Impact fuze

In military munitions, a fuze or fuse is the part of the device that initiates function. In some applications, such as torpedoes, a fuze may be identified by function as the exploder. The relative complexity of even the earliest fuze designs can be seen in cutaway diagrams.

A fuze is a device that detonates a munition's explosive material under specified conditions. In addition, a fuze will have safety and arming mechanisms that protect users from premature or accidental detonation. For example, an artillery fuze's battery is activated by the high acceleration of cannon launch, and the fuze must be spinning rapidly before it will function. "Complete bore safety" can be achieved with mechanical shutters that isolate the detonator from the main charge until the shell is fired.

A fuze may contain only the electronic or mechanical elements necessary to signal or actuate the detonator, but some fuzes contain a small amount of primary explosive to initiate the detonation. Fuzes for large explosive charges may include an explosive booster.

Professional publications about explosives and munitions distinguish the "fuse" and "fuze" spelling. The UK Ministry of Defence states (emphasis in original):

Oliver Hogg states the following about fuze:

Historically, it was spelled with either 's' or 'z', and both spellings can still be found. In the United States and some military forces,fuze is used to denote a sophisticated ignition device incorporating mechanical and/or electronic components (for example a proximity fuze for an artillery shell, magnetic/acoustic fuze on a sea mine, spring-loaded grenade fuze,pencil detonator or anti-handling device) as opposed to a simple burning fuse.

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