ROCKET USED IN

FUNCTIONING

ARMED CONDITION

FUZES USED WITH

ARMING TIME

VANE SPAN

MAX. BODY DIAMETER

OVERALL LENGTH

2-1/4" (without booster)

GENERAL:

The Mk 148 is similar to the Mk 137 nose fuze, but has smaller vanes and instead of a vane guard, is shipped with a protective cap which is removed when loaded on plane. Fires at impact angles as low as 5° and 10° for water or land targets allowing slight pe-netration. On hard targets, fires at impact angles not less than 20° to 25°.

OPERATION:

The weather cap is removed when the rocket is loaded on the launcher. After the rocket is loaded on the launcher, the safety wire is withdawn and the arming wire is in-stalled thru the arming wire guide. Two Fahnestock clips secure the arming wire. When the propellant is ignited, the forward motion of the rocket pulls the arming wire free and the force of inertia causes the setback block to set back against the setback spring. Since the vane locking pin is positively attached to the setback block, it is thus with-drawn to a position flush with or below the top of this fuze body. This frees the vanes to rotate, unscrewing the striker as they rotate. The vanes must make from 3 to 4 ro-tations during acceleration to unscrew the striker sufficiently to prevent re-engage-ment of the vanes locking pin as the steback spring gradually forces the setback block and locking pin up. After 8 to 9 rotations of the vanes, the striker will have unthreaded sufficiently to free the spring-loaded detonator shutter. The latter is then rotated by the shutter spring into the armed position where it is stopped by the stop pin, lining the detonator up with the striker and booster lead-in. As the shutter reaches the armed position, a spring-loaded detent carried in the shutter is forced into a recess in the striker guide, locking the shutter in the armed position. After an additional rotation or two, the end of the threads on the striker spindle are reached, in the fuze body. On im-pact, the striker is forced in, shearing the threads in the nose of the fuze body, and is dirven into the lead azide detonator.

Mk 147:

This fuze is used in the 7.2" CWR Model 15, and is similar to the Mk 148, except that it does not have an arming wire guide such as the Mk 148, and has no booster. Instead of the booster, there is an adapter which receives a burster tube to break open the rocket and eject the chemical filler. This fuze has a vane guard which consists of a cy-lindrical tube open at the top, with perforations around the tube just above the top of the fuze body.

Mk 147 Mod 1:

This fuze is a later modification of the Mk 146, and is identical to it with the except-ion of the vane guard which has been replaced on the Mod 1 by a protective cap.