Mk 3 Mod 1 (Nose Mechanical Impact)

Bombs

Functioning

Armed condition

Fuzes used with

Arming time

Instantaneous

General: The Nose Mechanical Impact Fuze Mk 3 Mod 1 is a water impact fuze desig-ned as an integral part of each bomb in which it is used. It consists of a fuze body, mounted in the nose of the bomb, and a vent-tube assembly running through the HC filler of the bomb. A washer in front of the fuze body serves to retain the firing pin, which is held away from the primer by a creep spring. The primer is mounted over a length of time fuse which extends to a quick match increment in the starting mixture at the rear of the vent tube. The after end of the vent tube is sealed with a blow-out disc.

The Adapter Mk 1 is attached to the protruding fuze body to ensure fuze functioning on either water or land impact. The adapter, which is attached to the protruding body by three set screws, consists of a cup-shaped head mounted on a freely moving plunger. The plunger, which is held in its guide by two stop screws, will transmit any blow on the cup to the firing pin. A spring-loaded horseshoe collar is mounted beneath the cup to hold the plunger away from the firing pin.

Operation: Upon release of the bomb, the arming wire is pulled, releasing the spring-loaded horseshor collar, which falls away from the adapter. The fuze is then armed. On impact with either land or water, the plunger drives the striker into the primer. The pri-mer ignites the time fuse, which burns 18 seconds and the sets off the quick match and starting mixture. The starting mixture ignites the HC filler. As pressure builds up in the vent tube, the seal is blown out. Since the bomb floats nose-down, the smoke passes out through the after end of the vent.

Remarks: In using smoke bombs for screeing landing operations, it was found that a fair number of bombs were dropped on land and the fuze did not function. The addition of the Adapter Mk 1 ensured functioning of the fuze on either land or water impact.

Figure 359. Nose Fuze Mk 3 Mod 1