DATA:

BOMBS USED IN

FUNCTIONING

ARMED CONDITION

FUZES USED WITH

ARMING TIME

130 vane revolutions

GENERAL:

The fuze resembles the AN-M103 in appearance, and has been designed specifically to be used against submarines or ships since it will not function on water, or at an im-pact angle of less than 45°. The blunt firing pin merely sets loosely over the primer in the cavity cup, and when struck by the striker shoulder is driven angainst the primer, initiating the delay. It is intended as a replacement for the hydrostatic fuzes.

OPERATION:

As the vanes rotate, the pinion gear revolves around the upper movable gear and lower stationary gear. Since the upper gear has 23 teeth and the lower gear has 22 teeth, the upper gear is pushed around clockwise with the pinion by the amount of one tooth per revolution of the vanes. The lower gear stop arm protruding into the striker. As the upper gear rotates, the arming screw unthreads from the striker, allowing the arming stem spring to lift the arming stem free of the detonator slider. After 130 vane revolutions the vanes fall away and the arming stem clears the detonator slider, which is moved across the fuze body by its spring and locked under the delay element by a detent and the slider locking pin. On impact with a hard surface, the striker body is for-ced inward, shearing both the locking pin and the shear threads and forcing the shoul-der of the striker against the blunt firing pin. The firing pin sets off the primer delay of .025 second, detonator, booster lead-in, and the booster in succession.

REMARKS:

When using this fuze the vanes should be checked by simply turning back and forth a few times in order to determind that the arming mechanism operates easily. The fuze will not function on water impact from altitudes of release up to 15,000 feet.

The Mk 244, Mod 0 incorporates a 4-second (minimum of 4, maximum of 5) delay in-stead of the 0.025 second delay of the Mk 243. Except for the delay, the two fuzes are identical. "4-Sec. Delay" is stamped in black letters on both sides of the vane cup sup-port of the Mk 244-0 to provide easy visual identification of the fuze.

To function the Mk 243 type fuze on soft ground, a striker plate has been added and the number of shear threads reduced 50% in the Mk 244-1, which retains the delay of the Mk 244-0. The modification has been made to allow use of this type fuze against ground targets in the event no marine targets are encountered on a mission. The mini-mum dropping altitude over land is 1000 ft.