SoA Forums

Quote from: RichT on May 26, 2021, 02:55:20 PM
- general toughness, fitness, stamina and endurance, the sort acquired naturally by people doing manual labour (like fencing contractors, or legionaries). I expect that a legionary would typically be at least the equal of their modern equivalants by this measure (and both legionaries and modern equivalants way ahead of the general modern population of course).

I am reminded of something I was told by a guy who'd been an instructor in Afghanistan, namely that American couch potatoes are more promising recruits than Afghan farmboys, because you can get the former into shape but you can't do anything about the latter having had their physical potential impaired by childhood malnutrition.

(The memorious may recall that when I brought this up in another thread, Patrick suggested that the instructor was mislead by a cultural disinclination on the part of the Afghans to put in their best performance on the training ground. I'm inclined to suspect the instructor knew his recruits better than Patrick did.)

I don't really know anything about typical nutrition among Romans of the class relevant for legionary recruitment, but their abovementioned short stature suggests it wasn't optimal. In particularly, it seems likely to have been low in protein.

So my guess would be that legionaries would perform worse than modern professional soldiers (but better than couch potatoes who haven't had a drill sergeant bash them into shape yet).

In terms of stature, we might note that the British armies minimum regulation height at the start of WWI was 5ft 3in.  This was later reduced to 5ft, to allow otherwise suitable men to join up.  The issue was the shocking levels of childhood nutrition and health in the cities. 

The height of Roman soldiers is an interesting question and probably depends on when you are looking at and where you were recruiting from.  Vegetius said the earlier legion had a height requirement of 5ft 10in (Roman) and this dropped to 5ft 7 in (again Roman) in the late Empire.  So, perhaps short to 21st century people but , by late 19th/early 20th century standards, pretty hefty.

QuoteOur legionary had to be able to throw his pilum the regulation distance (whatever that was) - we have no records of distance pilum throwing competitions AFAIK. 

QuoteAll of which means that the distance to which a pilum could be thrown, its weight, its 'muzzle velocity', its impact momentum etc etc might be the least important considerations and have very little influence on the range at which it was actually thrown.

This is precisely what I was getting at on the first page.

The pila was NOT a javelin that needs to be thrown as far and as accurately as possible - its as poor a comparison as treating every long stick as a Pike, or every self bow as a Longbow.  its just wrong.

to quote myself:

QuoteWho cares if any javelin can be thrown 100m if it just bounces off a shield.  Your achieved nothing with it.
What counts is the range it is effective at.  For a pila that means the range it penetrates the shield, and that is very close.
..
Ditto this crazy overhead volley nonsense.  Why?
...
you're using all this super efficient short range ammunition on blind area shots.

OK, enough of all these gut reactions, let's look at this with a bit of mathematics.

The force applied by a legionary (or athlete) to a pilum will be the same irrespective of its weight because it is limited by the thrower's body.  Similarly the distance over which he can apply such force is constant and given by the length of his arms.  Therefore, using the good old Newtonian equations of motion,

v² = u² + 2as

and

F = ma

We can rearrange this to show that v² is proportional to the reciprocal of the pilum mass.  Bunging this into a spreadsheet we get the graph below.  The top curve assumes the thrower has the physique of a modern oplympic athlete and the lower one assumes a somewhat less accomplished guy who can only chuck a javelin at 25 m/s rather than 30 m/s.

In terms of how far the pilum will go and how fast it will arrive at its destination, one can put the values into a ballistic spreadsheet and get the results below.

Mass (kg)	0.9	2.3
Launch Velocity (m/s)	23.5	14.7
Distance @22° (m)	40	16
Velocity @22° (m/s)	20	14
Distance @40° (m)	50	21
Velocity @40° (m/s)	18	14

The above assumes a drag coefficient (C_D) of 2.0, based upon what experiments have determined for typical arrows, and a shaft diameter of approximately 50 mm.  Varying C_D values does not change  distances and velocities by that much.

So, what all this shows is that a heavier pilum (pretty much irrespective of its aerodynamic characteristics) will not slow down as much as aa lighter one during flight, but the latter only loses 10% of its velocity anyway.  However, the heavier pilum only has about 40% of the range of the lighter one, which at 40-50 m makes it a fairly close range weapon.

