Smoke 120-lb. Mks I and II (Service)

Body Construction: The bomb consists of a cylindrical body to which the tail unit is secured. The body houses a metal container filled with a smoke composition, and a gun-powder ejection charge contained in nine celluloid capsules. The bomb body is a steel tube welded to a flattened nose-piece. The nose-piece is centrally tapped to receive the fuze, and, during transit and storage, is sealed by a nose transit plug and leather was-her. A suspension lug is welded to the exterior of the bomb body.

A steel flash plate, abutting the nose-piece within the bomb body, has steel collar se-cured to it. A small centrally-located hole is drilled through the flash plate, and is sealed by a paper disc. The nine celluloid capsules, each filled with 1 oz. 1 drm. of gunpowder, are retained in the collar by a cardboard sleeve, and felt and cardboard washers. The sleeve has six equi-spaced holes near its inner end.

The metal container, filled with approximately 50 lb. of smoke composition (H.C.E.), is housed in the bomb body against the flash plate. It has a 3-in. diameter hole sealed with a celluloid disc. Between this disc and the smoke composition there are four strawboard washers, each with a 1½-in. diameter hole; the hole so formed being sealed by two squares of primed fabric. The container is retained in position against the flash plate by a closing plate fitted into the rear end of the bomb body, and secured by four turned-over metal tabs.

Tail-Construction: The tail unit is secured to the bomb body by eight drive screws, and consists of a tail cone to which a cylindrical vane is secured by four vane supports.

Functioning: On impact of the bomb with the target, the magazine of the fuze explo-des after a delay of not less than ½ sec., during which period the bomb will have come to rest. The flash from the fuze magazine, passing through the hole in the flash plate and the celluloid disc, ignites the two primed cambric squares, which in turn ignite the smoke composition in the conatiner.

Concurrently with the ignition of the smoke composition, the flash from the fuze ma-gazine also passes through the holes in the cardboard sleeve to initiate the gunpowder ejection charge contained in the nine celluloid capsules. The resulting explosion of the gunpowder ejects the tail, the closing plate, the container of burning smoke composition, and the flash plate, clear of the crater formed by the bomb.

Suspension: Two bombs may be carried in a 250-lb. Small Bomb Container, or the bombs may be suspended individually by a single lug. The Bombs Mk II may be fitted with twin lugs for suspension in American aircraft.

Explosive Components:

Magazine – Gunpowder

Ejection Charge – Gunpowder in nine celluloid capsules

Main Filling – Smoke Composition (H.C.E.)

Remarks: The smoke composition contained in these bombs is liable to spontaneous ignition if it should become wet, particularly with sea water. The Bomb Mk II is similar to the Mk I in operation, the principal differences being a modified tail assembly and arran-gement for twin suspension lugs for carrying in American aircraft.

Figure 48 - Smoke 120-lb. Bomb Mk I