Why did the the Ming crossbows become so weak compared to earlier Chinese ones?

[Hurricane Six]

If the max dry fire speed max out below 330 ft/s, then that means the fastest possible bolt speed for a heavy crossbow is going to be less than that, no matter how light the bolt is.

Essentially.

That is why humans devised alternatives to large composite prods, just like nature conjured alternatives to exoskeletons. Despite a substandard recreation: http://www2.hsu-hh.de/hisalt/project...rsion_2016.htm

They managed 58.3% efficiency @ 86 m/s and ~1,000 joules. A proper recreation w/ back or leg sinew should do 70% efficiency and ~1400 joules

[Hurricane Six]

To recap Ming crossbow energy levels :

Heaviest standard 8 stone Han crossbow power = 4902 inch lbs * 30% efficiency = 2941 inch lbs =166 Joules (please Note: 8 Stone Crossbows are Extremely rare. ~40 joules 100 m/s)

Typical 6 stone strength Han crossbow's power = 3676.5 inch pounds * 35% efficiency = 145 Joules

Typical hammer thrower: ~3,000 joules

[Hurricane Six]

Regarding the hammer thrower, I omitted to say "Olympic" hammer-thrower

[Common Soldier]

To recap Ming crossbow energy levels :

Heaviest standard 8 stone Han crossbow power = 4902 inch lbs * 30% efficiency = 2941 inch lbs =166 Joules (please Note: 8 Stone Crossbows are Extremely rare. ~40 joules 100 m/s)

Typical 6 stone strength Han crossbow's power = 3676.5 inch pounds * 35% efficiency = 145 Joules

Typical hammer thrower: ~3,000 joules

I am not sure what Chinese unit is being translated as "stone", or where you got your values of lbs-inch.. Chinese crossbows had a typical powerstroke of 19", so 4902 in-lbs means a draw weight of 516 lbs. And for an 6 stone Han crossbow, the 3676 lbs-in means a draw weight of 387 lbs. Which means the "stone" equals around 67 lbs, which doesn't translate into any ancient Chinese unit of weight I am aware of.

Also, the efficiency seems low. 35% is what you could expect for a european crossbows, which have a shorter powerstroke of 6 to maybe 8", but tne Chinese crossbows likely had a higher efficiencies due to their longer powerstrokes.

A cranequin winched reonstructed European crossbow shot bolts with 200 joules at around 69 m/s, and I would expect the Chinese crossbows to have comparable power.

Finally, the 100 m/s seems rather high. at 100 m/s and 166 Joules, that impied the bolt mass was only 33: g, while European crossbow bolts were commonly 60 g, and long bow arrows were 1000 grains or 65 g. And in all the medieval crossbow reconstructions I have seen, speed was at most 70 m/s.

[Common Soldier]

To recap Ming crossbow energy levels :

Heaviest standard 8 stone Han crossbow power = 4902 inch lbs * 30% efficiency = 2941 inch lbs =166 Joules (please Note: 8 Stone Crossbows are Extremely rare. ~40 joules 100 m/s)

Typical 6 stone strength Han crossbow's power = 3676.5 inch pounds * 35% efficiency = 145 Joules

Typical hammer thrower: ~3,000 joules

As I said, I wonder what Chinese unit is being translated by "stone. I found no Ancient Chinese weight called a stone


HackneyScribgave in some other post 387 lbs for a 6 stone Han dynasty crossbow, which means the 'stone" was 64.5 lbs, which doesn't correlate to any Chinese weight I know of. The was a old Qin and Han stone, but that was 120 catties or more like 60 kg, around 132 lbs, which is too high for the crossbow. A draw weight of 790 lbs seems unrealistically high for the common lower draw weight crossbow that had no mechanical assist to draw.

[Hurricane Six]

I am not sure what Chinese unit is being translated as "stone", or where you got your values of lbs-inch.. Chinese crossbows had a typical powerstroke of 19", so 4902 in-lbs means a draw weight of 516 lbs. And for an 6 stone Han crossbow, the 3676 lbs-in means a draw weight of 387 lbs. Which means the "stone" equals around 67 lbs, which doesn't translate into any ancient Chinese unit of weight I am aware of.

387/6 = 64.5 lbs. That is right from Hackneyed Scribe:
http://www.twcenter.net/forums/showt...-crossbow-ever

If it is wrong, I would not be surprised. My analyses simply calculate the efficiency, energy, max dry fore speed, etc. I do not make up the base inputs (i.e. draw weight draw length, etc.).

Also, the efficiency seems low. 35% is what you could expect for a european crossbows, which have a shorter powerstroke of 6 to maybe 8", but tne Chinese crossbows likely had a higher efficiencies due to their longer powerstrokes.

There is no correlation between power stroke length and efficiency! See hborrgg’s posts here (particularly the post with the chart in it):
http://www.twcenter.net/forums/showt...bow-ever/page8
Also the 1200lb crossbow with the 7.5 inch power-stroke here: https://www.youtube.com/watch?v=G2Rl9DLUfao

Is significantly more efficient than the 1270 lb crossbow, when adjusted for launch velocity (remember apples to apples) with a 14.8 inch powerstroke:
https://www.youtube.com/watch?v=nY2untEwCnU

A cranequin winched reconstructed European crossbow shot bolts with 200 joules at around 69 m/s, and I would expect the Chinese crossbows to have comparable power.

They do. The difference in energy ~200 joules vs 166 joules) is from the superior draw force curve of the European crossbow. They store almost 60% of the theoretical maximum energy. The han crossbow would store only ~50% of its theoretical maximum due to the excessive powerstroke length. Remember, long powerstrokes, all else equal, will cause archery stack as the sting angle becomes very acute. This will decrease stored energy. Notice the effective lever change below (30% vs 6%)!!! Notice also the acute string angle.

Finally, the 100 m/s seems rather high. at 100 m/s and 166 Joules, that impied the bolt mass was only 33: g

Please reread my post. At 100 m/s energy would be 40 joules not 166. Crossbow would be operating at 7% efficiency.

