For those who don't have a large university library near them or subscribe to metallurgy magazines. . .
Materials Characterization 29:111-117, Peter N. Jones P115-116.
"The armor targets were set up in a frame that was adjustable in terms of angle of obliquity with respect to the incoming arrow. In front of this was a pair of sky screens that were used to measure the velocity of each arrow. The arrows were shot from a 70 pound self yew bow at a draw length of 28 inches. A detailed discussion of the characteristics of the longbow and it's history can be found in ref 5. The distance between the archer, Mr. John Waller, and the target was 10m. The arrow impacts were recorded by using a high speed Fastax camera, framing speed of 500 frames per second.
Each shot was recorded as
1. Failure to penetrate, recorded as F 2. Failure to penetrate and arrow broke up, designated as F&A 3. Penetration achieved, designated as P, as in figure 11 Table 3. Penetration results for a 70 pound longbow. Arrow Velocity Target Angle of Penetration Result Weight (m/sec) Thickness Obliquity (mm)
(g) (mm) (degrees)
62 39 3 0 0 F 55 40 2 0 11 P 60 39 1 20 0 F 62 39 1 0 51 P 60 39 1 20 43 P 63 38 1 20 43 P 61 39 1 40 0 F&A 65 37 1 40 0 F&A
As can be seen from Table 3, the arrows failed to penetrate 3 mm of plate, thus the armored head was completely protected. The 2-mm plate at normal obliquity was penetrated but with only 11 mm or arrowhead through the target. Medical opinion is that thi s is not enough to causes a debilitating wound [4]. Significant penetrations were achieved through the 1-mm plate, which would have caused loss of arm and leg function. The powerful effect of plate obliquity was well demonstrated with quite modest varia tions from normal, causing the arrow shaft to shatter. Penetration when it occurred was invariably by tensile tearing of the plate with some material detaching as spall. This latter phenomenon occurs because the iron is very dirty."
The targets were wrought iron plates, rolled to the appropriate thickness and annealed to the fully soft condition. The thickness selected represented the armours of head, breastplate and limb armor. The arrowheads were long bodkin points made of low carbon iron with a vickers hardness of 350.
Peter Jones also has an appendix (pp232-236) in Robert Hardy's "Longbow, A Social and Miltary History" that includes some of the math on one mechanism for armor pentration. (Interestingly it is not the one mentioned above.)
Kevin
(for those people whose mail readers don't like tabs, sorry bout that. It
looks fine in 10 point Courier New in MS Word.)
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