[Markus Fischer]

I recently watched the YouTube video from Tods Workshop, in which he shot historically accurate longbow arrows from his "lockdown-longbow" which shoots these arrows at the same speed as a british 160lbs yew longbow.

https://youtu.be/hc6dhMV_L54

In this specific video he shot the arrows at his Go-Pro protection device, which is a cheap/medium grade reenactment helmet with a polycarbonate visor.
One of the arrows passed cleanly through the front of the helmet and still had enough energie left to bounce of a steel tube on the helmets inside, as well as almost piercing a hole into the helmets backside.

At first Tod didnt comment much on this, because he thought the reason for that must be the rubbishy quality of the helmet.
But then he decided to measure the thickness at the spot in which the arrow penetrated, and it actually turned out to be 1,8mm thick.

https://youtu.be/v3QqdEX_ka8

And there comes my question:

How thick was the average medival european helmet?

There sure has been some enormous variation, so lets narrow our question down to a late 15th century sallet (i guess thats about what Tod shoots at in the video).

Probably there has also been some big variation within sallets, but if some people who are knowledgeable on this topic where to give some examples, we could come up with an approximation of the avarage sallet-thickness, in order to say how close this unintentional experiment would be.

I for myself dont know a whole lot about helmets, but I recently saw a reproduction of a sallet by Arma Bohemia at the price of 400€ or 490USD (I would consider this mid-range for a helmet) with the thickness being 1,5mm, so even less than the helmet in the video.

Of course one must also consider that Tods measuring device might be off a fair bit.

What do you think about this?

[Edward Lee]

Suppousedly helmets thickness are like breastplates, thick on the top/center and it thins out to the sides. For example if the top helmet is 3mm thick and the side might thins out to around 1mm more or less, as it applies to breastplates.

http://myArmoury.com/talk/viewtopic.php?t=947...p;start=20

http://myArmoury.com/talk/viewtopic.31601.html

Regarding the 400 euro helmet, it's probably not heat treated. Regarding armor strength there is a big difference between heat treated armor and armor that are not. It is so in modern terms and I would think it applies to the past as well.

[Sean Manning]

[Mike Ruhala]

A historical sallet could be several times thicker in that area than the one Todd shot and he shot it with the equivalent of a 160lbs bow which is pretty darn powerful. A faster impact on a smaller surface area(such as the arrow) also has better puncturing characteristics than a slower impact over a wider area(such as a sword strike.) A lot of historical armor doesn't appear to have been made from thin sheet metal of uniform thickness like we use now, it looks like they were starting with thicker plates and drawing them out to get thick center sections that taper towards the edges. The thicker sections tend to be on the front and/or tops of helmets and some were massively thick in these areas, like a quarter inch!

[Augusto Boer Bront]

Thickness will vary a lot.

Some are 1 mm, even in the front. Other go up to 4 mm or above.

There's a big range of thicknesses. all depending on what the helmet was expected to do and the type of troop wearing it.

Here's a small collection of thicknesses of bits of armour. Some are victorian fakes, one of them is made of cats iron, but you'll get the idea.

https://www.pinterest.se/kohlstruck/research-sources-of-armour/armour-measurements/

[Markus Fischer]

Well, considering the big variation seen in these pieces on Pinterest, the test by Tod could be quite accurate.

In fact most of these helmets reached from 1,5mm to 2mm at the front, which means that Tods Helmet was pretty much in between with its 1,8mm.
So one could say that a number of historical helmets wouldnt protect you against warbow arrows.

At the same time I noticed, that the breastplates often were below 2,5mm in thickness (at least these particular examples) which is the thickness of the Agincourt Breastplate tested in the famous Arrows vs. Armour video.

This means that this test probably cannot be seen as an ultimate answer...the results may have been very different if they choose an other breastplate (even if its from the same time).

Very interesting...it seems like one can never be 100% sure about something beating something else, simply because the variation was too big.

