Oh god.
Another inaccurate armor penetration test.
First of all the test method is crap.
Such a test should be made with a shooting machine and a
(flying)real arrow.
The arrowhead is a needle bodkin which were used to penetrate mail, not plate armor.
Also the needle bodkin is completly blunt and it isnt made of hardened steel.
The longbow was a very low poundage bow.
I would say it was a ~50+ pound bow
(english warbow draw-weight = 80 to 160+ pound)The arrow weight in the test was 63gramms which is realistic for a war arrow.
The starting velocity of the arrow was just 37.9m/s
(124ft/s) and this is very very slow.
Very strong and well made Longbows can shot war arrows
(with a weight which fits to the bow draw weight) with a starting velocity up to 63m/s+
(207ft/s).
The engergy of the arrow with 63gramms and 37.9m/s is 45.25J... with 63m/s it is 125.02J.
So the energy will be the 2.72x of tested arrow impact
But also with the weaker tested bow it schould absolutly be possible to penetrate plate armor at close range with a hardened and sharp bodkin
(which is designed to penetrate plate armor).
Enough said.
EDITSomething like this
(this is the bodkin I use for my war arrows)