Dimensions of Lithobolos

[Koyuncu]

Hi all,

Is there any source that mentions exact dimensions of lithobolos so we can reproduce it accordingly?

Thanks in advance.

[D B Campbell]

Is there any source that mentions exact dimensions of lithobolos so we can reproduce it accordingly?

Philon and Vitruvius give the dimensions of the various components. In my opinion, it's deciding how to assemble them that's the tricky part!

[Koyuncu]

One of my friends trying to model a 15 mina lithobolos and he is provided by certain values such as spring height is 2.2 meters. Yet, after modelling done according to those values, spring house look too wide. In historical sources if I remember correctly, dimensions were given in terms of proportions other parts. There is no certain values for such machines. Still, is there any calculations how should be dimensions of 15 mina lithobolos ?

[D B Campbell]

Still, is there any calculations how should be dimensions of 15 mina lithobolos ?

Wow -- that's quite a monster you're attempting. 15 minas = a quarter talent; this is the equivalent of a Roman 20-pounder! By way of comparison, the ballista recently (fairly recently) constructed by Len Morgan and Alan Wilkins is a 2-pounder.

There's no easy answer to your query. You and your friend will need to work through Philon and Vitruvius, calculating the dimensions of each component. As you probably know, the size of the "module" (diameter of spring-hole) is calculated by multiplying 1.1 x cube root of (100 x weight in minas) = 1.1 x cube root of (100 x 15) = 1.1 x cube root of (1500) = 1.1 x 11.5 = 12.6 daktyls = 24.3cm. The springs are 9 "modules" in height, which is 218.5cm -- so your 2.2m springs are quite correct.

What other components are you having trouble with?

[Koyuncu]

Thanks so much! I can't recall other values now but I will try to contact with him to get other values.

The actual problem is with those values spring house looks rather wide. Is this what it should look like or is there any problem with calculations?





Thanks in advance.

[D B Campbell]

The actual problem is with those values spring house looks rather wide. Is this what it should look like or is there any problem with calculations?

The "half-springs" (hemitonia) seem a little wide for the size of the "washers" (choinikides). Whose calculation have you followed?

Philon says that the "hole-carrier" (as you know, this is Marsden's name for the peritreton -- the rhomboidal top and bottom plate of each torsion-spring) should be 2 [sup]3[/sup]/[sub]4[/sub] diameters in length; he doesn't give the width, but says that the "side stanchion" (parastates) should be 1 + [sup]1[/sup]/[sub]3[/sub] + [sup]1[/sup]/[sub]4[/sub] diameters wide, so we may tentatively assume that the width of the peritreton is roughly the same. (For your 15-mina machine, the peritreton is [2.75 x 24.3cm =] 66.8cm long by approximately [1.58 x 24.3cm =] 38.5cm wide.) The washer (choinikis) itself is 2 diameters long and "as wide as the width of the hole-carrier", which (as we've seen) ought to be roughly 1 + [sup]1[/sup]/[sub]3[/sub] + [sup]1[/sup]/[sub]4[/sub] diameters. (For your 15-mina machine, the choinikis is [2 x 24.3cm =] 48.6cm long by approximately [1.58 x 24.3cm =] 38.5cm wide.) Thus, the washer should take up around two-thirds of the length of the peritreton -- yours looks as if it's only about one-third.

In practice, both Schramm and Marsden drew square washers on their diagrams, with sides of 1.5 diameters (curiously, Marsden's "List of dimensions" gives 2 x 2.5). Even these washers would seem larger than the ones on your drawings, I think.

[Flavivs Aetivs]

Thanks so much! I can't recall other values now but I will try to contact with him to get other values.

The actual problem is with those values spring house looks rather wide. Is this what it should look like or is there any problem with calculations?





Thanks in advance.

Looking good!

I know a lot of people in the Rome: Total War Modding community that would kill for that model by the way. How'd you get 3DS Max? Work? Student Liscence?

[Koyuncu]

@D B. Campbell, Here is the provided information about some values;

the 15-mina lithobolos, a torsion stone-projecting artillery piece. 15 mina is 14.3 lbs or 6.5 kg.

The device consists of an elevated stock, its lower end resting on or near the ground, its upper end (the muzzle, so to speak) poised in the firing housing. The housing contains two torsion springs, each with "throwing" arms attached to them, projecting out and back from the housing. A cable attached to each end of the arms serves as the sling for the stone, and attaches to a cable pulley built into the stock. The stock cable allows operators near the back of the stock to use a crank to prepare the machine for firing. See picture below: http://www.maquetland.com/v2/images_arti...los%20.jpg

The stock for a 15-mina lithobolos would have been about 7.3m long, including the "barrel" rail projection that extended about 2m past the housing.The torsion springs for a 15-mina lithobolos would have been about 25cm wide and 2.2m tall. The throwing arms would have been about 1.8m long.

The spring housing would have been about 3.5m wide, but less than a meter long, and 2.5m tall, but tilted. The pedestal for the spring housing would have been about 3m tall.

I am not sure if all those are historically correct or just made up numbers. By the way, I am sorry for disappointing news but he is actually modelling it not an actual reconstruction. I am so sorry if my sentence mislead you to think so.

@Aetius, He is actually a member of EB II mod team, a Roman Era mod for Medieval Total War II. I have no idea how he got 3dMax.

[D B Campbell]

By the way, I am sorry for disappointing news but he is actually modelling it not an actual reconstruction. I am so sorry if my sentence mislead you to think so.

"Modelling" on a computer? How disappointing. I thought you were building it!!

[Koyuncu]

"Modelling" on a computer? How disappointing. I thought you were building it!!

I beg your forgiveness for this mistakenly chosen word, reconstruct.

[Koyuncu]

Here, I found a detailed study about proportions with several sources, so it may help anyone.