perceived draw weight

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Alan Flashing
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perceived draw weight

Post by Alan Flashing » Fri Jun 19, 2009 4:22 pm

A question to all of you about perceived draw weight on Asian style bows.
In all the various Asian style bows that I have shot , all of them without exception regardless of the maker feel like less than the marked draw weight. So my question is does the design and in particular the siyah contribute to this lighter perceived draw weight. Do they just feel lighter in draw weight or does the design and use of the siyah acting as a fulcrum actually reduce the the draw weight? Would dearly like to know why they feel like this.
All the best,
Alan
Comox Tom
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Post by Comox Tom » Fri Jun 19, 2009 6:43 pm

It is because of string lift -off which changes the string angles which increases the draw weight at a slower rate than in the early part of the draw....
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Bede
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Post by Bede » Sat Jun 20, 2009 12:33 am

Perceived draw weight is affected by stacking as well as actual effort. In an eared bow, the force draw curve should not show an increase in the change of weight compared to draw length at the end.

By that I mean the last few inches of the draw should not increase in poundage at a greater rate per inch that the earlier ones. If one inch increased the draw weight by one pound in the middle of the draw, it should be the same or less towards the end of draw. On a well designed bow, the greatest increase occurs in the first 15 to 20 inches. When you compare this to a standard longbow or a modern recurve, the bow feels smoother to draw towards the end. Shorter longbows in particular stack and you see a marked increase in draw weight at the end of the draw. Modern recurves are often (and properly) optimised to their marked draw length. You can draw them farther, but the bow does not perform as well.

There are two other things that might affect the impression of strength. One is that the rate draw weight might not be correct for the draw length you use. You may draw 27 inches and the bow is measured at 30 inches. The other is that the rated draw length is wrong for the rated draw length. This happens occasionally in factories and goes unnoticed because most people do not test the weights of their bows.

In the comments above I am, referring to bows made from modern materials. Horn and sinew composites can change their draw weights due to temperature and usage. They still retain the force draw curve shape but the amount of energy can be reduced or increased.
Bede
Alan Flashing
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Post by Alan Flashing » Sat Jun 20, 2009 9:43 pm

Thanx Tom , Bede,
I guess that I should have posted this under hardware.
Alan
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Jos?Dom
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Post by Jos?Dom » Mon Jun 22, 2009 3:16 pm

About hornbows, as far as I know they change draw weight slightly. Stronger in Winter, lighter in Summer. I was told that the difference is only a few pounds. Anyone recorded this difference in draw weight along the seasons?
Alan Flashing
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draw weight

Post by Alan Flashing » Mon Jun 22, 2009 5:16 pm

Jose, yes I was aware of that with horn bows . My query was about horn as well as fiberglass/wood bows with siyah,s as to the felt draw weight.
All that I have shot feel like they have a lighter draw weight than stated.
As for my experience I have shot Saluki bows both horn and fiberglass, a couple of brands that I can not remember as well as one of Jaap Koppendrayer's bows. Also a couple of Korean style bows as well .
I was wondering if the siyah acts as a sort of fulcrum to lessen the felt draw weight. My 80# long bow feels like 80# to me.
Alan
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Jos?Dom
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Post by Jos?Dom » Mon Jun 22, 2009 6:04 pm

Hi Alan, yes I agree. Recurve bows (modern working recurves and rigid siyahs) are easier to draw and feel slightly lighter than longbows by its inherent function. But according to my limited experience, the problem is the thumbring shooting. It?s way easier to draw a bow with 3 fingers, I mean it?s harder for the thumb and feels heavier because the small contact area. Also, the shorter the bow, the harder it feels.
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Jos?Dom
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Post by Jos?Dom » Mon Jun 22, 2009 6:05 pm

Hi Alan, yes I agree. Recurve bows (modern working recurves and rigid siyahs) are easier to draw and feel slightly lighter than longbows by its inherent function. But according to my limited experience, the problem is the thumbring shooting. It?s way easier to draw a bow with 3 fingers, I mean it?s harder for the thumb and feels heavier because the small contact area. Also, the shorter the bow, the harder it feels.
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Bede
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Post by Bede » Wed Jun 24, 2009 1:39 am

Jose,
The experience that one has with a particular shooting style is the major influence on how you feel about whether it is easier to draw or not. I have used thumb rings for thirty years and to me a three fingered draw seems less easy on heavier bows. I really feel it in the ring finger which feels like it is being crushed.

