Editing Vannevar Bush (section)

==== Proximity fuze ====
[[File:MK53 fuze.jpg|thumb|Cut away diagram of the [[proximity fuze]] Mark 53|alt=A cut away diagram of an arrow-shaped object, indicating the location of the antennae, batteries and switches. ]]
In August 1940, the NDRC began work on a [[proximity fuze]], a fuze inside an artillery shell that would explode when it came close to its target. A radar set, along with the batteries to power it, was miniaturized to fit inside a shell, and its glass [[vacuum tube]]s designed to withstand the 20,000&nbsp;[[g-force]] of being fired from a gun and 500 rotations per second in flight.{{sfn|Furer|1959|pp=346–347}} Unlike normal radar, the proximity fuze sent out a continuous signal rather than short pulses.<ref>{{cite web |url=http://carnegiescience.edu/legacy/findingaids/DTM-2005-01-Proximity-Fuze.html |title=<nowiki>Section&nbsp;T "Proximity Fuze" Records, 1940–[1999] (bulk 1941–1943)</nowiki> |publisher=Carnegie Institution of Washington |access-date=June 7, 2012 |archive-date=August 14, 2011 |archive-url=https://web.archive.org/web/20110814184011/http://carnegiescience.edu/legacy/findingaids/DTM-2005-01-Proximity-Fuze.html |url-status=dead }}</ref> The NDRC created a special Section&nbsp;T chaired by [[Merle Tuve]] of the CIW, with [[Commander]] [[William S. Parsons]] as special assistant to Bush and liaison between the NDRC and the Navy's [[Bureau of Ordnance]] (BuOrd).{{sfn|Furer|1959|pp=346–347}} One of CIW staff members that Tuve recruited to Section&nbsp;T in 1940 was [[James Van Allen]]. In April 1942, Bush placed Section&nbsp;T directly under the OSRD, and Parsons in charge. The research effort remained under Tuve but moved to the [[Johns Hopkins University]]'s [[Applied Physics Laboratory]] (APL), where Parsons was BuOrd's representative.{{sfn|Christman|1998|pp=86–91}} In August 1942, a live firing test was conducted with the newly commissioned cruiser {{USS|Cleveland|CL-55|6}}; three [[pilotless drone]]s were shot down in succession.{{sfn|Furer|1959|p=348}}

To preserve the secret of the proximity fuze, its use was initially permitted only over water, where a dud round could not fall into enemy hands. In late 1943, the Army obtained permission to use the weapon over land. The proximity fuze proved particularly effective against the [[V-1 (flying bomb)|V-1 flying bomb]] over England, and later [[Antwerp]], in 1944. A version was also developed for use with [[howitzer]]s against ground targets.{{sfn|Furer|1959|p=349}} Bush met with the [[Joint Chiefs of Staff]] in October 1944 to press for its use, arguing that the Germans would be unable to copy and produce it before the war was over. Eventually, the Joint Chiefs agreed to allow its employment from December 25. In response to the German [[Ardennes Offensive]] on December 16, 1944, the immediate use of the proximity fuze was authorized, and it went into action with deadly effect.{{sfn|Zachary|1997|pp=176, 180–183}} By the end of 1944, proximity fuzes were coming off the production lines at the rate of 40,000&nbsp;per day.{{sfn|Furer|1959|p=349}} "If one looks at the proximity fuze program as a whole," historian [[James Phinney Baxter III]] wrote, "the magnitude and complexity of the effort rank it among the three or four most extraordinary scientific achievements of the war."{{sfn|Baxter|1946|p=241}}

The German V-1 flying bomb demonstrated a serious omission in OSRD's portfolio: guided missiles. While the OSRD had some success developing unguided rockets, it had nothing comparable to the V-1, the [[V-2]] or the [[Henschel Hs 293]] air-to-ship gliding guided bomb. Although the United States trailed the Germans and Japanese in several areas, this represented an entire field that had been left to the enemy. Bush did not seek the advice of [[Robert H. Goddard]]. Goddard would come to be regarded as America's pioneer of rocketry, but many contemporaries regarded him as a crank. Before the war, Bush had gone on the record as saying, "I don't understand how a serious scientist or engineer can play around with rockets",{{sfn|Zachary|1997|p=179}} but in May 1944, he was forced to travel to London to warn General [[Dwight Eisenhower]] of the danger posed by the V-1 and V-2.{{sfn|Zachary|1997|p=177}} Bush could only recommend that the launch sites be bombed, which was done.{{sfn|Bush|1970|p=307}}