The Ballista

There seems to be a considerable amount of wrenching on the evidence to force this field frame into being an outswinger.  Those little bronze roundabouts are charming, but the exit and entrance ramps are a puzzle for sure.  Where do the little cars go when they get to the top?  Why? I keep asking myself.  Why?  ….

Photo is of the machine called Constantine from the “Comitatus ballista” website.

Is this the kind of complex violation of the artifact that passes for experimental archaeology in your neck of the woods?  I’m all for leniency when it comes to hiding out in one’s analog bomb shelter, but really?  This forcing of the outswinger agenda is just too egregious to pass mentioning.

And, braided or plaited line for the springs?*  All strung up loose and goosey?  Never have I seen a deader looking torsion spring.  Perhaps it’s a work in progress.  If it is, then maybe this next photo will help by showing what a fully developed torsion spring should look like.

There is some serious and highly balanced strain going on in all those fibers.  You can sense it if you look closely enough.  (Click to enlarge.)

Poor old Constantine, the most I could find in the way of a performance report for him was the following statement,  “….and the performance was excellent.”

Well that really nailed it didn’t it?

I’ll just stick my nose in the air and mumble something about how these kind of attempts are more like theatrical props than they are genuine experimental archaeology projects.  Because, you know, “experiments”, “data”, and everything…..

And what’s with the wimpy wooden locking wedges?  You don’t think the Romans could spring the cash for metal ones?  If there was any power in this contraption the steep angle on those wedges would quickly cause them to loosen with all the high frequency vibration.

Honestly!  I dunno!  Kids and industry!  Send ’em to school.  Give ’em an education.  Whaddaya  get?  Outswingers of lameitude!

…..Did I just turn myself into another foot soldier for the Performance Police?

Yikes!   The slippery slopes of sanctimony!

*Step one in making a powerful ballista:  never use braided anything for the springs.  It kills the springiness compared to regular three strand.

Analog:  a person or thing comparable to another.  Not identical, just comparable.  The concept makes a useful redoubt when the authenticity police come knocking.

Truth is: my much vaunted bally-hoo about researching the propulsive qualities of sinew so we could compare it to the nylon used in most modern reconstructions, is, I regret to say, so much hot air.  At least for now.  Sinew V Nylon has been postponed for strategic reasons.

It is something better tackled in my seventies, if I’m lucky enough to get there.

If we are lucky enough to get there.

Perfectly logical, you see.

On 4/8/2016 4:19 PM, John Payne wrote:

You’ve said phoenix is approximately 70 percent (I think) the size of Firefly.  Looking at the artifacts I did the math on the hole carriers and the spring hole on the elenovo find is more like 85% the size of the orsova. I thought that dimension was the starting point for the craftsmen to get all the other measurements. Do you think they started to change that part of the formula for beefed up lightning ballistae? I hope someone stumbles upon a couple more of these machines. Not holding my breath.

P.S. I didn’t know that behemoth discovery channel ballista only got 120 yards! You say it was built by authorities in the field of ancient artillery study? My gosh how embarrassing. I’d have used a D9 CAT to stretch with myself. They should pay us to build something. All that money, beautiful beautiful, money to use.

And here is my reply:

.729 is the number I’ve been using.  You are correct that the spring diameter is the primary reference dimension that ancient craftsmen were supposed to use to scale their machines when being guided by the ancient formulas.  However, because this is an artifact based reconstruction, I figure that the overall height of the field frames should be taken into account when scaling the machine.  Others will no doubt disagree, but to my way of thinking this gives us a more accurate starting point for figuring the length of the kamarion and the  consequent distance between the springs.  Let’s face it, in the modern age, this is all pretty much guess or by golly.  Close enough for horseshoes and hand grenades etc.   The formula folks will sputter I’m sure, but as far as I’m aware, none of them have actually made a truly powerful machine yet.

And re: John’s P.S. :

Yeah, it does seem a shame that all that lolly produced so much feeble.  The fact that the BBC machine, designed by Wilkins & co., does not have any metal plating to reinforce all that beautiful woodwork, was a clear indication that this machine would be under-stressed and therefore a bit of a wimp.

Photo courtesy of carpenteroakwoodland.com

This is what happens when woodworkers take charge of torsion engine design.  In my experience with conventional “wood” machines, it takes lots of iron as well as wood to make a powerful ballista.  And also a willingness to exploit high levels of torsion to match all that frame strength  you created by using the iron reinforcement.

The two photos above are of my first machine, dubbed the “Gallwey”, after his Lordship, Sir Ralph Payne Gallwey.  Almost certainly, no ancient ballista ever looked like this piece.   Note, however, the use of iron plates on the inside of the boxframe and the through bolting to the plates on the outside.  This was a powerful outswinger with 1150 foot pounds of muzzle energy and a 750 yard maximum range.  You can hear what that kind of power sounds like in this ridiculously grainy video.    Click for vid: gallwey-1a     What you are seeing is a 1″ blunt bolt zipping through a target made of four sheets of 3/4″ plywood.  (For more on this Victorian knock-off, see archives, The Gallwey Carroballista, Dec 16, 2008.)

