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Post by greenman on Jul 4, 2012 22:54:24 GMT
Single line kites generaly use external ferrules. Trick kites generaly use internal ferrules. I know this rule has plenty of exeptions.
I have broken a few spars near to the ferrule over the years on single line kites, I have bent a few ferrules too, but i dont ever remember breaking a spar on a trick kite in a similar way.
Is there any reason why external ferrues are still widely used when using an internal ferrule & whipping the end of the spars would seem to be a stronger solution?
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Post by daz essex larsen on Jul 5, 2012 4:22:39 GMT
Just a thought,could you use both on a large slk,for extra strength
all the best from the Essex boy
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Post by batchoy on Jul 5, 2012 9:02:50 GMT
From a personal point of view it depends on how the tube has been made. A lot of single line kites have lower cost pulltruded spars which means the fibres are aligned along the length of the tube as a result you get a weakness by which the tube will easily split down its length. Using an internal puts a stress on the tube that wants to pull it apart just where its main weakness it. External ferrules apply compression forces on the tube and don't act to pull it apart.
High performance kites tend to use lighter pullwound/pullbraided tubes, because the fibres in the wound/braided tubes go around the tube they don't easily split longitudinally and thus you can use an internal joint.
On spars where there is a risk of bending the ferrule I have used both as Daz suggests but you need to extend the internal pin beyond the ends of the ferrule to overcome the spar breaking just where the ferrule ends.
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