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FORMULAS FOR PENETRATION.

From “Toles et Plaques de Fer et d’Acier en tir normal," par M. Jacob de Marre, Capitaine d' Artillerie de la Marine, Nevers, 1888.

In English units.
v = velocity at impact in f.s.
a = diameter of shell in inches.
p = weight of shell in pounds.
e = thickness of plate in inches.
E = thickness of wood backing in inches.
For penetration of wood backing,
E 0.6 = (3.79013) p1/2U / a0.9 U = velocity at impact in f.s.
For penetration of wrought iron,
e 0.65 = (3.03838) p1/2v / a3/4
For penetration of plates of Creusot steel,
e .07 = (4.99066) p1/2v / a3/4
For penetration of thin steel plates by steel shell from rapid fire guns and revolving cannon,
e .07 = (4.86572) p1/2v / a3/4
Quantities in ( ) are logarithms.
V = velocity at impact, for wood-backed plate,
V2 = v2 + U2


ORDNANCE OFFICE,

Washington, D. C., February 12, 1891.