[Hurricane Six]

As I said, I wonder what Chinese unit is being translated by "stone. I found no Ancient Chinese weight called a stone


HackneyScribgave in some other post 387 lbs for a 6 stone Han dynasty crossbow, which means the 'stone" was 64.5 lbs, which doesn't correlate to any Chinese weight I know of. The was a old Qin and Han stone, but that was 120 catties or more like 60 kg, around 132 lbs, which is too high for the crossbow. A draw weight of 790 lbs seems unrealistically high for the common lower draw weight crossbow that had no mechanical assist to draw.

Looks like you may be right. He had to back track and reinvent the weight of a stone (64.5 lbs) on historum. There is also a question about the actual draw length. It appears that 19 inches was too unwieldy due to the size of the crossbow prod.

[Common Soldier]

387/6 = 64.5 lbs. That is right from Hackneyed Scribe:
http://www.twcenter.net/forums/showt...-crossbow-ever

If it is wrong, I would not be surprised. My analyses simply calculate the efficiency, energy, max dry fore speed, etc. I do not make up the base inputs (i.e. draw weight draw length, etc.). 

64.5 kg would be close to the value of a Chinese picul, sometimes also called a stone, I think, so I wonder if HackneyScribe mistranslated as 64.5 lbs when it should have been kg. But then, the draw force would be unrealistically high for Chinese crossbows, at least hand held ones. Perhaps the rating of the crossbow mechanisms, which is what they were tested to, was not the rating of the actual crossbows. In engineering, you often use a safety factor of 2 when using equipment, so the device you are using is capabable of handling twice the actual load you expect to see. The crossbow mechanisms may have been tested to much higher loads than what the actual draw weight of the ceossbow. A 790 lbs ,rating of the mechanism becomes a more realistic 395 lbs draw weight.

And, since we don't have the stock and prod to go with the actual crossbow mechanisms, some of these crossbow mechanisms might have been for the much larger triple crossbows and other siege crossbows, which did use mechanical windlasses.




There is no correlation between power stroke length and efficiency! See hborrgg’s posts here (particularly the post with the chart in it):
http://www.twcenter.net/forums/showt...bow-ever/page8
Also the 1200lb crossbow with the 7.5 inch power-stroke here: https://www.youtube.com/watch?v=G2Rl9DLUfao

Is significantly more efficient than the 1270 lb crossbow, when adjusted for launch velocity (remember apples to apples) with a 14.8 inch powerstroke:
https://www.youtube.com/watch?v=nY2untEwCnU 

Ok.

Shorter draw lengths are often associated with higher draw weights, a higher draw weight compensating for the shorter draw. The heavier limbs of the higher draw weight can't move as fast, so you need heavier quarrels for efficiency, and the bolts they fire won't be as fast, even if they have more power - the increase in bolt weight doesn't effect the limb speed as greatly as for light ones, so the increase in mass of the bolt offsets the slight decrease in speed and more energy results.

A hammer toss is much slower in speed than an arrow, but the hammer is much, much more massive. Perhaps the efficiency seems lower for the higher draw because the arrows or bots they fire are actually lighter than they should be for optimum efficiency.



They do. The difference in energy ~200 joules vs 166 joules) is from the superior draw force curve of the European crossbow. They store almost 60% of the theoretical maximum energy. The han crossbow would store only ~50% of its theoretical maximum due to the excessive powerstroke length. Remember, long powerstrokes, all else equal, will cause archery stack as the sting angle becomes very acute. This will decrease stored energy. Notice the effective lever change below (30% vs 6%)!!! Notice also the acute string angle. 

When people think of power of a bow or crossbolt, they think of the energy of the arrow or bolt, and Bilcher's crossbow of 200 joules is actually more powerful than the Han dynasty crossbow. However, the Han dynasty crossbow probably shot a lighter bolt, so it might have had a longer range, since the lighter, less massive limbs probably could move faster, giving a higher speed to a much lighter bolt.




Please reread my post. At 100 m/s energy would be 40 joules not 166. Crossbow would be operating at 7% efficiency.

My mistake, I misunderstood at first what you wrote. But at 40 joules and a 100 m/s, the bolt mass would be only 8 grams, which is unrealistically low, I doubt you could have a bolt that low mass, it would break in use for the given draw force. So 100 m/s seems far to high a speed for the crossbow bolt.

Bottom line is that if what you say is true, the Han dynasty crossbows might not have all that more powerful than the more powerful medieval European crossbows, and that the shorter draw length of the Ming crossbows did not reduce the power quite as much as it first appeared, when compared to earlier dynasties.

[Hurricane Six]

64.5 kg would be close to the value of a Chinese picul, sometimes also called a stone, I think, so I wonder if HackneyScribe mistranslated as 64.5 lbs when it should have been kg. But then, the draw force would be unrealistically high for Chinese crossbows, at least hand held ones. Perhaps the rating of the crossbow mechanisms, which is what they were tested to, was not the rating of the actual crossbows. In engineering, you often use a safety factor of 2 when using equipment, so the device you are using is capabable of handling twice the actual load you expect to see. The crossbow mechanisms may have been tested to much higher loads than what the actual draw weight of the ceossbow. A 790 lbs ,rating of the mechanism becomes a more realistic 395 lbs draw weight.

And, since we don't have the stock and prod to go with the actual crossbow mechanisms, some of these crossbow mechanisms might have been for the much larger triplle crossbows and other siege crossbows, which did use mechanical windlasses.

Certainly a possibilityn but not my area of expertise. They did a reconstruction of a triple crossbow: http://greatmingmilitary.blogspot.co...-crossbow.html

The 3x crossbow was 390 pound draw weight and was pulled back via a primative winch. Velocity was 28 m/s.

Shorter draw lengths are often associated with higher draw weights, a higher draw weight compensating for the shorter draw. The heavier limbs of the higher draw weight can't move as fast, so you need heavier quarrels for efficiency, and tne bolts they fire won't be as fast, even is they have more power - the increase in bolt weight doesn't effect the limb speed as greatly as for light ones, so the increase in mass of the bolt offsers the slight decrease in speed and more energy results.

