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Post by Timo Nieminen on Sept 7, 2014 9:44:26 GMT
The 36" is the recommended max draw length for the Mind 50; my longest arrows are 90cm, so I'm only going to draw to 34-35" with those. I need to get some kyudo arrows; about 100cm is common for those. But yes, past the ear. Thumb draw as opposed to finger draw gives you about 2-3" more, with the wrist in the same position, a Manchu-style cylindrical ring gives you another 1", and then the thumb draw lets you take you hand back further. Drawing to in front of the rear shoulder is common enough in Asian archery - Manchu/Chinese, Korean, Japanese, Mongolian. Some photos of traditional shooting: www.manchuarchery.org/photographswww.manchuarchery.org/content/old-photographschinesemartialstudies.com/2012/0 ... resources/ and you can find photos of similar draws via Google Images for korean archery and Japanese archery (kyudo).
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Post by bigpete on Sept 8, 2014 6:31:42 GMT
Have you thought of making your own arrows out of bamboo stakes? I figured that you must shoot full traditional Asian style to achieve that draw length I've tried it but 20+ years of Mediterranean style kinda stops me from making the transition. :-)
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Post by Timo Nieminen on Sept 8, 2014 21:42:32 GMT
Garden stakes tend to be not very straight. I've considered getting a big bunch of bamboo arrow shafts, which can be gotten in lengths of 100cm. Or just to buy a bunch of pre-made arrows, e.g., from www.oulay.com/product.asp?classid=16&kkk=14 or similar. First, I need to make a batch of heavy arrows. Got some bowfishing shafts, 80g/1200gr each iirc. Finished product won't be quite as heavy as Manchu/Qing arrows, but close (100-125g was common). My rate of progress encourages me to buy pre-made arrows rather than bare shafts.
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Post by Karoliner on Sept 8, 2014 23:57:07 GMT
I've made one arrow from a bamboo garden stake.
It was a lot of work, especially the heat straightening, but it flew perfectly from a 60lb glass longbow when I was done.
I've tried making them again, but unless you're winging them into concrete walls, they seem to be more trouble than they're worth, with the amount of labor involved to produce matched shafts.
That being said, it did make a really nice arrow, and only broke when I hit a piece of rebar dead-on (we use rebar for the target stands in our 3D league).
I think everyone should try it at least once. I think I've got a link about making them somewhere, but I'll post it when I get back from 3D.
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Post by bigpete on Sept 9, 2014 7:12:37 GMT
Yeah I don't know I find them pretty easy to make,but then I don't get too fussy with them,and I use goldtips 99.9% of the time.
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Post by bigpete on Sept 13, 2014 7:45:14 GMT
I have been experimenting with a longer draw using full length carbon arrows so I think that would make a 33" draw and anchoring by my ear,surprising how accurate I can still shoot and just how much extra power you do actually get !
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Post by Timo Nieminen on Sept 13, 2014 22:03:08 GMT
With a longer draw with the same bow, you get a lot more power. Consider the force-draw curve when doing so: The area under the force-draw curve is the stored energy. With a shorter draw, we have the red area. With a longer draw, you add the blue are to that. Having a bow that goes to a longer draw, while reaching the same draw force (diagonal black line) still gives you more energy, since the area under that line is more than the red area. Which is, I think, the purpose of the cylindrical Manchu thumbring, as opposed to the tabbed thumbring most other thumbring archers use. With a ring 1" long, you draw 1" further, giving about 3% more energy if you go to the same draw force (second case above), or about 6% more energy with the same bow (first case above). You do lose accuracy, though. Enough to care about? In high-level target shooting competition, yes. At other times, it depends on what you're shooting at and why. Attachments:
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Post by bigpete on Sept 13, 2014 23:39:55 GMT
Yes I understand the increases but I must admit I was still slightly surprised. Basic rule of thumb is approximately 3# increase of draw weight for every extra inch drawn,and approximately 5 feet per second increase of speed for every inch extra drawn even if your poundage doesn't increase ie a bow that measures 45#@33" is going to be about 25 feet /second faster than a bow that is 45#@28". Also interesting is that you only gain about 3 fps for every extra pound of draw weight so in the above scenario the first bow is the equivalent of shooting a 51#@28" bow. With my bow set up where I'm getting 61#@29.5" I'd be getting around 72#@33" and an extra 17fps for a net increase of speed of about 50fps in theory,so basically like increasing my draw weight at 29.5" by around 17# which would mean drawing 78#@29.5. So it is a definite advantage to shoot a longer draw length from an efficiency perspective. I guess that's why so many cultures who used bows for warfare did use a very long draw length. I'd estimate your bow would be around 70#@36 and would be gaining about 40fps in increased draw length,and about 72fps in increased draw weight for a total of 112fps over it being shot at 45#@28",or basically like shooting an 83#@28" bow ! That's quite an increase ! I'd be really interested if my calculations are correct though,and the only way I'll know is running my bow thru a chrono. But it certainly illustrates my point ! As a matter of internet,I've been shooting a lot lately at 55m and I found switching from shooting my standard method I've been using for 25 years,to shooting the long draw method,only double my group size. I did try thumb drawing and it really didn't work for me,but I can certainly see why it was used to draw the relatively short Asiatic bows to such a long draw. Who says old dogs can't learn new tricks though :-) !!!
