String material for flight archery

[redhawk]

I?ve almost never the problems you are talking about, but I haven?t done much bows with 100lbs plus.
I do a very carefully choice of wood for recurves and siyahs. No knots, no twists, the growthrings run along the back and belly!!. No possibility to split. Usually I steam- bend them.

Our ancestors didn?t have any dacron or fast- flight. Anyway they did strong and durable strings for bows with 130lbs plus.

In 2003 I had problems with my linen- strings, so I decided to have a closer look to the subject. I found a farmer who cultivated flax organically, the linen- yarn produced with his flax is of outstanding quality.
He told me that the flax of 2003 is really bad, cause it was a really hot summer in Europe. Flax don?t likes low temperatures and wet conditions. The best flax grows near the sea sides of Belgium, the Netherlands, Ireland, Northern Germany.
Flax is a living material, you?ve to know it well, when you?ll use it for such a stressed object like a bow- string.
The modern cultivation of flax wants to produce as much as possible, not the best quality. Environmental pollution is for sure another reason for the nowadays worther quality of flax and other naturally grown string materials.

I have done some strings with organically cultivated silk, hemp, ramie and nettle, same results.

Michael

[Adam Karpowicz]

Alan:

The Crim-Tatar horn insert I mentioned in my previous post is just such piece of horn you describe, similar to the arrow nock inserts. These inserts were used in the Tatar and Indo-Persian bows. As I said, not of much help.

Adam

[Redhorse]

Is not simple horn plates on sides enough?

[M Hardman]

From what it seems about the point of breakage, I don't think anything with a grain will be enough. Nor do I think it would wise to just put steel in the tip. The break would might just occur elsewhere.

Adam, Having though about it vaguely, and using the clue that Bede gives that the break must happen at the end of the shot, due to its nature. And using the fact that equally short (if not shorter) bows use Fastflight with less issue. It is likely then that the design of the bow is contributing to it's fail. I would suggest (timidly if anything) that as the string is released, it and the bow begin oscillating quite happily as the bow returns to brace height, but then, as the string lands on the string bridge, the string has changed. It is now effectively shorter, but it still wishes to continue vibrating, to the same degree. This it cannot do (also due to the steel-like quality you describe). The shortened nature of the string may lead to the bow's fail. This idea isn't really helpful, but if you wish to cure the ailment, it's nice to know why it's there.

I've not worked anything through on this yet, and shall see if I can make any sort up model up and out of it, though I doubt success (my modelling has never been brilliant). I'm not even confident about how the string does oscillate to begin with. Has Mr B.W.Kooi done any work on this?

Regards

[Adam Karpowicz]

Mike, what you say may be correct and more research has to be done. I do not recall if Kooi did any modelling of string vs limb stress etc, but he did find that the acceleration of the limbs was not smooth in the composites. The tension in the string is very high when the string "shortens" at brace, much higher than in the straight bows, even if the straight bows are short. Clearly, something has to give, either the string or the bow. By the way, the Turkish bows do not have bridges.

Adam

[M Hardman]

Ah, my mistake, by bridge I meant 'the place where the knot sits (or would sit) on the belly side of the bow'. My own replica has a shallow groove that is made from a block of wood. I was under the impression that 'string bridge' was synonymous to this.

[Bede]

Mike,
A "string bridge" is generally an applied leather, bone horn or wooden pieces that accepts the knot of the string on the belly of the bow. They have many different shapes, but rarely have any grooves.

Adam,
Have you had strings break at the loop except from abrasion?

[Adam Karpowicz]

Yes, I had several instances when the strings broke at the loop. One of them was a too thin loop made of silk. The other were linen and B50. The loops in old strings were very thick, at least as thick as the string itself - no doubt for durability.

Adam