In the case of the crossbows I mention draw weight was within 6% (1270 lbs vs 1200 lbs). Power stroke was the major variable. Regarding the heavier limbs, I agree w/ you 100%. Take a look at adam's turkish bows:
http://www.atarn.org/islamic/Perform...s/image010.gif

Longer, heavier bows are much slower than their lighter, shorter counterparts. The 60 inch tartar bow is downright lethargic.

A hammer toss is much slower in speed than an arrow, but the hammer is much, much more massive. Perhaps the efficiency seems lower for the higher draw because the arrows or bots they fire are actually lighter than they should be for optimum efficiency.

True. Hammer throw velocity is ~30 m/s. As you decrease projectile weight, you decrease efficiency. Here are results from a primitive atlatl that were posted on historum:


'''The study was done in 1997 by Hutchings & Bruchert and I've linked it below.

Can anyone shed light on this? I cannot fault their methodology, and so I can only conclude that the atlatl is unspeakably powerful but had been forgotten by the time humans were wearing armour that would necessitate such energy to pierce.

https://s3.amazonaws.com/academia.ed...graphic_an.pdf

PDF from academia.edu. Search for "WK Hutchings, LW Brüchert - Antiquity, 1997" on Google Scholar if the above link doesn't work for you.

To put this into some context, the world record javelin throw currently stands at 98m. With an 800 gram javelin, this means it would have required (in excess of) 384 joules to achieve. And yet, this paper has a experienced enthusiast exceed this level of energy routinely. The heaviest atlatl was 545 gram and thrown at up to 53 m/s. That's 765 J!

How can such a simple tool exceed the han crossbow in energy?'''

Lighter arrows/darts resulted in lower energy levels, as can be expected.

When people think of power of a bow or crossbolt, they think of the energy of the arrow or bolt, and Bilcher's crossbow of 200 joules is actually more powerful than the Han dynasty crossbow. However, the Han dynasty crossbow probably shot a lighter bolt, so it might have had a longer range, since the lighter, less massive limbs probably could move faster, giving a higher speed to a much lighter bolt.

That is reflected in my numbers. While the Han crossbow stored less energy than their European brethren, they were stressed more (i.e. higher powerstroke), which lead to slighty higher dry fire speeds but lower energy with war weigh bolts.

My mistake, I misunderstood at first what you wrote. But at 40 joules and a 100 m/s, the bolt mass would be only 8 grams, which is unrealistically low, I doubt you could have a bolt that low mass, it would break in use for the given draw force. So 100 m/s seems far to high a speed for the crossbow bolt.

They would be flight bolts not meant for war. As long as you could fit the bolt in the channel, you could use very short (thus stiff) bolts. Turkish flight bows used short arrows in an overdraw device to achieve impressive distances.

[QUOTE=Common Soldier;15571599Bottom line is that if what you say is true, the Han dynasty crossbows might not have all that more powerful than the more powerful medieval European crossbows, and that the shorter draw length of the Ming crossbows did not reduce the power quite as much as it first appeared, when compared to earlier dynasties.[/QUOTE]

Which pretty much says that the Ming crossbows were not far inferior to han crossbows. The whole premise of this thread is questionable.

[Common Soldier]

I find what you wrote about the energy levels of the javelin and atlatl very interested. The energy levels far exceed those of any hand held bow or crossbow, and match those of even large siege bows. I Aka surprised that you could reach speeds as high as 53 m/s with a 1/2 kg atlatl spear, those speeds are comparable to what crossbow maker Bilcher achieved with his 20 lbs medieval composite crossbow shooting a lighter bolt.

The greater power of a javelin or spear might explain why in the West the spear was often preferred to the bow. The spear/javelin would have more energy. In Homer's Iliad, the spear was the weapon of the heroes, and only Paris and secondary characters had the bow as their main weapon. And while spear throws were often shown to be fatal, arrows seldom were. Even in the Homeric legend, it took poison on the arrow and not the arrow itself to kill Achilles, and In the Odyssey, Odysseus left his great bow behind when he went to war, which kind of indicates the importance that was place on the bow as a weapon. The Romans too, relied more on the is pilum than their bows.

One thing I am curious about is about is the difference in penetrating ability. Even the arrows have far less energy, it is concentrated in a smaller area at possibly a higner speed. A hammer toss has way much energy than any arrow, but it isn't going to penetrate even a cloth jacket armor, while the arrow might. Of course, the hammer is going to deliver a bigger blow.

I always thought the advantage of the crossbow was that it could deliver as powerful an bolt as a heaeay war bow without years of conditioning, but maybe that wasn't the main advantage. Perhaps it was the ability to aim it better that was the real advantage. With a crossbow, you could wait until you had the perfect shot before releasing, but you will get tired holding a regular arrow, so you can't wait as long before releasing the arrow. This gives a crossbowmen a greater advantage is firing at an exposed weakness. True, the crossbow had a slower rate of fire, but that mignt not be as big an advantage as commonly thought. Even if a long bowmen could fire 10 arrows a minute, since he only carries 24 arrows, it means he would be out of arrows in 3 minutes if he fired at top speed, and useless as an archer for the rest of the battle, which might last hours.

I agree, the entire premise of the thread could be wrong, if your estimates of Han Crossbows are correct. A short powpower stroke would use a shorter, less unwieldy prod, and so the Ming mignt have traded off a more easily handled crossbow with a shorter stroke to one with a larger, less maneuverable crossbow with a longer power stroke. In that light, the Mining crossbow would have been an advance, not a decline.

