ROCKET USED IN

FUNCTIONING

ARMED CONDITION

FUZES USED WITH

ARMING TIME

VANE SPAN

MAX. BODY DIAMETER

OVERALL LENGTH

5.5" (w/booster)

GENERAL:

This fuze is identical with the AN-Mk 219 bomb fuze (p. 159), except that it has been partially armed fifty turns of the arming vanes and a metal fork inserted between the vane carrier and the fuze body to take up the space left by the prearming pro-cess. This fork must be removed before launching the fuzed rocket. In addition, the pitch of the vanes has been increased to 40 degrees instead of the 18 degrees on the AN-Mk 219.

The fuze is stamped "Mk 152", and the fuze packing case is marked "FOR USE IN 7.2 IN. ROCKETS ONLY". Great care must be taken not to confuse the two fuzes because of their similarity. The AN-Mk 210 must not be used in place of the Mk 152, and vice versa.

When installing the Mk 152 in demolition rockets, a regular adapter ring for the AN-Mk 219 fuze (same as that used when installing the AN-Mk 219 in the nose of the depth bomb) must be used. The fuze cavity in the rocket body is deep enough to ne-cessiate the addition of the following with the Mk 152; one Mk 2 Auxiliary booster (2 inches long); one Mk 1 Auxiliary booster (3 inches long); and one cardboard spacer (im-provised) approximately 1/2 inch thick placed below the auxiliary boosters. Tests have indicated that a high order detonation can still be expected if an additional cardboard spacer is used in place of the auxiliary booster Mk 2; however, use of the booster is preferred.

When placed in the launcher, an arming wire, one end of which is attached to the launcher, replace the safety pin. This assembly prevents fuzes of other rockets in the launcher from arming as a result of the blast from rockets already launched. Both safe-ty pin and arming fork must be replaced if the rocket is not fired.

OPERATION:

There are two stages of arming. During the first stage, the upper gear is free to ro-tate and the lower gear, being attached to the hammer carrier which in turn is locked by the inner sleeve, is held stationary. During the second stage, the hammer carrier has risen to clear the inner sleeve and the lower gear is free to roatate while the upper gear is held stationary as it is attached to the arming shaft which was threaded up un-til it locked against the shaft extension nut.

First stage: As the rocket is launched, the arming wire is withdrawn and the vanes are free to rotate. Thru the system of reduction geras, the upper gear rotates to thread the arming shaft up until the head of the screw on the shaft locks against the shaft extension nut. A collar on the shaft lifts the hammer carrier and the entire arming assembly. Simultaneously with the locking of the arming shaft and the upper gear, the hammer carrier clears the inner sleeve to free the lower gear.

Second stage: The lower gear and hamme carrier are rotated in a counter-clockwise direction. The aligning lug on the hammer carrier engages the firing pin carrier, lining up the firing pin extension with the firing pin. Further rotation causes the firing pin carrier to engage the detonator carrier, lining the firing pin up with the detonator. The hammer carrier, firing pin carrier, and detonator carrier continue to rotate through 180 degrees, until the lip on the detonator carrier engages the inner sleeve. Simultaneously, the spring-loaded detent in the striker snaps into a recess in the hammer carrier, thus lock-ing the firing train components in an armed position. Since the upper and lower gear are now both locked, the two copper pin secured the lower gear to the hammer carrier are sheared and the vanes rotate freely. (If the air speed is less than 300 m.p.h., the air pressure will not be sufficient to shear the pins, and the vanes will merely cease rotat-ing.)

The fuze is now fully armed. On impact, the entire upper assembly of the fuze is for-ced inward. The shear wire in the arming shaft is cut as the upper part of the shaft telescopes into the lower part and the shear wire thru the firing pin is out as the firing pin extension forces the firing pin into the detonator. The detonator sets off the auxi-liary booster lead-in, booster lead-in, booster, and main charge auxiliary.