672
ARMOUR
| ments took place with Krupp process armour, in which
- remarkable results were obtained, the most important being
that shown in Fig. 8 (see Plate), which depicts the front of a plate 11 '8 inches thick after attack by three 12-inch projectiles. These have broken, leaving their heads lodged in the plate without cracking it. The highest striking velocity was 1993 feet per second. The shot weighed 712'7 lb, and it would have perforated an iron plate 25'9 inches thick. The remarkable feature is the scale on which this success was achieved; for while a 12-inch plate may resist perforation by a 12-inch shot nearly as well as a 6-inch plate resists that of a 6-inch shot, the strain in the way of fracture greatly increases in the thicker plate, for the width of the thick plate is often not very much greater than that of the thin one. In these trials the 12-inch plate was about 6 feet wide, and the 6-inch nearly 5 feet, so that while the 6-inch shot head formed a wedge little more than one-tenth of the width of the plate attacked, the 12-inch plate was attacked with a wedge nearly one-sixth of its width. The figure indeed shows what enormous wedges are driven into the plate, and the excellence of metal bearing such a strain is apparent. At the end of 1896 the three great Sheffield armour-making firms, Brown, Cammell, and Vickers, purchased Krupp’s process. Fig. 9 (see Plate) shows an admirable 6-inch plate submitted by Vickers for trial in March 1897. This entirely defeated the attack of six 6-inch projectiles striking with a velocity of about 1960 feet per second. All the armour at present made for the British Navy is practically on the Krupp process, although modifications may be introduced by each firm based on their own experience. Messrs Beardmore in Scotland have recently made armour by a process of their own, of about the same quality as Harveyed armour. Excellent armour-piercing projectiles are made by Elswick on the American Wheeler Sterling patent, and Elswick and Firth have made large deliveries of shot on Firminy’s patent. Many years ago Whitworth steel shot stood first in quality. Holtzer’s subsequently became best known, and have been used so universally as to furnish a sort of standard of comparison. Krupp makes excellent projectiles, so does the firm of St Chamond. Carpenter shot in America are hardly inferior to those of Wheeler Sterling, or to a notable shot recently made by Johnson. The latter have probably Fig. 10. obtained the greatest known penetration, but as they In 1890 a Schneider 10^-inch steel plate, containing are generally made solid and fired with caps, comparison nickel, behaved well at Annapolis under the attack of with others is difficult. In England Hadfields deserve 6-inch and 8-inch guns, exhibiting great toughness, and special notice as having by special processes developed nickel was introduced soon afterwards in American armour. admirable projectiles, and especially as having made cast In England considerable delay took place, because nickel steel of a quality rivalling good forged steel. Lastly, the plate, till thoroughly understood, appeared to be capricious Royal Laboratory has also made excellent armour-piercing in its behaviour, and the supply of armour was then being projectiles. Before leaving the subject of the behaviour of armour pressed forward to meet the demands arising from the increase in the British Navy. Nickel was, however, adopted under fire, one or two rough rules of thumb, which are in 1896. As above mentioned, nickel used with judgment based on calculation, may be given. The thickness of imparts toughness to armour without interfering with face wrought iron which a projectile may perforate is about hardening. Fig. 7 (see Plate) shows the front of a good one calibre for each 1000 feet of striking velocity; that is specimen of unhardened 6-inch Krupp nickel plate after to say, a 6-inch shot with 2000 feet velocity may perforate attack by 12, 15, and 17 cm. (4'7, 5‘9, and 6'7 inch) two calibres or 12 inches of iron, with 1500 feet it may guns. A fringed lip, characteristic of soft steel, rises up perforate 9 inches, and so on. The equivalent thickness round each shot hole, but no cracking is visible; the pro- of the best steel plate now known is rather less than half jectiles have rebounded from their holes owing to the that of wrought iron, so that a 6-inch shot will require elasticity of plate and shot. This plate is the bmu ideal something over 2000 feet velocity to perforate 6 inches of of armour for inland forts. Krupp had manufactured treated steel, while 1000 feet velocity will hardly carry it armour for some little time, but first became known as the through 3 inches. Attempts have been made to destroy armour by shells inventor of a special process at the World’s Fair in Chicago in 1893, where he exhibited a plate which had borne containing powder and high explosives, but hitherto it very severe attack admirably. In 1895 a series of experi- may be said that unless the projectile gets its head well
(then Lieutenant) English suggested that a wrought-iron cap on the shot point might give the same result. This did not prove successful with compound plates, but when the experiment took place with very much harder, but necessarily thin, water-hardened skins in Russia in 1894, the same device of iron or steel caps was tried with success. Similar results have been obtained since in America , and England, and it is probable that such caps may be used in actual war. Fig. 6 (see Plate) shows the back of a plate of Beardmore’s recently attacked. A capped shot point nearly bored its way through, opening the metal in a star-shaped tear at 7. Uncapped shot were set up, and acted as punches, partially dislodging discs of plate, as seen at 2, 3, and 5. Harveyed armour was adopted in Great Britain in 1892.
