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Salve John!
I don't know if operating this machine at 'full' power is such a good thing, we will not be doing this other than for our tests. Yes, it's true that the Roman army did but they had artillery specialists at hand to repair any damage. Personally I see operating this machine at full power being an unnecessary risk to both the public and the operators.
We will be pushing our machine to it's limits in May (at our own risk) and we may well have a failure of one or more of it's elements, but we will be taking full precautions to ensure safety of the operators (no public will be present). Len will be on hand to repair any failures as a result of our cavalier use of the machine but the data collected should be worth the risk.
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Be careful, do take good notes, and gigs of pix, and let us know how it goes. Your data may be some of the most important in quite a few years. Are you planning to skewer any shields, to see how that goes?
Oh, and put a long lanyard on the trigger mechanism. If it comes to it, the further away you're standing, the better your chances of escaping injury.
M. Demetrius Abicio
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Indeed, do take care: ours always makes me want to cower beneath my anti-cavalry shield. (yep, Len's build, details at http://www.comitatus.net/research_files/ballista.htm )
I look forward to seeing the results of your tests. 
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Salve David!
No, we won't be doing any penetration tests. This is primarily because I would like to use a target with well defined and repeatable characteristics and shields can vary in composition. Ballistic putty is expensive stuff so I'll have to leave that one for a while.
The main function of the tests will be to record and calibrate a set if ballistic tables for this particular machine. That involves measuring velocities, pull back force, firing angle and ballistic trajectories for each projectile fired. The main problem I see us having is in achieving a constant firing velocity when calibrating the ballistic table as the 'bow' string and springs will change subtlety over the duration of the test.
In an effort to come up with a compensating metric we will attach a strain gauge onto the foreside of each of the outer arms. This will allow us to know the pullback force for each shot. This can then be compared to the resultant firing velocity hopefully resulting in a calibration graph of strain versus velocity. We can then use the strain gauges to pull back the arms to a position where the resultant firing velocity is known and can be kept constant.
At the end of all this we should have a number of useful statistics. First we can measure the maximums such as pull back force, discharge velocity, distance etc. Secondly we will have a set of ballistic tables including projectile trajectories i.e. a series of tables relating pull back force versus firing angle. This will be done for 3 pull back settings and firing angles from 0 to 60 degrees elevation in steps of 5 degrees.
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Nice work by Len and it clearly works unlike the one waved about in France last year.
Yes its a Manuballista so why mount it on a stand!! It has no recoil so why fit it with an MG42 Butt??. How is it spanned? If its a belly bow do you have to unstep it from the stand each time you have to span it in which case do you really want an upright butt in your gut?
If its a winch then its hardly a Manuballista!!
Manuballistarius and proud of it
Quod imperatum fuerit facimus et ad omnem tesseram parati erimus
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Quote:Nice work by Len and it clearly works unlike the one waved about in France last year.
Yes its a Manuballista so why mount it on a stand!! It has no recoil so why fit it with an MG42 Butt??. How is it spanned? If its a belly bow do you have to unstep it from the stand each time you have to span it in which case do you really want an upright butt in your gut?
If its a winch then its hardly a Manuballista!!
Manuballistarius and proud of it
:? ? ? You really have me confused there derek...
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Quote:derek forrest:3a22z6sm Wrote:Nice work by Len and it clearly works unlike the one waved about in France last year.
Yes its a Manuballista so why mount it on a stand!! It has no recoil so why fit it with an MG42 Butt??. How is it spanned? If its a belly bow do you have to unstep it from the stand each time you have to span it in which case do you really want an upright butt in your gut?
If its a winch then its hardly a Manuballista!!
Manuballistarius and proud of it
:? ? ? You really have me confused there derek...
I think Derek is thinking along the same lines as Duncan's post earlier in this thread. It's a pretty basic concept to which some of us subscribe. It goes something like this...
Greco-Roman artillery can be divided into two major categories, individual hand-held weapons and larger crew-served weapons mounted on stands. Examples of hand-held weapons would be the gastraphetes(Heron), Xanten (the scorpio minor?), cheiroballista, and manuballista. The common and defining features of the hand-helds whether torsion or tension, wooden or iron-framed, in-swinger or out-swinger would likely have been portability, linear ratchets, and the ability to span the weapon manually (belly-cock, hand span or some combination) without resorting to an unwieldy turnstile or levers. Their larger cousins the scorpio major, ballista, and carroballista sacrificed mobility for the sake of power and range. Since they were mounted on stands a rear mounted winch could be used. The Greeks used linear ratchets, the Romans used rotary ones. After Vitruvius they apparently dropped the drum-and-pin type mechanism and adopted two individually ratcheted levers (Cupid Gem). By interpreting the washer diameter as much larger than the ones sucessfully demonstrated by Aitor Iriarte, Alan Wilkins has increased the draw weight so much that a winch is needed. Along with the winch he includes a linear ratchet (belt-and-braces for safety sake like my dad wears). Add to that four enormous bronze locking rings, and what was intended as a portable weapon has now become a slightly undersized crew served weapon. Neither quite fish nor fowl. He wisely chooses the Itallic A shaped Cupid Gem Base rather than the Vitruvian. Curiously, he retains the hinged prop from the Vitruvian, but then uses the crescent shaped fitting to support the case during winching. This is just as well, because if it isn't used to belly-cock the weapon it has little reason to be there. Like everyone else I admire the crafstmanship on these weapons and I can understand why they have become the gold standard, it's just that my interpretation of the available evidence leads to much different conclusions.
P. Clodius Secundus (Randi Richert), Legio III Cyrenaica
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Salve Randi
Have you read Alan's papers on the machine and the reasons he's come to this design? I'd be interested to know specifically at which point you part company with Alan's conclusions. Don't forget Marsden came to much the same conclusion himself. Alan did not use Marsden's research as such, he re-evaluated all available data from source, Greek, Latin and other from first principles i.e. translated all source material for himself.
