Impenetrable scutum?

[Endre Fodstad]

Those are quite sturdy looking planks Endre!
If that was the max penetration, I would be happy, tho' perhaps with a scuta, bit more penetration?

Yes, but remember that there is no leather, textile, consolidants or gesso covering on the planks, all of which would significantly increase the resistance the shield provides. As I recall it, the shield we shot at, while it received deeper penetratration than the pavise, had no arrows penetrating deeper than 2 centimetres through the shield - and the ones that hit the padded section didn't pierce the padding at all.

[Gaius Julius Caesar]

Good to know!

I wonder just how easy a spear or pilum could penetrate, unless thrown full force at point blank range?

[Endre Fodstad]

If we're just considering the Kinetic Energy and Momentum (ignoring all such effects as angle, shield curvature, etc), there are two tables here:





..all in norwegian, sadly. The upper table gives the momentum of the projectile, the lower table the total kinetic energy of the projectile - both have the momentum/KE as a function of the velocity. The momentum is probably just as if not more important than the kinetic energy regarding penetration.

A quick norwegian primer:
"Fart" means "velocity" and is given in m/seconds (and fps for your conveniece).
"pil" = arrow (total weight 0,0325kg)
"låsbuebolt"=crossbow bolt. (total weight 0,041kg)
l.spyd = light javelin, ca 800g
t.spyd = heavy javelin, ca 2000g

...note that the javelins velocity stop at 30m/s (olympic javelin velocities) for the light javelin and 15 m/s for the heavy javelin - still relatively solid throws, those.

Due to the relatively low velocities involved and the much larger masses of the javelins compared to the arrows or bolts, the arrow/bolts' greater potential KE and especially p have trouble reaching the same level as that of the javelins. However, this is a "force and momentum" only - comparison: as Hibernicus has demonstrated, these factors need not result in greater penetration. I suspect that thrower technique - which controls how stable the javelin goes and how well it concentrates its force and the angled nature of the scutum matters more than these physical factors in real life.

[Gaius Julius Caesar]

Yes , that is what I imagine.

[M. Demetrius]

Hibernicus says their hurled pila often bounce off, the source Demetrius mentions talks about (if I understand correctly) arrows.

They mention arrows in quite significant quantities (gee, if there were a thousand archers, they each launched 30 arrows! That's quite an assault...it does say elsewhere that the Pompeians had many archers, but doesn't list their entire group, or give a mention of census. What it does not say is that it was a civil war. That would make one imagine that all sorts of missiles would have been in the air, pila, javelins, arrows, rocks, lead sling bullets, spears, etc.

Somehow it seems utterly implausible to think that a one ounce arrow would penetrate a shield, while a many ounce pilum would not, considering the pyramidal points of both were essentially similarly sized, but who am I to question all these great minds? I thought pila were designed specifically to have great penetrating power, and are often mentioned by first hand users as penetrating shields, and sometimes pinning shields together in a shield wall (see De Bello Gallico).

Roman military mojo must have prevented pila from piercing scuta, I guess. If it's a question of multiple impacts weakening the shield, I can just imagine a soldier thinking, "Wow, that was the last hit my scutum can take without being penetrated! I wonder if the next thing is coming through? Yikes!"

All the text says is there were 120 holes. It does not say from what the holes were caused. Obviously Centurio Scaeva was not greatly wounded, so there must have been no great depth of penetration in any location behind which his body was close, or he would not have been present, one would think, at the accounting and awards ceremony.

[Endre Fodstad]

One must simply keep trying out throwing pila at shields and seeing what happens when one's technique (and throwing arm strength) improve. I also think that one of the major flaws our modern tests have is that we tend to stand way too close to the target - arrow fire at twenty meters is pretty risky if there is any cavalry nearby, even if you are mounted yourself, and most tests use, at the most, 15 meters (if even that). Similarily, all javelin-chucking I've ever seen in tests has been at very close ranges - 8 meters at the most - to avoid the dangers involved in missing the target and accidentially hitting something or someone in the background.

Oddly, even the tests carried out by the Royal Sandhurst academy of bowfire against 14th century plate armour was at an absurdly close range - and they had access to proving grounds for modern artillery, so hitting an undiscovered mushroom collector in a nearby shrubbery wasn't really a risk there.

[Hibernicus]

posted a photo of three of us standing on a scutum blank
Marketplace forum.. replica scutum blanks, thread.. 3 ply alder over oak, planed to 7mm

[Hibernicus]

about that destructive testing.. more news:

It looks like we'll have an expert who can speak with authority about wood, and about the wood we use compared to the wood used in actual examples of scutums

And equally exciting.. we're going to have iron with which to forge replica arrow heads and "Celtic" spear heads. Already have iron for pilum shafts.

