Artillery fuze

An artillery fuze or fuse is the type of munition fuze used with artillery munitions, typically projectiles fired by guns (field, anti-aircraft, coast and naval), 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 (time fuze), or on physical contact with (contact fuze) or detected proximity to the ground, a structure or other target (proximity fuze). Fuze, a variant of fuse, is the official NATO spelling.

Munitions fuzes are also used with rockets, aircraft bombs, guided missiles, grenades and mines, and some direct fire cannon munitions (small calibre and tank guns).

Broadly, fuzes function on impact (percussion fuzes) or at a pre-determined time period after firing (time fuzes). However, by the 18th Century time fuzes were aimed to function in the air and in the 1940s proximity fuzes were introduced to achieve more precisely positioned airburst. Therefore, the terms ‘percussion’ and ‘airburst’ are generally used here unless ‘time’ fuzes are being explicitly described.

Solid cannonballs (“shot”) did not need a fuze, but hollow balls (“shells”) filled with something, such as gunpowder to fragment the ball hopefully on the target needed a time fuze. Early reports of shells include Venetian use at Jadra in 1376 and shells with fuzes at the 1421 siege of St Boniface in Corsica. In 1596 Sebastian Halle proposed both igniting the bursting charge by percussion and regulating the burning time of fuzes, this was considered visionary and nothing much happened until 1682. These early time fuzes used a combustible material that burnt for a time before igniting the shell filling (slow match). The problem was that precise burning times required precise time measurement and recording, which did not appear until 1672. Before this the proofmaster often tested the burning time of powder by reciting the Apostles' Creed for time measurement.

It was not until around the middle of the following century that it was realised that the windage between ball and barrel allowed the flash from the propelling charge to pass around the shell. This led, in 1747, to ‘single-fire’ and eliminated the need to light the fuze before loading the shell. At this time fuzes were made of beech wood, bored out and filled with powder and cut to the required length. Experience taught that there was a minimum safe length. In 1779 the British adopted pre-cut fuze lengths giving 4, 4.5 and 5 seconds.

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