88 replies to this topic

[Tibet Libre]

Whats your problem? Do you want to cut off what has been otherwise a good discussion? Half of my posts I am obliged to attend to you trying to tell me which questions I am allowed and not allowed to pose. I am comparing stone thrower with stone thrower, if the concept of a stone is too difficult grasp, then what can I do?

So please lets keep the discussion on the topic without these endless diversions. I am well aware that torsion and traction catapults differ in a whole array of aspects, a couple of them you have mentioned, but right now I am just interested in

a. their respective effective ranges
b. typical sizes of projectiles
c. typical sizes of pulling crews

in theory and in what is recorded by the ancients.

Good day.

[Borjigin Ayurbarwada]

The weight of the stone thrown is the crucial difference between the trebuchet and the torsion catapult.

Here is the quote from Needham:

"A word or two may be added about the projective weights and ranges of these catapults. Estimates for the torsion types in ancient Greek texts vary between 160 and 600 yards for missles weighing up to 10 lb but the probable average, partly derived from experience with modern reconstructions, was really 330 to 410 yards. This span coincides with Chinese arcuballista figures (270 to 500 yards.). Ancient European sling and torsion catapults (onagers) threw stones of about 50 lb weight, occasionally up to 175 lb but never much more than 160 yards. Manned trebuchets sent larger missles, up to about 275 lb, from 80 to 190 yards, and fixed counterweight ones had a somewhat longer range. Anything as heavy as this was already dangerous for defensive masonry, whatever its character."

Range depends on the crew but the stones thrown by the trebuchet are usually twice as heavy with almost equal distance.

Comparing simply the range is meaningless, in fact stones of 100 ibs aren't going to do much against the ramed earth walls of Chinese fortifications, which are thicker and sturdier, it doesn't matter how far or fast a machine can throw the weight of their missile or how little crew they possess, if they can't even damage the fortification walls.

Edited by warhead, 27 April 2006 - 11:19 AM.

[Mei Houwang]

Whats your problem?

The need to make one side superior than the other. That's the problem. Any discussion that needs to make one country "better" than the other isn't a good discussion.

Edited by Anthrophobia, 27 April 2006 - 11:29 AM.

[Tibet Libre]

I dont know about these figures, looks to me all a bit confused and outdated.

For a start, he doesnt say which Chinese arcuballista he refers to (one bow, multi bow?) and with the trebuchet he doesnt carefully differ either. Take a look at Mick's article and you will see that even early non-pulling crew trebuchet dont surpass torsion catapults with comparable stones sizes:

Thus a "single bag counterweight beam sling on a trestle frame" from about 1100 AD has an effective range of 116m with 45 kg. Not too different from the figures I gave above for the 28 kg torsion ballista.

But anyway, I am not interested in counterweight trebuchets, but the pulling crew trebuchets (which I prefer to call traction catapults, because they were so much less powerful). Guess I have to wait for the ingenieur chinois de siege.

The need to make one side superior than the other. That's the problem. Any discussion that needs to make one country "better" than the other isn't a good discussion.

Last time I checked I was comparing catapults. Dont know though what you are doing.

Edited by Tibet Libre, 27 April 2006 - 11:47 AM.

[Borjigin Ayurbarwada]

I dont know about these figures, looks to me all a bit confused and outdated.


For a start, he doesnt say which Chinese arcuballista he refers to (one bow, multi bow?) and with the trebuchet he doesnt carefully differ either. Take a look at Mick's article and you will see that even early non-pulling crew trebuchet dont surpass torsion catapults with comparable stones sizes

They actually match the figures you gave quite well. The figure from your source of 28 kg is roughly 60 ibs. And 157 meter match Needham's "never much over 160 yards"

And your source says that "the lithobolos threw stones of 4,5 to 82 kg in weight" and on p.179 a onager is depicted which "shows a 80 kg" onager and, if I am not mistaken, one or two of the ancient catapult treatises mentions throwing 78 kg projectiles, but it must have been in any case a rare occurence, since a find of an arsenal of ancient artillery stone balls at Pergamum shows only two 78kg projectiles and thirty-three 52 kg projectiles among a thousand (Osprey, p.20)!85 kg is roughly 175 ibs. "

Its pretty much what Needham gave as well.

"Ancient European sling and torsion catapults (onagers) threw stones of about 50 lb weight, occasionally up to 175 lb but never much more than 160 yards."

Needham give his sources at the very bottom of the page. And his Chinese figures are taken from primary sources. There are no reconstructions for Chinese equipments of Han because there are limited sources on how they are reconstructed, and there haven't been much excavations found. But the fact that trebuchet can throw up to 275 pounds is not just the Chinese trebuchet, but manned powered trebuchet in general.

Thus a "single bag counterweight beam sling on a trestle frame" from about 1100 AD has an effective range of 116m with 45 kg. Not too different from the figures I gave above for the 28 kg torsion ballista.

This is not about comparing the distance under the same size of stone thrown, but the Counterweight's ability to throw larger stones weighing up to a ton, which the torsion catapult cannot do.(the same goes with manned).

Second, manned trebuchet isn't inferior to the counterweight, they are just used differently. The counterweight is solely used for its destructive power, otherwise it is inferior in speed.
The small manned trebuchet can be assembled and fired at a faster rate than the counterweight. Thats why Zhu Yuan Zhang of the Ming dynasty prefered the manned trebuchet in siege over those of the counterweight.

Edited by warhead, 27 April 2006 - 02:32 PM.

[Tibet Libre]

They actually match the figures you gave quite well. The figure from your source of 28 kg is roughly 60 ibs. And 157 meter match Needham's "never much over 160 yards"

You are now comparing ballista with onager, but, as I said, I am interested in comparing ballista with the manned traction catapult.