[Yilmir]

Heaviest standard 8 stone Han crossbow power = 4902 inch lbs * 30% efficiency = 2941 inch lbs =166 Joules (please Note: 8 Stone Crossbows are Extremely rare. ~40 joules 100 m/s)

Typical 6 stone strength Han crossbow's power = 3676.5 inch pounds * 35% efficiency = 145 Joules

Han crossbow prod are just very high draw height bow. It was a using a recurve composite bow as the prod. HackneyedScribe estimated at 60% efficiency. which is how he got:

http://historum.com/asian-history/13...ossbow-ii.html

Projectile Energy
Heaviest standard 8 stone Han crossbow power = 4902 inch lbs * 60% efficiency = 2941 inch lbs = 332 Joules
Typical 6 stone strength Han crossbow's power = 3676.5 inch pounds * 60% efficiency = 249 Joules
Andreas Bichler's 1200 lb composite crossbow = 4488 inch lbs * 39.04% efficiency = 1752.3 inch lbs = 198 Joules
Heavy Song dynasty bow made to pierce armor = 1840 inch lbs * 75% efficiency = 1380 inch lbs = 156 Joules
Tod Todeschini's 1250 lb steel crossbow = 4062.5 inch lbs * 30.5% efficiency = 1239 inch lbs = 140 Joules

He explained how he got the efficiency:
http://historum.com/blogs/hackneyeds...crossbows.html

There is no correlation between power stroke length and efficiency! See hborrgg’s posts here (particularly the post with the chart in it):
http://www.twcenter.net/forums/showt...bow-ever/page8
Also the 1200lb crossbow with the 7.5 inch power-stroke here: https://www.youtube.com/watch?v=G2Rl9DLUfao

Is significantly more efficient than the 1270 lb crossbow, when adjusted for launch velocity (remember apples to apples) with a 14.8 inch powerstroke:
https://www.youtube.com/watch?v=nY2untEwCnU



They do. The difference in energy ~200 joules vs 166 joules) is from the superior draw force curve of the European crossbow. They store almost 60% of the theoretical maximum energy. The han crossbow would store only ~50% of its theoretical maximum due to the excessive powerstroke length. Remember, long powerstrokes, all else equal, will cause archery stack as the sting angle becomes very acute. This will decrease stored energy. Notice the effective lever change below (30% vs 6%)!!! Notice also the acute string angle.

Except Andreas Bichler's test on recreated composite crossbow shows there is a positive correlation between power stroke length and efficiency in composite crossbows!
HackneyedScribe did post the Andreas Bichler's result in the blog post I just linked. I believe Andreas Bichler thinks so as well.

And the limbs length of Chinese crossbow (Qin, Han, Song) are significantly longer as shown in records and some archaeological finds, this do prevent stacking and explain why they are that size.
A Qin crossbow was found to have 1.3 meter length prod.

HackneyedScribe did address this as well:
"The Han crossbow does come with shortcomings. Han crossbow prods were composite, including sinew and horn materials. Compared to metal prods of winched crossbows in Medieval Europe, composite prods needs more maintenance and are more susceptible to bad weather conditions. The long powerstroke also requires a very long prod. Andreas Bichler noted how his 617 lb composite crossbow performed very badly because its 75 cm prod was too short for its powerstroke. The Han crossbow design requires a very long prod, otherwise the string would be pulling the bow limbs apart rather than storing energy (a case known as stacking). Thus each crossbowman requires more horizontal space for shooting, which forces crossbowmen to either use open skirmishing formation, or adopt special formations to compensate (such as the countermarch, which will be described below)."

By way the, you point on effective lever length is moot. Han crossbow uses heavily recurve composite bows as prods.
Here are pictures of Han era crossbow from Han era tomb mural.
https://en.wikipedia.org/wiki/History_of_crossbows#/media/File:Han_crossbow_arming_illustration.jpg

Look at the prod shape. It looks like turkish bow or other heavily recurve composite bows. As side note, you can also see the size of the prod is fairly large as well.
For example, the first picture of unstrung and strung turkish bows:
http://www.atarn.org/islamic/Performance/Performance_of_Turkish_bows.htm

Plenty of Han era finds of figurines and murals shows this.

As I said, I wonder what Chinese unit is being translated by "stone. I found no Ancient Chinese weight called a stone


HackneyScribgave in some other post 387 lbs for a 6 stone Han dynasty crossbow, which means the 'stone" was 64.5 lbs, which doesn't correlate to any Chinese weight I know of. The was a old Qin and Han stone, but that was 120 catties or more like 60 kg, around 132 lbs, which is too high for the crossbow. A draw weight of 790 lbs seems unrealistically high for the common lower draw weight crossbow that had no mechanical assist to draw.

Do you have a source on Han stone being roughly 60kg or 132 lbs?

HackneyedScribe is probably referring to Western Han 石 (shi, meaning 'stone').

https://zh.wikipedia.org/wiki/%E4%B8...1%A1#%E8%A1%A1
http://www.chinaknowledge.de/History...liangheng.html
Both source seems to give a 石 (shi, stone) is roughly 29760 grams or 65.60957lbs. I remember HackneyedScribe stated he based 64.5 lbs on an archaeological find of weight stated to be one 石 (shi, stone). It does fit to what we know about western Han 石 (shi, stone).

Perhaps the rating of the crossbow mechanisms, which is what they were tested to, was not the rating of the actual crossbows. In engineering, you often use a safety factor of 2 when using equipment, so the device you are using is capabable of handling twice the actual load you expect to see. The crossbow mechanisms may have been tested to much higher loads than what the actual draw weight of the ceossbow. A 790 lbs ,rating of the mechanism becomes a more realistic 395 lbs draw weight.

No Chu-yen slips are quite clear it is the crossbow that is weighted not the trigger.

For example, Slip 36.10: 官第一六石具弩一今力四石二斤射百八十五步完
which stats a 6 石 (shi, stone) crossbow now has a weight of 4 石(shi, stone) 2 斤(jin).
There are plenty of other slips that references weighting crossbows.

