String performance

[Muz1970]

I had a wisdom tooth out in hospital on Monday and while recovering at home I've taken the time to make up some gear. So in between sipping soup and taking panadol forte I've been reading lots on string performance verses the number of strands. As I wanted to make a new string for the bow I just finished I thought I'd take some notes and share them.

I like three bundle flemish strings on my bows made from D97 and usually go with 15 strands. I normally add an extra strand per bundle at each end to pad the loops. So for this experiment I've made a 12 strand string and have taken chronograph readings of both strings with identical brace heights and nocking points. And then added cats whiskers to the 12 strand string and taken a 2nd lot of readings.

The bow is 51# at 31" and I'm testing it with two different spine carbon arrows that both bareshaft perfectly.
400 spine with 100gn glue in target point with 5" feathers, 417gn, 8.17gn/#
340 spine with ally insert and 225 field point with wrap and 5" feathers, 537gn, 10.52gn/#

The results are

15 strand string, 417gn arrows 201fps, 537gn arrows 180fps.
12 Strand string, 417gn arrows 203fps, 537gn arrows 182fps.
12 strand string with cat whiskers, top down 1/4 of string length and bottom up 1/3 of string length, 417gn arrows 198fps, 537gn arrows 180fps.

So there is obviously a slight performance increase to be had but nothing major. I'm happy that I've ended up back around the same performance with the silencers on. Some of the guys on the US forums go down to 8 strands. Not for this black duck.....

[Stu Ballz]

Great way to recover.
Why have you put the cat whiskers 1/4 down and 1/3 up??

[perry]

String Mass most definitely has an influence on Performance but a more important factor is how much a String Stretches. Modern Synthetics are very low stretch. I'd like to see how much both of those Strings stretch. I think the 15 Strand String would have less Stretch than the 12 Strand and would impart energy more efficiently into the Arrow

I used to use Dacron for my Selfbows because it was cheap and readily available. Then I was given some Linen which I made a String from. Linen stretches far less than Dacron so the Bow Shot with almost no Handshock. The Linen String has more Mass but barely stretched when Shot. I liked TS1 on my Bows but I have not been able to buy it so I now use Dyneema on all my Bows. I wish I could find some more Linen Bow String Material

I'm with you on the low strand count Strings Muz, they might be strong enough but fitting Nocks etc is an issue. I did read all this sort of thing across on the Yank Forums, sometimes Folks just get too caught up in the Performance / Speed thing.

regards Perry

[cadet]

I'm curious about linen as a string type; I guess it's the same impulse that sees me preferring things like black powder, muzzle loading and paper patching over smokeless and jacketed with firearms. The trouble is, information and raw materials seem a bit thin on the ground.

[Muz1970]

Hi Stu Ballz, I read a post on here a while back about the placement of your string silencers. Tried searching for it but couldn't find it.

The basic idea is that they are placed at different distances so they cancel out different frequencies. This is the first time I've tried it this way. The bow is very quiet but may well have been if I had placed them where I used to at approx 12" from the tips. The theory of the article made sense at the time so I thought I'd give it a go.

Cheers Muz

[Muz1970]

Ok... Its called Heterodyning...and amazingly I remembered the right distances.

http://www.tradbow.com/public/Heterodyning.cfm

[Stu Ballz]

I am definitely going to try this.
This is why this forum rocks.
So much great info from people willing to give it.

[AndyF]

Hey there,

I 'got into' making flemish strings about 18 months back, mainly to add another craft to things but also to mess about making strings to match fancy arrow fletching etc. I played around a bit with string counts as well.

I tend to go three bundle, and having read a little about 'skinny strings' and arrow speed on US blogs I've gone down to 9 strands (with padded loops) on my 45-50lb bows and shoot 12 strands (padded to 15 or 18 in the loops) on the rest of my longbows which are all 55-57lb. I use D97 and don't seem to get much string stretch at all.

Having crono tested a little there is a small increase in performance. Not much, but not a bad thing on my lighter bows.

Haven't tried anything skinnier than 21 strands on my 120lb plus English war bows yet, and probably won't. When you're hoofing 12-1300 grain arrows about and trying to avoid dislocating your shoulders, a couple of feet per second increase in arrow speed isn't really top of mind.

[Dennis La Varenne]

Muzz1970,,

Congratulations on doing it 'scientifically'. My guess would be that there would be a similar difference over the varying string types. You are talking of an error of 1% in arrow speed. You can do much worse with a poor/inconsistent loose.

I have not heard of 'heterodyning' but it would be useful to have a look at it.

[clinton miller]

Some of the guys on the US forums go down to 8 strands. Not for this black duck.....

you should try it. i've been running 8 strand D97 on my 58# recurve and 12 strand D97 on my 70# recurve for a number of years now without any dramas what so ever.