It Failed Half The Time And The Navy Built It ANYWAY — Then A Hearing-Aid Tube Changed The Air War!

December 30, 1944. In the snow near Assenois, a German division, one in three of its men a survivor of the Russian front, did everything its veterans knew to live through shellfire, and its lead battalion was cut to pieces. Its commander blamed the American fighter-bombers, and one more thing he could not identify at all. In his report he called it "tree smashers." The answer was a new American shell fuse, and the heart of it descended from a little glass tube made for people who were going deaf. By 1940, pointing an anti-aircraft gun was largely a solved problem; timing the burst was not. A time-fused shell exploded wherever its clockwork ran out, and when the Blitz began, British gunners by their own estimate fired something like twenty thousand rounds for every aircraft they brought down. Merle Tuve's Section T set out to put a radio inside the nose of a shell: a set that would hear its own echo off an aircraft and burst close enough to destroy it. Every part had to survive about twenty thousand times the pull of gravity at the moment of firing. The parts came from the hearing-aid trade. Norman Krim's miniature tubes at Raytheon, about three grams each, were the starting point. In January 1942 only 52 percent of the test fuses worked, and the Navy ordered production anyway. Tuve's rule on the wall read "Aim at an 80% job." James Van Allen fixed the breaking filaments with a tiny coil spring. In Emporium, Pennsylvania, nicknamed "Girls Town", some three thousand women built the tubes, and at Sylvania's Ipswich plant, which assembled more fuses than any other place on Earth, nobody told the workers what they were making. A fuse that cost $732 in 1942 cost $18 by 1945, and more than twenty-two million were built. On January 5, 1943, USS Helena brought down a Japanese dive bomber with a shell that never touched it. In 1943 the fleet needed about 155 proximity-fused rounds per aircraft, against 508 time-fused. Against the V-1 flying bombs, along the coastal gun belt, the share brought down rose from 17 to 74 percent. Germany worked on more than thirty designs for a fuse like this, by some counts fifty, and not one ever reached a gun crew. This is the story of how a part made for the hard of hearing ended up bursting thirty feet above a German foxhole. CHAPTERS 00:00 Assenois, Ardennes 03:39 A Question of Time 08:53 An Idea in Plain Sight 13:57 The Hearing-Aid Tube 20:27 A Fuse That Heard Itself 29:21 Germany's Six-Month Rule 33:31 Girls Town 38:19 A Miss That Counted 42:29 Tree Smashers 46:48 What the Ear Lent the Gun If your mother or grandmother worked on those Sylvania lines in Emporium or Ipswich, or on any fuse line, put her name in the comments. Hardly anyone ever thanked those women by name. SOURCES AND CREDITS Archival film and photographs, all in the public domain: U.S. National Archives (U.S. Army Signal Corps and U.S. Army Air Forces photographs and films, U.S. Navy photographs and films, series 80-G, 111-ADC, 428-NPC; United News; Lewis Hine), Naval History and Heritage Command, National Museum of Naval Aviation, Library of Congress (Office of War Information, Alfred T. Palmer, Howard R. Hollem, Marjory Collins, National Photo Company, Lewis Hine, Carol M. Highsmith, Historic American Engineering Record, Historic American Buildings Survey, Sanborn maps), Imperial War Museums (UK Crown copyright expired), National Bureau of Standards (NIST), NASA/JPL, Prelinger Archives, Universal Newsreel, Internet Archive Book Images. U.S. patents of M. A. Tuve and R. B. Roberts, N. B. Krim, W. A. S. Butement, E. S. Shire and A. F. H. Thomson, R. H. Varian, H. B. Shapiro, W. D. Penn and W. Dubilier. U.S. Navy NAVPERS 16116 (1944); U.S. Army Center of Military History, H. M. Cole, The Ardennes: Battle of the Bulge; U.S. War Department TM-E 11-219. Public domain dedications (CC0) by Daderot, YaganZ, Abequinn14 and Chevsapher via Wikimedia Commons. Thumbnail portrait: Captain William S. Parsons, U.S. Navy photograph 80-G-700271 (U.S. National Archives). Technical drawings and animation: Design Under Fire. The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement. #WW2 #ProximityFuze #Documentary