I cannot read Greek and my Latin is poor to say the least, so I feel I'm not in a position to make an argument either way as I cannot interpit the source material let alone get my hands on it. Have you 'read' the various original source material?
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A point Alan has made to me is that the sources (Heron?) state that winches were added to artillery because torsion springs (made of sinew remember) were too powerful to draw by the power that a human alone could exert.
Crispvs
Who is called \'\'Paul\'\' by no-one other than his wife, parents and brothers. :!: <img src="{SMILIES_PATH}/icon_exclaim.gif" alt=":!:" title="Exclamation" />:!:
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Quote:Salve Randi
Have you read Alan's papers on the machine and the reasons he's come to this design? I'd be interested to know specifically at which point you part company with Alan's conclusions. Don't forget Marsden came to much the same conclusion himself. Alan did not use Marsden's research as such, he re-evaluated all available data from source, Greek, Latin and other from first principles i.e. translated all source material for himself.
I cannot read Greek and my Latin is poor to say the least, so I feel I'm not in a position to make an argument either way as I cannot interpit the source material let alone get my hands on it. Have you 'read' the various original source material?
Martin,
I avidly read anything Alan Wilkins has written, but that doesn't mean I draw the same conclusions. True, I don't read Greek or Latin, but I know a thing or two about weapons, mechanics, analyzing images, and I can read English translations. The first major schism occurs with the find of the Hatra frame. It is truly unfortunate that Eric Marsden didn't live to see it. It might well have changed his mind, in which case in-swinging metal-framers would probably be mainstream. Alan certainly advanced beyond Marsden's work, but walking further down the wrong road only gets you more lost. The bottom line is that Aitor's interpretation of the Hatra frame makes sense to me, Alan's does not. Aitor's cheiroballista has demonstated that using small washers and an in-swinging layout, a small, portable, and manually cocked weapon can be produced. It may not be very powerful, but neither were the first automobiles and look how they've turned out. Like many new ideas, Heron's design might have taken years to perfect before it was tuned and scaled enough to be practical on the battlefield. Configued as a traditional out-swinger the same small washers would result in a machine so underpowered it is useless. The answer was to double the size of the washers, scale down an Orsova arch and some field frames to fit. Voila, you have a cheiroballista. Of course, doubling the springs means they can no longer be manually drawn. No problem, add a winch. Never mind that the text doesn't include one. If the crescent shaped fitting gets in the way of the winch just turn it upright and find some use for it later. (side note: the only other weapon to include one was the belly-cocked gastraphetes where it served an actual and AFAIK undisputed purpose) Of course there are a few other problems to iron out. Frames need to be turned 18 degrees? Invent some enormous bronze locking rings (none mentioned or ever found BTW) and bend the ladder ends (also not mentioned). Forked ends of the arch don't fit? Just make the rear ones shorter. Never mind that the long surviving ends of the Orsova arch are diagonally not symmetrically opposed. (one front, one rear) Adding winch, levers, bronze rings and other bits makes it too heavy to shoot by hand so a base is required. The result, in my opinion doesn't really meet the criteria for a cheiroballista. It's closer to a carroballista except that the stock doesn't protrude in front of the frame, but that is a discussion for another day.
P. Clodius Secundus (Randi Richert), Legio III Cyrenaica
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Quote:A point Alan has made to me is that the sources (Heron?) state that winches were added to artillery because torsion springs (made of sinew remember) were too powerful to draw by the power that a human alone could exert.
Crispvs
Heron's Belopoeica, which was a recapitulation of Ktesibios' much earlier work, states that in order to increase the size and force of the projectile beyond what one could manually draw they switched to torsion. At the same time they added a winch and base, and deleted the crescent on the larger machines. Biton shows that this trend remained true in the case of larger tension weapons as well. Philon and Vitruvius appear to follow suit. Large crew served weapon = winch = base = no crescent. IIRC Heron is the only one to discuss hand-held individual weapons. Both, Ktesibios' gastraphetes and his own cheiroballista, include a crescent shaped fitting and neither mentions a base or winch. Given that both were written by the same person, why is it so difficult to accept that the crescent served the same purpose? Individual weapon = crescent = belly/manual cocked = no base. Why make it more complicated than it needs to be.
P. Clodius Secundus (Randi Richert), Legio III Cyrenaica
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Because you can? Salve, Randi. I was wondering when you would show up 
This crescent thingie argument will go on forever, I think. Seems to me common sense would dictate that it is used to span a small machine using your body weight. If the machine is so powerful it needs winche(s) to span it, it has to have a stand, and the crescent thingie goes away.
Dane
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Yes that's exactly what I mean. What Alan and Len have made is not a replica but a miniature Catapulta which is just the job if space is limited.
Quod imperatum fuerit facimus et ad omnem tesseram parati erimus
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Quote:Yes that's exactly what I mean. What Alan and Len have made is not a replica but a miniature Catapulta which is just the job if space is limited.
Salve Derek,
Exactly what eveidence do you base your conclusion on?
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I would adopt everything that Randi has said. The basic mistake is expanding the washers because to cope with those you had to make all the other modifications. The crescent is the give away as well.A belly bow is the only reason for it. On top of that Bernard Jacobs built and I have used it for 2 years and shot it maintained it and loved it since. It is a marvellous weapon: lethal accurate and easily spanned . It is man portable and easily shot from on top of a shield.
Incidentally I can see little point in testing miniature weapons to provide meaningful statistics or even full size ones unless you use the original tortion materials. We all use nylon and the results are unique to that material.
Quod imperatum fuerit facimus et ad omnem tesseram parati erimus
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