"Ancient European sling and torsion catapults (onagers) threw stones of about 50 lb weight, occasionally up to 175 lb but never much more than 160 yards."

Yeah, that what LJ said earlier, the onager and the manned traction catapult have comparable ranges under similar load.

But the fact that trebuchet can throw up to 275 pounds is not just the Chinese trebuchet, but manned powered trebuchet in general.

That why I asked LJ to feed his programm with some bigger sizes, just to show what effective ranges the manned traction catapult reaches under heavier loads than 1 or 20 kg.


LJ,

couldnt you post the link to your catapult calculator? Or feed it please with 50, 75, 100, and 150 kg.

Edited by Tibet Libre, 27 April 2006 - 04:09 PM.

[Mei Houwang]

Last time I checked I was comparing catapults. Dont know though what you are doing.

Nope, you are comparing "torsion catapults" to trebuchets. A usual torsion catapult is not a catapult but a ballista in every way except that it throws stones instead of bolts. That is what you are doing(and other things on cultural superiority, it doesn't take much mindpower to soak up all the posts in every thread and realize that it constantly compares how the things of Europe is better than everybody else in certain things).

Edited by Anthrophobia, 27 April 2006 - 06:28 PM.

[Borjigin Ayurbarwada]

Yeah, that what LJ said earlier, the onager and the manned traction catapult have comparable ranges under similar load.

This is not important, the traction catapult exerts a greater force, and hence can also throw heavier stones. It has the ability to throw weights twice as heavy over roughly the same distance as well, it depends on the crew size and the design itself.

[Liang Jieming]

You are now comparing ballista with onager, but, as I said, I am interested in comparing ballista with the manned traction catapult.
Yeah, that what LJ said earlier, the onager and the manned traction catapult have comparable ranges under similar load.
That why I asked LJ to feed his programm with some bigger sizes, just to show what effective ranges the manned traction catapult reaches under heavier loads than 1 or 20 kg.
LJ,

couldnt you post the link to your catapult calculator? Or feed it please with 50, 75, 100, and 150 kg.

The catapult calculator is a small programme. I can e-mail that to anyone who's interested. Just drop me an e-mail.

Here's the chart different projectile weights based on a 250men puller catapult (all other catapult specifications the same).



The graph shows a nice linear relationship between range and projectile weight. I suspect this would be just as true for torsion onagers as well.

********************************

I just spoke to Mick on his comments on onagers. He actually doesn't cite any primary sources, with his main two sources being the Greek and Roman Artillery book by Marsden and an Osprey series book.

This is not important, the traction catapult exerts a greater force, and hence can also throw heavier stones. It has the ability to throw weights twice as heavy over roughly the same distance as well, it depends on the crew size and the design itself

Warhead, if you don't mind, let me restate this in clearer terms.

The traction catapult doesn't exactly exert greater force, it just has a more variable ability compared to the onager. The same traction catapult frame can be made to range further, throw heavier projectiles, projectile trajectory etc. simply by manipulating the pullers on the catapult ie. playing with the number of pullers as well as varying the way the ropes are pulled/held (within a reasonable range due to constraints like standing space and throwarm strength). The onager has only two variables which can be changed, the torsional potential of the sinew/hair and the throwarm barrier. The sinew/hair has a limited range in which it can be torsioned. The relationship between the torque applied to the throwarm is not linear. Over torsioning will snap the sinew. Releasing torque on the sinew not necessarily gives an even reduction in range because you need to factor in creep in the sinew after long periods of maintaining a high torque. The torque in the sinew also needs to be maintained, again due to creep in the fibre. The better variable is the throwarm barrier which can be moved forward or backwards to change the angle where the throwarm is stopped ie. the projectile trajectory, but this is harder than it sounds because of the sling. Insuffient throwarm rotation would not fully deploy the sling. The release pin at the end of the throwarm is also needs to be readjusted to suit a new throwarm barrier angle or the sling might just shoot the projectile straight up, or worse, backwards.

Edited by Liang Jieming, 28 April 2006 - 02:25 AM.

[Liang Jieming]

Here's the graph for Projectile Weight vs. Number of Pullers (Men) with range constant at 50metres. This was probable the greatest advantage of the traction catapult, it's ability to vary it's projectile load without sacrificing range.

Very nice linear relationship. Easy for catapult commanders to calculate on the field. If 40men could fire a 25kg projectile 50m, and a 50kg projectile could be fired the same 50m by 64men, then a 75kg projectile requires 64 + (64-40) = 88men. Q.E.D.

[Liang Jieming]

Hmmm... all this work and no comments guys?

[Mei Houwang]

I want to comment but I can't think of anything. I think this goes for a lot of people in this forum. But if you keep on posting I'll keep on reading.

Edited by Anthrophobia, 13 May 2006 - 04:52 PM.

[shurite7]

Hmmm... all this work and no comments guys?

With this indepth material I think the only person who can respond is Mick from Switerland.

Cheers

chris

[Liang Jieming]

Hehehe ok then. I'll just keep posting more info then.

[Liang Jieming]

I been thinking and staring at the graphs for awhile now. The question that just begs to be asked is that whether a catapult design exists that would allow a traction crew to throw a decent sized projectile to the same ranges as the hinged counterweight catapults did. Surely they could since the only difference between the two was the counterweight pull force.

If I took a 350m range medieval hcw (hinged counterweight) treb, removed the hcw and replaced it with the equivalent number of pullers required to generate the same downward force, pulling at 9.18m/s acceleration downward (ignoring the contraint of space for some many people underneath the catapult), I dare say this reconverted traction catapult would perform exactly the same as the original hcw treb would.

Does anyone know what a typical weight for a medieval treb would have been? 5,000kg? 10,000kg? 20,000kg?

Edited by Liang Jieming, 17 May 2006 - 01:34 AM.