DATA:

Mk 3

OVERALL LENGTH

48.5 in.

BODY LENGTH

BODY DIAMETER

WALL THICKNESS

TAIL LENGTH

TAIL WIDTH

TAIL WEIGHT

WEIGHTS:

Type of Filling

Weight of Filling

Total Weight

Chg/Wt. Ratio

57.8%

FUZING:

Mk 3 Mod 1. Special nose fuze actuated on water impact.

BODY CONSTRUCTION:

Aluminum nose casting carrying a pyrotechnic charge attached to a hollow wood float which provides bucyancy. The nose carries, a water impact fuze, and at the tail of the float is a valve cap with the valve to prevent water from leaking into the interior of the bomb. The rear of the bomb is conical in shape and the aluminum nose is hemispherical.

TAIL CONSTRUCTION:

The tail consists of four fine bolted to the rear of the bomb with four tubular struts bolted to the fins. The fins do not extend upon the rear end of the bomb.

SUSPENSION:

Two movable suspension bands in Mk 3; one in Mk 1.

ACTION:

Impact operates the firing mechanism in the nose, detonating the primer which in turn ignites a length of time fuze giving a delay of 18 seconds, during which time the smoke bomb is returning to and becoming stable on the surface of the water. The time fuze ignites the quickmatch which in turn ignites the starting mixture and this initiates the action of the smoke mixture. Gas pressure formed by the burning smoke mixture breaks the vent discs and opens the valve cap at the tail end of the wooden float. The bomb then evolves a  dense withe smoke for about 7.5 minutes in the Mk 3, and 3 minutes in the Mk 1.

REMARKS:

This bomb should be dropped from an altitude of over 500 feet and should not be dropped in less than 40 feet of water where the bottom is soft enough to cause the bomb to stick and fail to return to the surface.

While designed for use over water, the bomb may also be effective if dropped over ordinary loam soil if dropped from an altitude under 2000 feet. If dropped form over 2000 feet or if dropped from any altitude onto very hard rocky ground the bomb will usually deflagrate. The HC mixture is a pressed powder safe under any normal storage or handling conditions. The smoke, while harmless in the concentrat-ions found in smoke screens in the open, is toxic in more concentrated form.

The Mk 1 Mod 2 differs from the Mod 1 in that it has a longer burning time with a maximum of 7.5 minutes, as in the 100 lb. Mk 3, and a minimum of 6 minutes. It also has the two suspension bands of the Mk 3.