Aitor Alert! Manuballista found!

[Antonius Lucretius]

Instead of getting people confused about what's a ballista and where's the catapulta, I'd suggest "catapults" as a generic term for torsion artillery, and "bolt shooter" and "stone thrower" to differentiate between both, which is definitely more clear for people who are not specialist ballistarii....
Also.. I just was thinking about it.
I've seen several working replicas of catapults , from small hand held models to big stone throwers. I've also read that sinew was used for the torsion springs. Knowing a bit the characteristics of sinew regarding its resistance to torsion I wonder if someone has ever tried it on a reconstruction.. So far, I've only seen rope, but maybe I'm wrong.
I suspects the results achieved with sinew would be truly impressive.

[aitor iriarte]

Antoninus,
Digby Stevenson uses sinew cord springs for his reconstructed (outswinging) cheiroballistra and he says that the results are impressive, which I believe, although I've never been able to see his machine! hock:
If you aren't able to make the sinew cord by yourself (like Digby does), it is a rather expensive commodity. I have had enough length made as to make a bowstring for my cheiroballistra for the last trials with horsehair rope springs. Unfortunately, I don't think that I'll be able to continue with my experiments this year and I hope to have more time on next one!
Another thing, the differences between catapults and ballistae were not only due to the kind of missiles they fired, but were mainly structural ones. I think that different names convey the different ideas..

Duncan,
I think that somebody (sorry, I cannot scroll back now! :oops: ) has pointed earlier on this thread that the Xanten catapult could be of an appropriate size to be mounted on a ship. I think that it is a serious possibility (wasn't it an underwater found?) and furthermore, a caliber of 45 mm would make the machine uncomfortable to cock by hand...


Aitor

[LUCIUS ALFENUS AVITIANUS]

SALVE

How many meters of rope can be needed for making such one little throwing-machine?

To make horsehair cord, i'm making some probes with horsehair adding some glue and simply cording. it's correct or there's another method?

[aitor iriarte]

Well, my small cheiro wears a total of about 10 meters and the spring thickness is just 24.6 mm. At a rough guesstimate, the Xanten little monster would need no less than 25 meters... :roll:
I don't know much on rope making, but they use to 'spin' thread an later twist three of those threads to make the cord...
I hope that we'll have time to discuss that matter and some more others at TÃ rraco Viva this month!

Aitor

[Aluscladiusmaximus]

I was at Xanten this weekend and I got to see some posters showing pictures of the Manuballista. They said they would email me the drawings of it . From looking at the new pictures the outside diameter of the washers appears to be 45mm so the inside would be smaller.

[surodago]

Some more fotos....




Picture from the Roman Military Equipment Pages of www.romancoins.info .
2 more fotos can be seen there.
[url:1tb5z16u]http://www.romancoins.info/MilitaryEquipment-Artillery.html[/url][/url]

[Aluscladiusmaximus]

I have been looking at the better pictures I got last weekend and I have produced a picture to show the difference between the frame being 21x21cm and 21x28cm. All the pictures I have seen make the frame look a little higher but not as tall as the 28cm picture shows. If the frame is 21cm tall if you add the height of the washers it comes to about 28cm. I think the sizes quoted include the height of the washers . On the comparison picture I stretched the frame but left the washers the same height.





Aulus cladius Maximus

[Praefectusclassis]

I installed a small gallery of photos of this find on the site: go here.

[Eleatic Guest]

Anyone having an idea about its effective range and penetrating power? What does the museum say? They had made a replica, hadnt they?

[aitor iriarte]

Unfortunately, the replica by the museum is clearly underpowered, i.e. the 'holes' aren't completely filled with cord... :?

Aitor

[hoplite14gr]

Another key point would be the material of the spring ropes, as John has pointed out. I really look forward anxiously to see it published soon (in German I guess!)<br>
I forgot to mention that the Greeks also used such kind of manuballistae. At Ephyra, in a fortification destroyed in second century BC, a modiolus of the same small size was was recovered.<br>
<br>
Aitor

<p></p><i></i>

Actually it was called "Gastrafetes" = released from the belly. It was said to be rested on the groin when ready to shoot.
Kind regards

[aitor iriarte]

Stefanos,
The gastraphetes, as described by Heron, was powered by a composite bow, not by torsion springs. Even the powerful arrow shooting and stone shooting machines described by Biton (which, of course, could be no longer hand-held and cocked by belly preessure! :roll: ) were still dubbed 'gastraphetai' by him. Probably, the term was used to name all sort of pre-torsion engines...

Aitor

[Eleatic Guest]

Hello,

Stefanos,
The gastraphetes, as described by Heron, was powered by a composite bow, not by torsion springs.

was it really a composite bow? Did Heron or any other ancient author write this explicitly? :-) ) I am asking because the other day I had a discussion about exactly that as somebody suggested that the Greeks switched to the torsion principle because they werent aware of the composite bow building technique.

And granted that the gastraphetes was a composite bow and the Greeks engineers soon moved to torsion bows, could we derive from that switch that torsion bows were generally superior in power?

Regards

[hoplite14gr]

Thank Aitor.
Linguisticaly though EN GASTRI = in the belly.
GASTRAFETES = leaving from the belly.
I agree with you thought tha Biton either over-generalises or talks metaforicaly
I can imagine the handheld version as composite bow but what of the bigger siege machines?.
Kind regards

[Aluscladiusmaximus]

Having built and used a manuballista I would say that you would not shoot from the belly as you could not hold the thing up. you would be trying to hold a 15 pound weight at the end of a yard long beam.
They are cocked using the belly to press down on the back while the front of the slide is in contact with the ground.
Wilkins books show artillery using very large Composite bows. They are about 15 feet wide the torsion artillery shooting the same size stone would be much narrower which would make it more convenient to use.
A composite bow can take a year to make so imagine how long it would take to make a bow large enough for artillery

Aulus Cladius Maximus