There is a complication that comes from this. If you feel uncomfortable with a type of draw, you concentrate on the negative impressions. The bow feels harder to draw, the release seems more uncertain, and you don't feel comfortable at full draw.

When I was learning to use the Chinese cylindrical thumb rings, I first tried to wear them the same way as I would use a Turkish ring. The result was that the string often would press hard against the tendons in the proximal joint of the thumb at its base. I could not draw a heavy bow with the rings at all. Even when it didn't hurt, I felt insecure remembering the pain. Later, when I saw a photograph of a nineteenth century archer and realised that I had the ring in the wrong position, I was able to pull the heaviest bows I could master with that ring.

Due to the nature of archers' rings, I usually draw a heavy bow firstly without anything on my thumb to see if my muscles are up to it. A ring is designed for shooting and if the bow is too strong you may shoot accidentally. Your bare thumb is going to hurt if you release a heavy bow so there is an unconscious desire not to let go.

What I am getting at through that story is that our perceptions of whether a bow is easy or hard to draw are of two kinds. One is objective and related to force draw curves and the physical nature of the bow and the other is psychological and related to our prior experiences and current state of mind. The comment about thumb rings brought that to mind. Strangely, the Manchu strength bows were usually drawn with the fingers and not with the thumb. I think they may have even used all four fingers, but they were not shooting. It might have been because it was easier or perhaps they had my problem with thumb rings where they seem to have a desire to shoot rather than just hold.
Bede
Alan Flashing
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draw weight

Post by Alan Flashing » Wed Jun 24, 2009 2:47 am

Bede , Jose,
This is much the way that the use of a thumb ring feels to me . I seem to feel the weight of the bow string not near as much as with three fingers.
Really feel that I could pull more poundage comfortably with a thumb ring than with three fingers.
Alan
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Jos?Dom
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Post by Jos?Dom » Wed Jun 24, 2009 3:27 am

Bede, you got a point. My comment is biased because I used the mediterranean release for 20 years and my thumbring experience is almost new (just a couple of years). I can understand in your case (and Alan too) it feels the opposite.
Just I wonder about the Chinese ring. I never tried one but I know they are radically different to the Turkish-IndoPersian type. How it's supposed to work correctly? The non-Chinese types seems to be more practical.
daryush
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Post by daryush » Wed Jun 24, 2009 10:28 am

Bede, how do the techniques differ with different types of ring? Do you have any diagrams to illustrate?
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Bede
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Post by Bede » Wed Jun 24, 2009 12:16 pm

When my computer is feeling better, I will do some diagrams.
There are basically about four standard thumb ring types.
(1) Leather tabs, which act to protect the pad of the thumb and are very accurate.
(2) Short lipped rings that allow a fully flexed thumbs and a classical draw.
(3) Long lipped rings that require a partially flexed thumb.
(4) Cylindrical rings (Manchu) which use the the partially flexed thumb to lock the ring.

In the old days the short lipped rings were regarded as Turkish and the long lipped rings were considered as Persian. Studying paintings and rings with inscriptions suggests that this kind separation is not universal.
Bede
Jakub
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Post by Jakub » Wed Jun 24, 2009 3:40 pm

Bede- I also waiting on the diagram. I will be grateful.
On Polish forums known as Turin :)
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Jos?Dom
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Post by Jos?Dom » Wed Jun 24, 2009 4:11 pm

What Bede said about some rings require the thumb partially flexed is a very important tip. At first I used to flex my thumb too much instinctively. that created unnecessary tension and also pain and frustation. When I learned Kyudo, you learn that the thumb isn?t flexed at all inside the rigid glove and that makes you understand that your thumb don?t need to be flexed in excess around the ring, just the necessary. That really improved my shooting.
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