DATA:

BOMBS USED IN

FUNCTIONING

ARMED CONDITION

FUZES USED WITH

ARMING TIME

VANE SPAN

MAX. BODY DIAMETER

OVERALL LENGTH

MATERIAL

Cadmium or zinc plated steel

GENERAL:

The M149 is a detonator-safe nose fuze for use in any G.P. bomb which can accom-modate the AN-M103A1 nose fuze. The fuze is designed for both instantaneous action on impact and for air-burst a short distance above the target as a result of blast wave from the first bomb of a stick bomb. The first bomb will detonate on impact while its blast if of sufficient intensity, will detonate the second bomb, etc., in the air over the target. For example, if 500 lb. bombs are dropped in train at 0.05 second intervals at air speed of 200 m.p.h. (14.7 foot spacing) from 10,000 feet, the burst of the second bomb in air will be at a point approximately 7 feet ahead of (horizontal separation) the first bomb and 23 feet above (vertical separation) the first bomb. Other bombs in the stick will function the same distance from the bomb which precedes them.

OPERATION:

As the arming wire is withdrawn, the vane cup rotates. After approximately 8 or 9 turns of the vane cup the release pin is ejected by its spring. The arming stem rises under pressure of its spring, permitting the detonator slider to align itself below the flash tube. After 12 - 13 turns of the vanes the vane cup falls off and the fuze is now fully armed. Bombs fuzed with the M149 should be released in close train to take ad-vantage of the air burst feature of the fuze. The first bomb of a stick will detonate on impact with the ground; impact simply snape the diaphragm to its reversed position causing the firing pin to strike the primer.

The second bomb of the stick will be detonated by the pressure blast of the first bomb. The blast of the first bomb will cause the diaphragm in the fuze of the second bomb to snap over while the bomb is still in the air a relatively short distance above the target and thus cause detonation. The third bomb will then function as the second, etc.

Should the diaphragm fail to function for air burst, the fuze can still fire from impact action.

REMARKS:

When installing the M149, the vane cup should be checked to see that it is free to turn. However, DO NOT unscrew the vane cup as only a few turns are required to arm the fuze. In the armed condition the fuze must of necessity be very sensitive. Handle accordingly.

The fuze is equipped with 3 suspension chambers so that as the diaphragm snaps in, it will not be resisted by an air cushion, which might prevent complete inward move-ment of the diaphragm.

This fuze is detonator safe. In the unarmed position, the detonator is lined up with the safety expansion chamber. If the detonator should function prematurely, the force of detonation is dissipated in this cavity, and will not set off the lead in and booster charges.

Production of the M149 fuzes has been discontinued, since VT fuzes offer better as-surance of air burst.