firsts as kite spars.

Generally, AFC tubes are stronger (can take more abuse), and are more
flexible for a given weight than Beman spars. If you want the best
performace, then use a Beman spar. If you want a kite that will take a
bit more abuse, then use an AFC spar. 

The differences are small however.

Many kites made in Europe use Beman spars. Beman is, I believe, a
French company. AFC is seen in kites made in the USA, since AFC is an
American company, although some kites made in the USA use Beman spars.

Easton (they make arrows, golf shafts, wind surfer masts, and baseball
bats, to name a few) manufactures a spar that consists of a thin
walled tube of high strength aluminum with graphite bonded to the
outside. The result is a fairly light weight and stiff spar that holds
up to abuse fairly well. Top of the Line, as well as Spectra Sports
use these spars in many of their kites.

To complicate matters even more, Easton also manufactures two
different types of graphite only spars.

|>  BTW what's a "four-wrap spine" ? 

There are three ways of making graphite spars. One way is to use a
process called "pultruding", which is a combination of extruding and
pulling. It's sort of like the way that rigatoni is made, a mixture of
carbon fibers and resin are extruded. This is then pulled until the
spar is the proper diameter and the result is set aside to cure.

The second method is to take a metal rod and to wrap a narrow strip of
carbon fiber fabric that has been impregnated with resin in a spiral
fashion around the metal rod. Once the wrap(s) are in place,
everything is placed into an oven to cure the resin. The spar is then
removed from the rod.

The later method results in spars that often referred to as "spiral
wound" spars. The number of wraps determine the stiffness and the
weight of the spar.

Glassforms uses a unique process which is sort of a combination of the
two. A layer of material is placed lengthwise along the spar, then
another layer is wrapped around this layer, and finally another layer
is placed lengthwise.

So, a four wrap spine is a spiral wound spar that has 4 layers of
graphite fabric. It is very stiff, fairly strong, yet light in weight.

There are many companies making carbon fiber or composite spars for
kites. Those that I know of include:

        Advantage       - spiral wound graphite
        AFC             - pultruded graphite
        Beman           - pultruded graphite
        Clearwater      - spiral wound graphite and fiberglass
        Easton          - aluminum/carbon composite, spiral wound
                          graphite, pultruded graphite
        Glassforms      - graphite, fiberglass, and
                          fiberglass/graphite mixtures.

Additionally, there is at least one other European manufacturer, and
one in Asia. I don't know much about either of these manufacturers.
Marty Sasaki                            sasaki@tle.enet.dec.com

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