Arming wires

The Navy is now procuring four standard arming wires for all bombs now in naval use, replacing the varied types previously in service. They will fit any bomb up to and inclu-ding 2,000-pounds; and, by adding an arming-wire extension which is part of the new system, can be used in bombs up to 4,000 pounds.

The new wires come straight are packed in hermetically sealed metal tube, protecting them from corrosion. Depending on type, the tubes conatin from 50 to 100 wires, includ-ing their clips and extra clips. The wires are cut, when installed, to fit the bomb.

The Arming Wire Mk 1 is a single-strand bronze wire, 57 inches long and 0.064 inches in diameter, joined to a swivel and loop. This assembly can be used on all bombs epen-ded with a single fuze, up to including 2,000-pound bombs. The Bureau of Ordnance re-commends using two of these Mark 1 assemblies to rig out the athwartship hydrostatic fuzes of depth bombs. One hundred Arming Wires Mk 1, together with 300 safety clips, are packed in an airtight metal tube (includes an extra clip for each wire).

The Arming Wire Extension Mk 1 is a flexible steel cable 16 inches long and 0.0625 in-ches in diameter. It incorporates a swivel loop arrangement and a brass spring clip. The Arming Wire Extension Mk 1 may be used with two Arming Wires Mk 1 to install arming for the 4,000-pound light-case bomb. In addition, it is used to lengthen wires on fragmenta-tion or incendiary clusters. One hundred of these extenison wires are packed in an air-tight metal tube.

The Arming Wire Mk 2 is a double-strand bronze wire of the same type, diameter, and length as the Arming Wire Mk 1. It is used on all bombs expended with a nose and tail fuze, up to and including 2,000-pound bombs. Fifty Wires Mk 2, together with 300 safety clips, are packed in an airtight metal tube.

The Arming Wire Mk 3 is a single-strand steel wire 57 inches long and 0.033 inches in diameter. The Arming Wire Mk 3 can be used any-where the 0.036-inch diameter Navy-type wire was used, and in addition can be used in all jump-out-pin type Fuze M111A2 in which a stronger wire is needed. One hundred Arming Wires Mk 3, together with 100 safety clips, are packed in an airtight metal tube.

The new standard assemblies do not replace special assemblies on any clusters, either fragmentation or incendiary, but the Wire Extension Mk 1 is used with such clusters so that their wires, which are too short for proper fitting, can be connected.

Arming wires are subjected to considerable wear from vibration. For that reason, tu-bes are supplied to protect a wire at its point of maximum wear. Use of these tubes on all bombs equipped with arming-wire brackets is mandatory. All old AN-type arming wires on hand and pre-cut to length for a bomb should be returned to the Army.