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Jean Thibodeau
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 Posted: Sun 01 Mar, 2009 10:02 pm Post subject: Chinese triple bow crossbows? |
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Just ran across this article about the use of multiple bows on certain types of Chinese crossbows where the bows are used to increase power to a single arrow ( Not 3 bows to fire multiple arrows, that would be something different ).
http://www.chinahistoryforum.com/index.php?sh...&st=30
http://en.wikipedia.org/wiki/Crossbow
A little search with Google gave some results but not as much information I am curious about like " WHY " and what would be the advantages.
1) More power ?
2) Same power but less stress on the bows?
3) Would this mean a longer power stroke or an effect similar to a modern pulley compound bow for greater efficiency.
History of use would be nice but maybe some of our members good with math and physics might be able to give us an opinion about performance advantages to these kinds of bows?
Oh, first became aware of these crossbows from a book I just bought:
FIGHTING TECHNIQUES OF THE ORIENTAL WORLD, AD 1200 - 1860, © Amber Books Ltd 2008,
ISBN-13: 978-0-312-38696-2
ISBN-10: 0-312-38696-6
Page 172 Text and illustration, SIEGE WARFARE.
You can easily give up your freedom. You have to fight hard to get it back! |
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Lafayette C Curtis
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| Posted: Mon 02 Mar, 2009 1:16 am Post subject: |
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| I suspect a combination of #1 and #2 would be the most accurate guess, since the Chinese didn't seem to have developed steel prods and the kind of power needed for the strongest siege crossbows might well have been in excess of the mechanical capabilities of a laminated or composite prod. Multiple laminated/composite prods connected by a system of auxiliary cables could have been the most practical answer to the solution. Unfortunately, I don't know whether there are any pulleys in the system or not; if there are, then it might have #3's compound-bow effect as well. |
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Jean Thibodeau
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| Posted: Mon 02 Mar, 2009 6:24 am Post subject: |
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| Lafayette C Curtis wrote: | | I suspect a combination of #1 and #2 would be the most accurate guess, since the Chinese didn't seem to have developed steel prods and the kind of power needed for the strongest siege crossbows might well have been in excess of the mechanical capabilities of a laminated or composite prod. Multiple laminated/composite prods connected by a system of auxiliary cables could have been the most practical answer to the solution. Unfortunately, I don't know whether there are any pulleys in the system or not; if there are, then it might have #3's compound-bow effect as well. |
Maybe not a pulley system per say but I was thinking of a certain amount of a leverage effect as a 12" ( Arbitrary number ) of draw spread over 3 bow staves might mean that each stave's 4" of draw would end up adding together ? Not sure of the physics or the geometry of the thing ? ( Well leverage is " geometry " after all ).
The fact that they didn't have steel prods is certainly one reason for using multiple prods/bows to not overstress each single prod but end up with the power equivalent of a much stronger single prod.
As a design idea, but not a historical one, I wonder what European crossbow makers might have made using 3 very powerful steel prods?
Oh, again if my " theory " that the draw length would be a multiple of what a single prod crossbow would be ??? I wonder if this means that one could use much longer bolts and take advantage of the efficiency of very long draw lengths ?
Very powerful crossbows ( 500 pounds or more ) end up being only slightly more powerful than a 150 pound longbow due to the short draw length because of inefficiency of the system, but compensate by using " brute force " i.e. much less efficient in using the stored energy but having much more stored energy that they end up more powerful at the target end.
( NOTE: The above based on reading the other crossbow related Topic posts here on " myArmoury " and not my personal knowledge of the physics of crossbows: My best guesses about these crossbows.   )
You can easily give up your freedom. You have to fight hard to get it back! |
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Li Jin
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| Posted: Tue 03 Mar, 2009 6:51 pm Post subject: |
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San Gong chuang nu. Also known as Ba Niu Nu or eight ox crossbow. The arrow is like a Javelin, is used in siege battle, in the right position it could fire and nail into the defense wall, so the soldiers can use it to get up the wall. Developed during
968A.D-975 A.D North Song. The other name for this weapon is One spear and three sword.
http://a0.att.hudong.com/07/24/01300000247159...3070_s.jpg |
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Jean Thibodeau
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| Posted: Wed 04 Mar, 2009 12:51 am Post subject: |
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| Li Jin wrote: | San Gong chuang nu. Also known as Ba Niu Nu or eight ox crossbow. The arrow is like a Javelin, is used in siege battle, in the right position it could fire and nail into the defense wall, so the soldiers can use it to get up the wall. Developed during
968A.D-975 A.D North Song. The other name for this weapon is One spear and three sword.
http://a0.att.hudong.com/07/24/01300000247159...3070_s.jpg |
Thanks for the reply.  With a spear sized bolt we are talking a siege weapon and if it could bury itself into a stone wall the power is not in doubt and very impressive.
I could also see these used on board of ships or on large warwagons as field artillery. ( In theory at least, but I don't know if these were use this way also ? ).
