page_title: Artillery fuze
section_title: Proximity fuzes
hierarchical_section_title: Artillery fuze / Types of artillery fuze / Airburst fuzes / Proximity fuzes
caption_attribution_description: This file is located here: http://www.history.navy.mil/pics/shell2.jpg archive link
context_page_description: An artillery fuze or fuse is the type of munition fuze used with artillery munitions, typically projectiles fired by guns, howitzers and mortars. A fuze is a device that initiates an explosive function in a munition, most commonly causing it to detonate or release its contents, when its activation conditions are met. This action typically occurs a preset time after firing, or on physical contact with or detected proximity to the ground, a structure or other target. Fuze, a variant of fuse, is the official NATO spelling.
context_section_description: The benefits of a fuze that functioned when it detected a target in proximity are obvious, particularly for use against aircraft.  The first such fuze seems to have been developed by the British in the 1930s for use with their anti-aircraft ‘unrotated projectiles’ – rockets.  These used a photo-electric fuze.
  During 1940-42 a private venture initiative by Pye Ltd, a leading British wireless manufacturer, worked on the development of a radio proximity fuze. Pye's research was transferred to the United States as part of the technology package delivered by the Tizard Mission when the United States entered the war.  These fuzes emitted radio waves and sensed their reflection from the target (aircraft or ground), the strength of the reflected signal indicated the distance to the target, when this was correct the fuze detonated.
  For the first 18 months or so proximity fuzes were restricted to anti-aircraft use to ensure that none were retrieved by the enemy and copied.  They were also called ‘variable time’ or VT to obscure their nature.  They were finally released for field artillery use in December 1944 in Europe.  While they were not perfect and bursts could still be erratic due to rain, they were a vast improvement on mechanical time in delivering a very high proportion of bursts at the required 10 metre height.  However, VT fuzes went far deeper into the shell than other fuzes because they had a battery that was activated by the shock of firing.  This meant the fuze recess had to be deeper, so to enable shorter non-VT fuzes the deep recess was filled with removable supplementary HE canisters.
  After the war the next generation of proximity fuze included a mechanical timer to switch on the fuze a few seconds before it was due at the target.  These were called controlled variable time’ (CVT) and reduced the incidence of early bursts.  Later models had additional electronic counter  measures.
caption: Mk 53 Proximity fuze for an artillery shell, circa 1945
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