The point is, without all that metal plating ……. well, forgetaboutit.  We’d have been lucky to get through the first sheet because the torque would have needed to be set so low for the machine to survive.

There are several passages in the artillery manual of Heron where the importance of metal plating on the wood framework is emphasized.  In Marsden, Heron says on page 29,  “You must see that the grain of the wood runs up and down the side stanchion and covers its sides on either hand with plates binding them with nails.”  Or later, on page 35, “You must also provide iron plates at critical points, I mean points that must withstand hard usage, and fasten them on with nails.”

While it is true that Heron was probably a few hundred years later than the machine represented by the BBC analog,  the indirect lesson from the old master is that real torsion engines are meant to be run at wood shattering levels of torque. His assessment that metal reinforcement was essential would have been as true for the Ancient Greeks as it was for the Romans.  Wood is wood, no matter how fine the joinery.

It seems that the team that built the BBC machine took on the most difficult of catapult reconstructions.  Apparently one that forbade the use of metal plating,  a stricture that is perhaps not as authentic as many purists seem to believe.  Probably they only had the ancient directions for all that fab looking joinery;  the addendum, “and then reinforce with metal plates”, somehow went missing.*

Interestingly, we see plenty of iron plating on various pieces of original framework that have been uncovered.  The Hatra is a good example of this.  Or how about this photo of the Emporium ballista, all decked out in iron.

Photo filched from Samuli’s, Greek and Roman Artillery Wiki.   (Note the handful of glandes in this museum display.  Surely the curator is not so avant-garde as to suggest that these missiles would be suitable fodder for a ballista?)

“Building the impossible” — as a professional metal worker that has his doubts about an overreliance on timber in high shock applications,  I always thought the BBC attempt aptly named.

*In contrast to his BBC machine, is Proffesor Wilkins use of metal plating on the Xanten-Wardt reconstruction made by those master modelmakers, Mr. Morgan and Mr. Feeley.  I particularly admire this rendition because it is an artifact based reconstruction.  A truly beautiful and authentic reconstruction in every respect.  … Well, other that is, than any indication of it’s performance specs.  At least, as far as I can find.

I wonder, are there laws in the UK that limit the power of torsion catapults?  I know that airguns have a power restriction on them over there.  It just seems strange that such an obviously deep piece of work has no test results available.

Here is Professor Wilkins paper on the Xanten-Wardt machine:

The Xanten-Wardt and Carlisle catapult finds

NTS:  Remember the youtube dude with the rolling pouch technique for shooting his slingshot. A similar style of spin casting may be possible with glandes fired from an inswinger.  ……Perhaps with a pivoting pouch, rigged inside of my usual twin line bowstring.  Wooden sabots could have different angles to force the twist in the pouch, and by this means produce various rates of rotation.  Whirring beasties of doom!  Terrified Gauls in the hinterlands, and all that.

….. Or, not.

’nuff said.

From Murray’s website comes this next photo.

The three types of people:

Here is another version I’ve had hanging on my wall these last few decades:

(1)  Bad Wolfie!

(2)  Hapless Sheeples!

(3)  The strength to protect the innocents, without letting that power turn you into something like the monster you’ve just defeated….

This 16th century woodcut strikes a particular chord in our family because we have all spent a good deal of time exercising our German Shepard, Oona,  by shooting blunt tipped longbow arrows and crossbow bolts for her.

(Many thanks to Semith Koyuncu for posting this artwork in his facebook blog.     https://www.facebook.com/messages/1606915887)

Archery of this sort is great family sport.  Dogs with a bent for retrieving, love it.  Needless to say, it is important to enforce some strict range rules, especially when using the crossbows.  Beyond the obvious utility of having a willing servant find and fetch your missiles,  it gives a working dog a sense of purpose and importance.  Just yesterday a bolt from my 14th century windlass crossbow burrowed itself into the pine duff a few feet.  It took Oona about ten seconds to find it.  Around here, a dog with a blunt in it’s mouth gives a whole new meaning to getting high.  (Thank you Anna. Very funny.)

I have tried to find more information on this woodcut.  Someone suggested it was Nordic in origin.  If anyone has an idea where it came from, I would love to hear about it.

I have observed two types of historians during the course of this little torsion project.  There are those I call the Occamists.  These stern fellows have taken it upon themselves to remind us all of what is strictly a part of the historical record and what is not.  Like faithful pruners of their gardens, they rarely meet ideas that don’t inspire them to acts of excision.

Then there are those of us who are perfectly well aware of the razor-like insights proffered by the Occamists, yet still find it valuable to extend our observations by using a combination of imagination and logic in an attempt to flesh out those areas of ancient technology that belong to the realm of the not strictly known.

The Occamist faction seems to delight in reminding their more, shall we say, creative colleagues, that they are susceptible  to a dreaded disease known as “blue sky thinking”.  Often, these dour guardians of historical precision,  take it upon themselves to administer dire correction to anyone who strays outside the fold of absolute certainty.  Or at least, their version of it.