The "Han Chu-yen Wooden Slips" are excavated in the Edsen-gol River, Inner Mongolia and Gansu Province by the Swedish archaeologist Folke Bergman between the years of 1930 to 1931.
They are a collection of records kept by the Han soldiers in the frontier dug up roughly 2000 years later.
You can find them online as well.
http://ihparchive.ihp.sinica.edu.tw/ihpkmc/ihpkm_op?.85d300571000000000000001E0000^000000006310000000000D013f29

For the 36.10 slip:
http://ihparchive.ihp.sinica.edu.tw/...00001000000000
http://ihparchive.ihp.sinica.edu.tw/ihpkmc/fullimg_op?@16^1567686660^4@@943731336
You can see it says 官第一六石具弩一今力四石二斤射百八十五步完

And, since we don't have the stock and prod to go with the actual crossbow mechanisms, some of these crossbow mechanisms might have been for the much larger triple crossbows and other siege crossbows, which did use mechanical windlasses.

We do have Qin or Han era stocks with the trigger still inside them. This confirms those triggers are for handheld versions.
https://en.wikipedia.org/wiki/Histor...seCrossbow.JPG

[Common Soldier]

Han crossbow prod are just very high draw height bow. It was a using a recurve composite bow as the prod. HackneyedScribe estimated at 60% efficiency. which is how he got:

http://historum.com/asian-history/13...ossbow-ii.html

Projectile Energy
Heaviest standard 8 stone Han crossbow power = 4902 inch lbs * 60% efficiency = 2941 inch lbs = 332 Joules
Typical 6 stone strength Han crossbow's power = 3676.5 inch pounds * 60% efficiency = 249 Joules
Andreas Bichler's 1200 lb composite crossbow = 4488 inch lbs * 39.04% efficiency = 1752.3 inch lbs = 198 Joules
Heavy Song dynasty bow made to pierce armor = 1840 inch lbs * 75% efficiency = 1380 inch lbs = 156 Joules
Tod Todeschini's 1250 lb steel crossbow = 4062.5 inch lbs * 30.5% efficiency = 1239 inch lbs = 140 Joules

He explained how he got the efficiency:
http://historum.com/blogs/hackneyeds...crossbows.html

Bichler also had a 1270 lbs crossbow that shot a 260 g bolt at 433 Joules, and 348 g bolt at 488 J, with a stored energy of 1277 J. This works out to around 34% for the 260 g, and 38% for the 348 g bolt efficiency. Bichler said the powerstroke was 375 mm (~ 15"). As you can see, the heavier bolt is more efficient than th lighter bolt. Even with a significantly longer powerstroke, the efficiency of the 1270 lbs crossbow was not much different than the 1200 lbs crossbow. Note, that Bichler's 375 mm is only slightly shorter than the typical 19" for a Han crossbow.

https://www.youtube.com/watch?v=nY2untEwCnU

What was the weight of the Han dynasty crossbow bolt? The Song Dynasty crossbow bolt? The weight of the bolt can significantly effect the efficiency., and for a 60% efficiency, what bolt weight are we assuming? Based on Andreas Bilcher's results, you can't assume efficiency will be the same for all bolt weights. A lighter bolt will give a longer range, but less efficiency.

Also, the 60% efficiency for a 6 or 8 stone crossbow is just as estimate, no one has yet built a reconstruction Han crossbow of such weight, and you can't automatically assume the efficiency seen for a lower draw weight crossbow automatically applies to one with a much heavier draw weight. One thing effecting efficiency is that much heavier draw weights require more massive prods, which can't move as fast. To achieve greater efficiency, you have to use heavier bolts. The heavier prod speed is less effected by increasing weight of the bolt, resulting in higher energies and efficiencies with a heavier bolt.


PS - Although 10.5 kg (23 lbs) is somewhat heavy for a handheld crossbow, the M60 rifle, which can be fired standing, also weighs 10.5 kg, and has a much greater recoil. Also, I have seen re-enactors rest large crossbows on their shoulders, which would carry most of the weight of the crossbow. I know Bichler had rested the bow on table when he fired it, but that doesn't mean he couldn't have held it on his shoulder to fire. So while it was likely mostly mounted to fire, it could have been fired by hand.


]

Except

Andreas Bichler's test on recreated composite crossbow shows there is a positive correlation between power stroke length and efficiency in composite crossbows!

Actually, when you compare the efficiency of Andreas Bichler's 1200 lbs crossbow and his 1270 lbs crossbow, the efficiencies are comparable, even though the 1270 lbs powerstroke is much longer. Bichler said the 1200 lbs crossbow had a 190 mm powerstroke,and the 1270 lbs had 375 mm powerstroke.

Update - note the 1277 Joules came from actually measuring the force curve at 25 mm increments, not usifn the 1/2* final draw weight* powerstroke equation.

Do you have a source on Han stone being roughly 60kg or 132 lbs?

HackneyedScribe is probably referring to Western Han 石 (shi, meaning 'stone').

https://zh.wikipedia.org/wiki/%E4%B8...1%A1#%E8%A1%A1
http://www.chinaknowledge.de/History...liangheng.html
Both source seems to give a

石 (shi, stone) is roughly 29760 grams or 65.60957lbs. I remember HackneyedScribe stated he based 64.5 lbs on an archaeological find of weight stated to be one 石 (shi, stone). It does fit to what we know about western Han 石 (shi, stone).

I noticed that from the Sui dynasty onward, the weight of the jin was around double that of the Han dynasty, and remained so for the rest of Chinese history. I did not realize there was such a drastic, doubling, of the value of the weight.

Also, the ratio between the Chinese stone, and the jin/catty seems to have varied somewhat, from a 100 to 120 jin per Chinese stone/picul/dan/. How certain are we of the ratio the stone to the jin or catty in Han dynasty times? If the value of the jin could change so drastically in just a few hundred years, could the ratio of jin to stone also have change significantly in the same time? If we are relying on Sui dynasty documents or later to determine the ratio of the stone to jin, we may be seriously off in our estimates of the draw weights.

We have actual Han dynasty labeled jin weights, so we can be confident of their value. But do we have actual samples of labeled Han dynasty weight in stones/piculs/dans? It would be an easy, but mistaken thing of assume the same ratio held true in the Han dynasty as it was in later dynasties, and it would radically change what the power output would be.

