[Marc Ritz]

I have watched way too many arrow penetration tests like most of you but interestingly enough, this unscientific video by Jörg Sprave got me really curious: https://youtu.be/_LD4HKylYAU?t=919

He used a contraption to shoot an authentic 170 lbs English Longbow with proper arrows at a 1 mm flat, steel target. It produced a penetration of around 1-2 inches. While that is meaningless by itself, he followed it up with a carbon target arrow shot from a compound bow.

Based on your experience, how much penetration would you expect? Personally, I thought the arrow would explode or just push the tip into the metal. In reality, it produced around 6 inches of penetration.

I thought that's interesting. Kinetic energy really seems to be king when it comes to metal armor penetration, and it seems to be more important than momentum. The compound bow just outclasses the warbow when it comes to kinetic energy.

But it doesn't. The compound bow was a Liberty One. Thankfully, these bows get tested by their manufacturer, and they are very transparent about their performance. They produce around 88-93 Joules of energy with target arrows (20-25g). Source: http://www.libertyarchery.com/BowReports.html

That is much less than the English longbow actually. They do around 130 Joules at a draw weight of 170 lbs with war arrows.

So, how come the compound bow with target arrows did so much better? The compound crossbow after that shot the same target arrows through the steel up to the feathers. Does it all come down to arrow shaft diameter and we have focused too much on energy?

A heavy composite bow allows for lighter arrows to be shot. A 40g arrow from a 180 lbs composite bow would produce 280 fps and 147 Joules of energy (compound bow speed at almost double the arrow weight). These Ottoman war arrows were comparatively thin. 6 mm at the nock, 9 mm at the center, 5.5 mm at the tip. I'm no expert in aluminum arrows for compounds but that seems to be comparable.

(calculated performance by Karpowicz: https://sci-hub.se/https://doi.org/10.1017/S0003598X0009565X
And here an example of a light Ottoman arrow: https://mandarinmansion.com/item/rare-ottoman-war-arrow)

Asiatic composite bows were able to shoot thin arrows at speeds comparable to compound bows but with much greater kinetic energy than commercial compound bows and similar English longbows. Does that mean that we should expect them to be much greater at metal armor penetration? Are we going to be surprised once the current generation of warbow archers gets their hands on high-quality composite warbows? Joe Gibbs already received one. Did he share any insights? Do we need penetration tests with these thin, barreled Ottoman war arrows shot from heavy composite bows?

[Bartek Strojek]

There are many thing here that can come into play, but certain thing is that carbon and aluminium arrows are generally stiffer and tougher for given weight/diameter compared to wooden ones.

Especially in case of pine wood, like those Ottoman arrows. They would be probably snapping pretty easily launched into steel that hard.

So reducing the diameter to concentrate the energy probably works way better with carbon fibers or aluminium that have way higher cross-sectional density and mechanical properties in general.

They can punch trough sheet of given gauge and keep sliding trough, while pine wooden shaft would get badly damaged sooner or later.

In any case, there doesn't seem like there were some efforts to make those war arrows really narrow - Manchu and Japanese were using very heavy arrows.

And here, if someone'd actually wanted very narrow shaft, he probably would have used some dense wood instead of pine - to shave some millimetres away.