Of course the trouble is, when it comes to the study of ancient catapults, what is actually known for sure makes paltry pickings for further study and examination.   This is where the arts of extrapolation and thoughtful experimentation must take over to light the way.  Without a considered use of imagination to suggest how these machines were built and affected the ancient world, the whole area of historical catapult study becomes moribund and repetitive in the extreme.

What we do know is far exceeded by what we do not know.  We can gage the depth of this ignorance by those few scholars that have tried to replicate ancient catapults and generally failed miserably to get any decent performance out of them.

However, there is a modern breed of experimental archaeologist that prefers to blend the “known” with an experimental approach that is oriented towards developing high-performance.  And by this methodology, further our understanding of how these remarkable machines probably worked and looked.

What the Occamists might call “blue sky thinking” , I prefer to call, “ripe fruit on low hanging branches”.  Perhaps there is no irrefutable direct evidence that a particular type of technology existed, but because it would have been so easy to achieve, and is a natural outgrowth of well known technologies that are a part of the historical record, and, very importantly, because this “ripe fruit” technology would confer substantial benefits to it’s users, there is every likelihood it did exist.  Enough anyway, to make looking for the signs of it a worthwhile endeavor.  Absence of evidence is not evidence of absence.  And because the Occamists are constitutionally averse to using their imaginations in these matters, they make poor readers of what signs do exist.

Take for example, the subject of shooting lead bullets (or glandes) from ballistas that normally only fire bolts and light javelins.  In my experiments with Firefly I was able to make this double bowstring, with a pouch,  in an afternoon.

It was my first attempt at making a sling string, and yet in short order I was able to boost that one pound lead egg up to 318 feet per second.  This next video shows the effect at 50 yards of one of these projectiles travelling at 295 fps on four sheets of 5/8″ plywood.

Click for vid: glandes 1

In the next video we see the first rough shot prior to sighting in.  It struck a good foot above the plywood targets, slipped through the camo netting and tarp, ploughed through a dense hay bale and smacked a two foot splinter out of the 2″ X 8″ douglas fir backstop, and then went on to God knows where .  You can hear the sound of it hitting that fir backstop if you listen carefully.

Click for vid:  glandes 2

Here is a view of one of these whirring beasties speeding downrange.  (Unfortunately Firefly is not visible as she is hidden inside the open door of my shop.  There was no way to move her back then.)

Click for vid:  glandes 3

If you turn up the volume and look at this last video on a big screen, in a darkened room, you can gain a sense of how these projectiles must have appeared to their recipients. (Okay, hypothetical recipients.)  Just visible is a glint of lead in the left of the open doorway, followed by a streak of grey to the left of center screen, and then a small splash of dirt on the lower left as the glans grazes the top of the dirt backstop. The knocks you can hear after that are from the glans crashing into the tree line 40 yards further on.

In my last excursion into glans testing (back on  April 9, 2012, see archives), a sling string was used to launch 14 glandes at once, each weighing 31 grams.

The effect of this “shotgun” pattern can be seen as seven of the fourteen glandes blew through  a 1/2″ thick plywood patterning board at 35 yards.  The seven that missed during this shot could been seen going through the air in a similar pattern directly to the right of the plywood.  So the actual pattern is twice what the video actually shows striking the plywood.

Click for vid: glandes 4

Please keep in mind this patterning exercise was really just a first attempt, conducted in a single day.  How effective would a shotgun technique like this have been in ancient combat?  Especially if the technique was well developed and several times more devastating than the one seen in the video?  That is largely a matter of context.  For opposing an assault through a breach in a wall, or one that was funneled into an appropriate kill zone, the shock of it would likely be quite demoralizing for the attackers. Especially if multiple machines fired at once or in volleys. Perhaps at lower power settings the Romans would have found it useful for crowd control.   Who knows?

The point of all this is to illustrate the concept of “ripe fruit on low hanging branches”.  The Occamists, with their penchant to oversimplify, are not in a position to consider the existence of these easily attainable technologies.  I know they consider themselves to be defenders at the gate, keeping at bay the hordes of speculators that threaten their ivory towers, but let’s face it, the Occamists are also somewhat bereft of imagination and therefore unlikely to connect any of the fairly obvious dots.  Especially the pragmatically opportune ones.

Ejecting high speed glandes was a part of this project that was accomplished without a lot of undue fuss.  In other words, performance like that shown in the above videos was achieved with very little effort on my part.  Why the Romans wouldn’t have included a simple, inexpensive sling string for shooting glandes and the like in their normally bolt shooting ballistas, seems remote to those of us that have actually done the experiments.

“Blue sky thinking”  or “easy pickings”?  As my wife Rebecca says,  “it is better to know that you believe, than to believe that you know”.  The Occamists, and their predelicton to streamline all avenues of thought, are not well suited to exploration.  Probing the unknown is what this game is about.  That requires imaginative and physical engagement,  tempered with careful caveats, not just smug criticism devoid of any sense of the potentialities involved.