Polybolos

[Anonymous]

Is there any evidence that the Romans used the polybolos? <p></p><i></i>

[Dan Howard]

[resurrect old thread] No replies? Philon gives a detailed description of it. Dionysius describes something similar in the 3rd C BC. Does anyone have any other evidence for it? Was it commonly used by the Romans?

[Crispvs]

Alan Wilkins has make a working model of a polybolos which we have used in one or two demonstrations but simply to demonstrate the principle, as he says that it seems to have been used for only a short time and fell out of use some time in the third century BC. He suggested, based on the results of tests he did with his reconstruction, that the reason for its discontinuation was that it may have been too accurate and thus two predictable, as several projectiles hitting the same spot in quick succession would have told defending soldiers exactly which spot to avoid. Thus he guesses that although the principle was fantastic it may not have been a very effective weapon in reality.

Crispvs

[Carus Andiae]

Yes, Alan Wilkins' polybolus was demonstarted on the Adam Hart-Davis programme What the Romans Did For Us. They encountered the problem of excessive accuracy.

[Dan Howard]

I find it hard to believe that a weapon would have been discontinued because it was TOO effective. It is possible that it was not suitable for siege warfare but a weapon of this accuracy and rate of fire would have dozens of applications on a battlefield.

[Crispvs]

Do we know how often artillery was employed in open battle during the Hellenistic period? I was under the impression it was considered useful either as static (albeit often traversable) defences or as siege engines. In either of these applications a weapon which was too predictable to the enemy would be of debatable value to its owner, versus something which the enemy could not predict and therefore prepare for. Perhaps someone with a greater knowledge of Hellenistic warfare than me would like to comment.

Crispvs

[Dan Diffendale]

Could not the machine simply be rotated a smidge? Solves your over-accuracy "problem."

[Carlton Bach]

I don't know the exact details of this weapon, but if the draw weight is identical to regular scorpiones, wouldn't the spanning time be fundamentally the same? Could the polybolos mechanism improve the time it took to draw back the string? I doubt it, and if not, the only operation that was made easier was the loading of the bolt into the groove. The energy still needs to be put in manually by the same number of men using the same mechanism. That means little time savings, but a personnel saving - one less loader. That is not as significant a difference in the first place, and if the polybolos has to be manually re-aimed after every shot anyway, it probably just wasn't worth the effort.

[aitor iriarte]

And, oh heck! Most of my books are currently packed in crates! :x
If I recall well, the main reason why Filon dismissed the Polybolos was its lack of power compared to a normal catapult of the same size... (Please correct me if my memories are blurred, as usually... :oops: )
Wilkins' reconstruction on the BBC programm cannot be a better prove of the machine's feebleness, you could achieve almost the same range throwing the arrows by hand...
Notwithstanding, the Chinese developed a very similar system for their portable bamboo crossbows, which remained in use to the end of XIXth century! hock:

Aitor

[Crispvs]

Both Alan Wilkins' reconstruction and an earlier one by General Erwin Schramm utilised a chain drive mechanism worked by rotating a revolving handle back and forth. This drive both cocked and released the shooting mechanism as two parts of one action. It also released bolts one at a time into the slider track from a magazine above which could be stocked with six bolts. I have not read the original details of the polybolos so I don't know how much of this detail comes from the original writings but if Wilkins and Schramm both employed the same principles I think there must be some documented basis for each element.

Regarding the speed of reloading, using the chain drive mechanism Alan's rate of fire was impressive. During a session to compare the differing rates of fire of our different artillery pieces, we were probably reloading and shooting as fast as we have ever been able to and managed to achieve a rate on both the manubalista and trispithimus of just on three bolts per minute. For comparison, even at this rate of shooting we were still loading our second bolt when Alan shot his sixth from the polybolos, demonstrating the speed achievable with the chain drive.

With this stunning rate of fire, as Alan Wilkins says, there must have been a very sound reason for it not continuing in service for very long. The only thing he has been able to suggest (on the assumption that cost would not have been a significant factor if it was so very useful) is that one of its apparently good features must have acted as an Achilles heal and he concluded, based on a comparison with the Bren gun (which was too accurate at first and had be be deliberately damaged in order to achieve the spread required of a machine gun) that the accuracy was probably what made it undesirable.
I have not seen Alan Wilkins for well over a year now and so I do not know if he has done any more work on the polybolos project. Perhaps the next conversation will be as enlightening as the last.

Crispvs

[Dan Howard]

I am thinknig that the Bren gun being deliberately damaged is a myth. Its spread was considered too concentrated for suppressive fire but its accuracy was welcome in many other tactical aspects on the battlefield. I can't find anything to suggest that it was deliberately crippled to reduce its accuracy. Though I don't normally like Wikipedia this entry covers the main points fairly well.
http://en.wikipedia.org/wiki/Bren_gun

If the draw strength was too low to give penetration or decent range, then this seems the most likely reason for it not being used. Unless reliability was perhaps a problem.

[Carlton Bach]

A *single person* can operate the polybolos at an impressive rate of fire? What exactly is the draw weight? It can't be much - in fact, it almost has to be less than the bog-standard crossbow. If the weapon is that weak, what's the point? Might as well just throw javelins - a good javelineer doesn't jam or seize up, and he can aim better.

The Chinese repeating crossbow was very weak - that was why it was designed for distraction and harrassment, not a killing weapon.

[Arngrim]

Why would a fixed-fire repeating weapon be inefficient? I remember using that principle in my military training. In low/non-existing visibility situations (Before night-vision eqipment made its appearance in the Swedish army) we made fixtures for our fire-arms, for interlocking lines of fire. Granted, the combat experience of the swedish armed forces are a little scarce since the Napoleonic wars, but we learned from the Finns, who, unlike the Germans, thwarted the Soviet avalanche 1944.
(Does my swenglish make sense?)

[ambrosius]

I am thinknig that the Bren gun being deliberately damaged is a myth. Its spread was considered too concentrated for suppressive fire but its accuracy was welcome in many other tactical aspects on the battlefield. I can't find anything to suggest that it was deliberately crippled to reduce its accuracy.

Absolutely! A Bren gun being deliberately damaged? What are you on,
Crispus, man? :lol: Since when was it considered a disadvantage for an
automatic weapon to be "too accurate" (by which, I take it you mean:
'too consistent/precise in its fall-of-shot')? ROTFL

What about the German MG34/42, then, with a rate of fire of 1,000 rpm?
Did the Germans ever worry about having 100 or so rounds fall on the same target? That's called firepower. For starters, at 1,000 yards, you only have to waggle the stock slightly to achieve an enormous spread of
shot, either right-to-left or up-and-down, which gives you a spread in
both latitude and range. It's far preferable to have a weapon which is
accurate/constistent in its fall-of-shot, and then leave the gunner to
adjust the spread himself as he sees fit. I'd way prefer that to having
something which couldn't hit a barn-door at 100 yards and just spat fire
all over the place. And the same goes for ballistae.

Now, as for the specific case of the Bren, my Grandad was a marksman
in WWII, and he valued the Bren's accuracy as a sniper's weapon. He
said it could also be sellected for either rapid-fire or single-shot, in the
circumstances when you might want to use it as a sniper's weapon. All in
all, it was a very versatile weapon. Light enough to be carried and used
by one man (unlike belt-fed MGs) accurate enough to snipe with, yet
also with the option of high firepower.

If the draw strength was too low to give penetration or decent range, then this seems the most likely reason for it (the Polybolos) not being used. Unless reliability was perhaps a problem.

Absolutely again. :wink:

Ambrosius

[Dan Howard]

So do we have any figures for the draw weight of this thing?