**Update - I overlooked where you did say that HackneyScribe did indeed base his value on an actual Han ere weight marked a stone.. That would seem to settle the matter, But it would be nice to have the actual reference fronm HS nimself.******



PS

H

istorically, during the Qin and Han dynasties, the stone was used as a unit of measurement equal to 120 catties. Government officials at the time were paid in grain, counted in stones, the amount of salary in weight was then used as a ranking system for officials, with the top ministers being paid 2000 stones.^[9]In the early days of Hong Kong as a British colony, the stone (石, with a Cantonese pronunciation given as shik) was used as a measurement of weight equal to 120 catties or 160 pounds (72.6 kg), alongside the picul of 100 catties.^[6] It was made obsolete by subsequent overriding legislation in 1885, which included the picul but not the stone.^[10]
https://wikivividly.com/wiki/Picul

No Chu-yen slips are quite clear it is the crossbow that is weighted not the trigger.

For example,

Slip 36.10: 官第一六石具弩一今力四石二斤射百八十五步完
which stats a 6 石 (shi, stone) crossbow now has a weight of 4 石(shi, stone) 2 斤(jin).
There are plenty of other slips that references weighting crossbows.

The "Han Chu-yen Wooden Slips" are excavated in the Edsen-gol River, Inner Mongolia and Gansu Province by the Swedish archaeologist Folke Bergman between the years of 1930 to 1931.
They are a collection of records kept by the Han soldiers in the frontier dug up roughly 2000 years later.
You can find them online as well.
http://ihparchive.ihp.sinica.edu.tw/ihpkmc/ihpkm_op?.85d300571000000000000001E0000^000000006310000000000D013f29

Yes, we do have a lot slips, but perhaps we are misunderstanding what they meant when they talk about a 6 stone crossbow. Question, do we have anything from the Song Dynasty, either marked crossbow mechanisms, or similar types of slips? According to the links HackneyScribe provided, we should see a sudden drop in the rating of the crossbows, since a Chinese "stone" in the Sui, Song, and later dynasties was twice as much as the stone weighted during the Han dynasty.

A 6 stone crossbow in the Han dynasty would only be 3 stone crossbow in the Song, simply because the Song dynasty jin, and hence the stone, was twice as great as a Han dynasty stone. And if we don't have the same evidence for the Song, as we do for the Han dynasty, why not? The Song dynasty was centuries more recent, which makes it more likely we should have even more of the same kind of evidence for the Song than the Han. (Could it be that the Song used less durable paper records over the wooden/bamboo slips?)

We do have Qin or Han era stocks with the trigger still inside them. This confirms those triggers are for handheld versions.
https://en.wikipedia.org/wiki/Histor...seCrossbow.JPG

Yes, but could the same mechanism also be used for a larger siege crossbow? Since the components of the trigger were made by casting, it would be easier to make the same mechanism to work in both hand crossbows and siege crossbows, to simplify logistics and supply. Sure, it would mean over engineering the mechanism for a hand crossbow, but what is wrong with that? Any cost saving is less bronze being used could be offset by having to make additional molds, stocking additional mechanisms.

We have very few prods from ancient China, and none in very good condition, so estimating the draw force from these crossbow prods seems very problematic. Also, compared to Song dynasty, why do we have so many more examples from the earlier Han dynasty? It is not like the Song didn't use crossbows, and you would think that, being centuries newer, they would be more likely to be preserved than Han dynasty crossbows. From what I have been told, the Song crossbows continued the Han dynasty design, it was only in the Ming dynasty you see a major change.

It is just, why would the Ming dynasty go to what you say in a far less powerful design, with no real big advantage? Military technology usually doesn't go backwards like that, and there wasn't in China the same kind of discontinuity due to a collapse that you saw in Europe in the dark ages. There were some major Roman technology that Europe and the world didn't really regain until the 20th century, and we see a broad decline in all kinds of technologies in the early middle ages compared to Roman times, that kind of thing didn't happen in China. If the Han dynasty crossbows were not as powerful as claimed, then the Ming actions all makes sense. Otherwise, it still doesn't make a lot of sense to me, why the Ming would abandoned the superior Han design to adopt a design more similar to European crossbows (short draw length).

[Common Soldier]

PS - traditionally, the picul Chinese "stone", was the weight that a man could carry with a shoulder pole. The Han stone would be only half the weight of the value of the stone in later dynasties, implying in Han times men were considered capable of only carrying half the weight in later dynasties, unless the purpose of the stone changed.

If we had some slips from the Song dynasty, and Song dynasty crossbow mechanisms with the rating on them, it would quickly resolve the,matter. Either the ratings fans slips would show average stone values half the Han dynasty, or it would show the same stone values, indication our understanding of what is meant is likely wrong.

[Hurricane Six]

Han crossbow prod are just very high draw height bow. It was a using a recurve composite bow as the prod. HackneyedScribe estimated at 60% efficiency. which is how he got:

Estimated! By using a general statement of 75% efficiency for light composite bows, then increasing the efficiency of heavy crossbows by decreasing their stored energy. With 1270 joules of stored energy, this Crossbow is 33.9% efficient with a 260 gram bolt and 38.2% efficient with a massive 348 gram bolt (refering to the 1270lb long bpowerstroke great crossbow]. He said it only stored 1064 joules and said it was 45% efficient. He got his numbers wrong! Then he averaged them out and rounded up! Hardly scientific!!!

According to Bilcher: “All my experiments showed an efficiency between 30 and 40% efficency.”

Remember, Hackneyed used the say the efficiency of the han crossbow was 75%:
From HackneyedScribe's original calculation "Typical 6 stone strength Han crossbow's power = 387 lbs draw weight * ~19 inch powerstroke * 75 percent efficiency = 5514.75 inch-pounds”

Nowhere near 60%. If hackneyed was wrong w/ 75%, why would you trust him with his 60% efficiency? Please explain yilmir. Also note that he conveniently edited his 75% efficiency when he found out he was wrong.

Except Andreas Bichler's test on recreated composite crossbow shows there is a positive correlation between power stroke length and efficiency in composite crossbows!
HackneyedScribe did post the Andreas Bichler's result in the blog post I just linked. I believe Andreas Bichler thinks so as well.

