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Tiny miracle: The proximity fuze

Collier, Cameron D.  ; Annapolis Vol. 13, Iss. 4,  (Jul/Aug 1999): 43.

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"It helped blaze the trail to Japan," said James Forrestal. Above, a carrier crew cheers as a Japanese dive bomber crashes amidst air bursts off the Marianas. It was "devastating," said George Patton. "It" was the variable time (VT)/proximity fuze that turned near-misses into kills.

Late in 1944, as General George Patton's Third Army was moving toward Germany, he wrote a letter to the War Department describing the success his troops had experienced with a new artillery shell and fuze:

The new shell with the funny fuze is devastating. We caught a German battalion, which was trying to get across the Sauer River, with a battalion concentration and killed by actual count 702. I think that when all armies get this shell we will have to devise some new method of warfare. I am glad that you all thought of it first.1 The idea of a target-influenced fuze was not new; similar fuzes for bombs and rockets existed at the outbreak of World War II.2 But it was a fuze rugged enough to be fired from field artillery and antiaircraft weapons that had prompted Patton's letter. The fuze, developed largely by the Department of the Navy, has had significant effects on U.S. combat capabilities.

The proximity fuze functions as a small radio station in the shell's nose. The basic components are a vacuum tube (six inches long and three inches in diameter) a battery, and a radio transmitter and receiver; a small glass tube filled with electrolyte solution acts as the battery. After the shell is fired and begins rotating, centrifugal force pushes the solution to the outside of the tube, where a chemical reaction occurs with small pieces of metal surrounding the tube. This produces an electrical charge which in turn arms the shell and sends out a...