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Timo Nieminen




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PostPosted: Fri 27 Apr, 2012 2:21 pm    Post subject:         Reply with quote

That's if the loaders need to work at full power to do the slow loading, and their maximum power output is the same using both methods of loading.

For a lot of human motions against resistance, the limit is how much force can be exerted, not power. Energy = force * distance, so fast and slow can yield the same stored energy. Power = force * velocity, so the maximum power does limit how fast you can do it, but if the fast motion is much slower than this maximum power limit, the slow motion won't produce much more force.

If the slow method is a short-handled windlass, compared with a fast method using a long lever involving a lot of all-body motion, the slow method will be lower power.

(Not watts/second, but watts * seconds, which is the already-existing joule (J).)

"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Matthew Amt




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PostPosted: Fri 27 Apr, 2012 6:47 pm    Post subject:         Reply with quote

Right, it's the *distance* the arms are moved that matters, not the time it takes to move them. The springs store the energy generated by their twisting. Time *will* be a factor in the discharge: slow-moving arms will impart less force than faster-moving arms of the same weight and length. From what I've seen of catapults going off, the technical term is "pretty darn fast!"

Matthew
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Kevin S.





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PostPosted: Sat 28 Apr, 2012 8:56 am    Post subject:         Reply with quote

I have some more questions for Mr. Matthew Amt and anybody else knowledgeable with this subject about the Roman onagers.

To clarify, this is the machine


I have heard that there are many reliable modern day replicas of the Roman onagers.
1.Which reliable replicas have the highest the maximum throwing range with the heaviest weights?

2.What is the accuracy of the Roman onagers, based on reliable replicas?

3. What is the rate of fire of the onagers?

Thank you
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Matthew Amt




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PostPosted: Sat 28 Apr, 2012 3:34 pm    Post subject:         Reply with quote

Oog, unfortunately I don't think any of those questions can be conclusively answered. For ballista-style artillery we have a good description combined with a number of depictions and archeological finds, but I don't think there is any of that for the onager. The reconstructions I've seen vary quite a bit, and I have no idea which ones might be more historically accurate. (Many that I've seen are clearly NOT accurate, more like big toys--though they can be impressive!) Shooting one of those can tell you "The actual Roman machines could probably shoot at least this far", but not a lot more.

Also have to say that that little illustration does not look very convincing to me! I suspect it's too tall, for starters, and that the missile should be held in a sling, not a cup. The spring and the winding mechanisms should be more visible! On many reconstructions, the arm travels through an arc of 150 degrees, not just 90, though I don't know which may be correct. These are just my gut reactions--I don't want to sound like an expert on artillery, because I'm not!

Vale,

Matthew
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D. Phillip Caron




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PostPosted: Sat 28 Apr, 2012 7:46 pm    Post subject:         Reply with quote

Thinking about how an automatic bow might have worked is interesting, but what would be the target? An arrow is target specific. It's target would have to be very large. The weapon would have to be re sited periodically due to vibration. Like modern artillery it would have natural projectile dispersion to left and right as well as depth. A massed infantry target would be reasonable, but a ship would not be so. The target would have to be big and slow moving. As a defensive fort type weapon it could be effective given an indirect fire means (no line of site). Set it in the middle of camp, rotate it to the needed direction then fire over the wall at the distant target..
I have no doubt that the Romans could make one of these things, but it's use would have been somewhat specific.

The first casualty of battle is bravado, the second is macho.
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William P




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PostPosted: Sat 28 Apr, 2012 10:14 pm    Post subject:         Reply with quote

also note that it has a counterweight

and more importantly its from the game rome total war'

this catapault is DFINATELY not historically accurate as is much of the game.

the repeating ballista also exists in the game its 2 drawbacks in the game are less accuracy and less range than the long range ballistas (for ierd reasons the scorpian is the long range ballista and the stone throwing ballistas are non existant. )but range is the same but less accuracy than a regular ballista.
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Matthew Amt




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PostPosted: Sun 29 Apr, 2012 7:26 am    Post subject:         Reply with quote

D. Phillip Caron wrote:
Thinking about how an automatic bow might have worked is interesting, but what would be the target? An arrow is target specific. It's target would have to be very large.


Any formation of troops! Especially some section or unit that was thought to be a particular problem, like a cavalry unit or an elite group of infantry. Or you could focus on a command group, which could include not only the general but aides, messengers, horn-players, standard bearers, and guards--quite a nice and recognizable cluster. Even if you don't kill the general, you'd keep him hopping and moving and ducking, looking for cover rather than keeping an eye on the battle, directing his troops, and being a huge inspiration to them simply by being visible. The psychological effect of that would be enormous.

One of the huts at Maiden Castle apparently attracted some attention, since the area around it is peppered with catapult bolt heads. It must have been a rallying point during the attack.

Josephus tells a story of a siege in the Jewish Revolt. Up on the wall, all the defenders were hunched down behind the battlements taking cover. Josephus and another officer wondered what was up, and the other officer steps up to an embrasure and looks out. His head was immediately knocked off by ballista stone. The machine had been "sighted in" on that spot and the crew was just waiting for a head to appear to pull the trigger.

So the targets don't have to be *very* large, really. It certainly helps if you have a chance to do some preparatory shots, but I expect plain experience would help a lot with that. I agree that the repeater would need constant adjustment in aim, but if you had one guy cranking and another aiming, that would work--literally a "machine-gun" crew!

Quote:
As a defensive fort type weapon it could be effective given an indirect fire means (no line of site). Set it in the middle of camp, rotate it to the needed direction then fire over the wall at the distant target..