Bilcher said the Opposite:

Bilcher Question: Quick Question: Why is this crossbow (long pwerstroke bow) less efficient than this one (short powerstorke Crossbow). Is it because there is no correlation between powerstroke length and efficiency?

Bilcher response: “I think you are right”.

Tell me Yilmir why his 1270lb crossbow with the long powerstroke is less efficient than his 1200 lb crossbow with the short powerstroke? Please explain Yilmir.

And the limbs length of Chinese crossbow (Qin, Han, Song) are significantly longer as shown in records and some archaeological finds, this do prevent stacking and explain why they are that size.
A Qin crossbow was found to have 1.3 meter length prod.

In that case the efficiency would be very low (around 20%) when using medium weight bolts and the crossbow would have a low dry fire speed. A large composite prod would be very heavy and would only perform decently with very heavy bolts (around 40% efficiency max).

By way the, you point on effective lever length is moot. Han crossbow uses heavily recurve composite bows as prods.

All else equal, longer powerstroke, the more stack, regardless of unstrung shape. Your point is moot. Adam korpowicz’s reflexed composites with large draw length to prod ratios stacked violently. See the link below. Notice the coefficients!
http://www.atarn.org/islamic/Performance/performance_table.htm


So if the Han crossbow did have a large heavy prod, it would store more energy, but have a lower dry fire speed much like the tartar bow.

http://www.atarn.org/islamic/Perform...rkish_bows.htm

As side note, you can also see the size of the prod is fairly large as well. .

Which means the prod is heavy, thus reducing efficiency!

Please note I did not use estimates like Hackneyed. I used actual result from real composite bows and in depth modeling.

[Hurricane Six]

Actually, when you compare the efficiency of Andreas Bichler's 1200 lbs crossbow and his 1270 lbs crossbow, the efficiencies are comparable, even though the 1270 lbs powerstroke is much longer. Bichler said the 1200 lbs crossbow had a 190 mm powerstroke,and the 1270 lbs had 375 mm powerstroke.

Make sure to adjust for velocity. The 1200 lb crossbow was shooting at 70 m/s and the 1270 lb crossbow was shooting at 58 m/s. So if you increased the bolt speed of the 1270 lb crossbow to match the 1200lb crossbow, you would get an efficeincy lower than the 1200 lb crossbow. Thus negative correlation between powerstroke and speed!

Straight ffom Bilcher on heavy composite crossbow efficiency:

Bilcher: "50% could be possible but only with a very heavy bolt and at the cost of speed. So a speed between 50 and 60m/s is the best choice between power and large range but the efficiency will be between 30 and 40%."


Here is what Hackneyed said about Bilcher's crossbow's: Originally Posted by HackneyedScribe Bichler's cranequin crossbow have a efficiency of 60% and his Great Horn crossbow have an efficiency of 80%.

http://historum.com/war-military-history/130572-advantages-crossbows-vs-english-longbows-14.html



But it has less than 40% efficiency! Not 80%!

[Common Soldier]

To be fair to HackneyScribe, he used the typical 1/2 * Draw weight * powerstroke = stored energy. That equation assumes a linear increase in draw force per distance string is drawn, which is usually a reasonable assumption for the relatively short powerstroke.

In this case, perhaps because of a relatively long powerstroke, it appears that the 1277 crossbow was not linear. Bichler said he apparently measured the force every 25 mm, so he got the stored energy value from the powe curve. The value of the 1200 lbs stored energy was calculate, so perhaps if he had measured it like he did the 1270 lbs crossbow, the efficienty results would have been different too. Of course, Bichler's results might nave been measuement error too- measuring the force while you draw the string is probably less accurate than measuring the force at the end of the full draw. Misreading of a few values could through off tne stored energy calculations.

But Bichler's results does give pause about using that standard 1/2*F*d formula for bows with longer draw lengths. It is possible that the store energy caluclations for the longer powerstroke Han crossbows could be off. I supposed it might not matter, if the value of efficiency is also adjusted.

There are a few aspects regarding draw weight and powerstroke length.

1. Higher draw weights require more massive prods, so some of the energy is required to moving the prod limbs rather than the arrow, effecting efficiency.

2. Short draw lengths require stiffer, more massive limbs to move, meaning loss of energy to the golt.

3. Lower draw weights means you can use a less massive prod, but you have to move the prod a greater distance, and energy used = Force x distance. = Mass * acceleration * distance. So you save energy by having less mass to move, but you have to move the lighter weight prods a greater distance, which requires more energy. Which scenario would result in overall less efficiency probably depends on the specifics of the bow - the materials used, etc..

4. The shorter draw length has less time and distance to accelerate the arrow, to transfer energy to the bolt. That is often cited as a factor, I am not sure it really is. Even a short distance mignt be enough to effectivelh transfer the energy of the prods to the bolt.


It seems, that the benefit of being able to use a lower draw weight and hence less massive prod outweighs the disadvantage of moving the prod or bow limb a greater distance, for lower draw weights. However, for a high draw weight crossbow like the 8 stone crossbow, I am not sure that applies any more. You are going to have to move a fairly massive prod over a considerably longer distance. A 600 lbs Chinese crossbow mignt be less efficient than a 600 lbs European crossgow, although more powerful due to the longer powerstroke.

Personally, I think the Han 6 and 8 stone crossbows will be more efficient than the 1200 lbs European crossbow, but less than the 60% HackneyScribe predicts, say more like 45 to 50%. That would still make the Chinese 8 stone crossbow more powerful than all but the 1270 lbs European crossbow.

[Hurricane Six]

What was the weight of the Han dynasty crossbow bolt? The Song Dynasty crossbow bolt? The weight of the bolt can significantly effect the efficiency., and for a 60% efficiency, what bolt weight are we assuming? Based on Andreas Bilcher's results, you can't assume efficiency will be the same for all bolt weights. A lighter bolt will give a longer range, but less efficiency

YOu may have provided the question that gives us the definitive proof!. I did not even thin of it!. If we know the bolt weight and the range of the crossbow, we can estimate the energy level!