You can easily give up your freedom. You have to fight hard to get it back! |
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Li Jin
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| Posted: Wed 04 Mar, 2009 12:58 pm Post subject: |
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Actually, Sir you are correct. This weapon is base built on a wagon, or as a wagon. Usually the word Chuang means Bed, and Nu means crossbow, so chuang nu means Crossbow on a bed, so meaning is carried by a wagon. operated by five to seven people. The earliest model were developed in east Han, made from bronze. The creator named Chen Qiu said: Bow made from great wood, Feather spear as arrow, Fired by device, farther then a thousand steps, which delivers power. This weapon could actually fire about ten arrows at the same time, Sounds like Katyusha rockets.
About the weapon, the Ba Niu Nu, is huge, and it has to be operated by alot people, book says nearly hundred but I'm not sure. The ones above is the older model. |
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Robin Palmer
Usergroups: None
Location: herne bay Kent UK Posts: 138
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| Posted: Fri 06 Mar, 2009 8:34 am Post subject: |
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Hi jean
Discovery channel had a bit on it in their anciant discoveries series plus a reconstruction of one they were used for siege work both to defend and attack. Range about 1000 yards was quoted bow limbs were massive all linked together via one cord. I am also positive that the Ospray series include one one oriental siege warfare and have an illistration of the weapon. |
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Jean Thibodeau
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| Posted: Sat 07 Mar, 2009 4:12 am Post subject: |
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| Robin Palmer wrote: | Hi jean
Discovery channel had a bit on it in their anciant discoveries series plus a reconstruction of one they were used for siege work both to defend and attack. Range about 1000 yards was quoted bow limbs were massive all linked together via one cord. I am also positive that the Ospray series include one one oriental siege warfare and have an illistration of the weapon. |
Thanks, will look into the book as I think it's available from KoA and might include it with some other order.
1000 yard range is impressive and I wonder at what velocity the missile leaves the crossbow ? ( one could say muzzle velocity but technically there isn't a muzzle.  ).
My best guess would be at least 200 ft/sec. but 300 ft/sec might be possible as modern composite pulley crossbows get close to these velocities.
I would still be curious to read what someone really good with the physics of the thing might be able to guess at power and leverage advantages if any of using 3 interacting bows and the possibly longer effective draw.
You can easily give up your freedom. You have to fight hard to get it back! |
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Robin Palmer
Usergroups: None
Location: herne bay Kent UK Posts: 138
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| Posted: Sat 07 Mar, 2009 4:50 am Post subject: |
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Hi jean
On the matter of ballistics you might want to consider the effect of kinetic enegy the missile were not exactly small or light so while initial velocity may not have been huge it carried a lot of enegy. |
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Jean Thibodeau
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| Posted: Sat 07 Mar, 2009 2:06 pm Post subject: |
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| Robin Palmer wrote: | Hi jean
On the matter of ballistics you might want to consider the effect of kinetic energy the missile were not exactly small or light so while initial velocity may not have been huge it carried a lot of energy. |
Yes momentum. I think with mechanical throwing engines 200 to 300 ft/sec is probably the maximum one can expect from any reasonable machine as the speed one can get the bow string to move is not going to go up much more as the return speed of the limbs are limited by the elastic properties of the material used in a composite or steel prod.
But if one increases the strength of the machine it can throw a heavier projectile at close to the same speed as a lighter projectiles because of the extra draw weight.
Even at a more modest 150 ft/sec is going to be powerful if it can get a very heavy missile with lots of mass.
You can easily give up your freedom. You have to fight hard to get it back! |
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Lafayette C Curtis
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| Posted: Sat 07 Mar, 2009 10:50 pm Post subject: |
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Just wanted to add that the idea of a multiple-limb bow isn't unique to China--there's also the Penobscot bow, or at least a modern reproduction of it:
http://www.woodlandarchery.com/prod12.htm
And I noticed an interesting question:
| Quote: | | As a design idea, but not a historical one, I wonder what European crossbow makers might have made using 3 very powerful steel prods? |
Probably it wouldn't have been worth that much since, by the time the Europeans could make bows with steel prods, trebuchets and gunpowder artillery had far exceeded the potential power that a crossbow-like device could deliver. The same might have happened in China, especially after the Mongols brought back counterweight trebuchets from the West (bringing things full circle from the time trebuchets were introduced to Europe and the Middle East from China through either Persia or Central Asia); the multiple-prod crossbow seems to have been an evolutionary dead-end that did not lead to notable further developments. |
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Robin Palmer
Usergroups: None
Location: herne bay Kent UK Posts: 138
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| Posted: Mon 09 Mar, 2009 3:48 am Post subject: |
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Hi jean.
I am no expert but as I understand it the long bow style of limb tends to be suited better to shooting heavy missile while the faster limb action of the recurve suits lighter higher velocity arrows. The illustrations I have seen of the triple bow show long thick self bows which would be ideal for shooting heavy missiles. The longer slower shove would be ideal for launching the heavy missiles.
yours Bob plamer |
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Lafayette C Curtis
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| Posted: Wed 18 Mar, 2009 7:12 am Post subject: |
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| Robin Palmer wrote: | | I am no expert but as I understand it the long bow style of limb tends to be suited better to shooting heavy missile while the faster limb action of the recurve suits lighter higher velocity arrows. |
Only if the recurved bow is short and light (in terms of physical weight, not draw weight)! Remember that "recurve" does not equal "composite," that a static recurve is different from a working recurve (both of which are found in Chinese bows), and that composite bows aren't always the short flight bows that they are often represented by in popular culture. |
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