Flight shooting strings

[Tuomo]

Primitive bow classes (USA Archery rules) requires natural string materials. So, what kind of natural material strings you are using? Flax, silk or something else? What is average weight of the string? Length? Endless two loops, flemish two loops or flemish one loop. What is strength factor - two, three, four, five or something else? Straight strands, twisted strands or braided stands core of the string?  What else you could tell? I am just curious...!

[loon]

ramie is interesting too

[Badger]

   I use flax string, 4 times draw weight, flemish most of the time occasionally endless. I think a material like silk can get away with less weight because it equals out the tension on the strands much better because of stretch. I have used nettle and found it slightly stronger than flax.

[Tuomo]

Please, tell more, weight, length, etc.

I have been playing flax yarns. I have bought some well known Irish flax yarns, like Barbour's, Campbell and Patons. Every of these are quite good. Here is one example, Campbell 30/3 linen, 16 strands, 200 pounds, 165 cm (65"), tenacity 32,5 cN/tex, 83,7 grains without wax and center serving, 90,5 grains waxed and 96,5 grains waxed and with center serving. Servings are cotton. And this was old linen. With new and a bit better linen, about 75 grains string could be possible.

By the way, this is the best linen yarn I have now. My best silk thread (filament silk, not spun) has tenacity 41,20 cN/tex, so it is about 27 % stronger per mass than the Campbell linen yarn. Silk of course stretches but I don't think it is a problem, if the string is well prestretched.

[loon]

Do your plant fiber endless strings break at the loops? Apparently ramie strings for Turkic hornbows were made with something like flemish twist at the loops and plenty of serving because, if endless, the halving of # of strands at the loops resulted in breakage

[Badger]

  Loon, even though the strands are 1/2 in the loops they are still close to equal strength because the tension is divided bewtween two loops. About 150 grains is typical for a 65" string using a flemish twist. I have to use silk to go below 100 grains. 125 grains is about the least I can get by with and that will usually break in less than 6 shots. I think If I started using continuous loop I could get that number down but I am slow at making the continuos loop strings.

[Marc St Louis]

Not a flight string but it is a linen string.  This one is a 22 strand 16/2 Barbour linen with a 375# break strength, length 57".  Weight waxed with serving is 140 grains.

[Badger]

  Mark, did you test the strands or is that the rating. You have always made great endless loop strings.

[Marc St Louis]

I tested the strands Steve.  They were breaking between 17 and 19 lbs

[Tuomo]

Well made continuous loop string (endless) and two loop flemish string weight about the same.

Steve - is that 125 grain string with Pyrosupplies linen or something else? Where it breaks? Loop, nocking point or somewhere else? I have got some good Swedish linen, which is a way better than old Barbour's etc. 200 pounds, 65" endless string weights about 90 grains with servings.

But, how big factor string weight really is in flight shooting? With good flight bow and arrow, is 90 grains string really "much" better than for example 130 grains string? Yes, I know that it equals about 10-15 grains in arrow weight but does that really matter?

[Badger]

  Same as pyro supplies. Most of all our linen comes from the same mill. Mine usually break in the main body of the string usually toward one end or the other. I didn't break any last year as I got lazy and went to 125 grains, more strands.

[avcase]

We spend all kinds of time trying to squeeze a little more performance out of our bows. It makes sense to try to get the most out of the string too.  For maximum performance, a flight bow string should have minimal mass and maximimum stiffness. Rubber band-like elasticity hurts performance. I feel a couple extra strands of string may not be too bad a problem as long as the forces are evenly distributed to each strand because it makes the string stiffer.

Tuomo,
The last linen flight strings I made for a 50# bow (about 200# breaking strength) are 80-85 grains, fully silk served with reinforced loops. But these were shorter than yours at 54"-58" long. I use endless loop construction and no wax. I often use the thin Barbours 25/3 or 35/3 which has a strength-to-weight ratio almost as good or better than Dacron.  I haven't had issues with these strings breaking at the salt flats for many years now.

I made a 400# string for a simple composite bow that Steve made for Jozsef Monus this year. I think the string was around 64" long, and weighed around 140 grains fully served with reinforced loops. The string was a bit long giving the bow a low brace height and I thought the resulting high forces would break the string to bits, but it held together without any issues.

Alan

[loon]

I would imagine that a shorter string would need to be stronger due to higher tension at brace?..

[Badger]

  Loon, the string angles of a lower brace put much higher strain on the bow than any other position it will be in. I have had string break right in half a few times when I had them a bit too long and marginal strength to start with.

[Tuomo]

Here is one string made from Swedish 35/3 linen. Breaking strength is 200 pounds, length 57", 16 strands, little waxed and with 4" center serving. Weight is 68,8 grains. It weighted 63,8 grains without center serving and wax, and 66,2 without wax. I served it same material as the string body.

With endless string, serving material and waxing is quite important factor. I have used quite thick silk servings (loops and center), which weighted 40-50 grains totally, plus about 10 grains wax. With this string, servings weighted only 7,5 grains and wax about 2,5 grains. Quite a remarkable difference! And more important than string body yarn qulity. For example, if the linen yarn would has 50 % more strength per mass, the string body mass saving would be 18 grains. And 10 % would equal about 4,5 grains. Linen, which has 10 % more strength per mass (compared for example to good quality Barbour's linen) is very difficult to obtain.