Roman crossbow

[Flavivs Aetivs]

From my Emails with John Conyard:

I fear size of the crossbow is conjectural since we only have iconography to go on. But common sense suggests the tiller would have to be made to match the power of the recurve bow you are using. Draw length should be matched to the bolts shown in iconography, but we cannot get any general agreement on that either. I went for a hunting style bow, others prefer a larger weapon.

This thread may be of help:

http://www.romanarmytalk.com/19-greek-mi...=15#341468

I put up a sort of basic steps on my website:

The late Romans invented the crossbow around the 3rd century AD, although they had been using a handheld version of the scorpio called a "manuballista" since the 2nd century AD. The Arcuballista wasn't exceptionally powerful, as it used wooden rather than Iron arms, but was easy to use and maintain. There have actually been 3 finds of Arcuballista parts, dating to the 5th and 6th centuries in Britain. Many of them were decorated on the sides with carved bone strips inserted into the stock. These also may have had some sort of effect when the bow fired, possibly stiffening the wood.


BASIC CONSTRUCTION:

The Arcuballista was an ash self-bow about 90-120cm in length, inserted into at least a 60 cm stock, with a 50cm grove for the bolt. At the back of the groove behind the bolt should be a bone or iron rolling nut, attached to a metal Z-bar, which acts as a trigger. The string should be natural rope or sinew, and bone nuts can only take so much draw weight, so it is recommended for higher draws you use an iron nut. The handle should be attached to the back of the stock.


An easier configuration is the sliding handle configuration, which has a flat nut on a pivot above the handle, that is kept from dropping by the insert of the handle into the wood. The handle is then pulled back, dropping the front of the nut and allowing the crossbow to fire.


- It is recommended a spring is mounted onto the Z-bar to reset the the firing mechanism, as we know the Romans used these all the time in doorknobs.

- The draw weight varies - do what is appropriate for you, but it shouldn't go above 80-90 pounds maximum.

- To span the crossbow, it is not spanned like a medieval one as that would break the arms. Instead place the arms perpendicular to you, with your legs spread on either side, with one hand on the handle and the other drawing the string. This is how you span the Arcuballista.