Hmm, better just to put them up on the rampart. It's pretty clear that at least sometimes the Romans built special bastions or platforms for the artillery, if needed. And there are plenty of machines, so it's no problem to disperse them around the perimeter. Plus, camps may be larger than you think! A catapulta in the middle of a 50-acre marching camp would not shoot much farther than the ramparts.

Valete,

Matthew
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D. Phillip Caron




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PostPosted: Sun 29 Apr, 2012 7:48 am    Post subject:         Reply with quote

I doubt that the 10,000 failures in usage would have been well documented. I base my observations above on a lifetime spent as a war planner and war fighter. Weapons and tactics do change, but the principals remain the same.
The first casualty of battle is bravado, the second is macho.
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Kevin S.





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PostPosted: Sun 29 Apr, 2012 8:16 pm    Post subject:         Reply with quote

Matthew Amt wrote:
Oog, unfortunately I don't think any of those questions can be conclusively answered. For ballista-style artillery we have a good description combined with a number of depictions and archeological finds, but I don't think there is any of that for the onager. The reconstructions I've seen vary quite a bit, and I have no idea which ones might be more historically accurate. (Many that I've seen are clearly NOT accurate, more like big toys--though they can be impressive!) Shooting one of those can tell you "The actual Roman machines could probably shoot at least this far", but not a lot more.

Also have to say that that little illustration does not look very convincing to me! I suspect it's too tall, for starters, and that the missile should be held in a sling, not a cup. The spring and the winding mechanisms should be more visible! On many reconstructions, the arm travels through an arc of 150 degrees, not just 90, though I don't know which may be correct. These are just my gut reactions--I don't want to sound like an expert on artillery, because I'm not!

Vale,

Matthew


Aww shucks Sad Thanks for the answer anyways.
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William P




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PostPosted: Mon 30 Apr, 2012 5:15 am    Post subject:         Reply with quote

oh and one benefit ive realised of the repeating ballista is really in a way similar to the benefits of Squad based LMG's, one old american WW2 video showcasing the weapons for infantrymen noted that a BAR has the capacity to fire the same amount of bullets as about 5 men with M1 garands so therefore in the capacity of laying down suppressing/ covering fire, a BAR can replace 5 men with M1 garands, leaving those 5 men to do something else like flank an enemy position.

the repeating ballista may work similarly. say it takes 2 men to operate a repeating ballista (one o operate the mechanism, the other to aim and shoot and a regular ballista of comparative size, requires about 3 men (one to load one to crank and one to direct the fire, ) to operate,
if 1 repeating ballista can shoot at a rate thats 3 times faster than normal ballistas, therfore to have 1 repeating ballista relieves 3 ballistas from having to provide covering fore for a seige tower say, these 3 leftover ballista can therfore be set to do something else, maybe provide fire on another area of defences, or if in the field, shooting at another battalion

another question about the polybolos.

was the polybolos truely a eurythone aka 'giant crossbow' ballista like the mythbusters version was, or was it a palintone aka a torsion catapault? note it was made by dionysis the elder if i remember correctly
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Leo Todeschini
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PostPosted: Mon 30 Apr, 2012 5:12 pm    Post subject:         Reply with quote

A chap I am working with just sent this link about repeaters.

http://www.sciencedirect.com/science/article/...4X09001402

Tod

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Kurt Scholz





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PostPosted: Thu 22 Nov, 2012 10:22 am    Post subject:         Reply with quote

William P wrote:
oh and one benefit ive realised of the repeating ballista is really in a way similar to the benefits of Squad based LMG's, one old american WW2 video showcasing the weapons for infantrymen noted that a BAR has the capacity to fire the same amount of bullets as about 5 men with M1 garands so therefore in the capacity of laying down suppressing/ covering fire, a BAR can replace 5 men with M1 garands, leaving those 5 men to do something else like flank an enemy position.

the repeating ballista may work similarly. say it takes 2 men to operate a repeating ballista (one o operate the mechanism, the other to aim and shoot and a regular ballista of comparative size, requires about 3 men (one to load one to crank and one to direct the fire, ) to operate,
if 1 repeating ballista can shoot at a rate thats 3 times faster than normal ballistas, therfore to have 1 repeating ballista relieves 3 ballistas from having to provide covering fore for a seige tower say, these 3 leftover ballista can therfore be set to do something else, maybe provide fire on another area of defences, or if in the field, shooting at another battalion

another question about the polybolos.

was the polybolos truely a eurythone aka 'giant crossbow' ballista like the mythbusters version was, or was it a palintone aka a torsion catapault? note it was made by dionysis the elder if i remember correctly


The idea that a more automated ballista can operate faster or with less personnel is an interesting approach and much better than the "ancient machinegun"-nonsense.
Less persons to operate would make sense for the limited space in riverine patrol boats, as reconstructed in the Mainz shipping museum.
Faster operation could have been the initial driving idea, but it's rather about replacing the bolt loader and add him to the cranking crew with corresponding increase in rate of shot (like 2-3 times faster than the standard version).
The Chinese repeating crossbow highlights how very high rate of shot in human powered devices results in low kinetic energy output for projectiles.
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Alexander H.




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PostPosted: Tue 15 Sep, 2020 6:28 pm    Post subject:         Reply with quote

Bumping this topic:

With my newfound ability to access papers behind paywalls I have stumbled across the amount of kinetic energy a carroballista firing projectile weights of 195 grams can generate:

Lead Ball: 688 joules at 171 meters, 491 at 312 meters, 412 at 408 meters.
Bolt 772 at 178 m, 608 at 320 m, 505 at 442 meters.

I've attached an image to this post.

Below is a link to the paper's abstract.

https://www.sciencedirect.com/science/article/abs/pii/S0094114X14001529



 Attachment: 205.42 KB
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