Arrow verses Armor – Penetration Experiment
To check the effectiveness of period arrow heads.
I used a 15 kilo (33 pound) Japanese longbow at 20 yards for all tests. Shooting at a multilayer target block with actual Edo period arrow heads, I recorded my results, I also conducted a few experiments to check the effectiveness of the Japanese bow and arrow combination. The following results were noted:
Block penetration and arrow drop at 20 yards
Field tip (125 grain) on bamboo shaft, the average penetration was 6 to 8 inches. This was my arrow penetration and drop standard.
Sankaku (triangular or diamond armor piercing, 245 grain) on bamboo shaft, the average penetration was 8-12 inches. Arrow drops of 1 inch over 20 yards.
Tsubeki-ne (Chisel shape, 317 grain) on bamboo shaft, the average penetration was 6-12 inches. Arrow drop 2-3 inches over 20 yards.
Hira-ne (413 grain) on bamboo shaft, the average penetration was 8-12 inches. Arrow drop 6 to 8 inches over 20 yards.
Armor Penetration at 20 yards
All arrow heads vs .030 inch aluminum. No problems with penetration and stayed within limits above and no damage to the tips.
Field tip (125 grain) vs .043 inch (18 gauge) mild steel plate. The field tip bounced off the target while making a small hole in the plate, tip flattened.
Sankaku (triangular or diamond armor piercing, 245 grain) vs .043 inch (18 gauge) mild steel plate. Full penetration of arrow head (1 5/8 inches), the bamboo shaft stopped the arrow, minimal damage to the tip.
Tsubeki-ne (Chisel shape, 317 grain) vs .043 inch (18 gauge) mild steel plate. Full penetration of arrow head 1.5 inches, minor damage to tip.
Hira-ne (413 grain) vs .043 inch (18 gauge) mild steel plate. Over 3 inches of penetration along the 4 inch metal shaft with minimal damage to the tip. Penetration of this depth could cause death.
These test provided a good indication of the Japanese bow performance against steel armor and displays why archery was considered an important part of the samurai weapons even after the introduction of the gun to Japan.
Block penetration. The arrow heads acted as expected, the tips with a cutting edge doing better than the field tip.
Accuracy. Not affected after accounting for the weight and flight differences of each arrow head, over several shots I was able to place shots with accuracy into the block target.
Armor penetration. I was impressed that the arrow heads went through the 18 gauge mild steel plate as well as they did. My reproduction samurai armor is approximately 18 gauge in thickness and most period armor is 18 to 16 gauge in thickness.
The ease of penetration of the steel plate proves that even with a bow of light draw weight the arrow heads functioned as designed. The limited penetration on some of the arrows would help to explain the period ink block prints of samurai with ten or more arrows sticking out of their armor, each doing some damage but none inflicting a killing wound.