Contact fuze

This used a simple protruding plunger or striker at the nose, which was pushed back to drive a firing pin into the detonator.

Its ability to burst immediately at ground level was used to clear the barbed wire entanglements of no man's land, rather than burying itself first and leaving a deep, but useless, crater.

The simplest form of artillery contact fuze is a soft metal nose to the shell, filled with a fulminating explosive such as lead azide.

As an artillery shell lands with a considerable impact, the "soft" nose may be made robust enough to be adequately safe for careful handling, without requiring any protection cap or safety mechanism.

Graze impacts trigger the inertia mechanism, where instead the pellet in a heavy carrying plug travels forwards onto the striker.

Owing to the risk of an aircraft crash, or even the need to land with an undropped bomb still on board, these are protected by sophisticated safety systems so that the fuze can only be triggered after it has been dropped intentionally.

The bomb was intended for air burst detonation and was fitted with both radar height-finding and barometric fuzes.

As the device was so secret, and the risk of informative fragments or plutonium being recovered after a failed drop was considered to be unacceptable, it was fitted with supplementary contact fuzes that were only intended to destroy the weapon beyond recognition.

The intended fusing was an extremely low air burst of only a few feet, so as to maximize the clearance effect and minimize cratering.

The contact with solid ground activates the interior firing circuits which leads to the detonation of the ordnance device.