Description
The Fuze M81 consists of the Artillery Fuze M48A2 assembled with either the Booster M21A1 or the Booster M21. Depending on where the fuze is assembled, it may be marked M81, M48A2, or M51.
Much like the Navy’s Fuze Mk 29 or Mk 30 in construction, this fuze adds a delay firing train. The choice of instantaneous (superquick) or delay firing is made on the selector sleeve of the interrupter device—the slot being set parallel to the longitudinal axis of the fuze, or within 15 degrees either side, for super-quick action, and at right angles thereto for delay action.
Functioning
No action takes place upon firing until sufficient rotational speed has been established to overcome the resistance of springs and set-back force on the several safety devices. When the fuze is set for super-quick action, after it leaves the muzzle, centrifugal force causes the interruptor to move outward, opening the passage. At the same time, the plunger pins locking the delay assembly in the unarmed position also move outward, releasing that assembly in preparation for impact. The plunger-pin lock then swings on its pivot under centrifugal force, placing an arm against the inner end of each plunger pin, preventing the return of the pins to the unarmed position. Upon impact, the firing pin of the superquick action is driven against the detonator, initiating the super-quick action. Inertia causes the delay-action plunger to move forward, driving the primer against the delay-action firing pin and initiating the delay action. In normal functioning with super-quick action, the delay action has no effect, since the superquick train will have caused the rocket to explode before the delay train can burn for its prescribed time. However, should the superquick action fail, the fuze will function with delay action rather than become a dud. When set for delay action, the interrupter is restrained from moving.
Upon impact, the super-quick firing pin and detonator function, but the effect is prevented from being transmitted to the shell.
Hazardous Components
No information about hazardous components.
See Also
Source(s)
OP 1664, Volume 1 - US Explosive Ordnance (1947)
TM 9-1904, Ammunition Inspection Guide (1944)