[Matthew P. Adams]

Then factor in the type of head used on the bolt. Was it a bodkin, a broadhead, how sharp, was it heat treated, and if so how well, can all factor in. Then movement, heads move both incedentally and also on impact. What happens if I'm turning my head, or I get jostled sideways? What's under my helmet? Am I wearing a padded arming cap? I know at one point men wore a secrete, a steel skull cap offering protection under a hat, were they ever worn together with a helm? I have no idea, but if so it would certainly add protection.

It's fun to run tests, and I certainly like watching them on YouTube, ESPECIALLY the Todd's Stuff channel, but it's really hard to draw any overarching conclusions from them. I know I'd take the sturdiest armor I could afford, and that any helmet is waaaay better than no helmet.

I ride a motorcycle and even though I'm an ATGAT rider (all the gear all the time) comfort can often be more important than protective qualities. The gear that fits is the gear that gets used. The point is that you could make an absolutely arrow proof helmet, but if it's hurting my spine I won't be able to wear it for a very long time. If I have an arrow proof helmet hanging from my saddle, or back in a wagon, it does me less good than a lighter weight, less protective helmet that I can wear on my head through 4 hours of heated battle.

[Raman A]

Check Matthias Goll's PhD thesis for measurements: http://myArmoury.com/talk/viewtopic.31261.html

Looking at Goll's data on sallets (what he calls type VII helmets) it looks like the average thickness actually is right at 1.8 mm. However, like Sean and pretty much everyone else already said, just looking at averages can be dangerous and we can't really draw any definite conclusions. First, my understanding is that Goll's measurements for sallets and armets are of the skull only and do not factor in overlap with the visor or brow-reinforcing plates, which could significantly increase the effective thickness at the overlapping areas. Second, thickness varies quite a bit between examples as well as at different spots on the same example. Some of the helmets had maximum thicknesses over 4 mm (although curiously those areas appear on the nape of the helmets and might just be a byproduct of their construction rather than an intended feature), while some helmets have areas less than 1 mm thick. At least one helmet has a spot only half a millimeter thick on the top-right of the skull. Many of the helmets have average thicknesses across their surface significantly higher than 1.8 mm, in the 2-3 mm range, while others are much lower.

There's also metallurgy to take into account. In Alan William's The Knight and the Blast Furnace he estimates that there's a quadratic correlation between plate thickness and energy necessary for a given projectile to penetrate, so even small differences in thickness can make a big difference in protection, but in the same book he also shows how much the metal quality in terms of hardness and micro-structure makes a difference. A thinner armor can potentially be as or more protective than a thicker one. In the Graz test a pistol penetrated 3 mm of modern mild steel but was stopped by a 3 mm section from a 1570 horse armor. "The fact that modern mild steel failed to absorb all the bullet's kinetic energy, while the 16th-century breastplate did, can probably be attributed to the early armourer's skill at cold-working the breastplate and hardening its surface." https://journals.lib.unb.ca/index.php/MCR/article/view/17669/22312

[James Arlen Gillaspie]

I may have missed someone else mentioning it, but another huge factor is RANGE. Missile weapons could usually be expected to operate in a certain range in the battle space, and Tod tends to be a bit close, because he doesn't want to miss. Also, charcoal iron and steel's laminated structure can be more difficult to penetrate due to its tendency to inhibit crack exploitation. The projectile produces a crack and widens it out to pass through, but a laminated structure means it cracks through the first layer and then has to start all over again with a lot less energy.

[Leo Todeschini]

James Gillespie wrote

[Dan Howard]

Work-hardening is often an overlooked factor. A skilled smith is better at cold-working the metal so it doesn't need to be annealed as much, which leaves the final product (even low-carbon steel) significantly harder. This was demonstrated at the Graz test mentioned above where the modern plate was compromised by the pistol but the 16th century one (of similar thickness and carbon content) was not.

[Graham Shearlaw]