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Post by Timo Nieminen on Sept 14, 2014 6:54:08 GMT
Step 1: Measure the force-draw curve for your bow. There are some digital luggage scales that should work well - the kind that you hang the suitcase from. Step 2: Calculate the area under the curve. Step 3: Figure out how much extra energy you get for extra draw distance. Step 4: Check whether that agrees with the chrono. OK, the simple calculation, assuming a linear force-draw curve, is easier. The main bow I shoot is a Chinese sort of Manchu style bow, 45@28". Brace height of 6", so it's approximately 2lbs per 1" drawn back. So if I draw it to 34", that's another 6" and about 12lbs extra. That's about 25% more draw weight, and it's drawn about 25% further (compared to 28" - 6" brace height). Which should give about 63% more energy. So 45@28" drawn to 34" should be approximately equivalent to 75@28" drawn to 28" while staying under 60lbs all the way. So, your numbers look good. (For a bow measured/specified to be F@X", with brace height B", and you draw it to Y", the force at full draw to Y" should be about F*(Y-B)/(X-B), and the energy should be [(Y-B)/(X-B)]^2 times the energy if drawn to X". So the "equivalent bow" would be {F*[(Y-B)/(X-B)]^2} x".) Not all Asian reflex-recurves were short, and not all were drawn to long distances. The Manchu bow is about the length of a European longbow, and the Japanese bow is often longer. Of the short Asian bows, Korean bows are probably the ones drawn the furthest; Korean arrows are commonly over 90cm/36", while Ottoman arrows look like they averaged about 67cm/27", and Indian arrows about 72cm/29". (Turkish archers did use overdraw devices, though, so the arrow length isn't a limit to the draw length.) Manchu/Qing Chinese and Japanese arrows were usually over 90cm/36", up to over 1m.
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Post by bigpete on Sept 14, 2014 7:25:47 GMT
Have you actually measured your draw weight at your draw length using a set of scales? Or shot it through a chrono ?
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Post by Timo Nieminen on Sept 14, 2014 7:51:52 GMT
Step 1: Find my scales. I cunningly hid them from myself. .... Done!
Step 2: Get new batteries.
Plan was to measure force-draw curves fairly accurately, which is easiest with an assistant. One measurement at a single length is easy enough, but I need new batteries first. I expect the actual curve to be fairly flat - the really convex force-draw curves are for strongly reflexed bows, especially with large siyahs. The typical lightly reflexed bow with short siyahs tends to have a force-draw curve not too far off linear.
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Post by bigpete on Sept 19, 2014 12:07:21 GMT
OK just been up at the shop doing some testing using a 450gn full length carbon arrow fletched with 4 5" wild turkey feathers. First bow was my red china bow. Got 162 fps drawing 61#@29.5", and 182 fps drawing 67#@32". Second was my new yellow china bow. Got 177 fps drawing 74#@29.5" and 195 fps drawing 88#@32". Both bows are from longbowmaker668 on eBay,but the red one has more recurved siyahs and string bridges,and the yellow one isn't quite as recurved and doesn't need string bridges. I think he refers to them as a mongol and a Hungarian style bow respectively. The red one seems to draw a lot smoother and pinches my fingers a lot less as well a shooting faster in respect to its lighter draw weight. I'll chuck up photos tomorrow if I get time Attachments:
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