Changes

The rapid development of the warplanes after 1914 necessitated a means of defense. Guns of secondary batteries were given sufficient elevation for use in air attacks, and projectiles and fuses for use against aircraft were developed. With the onset of World War II, 20mm Oerlikon (which were too light) and especially 40mm Bofors automatic guns were used in increasing numbers, especially against Japanese Kamikaze planes. The Bofors was designed by the Swedes in the 1930s. The US Navy alone built more than 22,000 of these antiaircraft guns for use on carriers, battleships, PT boats, and minesweepers. They were particularly effective against Japanese aircraft in the Pacific.<ref>Don Preul, and A.J. Daverede, "The 40mm Bofors Cannon." ''Nautical Research journal'' 2005 50(3): 159-165</ref>  

The rapid development of the warplanes after 1914 necessitated a means of defense. Guns of secondary batteries were given sufficient elevation for use in air attacks, and projectiles and fuses for use against aircraft were developed. With the onset of World War II, 20mm Oerlikon (which were too light) and especially 40mm Bofors automatic guns were used in increasing numbers, especially against Japanese Kamikaze planes. The Bofors was designed by the Swedes in the 1930s. The US Navy alone built more than 22,000 of these antiaircraft guns for use on carriers, battleships, PT boats, and minesweepers. They were particularly effective against Japanese aircraft in the Pacific.<ref>Don Preul, and A.J. Daverede, "The 40mm Bofors Cannon." ''Nautical Research journal'' 2005 50(3): 159-165</ref>  

Anti-aircraft gunnery was a tradeoff between 5" guns, with their long range, and 20 and 40 calibre short-range guns with a high rate of fire.  The breakthrough came in 1943 with the introduction of the '''[[proximity fuze]]''' (or "VT fuze") in 5" shells. It had a radio and receiver and when a signal bounced back, it was within range of the target, and exploded. The effect was to make the target 50 times bigger and thus much easier to hit. The fuzes played a decisive role in defeating the Japanese Kamikaze attacks of 1944-45.  The British had invented the device but lacked the massive industrial capacity needed to produce it in quantity, so shared the blueprints with the U.S. Navy. The basic components are a vacuum tube (six inches long and three inches in diameter) a battery, and a radio transmitter and receiver, all of which have to be rugged enough to withstand 20,000 Gs when shot out of a gun at high velocity. After the shell is fired and begins rotating, a chemical reaction produces an electrical charge which in turn arms the shell and sends out a radio impulse. The return signal, reflected from the target, detonates the shell prior to impact and produces the devastating effects.<ref>The Germans started in 1930 but never invented a working device. Geoffrey Bennett, "The Development of the Proximity Fuze." ''Journal of the Royal United Services Institute for Defence Studies'' 1976 121(1): 57-62. Issn: 0953-3559; Ralph B. Baldwin, ''The Deadly Fuze: Secret Weapon of World War II.'' (1980); Cameron D. Collier, "Tiny Miracle: the Proximity Fuze." ''Naval History'' 1999 13(4): 43-45. Issn: 1042-1920 Fulltext: [[Ebsco]]</ref>

Anti-aircraft gunnery was a tradeoff between 5" guns, with their long range, and 20 and 40 calibre short-range guns with a high rate of fire.  The breakthrough came in 1943 with the introduction of the '''[[proximity fuze]]''' (or "VT fuze") in 5" shells. It had a radio and receiver and when a signal bounced back, it was within range of the target, and exploded. The effect was to make the target 50 times bigger and thus much easier to hit. The fuzes played a decisive role in defeating the Japanese Kamikaze attacks of 1944-45.  The British had invented the device but lacked the massive industrial capacity needed to produce it in quantity, so shared the blueprints with the U.S. Navy. The basic components are a vacuum tube (six inches long and three inches in diameter) a battery, and a radio transmitter and receiver, all of which have to be rugged enough to withstand 20,000 Gs when shot out of a gun at high velocity. After the shell is fired and begins rotating, a chemical reaction produces an electrical charge which in turn arms the shell and sends out a radio impulse. The return signal, reflected from the target, detonates the shell prior to impact and produces the devastating effects.<ref>The Germans started in 1930 but never invented a working device. Geoffrey Bennett, "The Development of the Proximity Fuze." ''Journal of the Royal United Services Institute for Defence Studies'' 1976 121(1): 57-62. Issn: 0953-3559; Ralph B. Baldwin, ''The Deadly Fuze: Secret Weapon of World War II.'' (1980); Cameron D. Collier, "Tiny Miracle: the Proximity Fuze." ''Naval History'' 1999 13(4): 43-45. Issn: 1042-1920 Fulltext: [[Ebsco]]</ref>