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David Long
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 Posted: Tue 25 Jul, 2006 1:53 pm Post subject: historical draw weights |
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My second question would be: What was the most common draw weight found on military crossbows of the Hundred Years war era?
Dave Long
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Risto Rautiainen
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| Posted: Tue 25 Jul, 2006 10:58 pm Post subject: |
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I don't know the answer, but I think it would be hard to determine. The crossbows used during the HYW were mostly of composite construction and I believe none of the surviving examples are in a condition that they could be tested. And I believe it would be very hard to try to determine the draw weights just by looking at the outer dimensions, because their lamination styles would vary. Of course all of this is just guessing. Maybe someone has more information on the subject.
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Carl Scholer
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| Posted: Wed 26 Jul, 2006 3:03 am Post subject: |
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Yea, I also don't know of any prods that survived from the war being tested for draw. The best I can give you is some speculation based on modern reproductions and material analysis.
During the 14th century composite prod crossbows were standard and while there is some evidence for the existence of steel prod crossbows during that century they don't become even remotely common until the early 15th century. From what I've heard from David Ruff (a manufacturer and enthusiast of crossbows) on this forum composite prods can have draw weights up to 200-300lbs. From pictorial evidence I have seen from the 14th century the belt hook pull method was by and far the most popular spanning method in use during this century as well. Composite prods were lighter and more efficient then steel prods in terms of energy usage and a 200lbs composite prod should, based loosely on data I've gathered from modern tests, be equivalent to a 150lbs longbow in power.
During the later part of the hundred years war more powerful windlass cranked steel crossbows came into use that had draws of more than 800lbs, and while less efficient than compost prods in their use of energy they more than made up for this inefficiency through sheer storing capacity. A modern 450lbs steel prod crossbow can match a modern 150lbs longbow in terms of velocity with similarly weighted projectiles.
David Ruff's Website,
http://www.uccrossbows.com/
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David Ruff
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| Posted: Wed 26 Jul, 2006 11:01 am Post subject: |
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| Carl Scholer wrote: | Yea, I also don't know of any prods that survived from the war being tested for draw. The best I can give you is some speculation based on modern reproductions and material analysis.
During the 14th century composite prod crossbows were standard and while there is some evidence for the existence of steel prod crossbows during that century they don't become even remotely common until the early 15th century. From what I've heard from David Ruff (a manufacturer and enthusiast of crossbows) on this forum composite prods can have draw weights up to 200-300lbs. From pictorial evidence I have seen from the 14th century the belt hook pull method was by and far the most popular spanning method in use during this century as well. Composite prods were lighter and more efficient then steel prods in terms of energy usage and a 200lbs composite prod should, based loosely on data I've gathered from modern tests, be equivalent to a 150lbs longbow in power.
During the later part of the hundred years war more powerful windlass cranked steel crossbows came into use that had draws of more than 800lbs, and while less efficient than compost prods in their use of energy they more than made up for this inefficiency through sheer storing capacity. A modern 450lbs steel prod crossbow can match a modern 150lbs longbow in terms of velocity with similarly weighted projectiles.
David Ruff's Website,
http://www.uccrossbows.com/ |
I have built and shoot a 380 to 450lb steel prod crosbow that is able to pierce upto upto 3mm carbon steel plate (1075) that has been harden and then tempered to about a rockwell 46-48. I have not done period testing as of yet, we are making some period examples found in the walace collection and will be firing on them with 100 to 1900lbs crossbows to see what will happen.
Composites are an interesting breed of prod. I have made and have a few in the 130 to 260lb area. They registar a faster speed then a equal weight steel prod and seem to hold a tad more impact then a equal steel prod. But they will (what i have made) after about 300lbs. My thinking is the materials can not hold up to the "abuse" of firing. This also holds true with modern materials like wood and fiberglass (bo-tuff) the limit seems to be the same.
Im not saying what a medieval man could do, but i know i personally can hand span a 240lb steel prod, its work but i can do it, load and fire in about 15 seconds. The belthook was a 50% let off, this of course would aid in the ability to fire longer and not get tired, so i would imagine this is why they were used. It does however add about 30 seconds to the mix. The other issue with a belt hook is period examples i have seen cock the string off center which effect accuracy by shooting slightly left or right - this can be compensated for and it actually the same each time the string engages (mechcanical release) but still effects both accuracy and power as the bolt will be effected as it comes off the string and hits air. I have recorded as much as 7 to 25 feet per second when a period example hook it used compared to cocking the string straight using the same bow and bolt.
David
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Jean Thibodeau
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| Posted: Wed 26 Jul, 2006 3:51 pm Post subject: |
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| David Ruff wrote: | The other issue with a belt hook is period examples i have seen cock the string off center which effect accuracy by shooting slightly left or right - this can be compensated for and it actually the same each time the string engages (mechanical release) but still effects both accuracy and power as the bolt will be effected as it comes off the string and hits air. I have recorded as much as 7 to 25 feet per second when a period example hook it used compared to cocking the string straight using the same bow and bolt.
David |
David: I assume this means that there is only one hook over the crossbow string pulling it up. I also assume that using one hook is how we " know " it was done !? But if I was designing a hook I would use two hooks or a wide double hook that would engage the string on both sides of the stock and pull equally on both sides: There may be good reasons not to do this historically or design wise that I don't know about but it seems like an obvious solution to the problem.
(Edited: I just delete a part of my post that was highjacking the topic, I will maybe re-post as a new topic later: my apologies)
You can easily give up your freedom. You have to fight hard to get it back!
Last edited by Jean Thibodeau on Thu 27 Jul, 2006 4:08 am; edited 2 times in total
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Chad Arnow
myArmoury Team
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| Posted: Wed 26 Jul, 2006 3:56 pm Post subject: |
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| Jean Thibodeau wrote: | Oh, by the way I've been looking at your web site and I'm thinking of ordering one of the horsebows: How much more cost would be a 100 pound draw ? ( You can give a short answer here publicly, or maybe start a new topic about the horse bow so as to not highjack this topic too much, or as a P.M. , details we could work out using E-Mail )
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If you don't want the thread hijacked, why did you post this in the first place?
ChadA
http://chadarnow.com/
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David Ruff
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| Posted: Wed 26 Jul, 2006 8:34 pm Post subject: |
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| Jean Thibodeau wrote: | | David Ruff wrote: | The other issue with a belt hook is period examples i have seen cock the string off center which effect accuracy by shooting slightly left or right - this can be compensated for and it actually the same each time the string engages (mechanical release) but still effects both accuracy and power as the bolt will be effected as it comes off the string and hits air. I have recorded as much as 7 to 25 feet per second when a period example hook it used compared to cocking the string straight using the same bow and bolt.
David |
David: I assume this means that there is only one hook over the crossbow string pulling it up. I also assume that using one hook is how we " know " it was done !? But if I was designing a hook I would use two hooks or a wide double hook that would engage the string on both sides of the stock and pull equally on both sides: There may be good reasons not to do this historically or design wise that I don't know about but it seems like an obvious solution to the problem.
(Edited: I just delete a part of my post that was highjacking the topic, I will re-post as a new topic later: my apologies) |
I have never seen a historical double hook - maybe they exsist?. Yes that is why the string is off center and at 200lbs is dangerious and very hard to scoot the string over to center. On my medievals i sell period belthooks, but also recommend to spend the 20.00 for a modern rope cocker - they work on medievals AS LONG as there is a small groove in the butt of the stock to "grab". My feeling is if the prod continues to be used off center it can damage the prod in the long term.
David
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This is a standard topic