The Radio Proximity Fuse

The proximity fuse was a radio transmitter/receiver that detected an object in its path. When the object was close enough, about 30 feet, the fuse would go off. Before the proximity fuse, the range to the target had to be estimated and that range dialed into the shell. This was difficult against a maneuvering attack aircraft. The trick was to get the tiny radios rugged enough to withstand firing from an anti-aircraft gun. The success of the proximity fuse was confirmed with tests aboard Cleveland (CL-55), 12 Aug 42, which downed three drones with four shots from 5" dual purpose guns. The fuse was ordered into mass production. The first combat use of the proximity fuse was by the Helena (CL-50) off Guadalcanal, 5Jan43. The proximity fuse was such a valuable secret that it was forbidden to be used over enemy territory until late in the war in case the enemy found a dud and become aware and possibly reproduce the technology or develop a countermeasure. Heralded as an "organizational achievement transcending anything of the time ... one of the most effective alliances among the military, academia, and industry," the development of the Proximity Fuze during World War II was credited for reducing the duration of the war by at least a year. WWII is singularly distinguished as the only war in history in which the outcome of the war was significantly influenced by scientific breakthroughs that created weapons unknown at the war's commencement. Development of a radio-transmitter proximity fuse to detonate near a plane would require not just technological breakthroughs involving a variety of fields of expertise, but miniaturization of electronic systems that had never been accomplished, plus near perfect cooperation and coordination of the military forces (specifically the Navy and Army), universities (principally five), diversity of scientists from a variety of fields, industry (engineering laboratories, quality control, and production facilities), amateur radio operators, ordinance experts, testing facilities, along with an unprecedented level of teamwork.1 Further, the project had to remain top secret during the war, despite ultimately employing about 1 million people in the production effort. The magnitude of the manufacturing ramp-up is noteworthy. 22 million fuze units, composed of over 300 components, were produced between 1942 and 1945. During this time the cost per unit dropped from $742 to $18. Overall, 110 plants were involved in production of the fuzes and their components without a single breach of security, resulting in neither German nor Japanese intelligence having knowledge of the technology nor its deployment. Key Issues: Development of the Proximity Fuze, used to detonate bombs & Anti-Aircraft shells required: 1. massive breakthrough in technology, 2. rapid innovation and continuous improvements, 3. unification of diverse inputs of thinking, 4. superb organizational coordination within the alliance 5. flawless speed of execution from research to development to commercialization to field proliferation. Critical Measures of Impact: a. Prior to the war's outbreak, anti-aircraft fire was incredibly inaccurate: Typical Rates of accuracy: 1940: Without Fuze: Thousands of Rounds per airplane destroyed by ground-fire during day, tens of thousands of Rounds per airplane destroyed at night 1944: With Fuze: 90% kill rates of V-1 Buzz Bombs with 10 rounds of fire, similar impact on Japanese Kamakaze attacks on US Pacific Fleet Nearly total elimination of Japanese Aircraft and ships in Pacific Theatre b. Citations from Eisenhower, Patton, & Churchill for the fuze's impact on war c. Production of Proximity Fuzes: 1940: None 1945: 22,000,000 fuses produced, incorporating miniaturized electronics: 140,000,000 miniaturized rugged vacuum tubes and numerous impact resistant components totaling over 1 billion components Nearly 100% reliability and safety in sub-zero weather and tropical heat Employed over 1 million people in production in 110 plants, with such total secrecy as to be unknown to either Japanese or German intelligence d: Ability to withstand shocks of: 20,000 G-forces at impact of firing 5,000 G-forces shell spin during trajectory