Crossbow v. armour

[Erpingham]

Following a fashion seen elsewhere on the forum, here is an interesting little YouTube video

https://www.youtube.com/watch?v=Uoz0eggQen8&feature=youtu.be

It is one of the Tod's workshop series and I do tend to find Tod quite sensible and low key about this sort of thing.  However, in this case, I was surprised how surprised he was about the results.  Bit of a shame he didn't go for a composite of mail and fabric armour though - I suspect it would have stopped all his selection of arrows.

[Imperial Dave]

to add to that, in my experience, quilted armour is surprisingly effective in its own right. I had a quilted arming jack in my reenacting days and was incredibly protective at cushioning blows although I have to admit I was never shot at with sharp bodkins! add on top of that mail or jerkin and its pretty effective. 

[manomano]

I hope these images  could be of some interest.
Shoots are from a LB , but this only  a ballistic problem : the weapon used is secondary.

- Weight of the shot
- Shape of the point
- Material of the shot
- Terminal velocity
- Final energy of impact.

From my database, i dont' remember the authors : I apologize deeply for this.

Some notes:
Against a solid plate the shot simply  can penetrate or not,
against several layers of material it's possible that the point is deviated by the first layer, so the impact on the second layer is not longer at 90 grades, so less effective,
the same thing is against mail supported in the back by a layer of leather,:
moreover if the mail is stably fixed on the leather , the rings will be more effective.

[Erpingham]

The tables are from this article

https://www.academia.edu/5520314/Arrows_Against_Linen_and_Leather_Armour

Having read this, I wasn't surprised by the results in the video.

[Imperial Dave]

funnily enough I was thinking of quilted armour and the parallels with cricket. From wikipedia a excerpt re the construction of cricket pads from 100 years ago

Traditional pads were made from canvas which had cotton stuffing inserted between stitched-in cane wood strips that ran vertically up to the knee roll. The material would then be painted white with water-soluble canvas paint.

ok we arent talking pointy sharp things but they have to withstand up to 90mph ball weighing 160g = 130 Joules of energy

[Erpingham]

ok we arent talking pointy sharp things but they have to withstand up to 90mph ball weighing 160g = 130 Joules of energy

I had some interesting formulas about the importance of the energy density of an impact against armour (i.e. the area the energy is delivered over) but I've mislaid them - need to track them again .  This is stuff on modern armours but the principles are applicable.

[Imperial Dave]

yes of course. Energy is energy (kinetically wise). Be good to see more info on such comparisons

[Nick Harbud]

Energy is indeed energy, but it is probably more important to look at momentum as

Force = rate of change of momentum

Considering projectile energy is generally only useful if one is trying to shatter the target as opposed to penetrate it.

[Erpingham]

Fair point Nick, but actually protection studies do focus quite a bit on KED - kinetic energy density.  It also seems to be used quite a bit in the design of non-lethal weaponry (mechanical variants thereof).

[Imperial Dave]

that was my understanding as well but obviously there are many nuances to this particular field of study (ballistics). I did have a paper on it from the Dutch MOD somewhere so I'll see if I can dig it up

[Erpingham]

It's not the original paper I had but it covers the same ground

https://www.researchgate.net/publication/254911398_Towards_a_better_science-based_evaluation_of_kinetic_non-lethal_weapons

This should have enough equations to keep Nick happy too

On the general idea of lethality of blunt force impact, this paper (complete with set of presentation slides) has some good summaries

https://archive.org/details/DTIC_ADA532158/page/n9/mode/2up

[manomano]

I think this may be usefull:
Sorry,this free book  is in italian and on modern guns, but physics is physics.

https://www.earmi.it/download/libri/moribal2.pdf

Some further considerations:

Obviously is not necessary to kill a enemy soldier on the spot but  simply incapacitated him.

So,
-  Areas on the target where a hit can produce significative damage.
-  Percentage of these areas on the full target
-  Percentage of expected hits vs ammunitions expenditure and rate of fire
-  Loss of effectiveness during spend time.

A bow have a considerable rate of fire but the shooter become tired and so successive shoots less effective,
precision and penetration  is not great over point black range.
Crossbow is more accurate, penetration is better even at longe range, the shooter dont'  become tired, but rate of fire is terrible.
Sling and staff sling are very imprecise, but rate of fire is very high and have a concussive effect also on the best protected target.

[Imperial Dave]

thanks both, more data than you can shake a stick at!