As I write this the Orsova ballista project is perhaps two thirds of the way down the path to firing its first shot. Things have progressed a fair bit from the photo shown in yesterday’s entry, it was taken last March. I will present some new pics soon so that these posts can catch up with the present state of progress, and then this blog will be performing its true function, that of a journal. I was asked when I started this project why I didn’t make some kind of proof of concept model before investing all of this work in it. The answer to that lies in the fact that we are presented with a wealth of information from the artifacts themselves. It became clear early on that by simply reproducing the artifacts we would have a viable starting point. As that part of the project was fixed, no further decisions about the final design needed to be made until the artifacts were reproduced. By the Spring of 2008 the field frames were finished, exact duplicates of the originals shown in the technical sketches seen below. These drawings are my sole source to dimension the artifacts and I have adhered to them closely. They come from, Recent Finds in Ancient Artillery, by Prof. Dietwulf Baatz.
I am not going to claim that my reconstruction will look exactly like the original Orsova ballista. Clearly the field frames and arched strut shown in the drawings will, but because all the other parts are missing no one can say for sure what the entire machine looked like. That being said, I came to the conclusion early on that there were really only two ways to design this thing. I could make a machine that appeared consistent with what people expected a late model Roman ballista to look like, (witness the illustration just visible in the museum exhibit from yesterday’s post) or I could let my imagination roam over the artifacts themselves and see what was suggested by the mechanical logic inherent in them. Having gazed at pictures of the artifacts for many hours I became convinced that the Orsova ballista was a high technological achievement for the Romans. The artifacts had all the elements of a flexible modular design that could have great tactical advantages in the kind of fluid warfare that started to emerge at the end of the Roman empire. The connecting loops on the field frames and the tangs on the arched strut suggested a system that could be fitted together with wedges and then knocked apart quickly for maintenance or transport. A ballista is a lot of kit to lug around, I find it impossible to believe that the Romans would settle for second best on anything when it came to such a super weapon. If a modern researcher could dream up the innovations needed to maximize accuracy, power and reliability using these artifacts, it is probably a safe bet to say the resourceful Romans did too. Occam’s razor tells us that less is more if it is consistent with the facts. Therefore, so long as the design of this reconstruction was in keeping with Roman blacksmithing, woodworking and cordage techniques, I felt somewhat free in how it should look and operate if it could be shown to give superior performance.
My experience generating power and accuracy with my first ballista told me a lot about how to approach this one. For example, it is generally understood that vibration is the enemy of accuracy. Most interpretations of late model Roman ballistas do not show any angled support struts bracing the field frames back to the stock. “And why not?”, we might ask. They will shoot okay without them, is the obvious answer. Very likely they would, but shooting “okay” is not what I am after and I suspect not what the ancients were after either. My experienced with the Gallwey reconstruction indicated the great importance of rigidity in the relationship between the stock and the box holding the spring bundles. When I introduced struts to that machine, group size at 50 yards shrank from a foot or so down to the 3″ mentioned earlier. I believe it is a mistake to be too slavish to the writings that have come down to us from the ancients. Heron may not have given reference to struts in his technical description of the earlier cheiroballista, however from a mechanical standpoint they certainly seem worth considering. The “absence of evidence is not evidence of absence” scenario seems to be in full effect here. As such my reconstruction will experiment with them, suspecting they would be an improvement the ancient engineers would likely not have missed if they improved accuracy. Again, I mention all of this just by way of example. An indication of approach as it were. My whole interest in making these engines might be likened to an extreme sport. Accuracy and raw power on the shooting range are my main considerations in determining design, just so long as it is reliable and consistent with something Roman technology could have actually produced. Given the ruthless logic of Roman weapon designs, I would suggest that this pragmatic approach might be closest to the truth. And if it isn’t, perhaps there will be some shreds of insight available that might not have existed had a safer more scholarly path been followed. Thanks to the brilliant work of Michael Lewis and Aitor Iriarte, a new interpretation of how the Orsova machine may have worked surfaced at just about the same time I was handling my newly made field frames. Their notion of an inswinger ballista was a revelation that put the Orsova artifacts into sharp focus. It tied in perfectly with my obsession over accuracy, power and the radical engineering potential of ancient artificers. The mystery was starting to deepen with the realization that with the inswinger, the Romans had apparently developed a new and powerful way of utilizing the twisted bundles of sinew that powered their ballistas. Ironically their burst of innovation happened at a time when the empire itself was destined to disappear.
Very cool rendition of an inswinger by Dominic Andrews
And back to the Gallwey for a moment.
Shooting last summer, two flyers and four shots in a nine inch group on the 85 yard range. Less than stellar compared to “back in the day”, ten years ago. Note the long cocking lever. Half power shooting, so things are relatively safe.
The extreme sport aspect of high powered ballisata shooting.
A 3″ x 4″ ash limb fractured after 22 shots at full power. Heavier 3 3/4″ X 4 1/4″ limbs (fitted out with epoxy soaked kevlar wrappings for safety) solved the problem. The limb let out a painful crack, and then collapsed against the stock with an enormous thwack. No splinters or other flying anomalies were detected. Wife was less than impressed when I relayed the details.
