Over-all length

Body, diameter

Tail length

Tail width

Filling

Weight of filling

Total weight

Charge/weight ratio

Fuzing

Mk 3 Mod 1

Construction: An aluminum nose casting, carrying a pyrotechnic charge, is attached to a hollow wood float which provides buoyancy. 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. The tail consists of four fins 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 are used on the Floating Smoke Bomb Mk 3 Mod 0; the Mk 1 Mods 1 and 2 may have either one or two suspension bands. The latest issue has one band and one attached lug, so that the bombs may be suspended from the single- and double-hook racks.

Action: Impact operates the firing mechanism in the nose, detonating the primer, which in turn ignites a length of time fuse 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 fuse ignites the quick match which, in turn, ignites the starting mixture and this initiates the action of the smoke mixture. Gas pressure formed by the burning smoke mix-ture breaks the vent discs and opens the valve cap at the tail end of the wooden float. The bomb then evolves a dense white smoke of about 7.5 minutes in the Mk 3 Mod 0; 2.5 to 5 minutes on the Mk 1 Mod 1 and 5 to 7.5 minutes in the Mk 1 Mod 2.

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 over 2,000 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 and handling conditions. The smoke, while harmless in the concentrations found in smoke screens in the open, is toxic in more concentrated form.

The 50-pound Floating Smoke Bomb 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-pound Mk 3 Mod 0, and a minimum of 5 minutes.

Figure 302. Navy 100-pound Smoke, Incendiary, and Chemical Bombs