FUZING

COLOR & MARKINGS

OVERALL LENGTH

WITDH ACROSS FLATS

TOTAL WEIGHT

DESCRIPTION:

Consists of hollow magnesium-alloy body at one end of which is a cast iron or steel nose, the body being cast onto the nose during manufacture. A magnesium-alloy tail plug, which may be of solid or open construction, is screwed into the other end of the body. Fixed to the tail plug by two drive-screws is a timplate tail closed by a tail cap. The tail plug houses a striker, creep spring, ferrule having four tabs, and a brass cap holder containing a 1.7 grain detonator. When the bomb is packed in its case, move-ment of the striker towards the detonator is prevented by a spring-loaded safety plun-ger housed in a sleeve fitted into the tail plug. Two vent holes, plugged by cork inserts, are provided in the body to occumnicate with the space between the cap holder and the filling of the bomb. A strip of primed cambric is located in this space. The Mk IIIE is identical to the Mk III except for a black powder exploder just aft of the nose plug in the body cavity. The main filling is thermite.

FUNCTIONING:

When bomb is released, the safety plunger springs out and on impact the striker overcomes the resistance of the creep spring bends the tabs on the ferrule (brass cross) and strikes and fires the detonator, the products of combustion from the deto-nator blowing the cork inserts out of the vent holes. The flash from the detonator is conveyed by the primed cambric strip to the gun-powder-shellac paste on the inside of the washer, which ignites the pressed priming composition and in turn the igniter pel-lets. The magnesium-alloy body starts to melt about 25 sec. after the bomb is ignited, and burns for about 10 minutes. In the Mk IIIE bomb, after 1¼ to 4 minutes, the pow-der in the burster is ignited and explodes.

SUSPENSION:

Carried in the Small Bomb Container or in a Cluster Projectile

SIMILAR INCENDIARIES:

4 lb. Mk II and IIE: Similar to the Mk III and Mk IIIE, but have following differences: (a) bombs bodies have smaller bore, (b) cap holder are of magnesium-alloy, (c) bomb bodies have four cork-plugged vent holes, (d) tail plugs are of solid magnesium-alloy, and (e) nose are of steel.

4 lb. Mk I and IE: Similar to hte Mk II and IIE respectively, but differ in the following respects: (a) length of bomb is 21.5", (b) use a 1.62 grain detonator.

4 lb. X, with 2 & 4 minute delays, Mk I: Similar in construction to the Mk III, except that a C.E. exploder is contained in the steel nose plug, as shown in the drawing oppo-site; this exploder being initiated after delay of either 2 or 4 minutes, depending on which bomb it is. The letter "X" is stamped on the outside followed by a number "2" or "4" indicating which delay is incorporated in the bomb. The marking bands are the same as on the Mk IIIE, except that the red band between the two black bands is 1" instead of ½", and the base of the tail is not painted red.