A bit of maths is always welcome.

A couple of thoughts
- the maximum range of a 2.3 kg pilum (if I'm reading these figures right) is 21 m (not 40-50 m), making it an extremely close range weapon.
- the penetrative power is I assume proportional to the velocity on arrival, which doesn't change much with range, so a maximum range shot (which at 21 m is not saying much) has the same penetrative power as a minimum range shot. So purely in terms of penetration, it doesn't much matter when you throw it.

Interesting, though the points we have made above still stand - the maths and physics may be the least important aspect. You wouldn't learn much about optimum 18th C musketry ranges by calculating the muzzle velocity, bullet mass etc of a Brown Bess, because tactical and human factors massively outweigh physical ones. (Though it would at least tell you maximum theoretical ranges).

The 900g pilum at 50m still has about 145 J of energy, more than enough to perforate a shield or mail armour.

That leaves open only the question of (in)accuracy limiting range.

Quote from: RichT on May 28, 2021, 10:18:48 AM
- the maximum range of a 2.3 kg pilum (if I'm reading these figures right) is 21 m (not 40-50 m), making it an extremely close range weapon.

That is correct.  The lighter pilum has a range of 40-50 m.  The heavier pilum can reach 16-21 m, depending upon elevation.  IMO, the longer range may be impractical due to the difficulty of launching such weapons at 40-45° elevation. Notwithstanding, all of this confirms the view of many rulesets that the pilum is not an independent distance-effect weapon, but an adjunct to close combat.

Quote
- the penetrative power is I assume proportional to the velocity on arrival, which doesn't change much with range, so a maximum range shot (which at 21 m is not saying much) has the same penetrative power as a minimum range shot. So purely in terms of penetration, it doesn't much matter when you throw it.

How you measure effect depends upon whether you judge these things to be a matter of momentum (bearing in mind that Force=rate of change of momentum) or kinetic energy, which is ½mv². To do the sums for the arithmetically challenged; the lighter pilum has  momentum of 18 kg.m/s and KE of 180 J; the heavier missile has momentum of 32.2 kg.m/s and KE of 225.4 J. Therefore, the heavier pilum should hit with distinctly more oomph, but you need to wait until you see the whites of the eyes before unleashing hell.

Feels smug

I think the earlier comment about Hanoverians holding fire till close range was a simple equation of firing at a distance = few hits, and no time to reload, versus, hold your nerve to the last minute and your carefully prepared, loaded properly, first fire would do a lot of damage before possible impact. Also fire disrupting formations would cause a faltering in the charge. Also, reloading in a hurry with fixed bayonets sounds like a surefire recipe for self inflicted hand injuries...

There is a bit more to it than just holding nerve.  Not much, but a bit

But it is also true that in the same way veteran phalangites could tell the quality of their opponents by how steady the vertical pikes were held, so too veteran black powder troops could tell how resolute an opponent was by how well they held their fire.

Boils down to :
When attacking formed infantry in the open, if the
first round comes at over 200m - they are fools who will run early
First round at around 150-200m - basically trained and commanded , keep going and see how they stand
First round at 100m - decent troops. You're guys are likely to halt and return fire if you don't keep them advancing.
First round not yet fired at 60m then either they have no ammunition, or you really don't want to find out what's going to hit you in ten paces, highly likely your men break first now.

Which is all together a combination of troop training and quality and nerve and officer quality.

Trooper nerve isn't much use if your officers have you discharge at ineffective range .  But no officer can hold the line if the men won't stand

I think Mark's comment feeds back nicely into Caesar's Legions at Pharsalus where they stopped and regrouped and reorganised when there was no countercharge
This sort of thing may well be dealt with at a lot lower level than the General

Feels more smug.

Will this "agreeing with Mark" thing last past lockdown?  I could get used to it, you know.

Quote from: Mark G on June 02, 2021, 07:39:26 PM
Feels more smug.

Will this "agreeing with Mark" thing last past lockdown?  I could get used to it, you know.

In an infinite universe anything is probably possible