Used in: 7.2-inch projector charge Head Mk 4 (High Capacity) with Projector Charge Tail Mk 6.

Overall dimensions and weight of fuze:

Length

Diameter (maximum)

Body threads

Weight

Applicable specification: OS 3418

General arrangement drawing: 438552

Sketch list of drawing & specs: 109483

Explosive components: Identical with Fuze Mk 156 Mod 0.

General. Fuze Mk 158 Mod 0 is identical with Fuze Mk 156 Mod 0 in all respects ex-cept that Fuze Mk 158 Mod 0 has a setback collar shear wire through the setback collar and the plug as an added safety feature. Fuze Mk 158 Mod 0 is used only in the 7.2-inch Head Mk 4 when assembled with the Projected Charge Tail Mk 6. The projector charge round (which is not a rocket) as fired from a Projector Mk 10 or Mk 11 is subjected to considerable setback which permits the use of a setback collar shear wire. The propellant in the 7.2-inch rocket, incorporating a Fuze Mk 156, does not impart sufficient setback to serve a collar shear wire.

The description and all instructions outlined for Fuze Mk 156 Mod 0 apply to Fuze Mk 158 Mod 0. The addition of the setback collar shear wire does not change the function-ing of the fuze in any way except that it requires a greater initial setback force to initi-ate arming.

Use. Fuze Mk 158 Mod 0 is used in 7.2-inch High Capacity Projector Charge Head Mk 4 assembled with the 2.25-inch Projector Charge Tail Mk 6.

Figure 32 – Nose Fuze Mk 156 Mod 0 or Mk 158 Mod 0, Cross Section View,
Unarmed Position

Figure 33 – Nose Fuze Mk 156 Mod 0 or Mk 158 Mod 0, Cross Section View,
Armed Position

Firing. Instantaneous or superquick firing upon impact is identical with Fuze Mk 156 Mod 0.

Acceptance test data. The acceptance data for Fuze Mk 158 Mod 0 are the same as for Fuze Mk 156 Mod 0 except that in the Premature and Blade Test half of the fuzed rounds are launched at 130 feet per second and the balance are launched at 150 feet per second instead of at 170 feet and 190 feet per second. In addition a collar shear wire test is required on the Fuze Mk 158 Mod 0. This requires that inert fuzes from every tenth lot be assembled in 7.2-inch Heads Mk 4, inert load, with loaded Projector Charge Tails Mk 6 and fired at a propellant temperature of approximately 0° F for ground impact from a Projector Mk 10. The fuzes are suitable protected by a reinforced cap to prevent multilation of the fuze and inspection is made to ascertain that the collar shear wire has been sheared. Failure shall cause rejection of the lot.

See Fuze Mk 156 Mod 0 and substitute Projector Charge for Rocket.

See Fuze Mk 156 Mod 0 and substitute Projector Charge for Rocket.

See Fuze Mk 156 Mod 0 and substitute Projector Charge for Rocket.

See Fuze Mk 156 Mod 0 and substitute Projector Charge for Rocket.