American Projectiles and Explosives - Chemical, Incendiary, Smoke - "MK" Series Bombs

American Projectiles and Explosives



Explosive Bombs

"MK" Series

100-pound Incendiary Mk I and Mk 28 (Obsolete)

Overall length: 45.5 inches
Body length: 33.7 inches

Body diameter: 8 inches
Wall thickness: 0.05 inches
Tail length: 11.75 inches
Tail width: 11.3 inches

Filling: Gasoline, Gasoline-Gel, Gasoline and Waste, rubber

Weight of filling: 42 to 45 pounds
Total weight: 65 to 68 pounds
Charge/weight ratio: 65% (approx.)

Construction: The bomb is of three-piece sheet-steel construction, with a hemispherical nose piece and aconical tail cone welded to a tubular body.  The bomb has two suspension lugs on bands or a single lug on a band near the center of gravity.  The tail assembly consists of four sheet-steel vane welded to the tail cone, which, in turn, is welded to the body.

Color: The bomb is painted grey overall, with a bright red disc, four inches in diameter, in the middle of the body.


Remarks: This bomb is similar to the 100-pound Incendiary Bomb AN-M47A2, except that it is equipped with a filler cap.  Both bombs are prone to leak and should be examined frequently.

There is also a 100-pound Incendiary Bomb Mk I, which is almost identical to the old Army M47, both of which are obsolete.






100-pound Chemical Mk 42

For photo, see above

Overall length: 39.43 inches
Body length: 27.7 inches

Body diameter: 8 inches
Wall thickness: 0.17 inches
Tail length: 9.46 inches
Tail width: 11 inches

Filling: Mustard gas

Weight of filling: 43 pounds
Total weight: 86.5 pounds
Charge/weight ratio: 50%


Construction: The steel tube is swaged aft.  An adapter screws into the nose and is threaded to receive the fuze.  A burster tube containing TNT, running the length of the bomb, screws into the after end of the adapter.  The after end of the body is closed by a male base plate, which is threaded for the tail assembly to be fitted.  The bomb is filled through the nose.  Suspension is by two lugs seven inches on either side of the center of gravity or a single lug 180 degrees removed and at the center of gravity.  The bomb has a box-type, four-fin tail, secured by a locking nut.


Markings: The bomb is painted olive drab overall, with two green bands 1/2 inch wide and 1/2 inch apart abaft the nose.

50-, 100-pound Floating Smoke (Obsolescent) Mk 3 Mod 0 (100-lb), Mk 1 Mod 1 (50-lb), Mk 1 Mod 2 (50-lb)

For photo, see top

Mk 3 Mod 0

Overall length: 48.5 inches

Body diameter: 10.25 inches
Tail length: 13 inches
Tail width: 14.25 inches
Filling: HC Mixture
Weight of filling: 59 pounds
Total weight: 102 pounds

Charge/weight ratio: 57.8%


Mk 1 Mod 2

Overall length: 38.29 inches

Body diameter: 8.85 inches
Tail length: 9.4 inches
Tail width: 8.94 inches
Filling: HC Mixture
Weight of filling: 28 pounds
Total weight: 54 pounds

Charge/weight ratio: 51.8%

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 no 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 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 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 mixture 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 for about 7.5 minutes in the Mk 3 Mod 0; 2.5 to 5 minutes in 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 an altitude under 2,000 feet.  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 or handling conditions.  The smoke, while harmless in the concentration 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.

Next Time: Chemical, Incendiary, Smoke - "AN" Series Bombs