According to HAcneyed:

Slip 14.026: 一今力五石廿九斤射百八十步辟木郭
Translation: Present strength 5 stone 29 jin (341 lbs) and will penetrate a wooden wall at 180 paces (252 meters).
Slip 515.46: 三石具弩射百廿步
Translation: 3 stone (193.5 lbs) crossbow, fully assembled, shoots 120 paces (168 meters)
Slip 36.10: 官第一六石具弩一今力四石【四十】二斤射白八十五步完（The words in 【】 is used to display what the word on the slip means, but the actual word cannot be typed by computer as the word is no longer in use)
Translation: Number one 6 stone crossbow, fully assembled, present strength is 4 stone 42 chin (285 lbs), and it will shoot to the end of 185 paces (259 meters).
Slip 510.026: 五石具弩射百廿步
Translation: Five stone crossbow fully assembled, shoots 120 paces (168 meters)
Slip 341.3: 具弩一今力四石射二百…(too smeared to make out)…
Translation: Fully assembled crossbow, present strength 4 stone (258 lbs), shoots two hundred and …[text too smeared to make out] (280-418.6 meters).
Slip 14.62A: 一今力三石廿九斤射百八十步辟木郭
Translation: Present strength 3 stone 29 jin (212.2 lbs) and penetrates wooden wall at 252 meters.


Such precise casting techniques allow a more aerodynamic bolt. Because this aerodynamic design only focused on the bolt tip, having the tang of the bolt be made out of iron would not affect its flight. Therefore, with iron being the cheaper metal, it was only natural for Han metallurgists to design crossbow bolts with a bronze head and an iron tang. Regarding weight, it is standard for crossbow projectiles to weigh 2 liang per stone. This meant that a Han quarrel for its most common crossbow of six stone would weigh 93.75 grams.

http://historum.com/asian-history/13...ossbow-ii.html

So range would be between 168 meters and 280 meters. Bolt weight would be 93 grams. This performance is similar to heavy warbows:

A longbowman in "The Great Warbow" sent an 87 gram arrow to 231 meters. So the range of both weapons are similar using a similarly weighted projectile. Using the same longbow, it sent a 74 gram arrow to 260 meters and a 53.6 gram arrow to 328 meters.

So energy levels for a six stone crossbow with a 93 grams bolt shot to 280 meters would have ~160 joules of energy. Using the lower distance of 168 meters, we would get ~90 joules of energy.

Once you know the bolt weight (93 grams) and distance (168 meters - 280 meters), you can estimate the energy levels.

I think we cracked it!

[Common Soldier]

Keep in mind, when you use distance to calculate the energy of a crossbow, you will inderestimate the energy of the crossbow, because the bolt won't go as far as the initial energy of the bolt would predict due to air drag. A not insignificant percentage of the enrgy of tne bolt will be lost due to air friction, reducing the distance the bolt will travel.

It is complicate to calculate the drag, since it depends on tne shape of the bolt, the speed of the bolt etc. to give an idea of the effect on drag. Tod's 1250 lbs crossbolt had a range of 235 m, using an 88 g bolt. That works out to around 101 J based on tne distance the bolt traveled, but the actual energy was 140 J, so about 40J was lost due to air drag. Since drag is speed dependent and the shape of the bolt, it will vary between crossbows and bolts.

[Hurricane Six]

Keep in mind, when you use distance to calculate the energy of a crossbow, you will inderestimate the energy of the crossbow, because the bolt won't go as far as the initial energy of the bolt would predict due to air drag. A not insignificant percentage of the enrgy of tne bolt will be lost due to air friction, reducing the distance the bolt will travel.

It is complicate to calculate the drag, since it depends on tne shape of the bolt, the speed of the bolt etc. to give an idea of the effect on drag. Tod's 1250 lbs crossbolt had a range of 235 m, using an 88 g bolt. That works out to around 101 J based on tne distance the bolt traveled, but the actual energy was 140 J, so about 40J was lost due to air drag. Since drag is speed dependent and the shape of the bolt, it will vary between crossbows and bolts.

I did consider drag. Minimum energy in vacuum would be 280*9.81=2746.8. 2746.8^.5 = 52.4 m/s. 52.4 m/s^2 * .093 X .5 = 128 joules. Keep in mid that Tod's bolts are short and fat. They are like a mack truck. Han crossbow bolts are long and slim like a top fuel dragster. My calculation for the han bolt equals 79% of theoretical maximum range in vacuum. Tod's bolt reached 73.4% of its theoretical maximum range. Even if the han bolt was less aerodynamic than Todd's bolt and reached just 70% of theoretical maximum range, it would have just over 180 joules of energy.

Remember, I calculated a 6 stone Han crossbow at 145 joules @ 70 m/s in a previous post (70 m/s is what I feel is a great velocity that balances efficiency of the crossbow with a flat trajectory and is a good velocity point when comparing crossbows). Based on actual performance data, the Han crossbow is 39% efficient @ 59 m/s (slower speed = higherefficiency for realistic projectiles). This is in perfect agreement with my numbers.

BTW. I used this program to calculate distance w/ drag.

https://phet.colorado.edu/sims/html/...motion_en.html

[Hurricane Six]

On the topic of Chinese crossbows, I found a translation on the most prolific chinese crossbow: the Chu-ko-nu.

"Zhuge Crossbow, it has a straight magazine on top containing over 10 bolts, its wings (the bow part?) is made up of the softest wood. With a separate wooden mechanism, it quickly loads and looses. Though intricate, its power is weak, so its range merely 20 paces."

20 paces seem a bit short, but I think they are talking about the effective range, not maximum. Accuracy was also likely poor (no fletchings), but it served the Chinese well into the 19th Century and remained virtually unchanged since its inception.

I couldn't find projectile energy levels, but ~30 joules seems about right.

I also been looking into the accuracy of bows, crossbows and early firearms. Seems to be a lot of misinformation about the relative accuracy of these weapons. I will likely start a new thread detailing the accuracy levels of these weapons. So watch out for that! The results are eye opening to say the least!