[SOCL]

Doesn't the question come down to the life expectancy of a scutum? How long was a soldier expected to use the same one before he needed a new one. Granted, combat and weather were likely to factor into this--after being at Castra Lafe this year, I can't imagine the life expectancy of a scutum in Britain to be marvelous--but how strong is Roman-grade strong? Does that make sense? :?

[Dan Howard]

Since the shield was developed at the beginning of the bronze age, its primary purpose was to fend off arrows. Any shield that couldn't perform this basic function would have been augmentecd till it did or not carried into battle. The need to fend off thrown spears came later and again the same thing would have happened. If it didn't resist all but the rare flukes then it would not have been used.

[Hibernicus]

To answer some questions from Lucius Tertinius Severus ...

Forgive my ignorance, Hibernicus, I am admittedly not a manufacturer or anything of the sort, but what sorts of experts are you requiring and waiting on?

Since it's all in the very early stages I do not know what the final outcome of the extent of the testing will be. We put our own testing on hold pending the outcome of this other possibility... but we are working with an organization that has proposed doing serious testing of the scutum (armor and weapons too). A company they work with does ballistics testing and stress testing and such ... so yeah, fast action cameras, sensors, ballistics gel dummy with real skeleton inside etc... (no, its not Mythbusters)


The other question is: why? Why do you require all these things to test these shield strength?

Certainly not required but having the machines and their results gives us quantifiable information.

There isn't, to the best of my knowledge, a source that states the sort of "minimum standards" for shield strength.

No minimum standards for strength in the historic record as far as I can tell. We have the accounts of scutums vs pilum in one of the Civil Wars but under what circumstances: wet, damp, old, battle damaged... factors that I believe affect the effectiveness of the scutum.

One thing we hope to do is test against the three known wood combinations: alder over oak, birch over ash, and planewood over planewood to see if their is any difference and then test against other woods.

In fact, we're hard pressed to find sources on the materials of the shields alone! I don't see the logic in saying you shields can stand x amount of weight, when we don't know how much the actual thing could hold up or was meant to hold up. Confused

We DO, for the most part, know what materials were used. (still waiting to learn the exact form of the hide glue used to afix the wood.. was it horse or cattle? or both? ) The fact that an expert will be able to advise/testify to the sameness of the wood used (as to its known measured strengths, species variety by species variety) will to that extent make it possible for us to be more historic. If the expert says that there is little or no difference between the oak species used 2000 years ago and a species we use today then that wood will act the same under the same circumstance. All materials will be vetted for their historic "accuracy".

If the experts testify that the wood, glue, hide, weapons etc are as close to historic as possible then the test results may actually teach us something about what we already guess at based on what we've read and from our own experiences.

We know the scutum worked, otherwise why have them? How did they work? Why did the ancient makers choose alder over oak and not yew over pine? Does the alder over oak stop a Celt javelin or arrow? Does an arrow go right through the other?

Besides, wouldn't it be fun to see some large Icenii looking guys slamming full force into a scutum then have the scutum retested for strength and flexibiity?

These are some of the possibilities were are working on.

[Paullus Scipio]

I would agree with, and endorse, Dan's logic here.....any implement which did not fulfil its function would either be abandoned, or modified until it did! This has always been the case, especially with weapons. A lot too depends on the enemy's capabilities....offence and defence tend to evolve as counters to one another ( a modern example is Tank/Anti-tank warfare, with an arms race between size of anti-tank gun or weapon, against armour development....).There are many ancient examples too...one is the Persian wicker shield/pavise( gerron/spara). It evolved as Infantry protection against nomad cavalry arrows, and was perfectly effective for this, but proved less up to the task of resisting large Greek thrusting spears (Dory), as described by Herodotus

And as always, the various design factors - 'weight' being an important one, as well as available materials - compete with one another. We see in the evolution of the scutum that the trend is to modify it to make it lighter, while still leaving it strong enough for the job ( the same evolutionary trend can be seen in the Greek Hoplite shield (Aspis).

The shield as ultimately developed is just strong enough to resist most blows, but not all - a 'compromise' of the various design factors.
....and that is the outcome I would expect to see from Sean's testing. Incidently, for this purpose, it hardly matters if the reproduction is exact down to the number of wood fibres in each strip, or the correct species of wood, or the weapons the exact type of hand forged iron, because the test parameters are simply not that fine !! 'Approximate', provided it is reasonably so, will do !