Bombs and bomb loading

Although it is easy to comprehend the tactical employment and strategic value of present day bombing, little is known by John Public and GI Joe of the task of filling these missiles of destruction with such modern explosives as Amatol, TNT, composition B, explosive D, and Torpex; the care exercised in handling bombs; and the many surveillance factors involved in storage.

For a successful bombing mission every element of the complete finned and fuzed bomb must function properly or the entire round of ammunition is lost. If a five cent primer fails to function or a low order detonation results from improper loading technique, not only may a bomb costing hundreds of dollars be wasted, but lives may be lost, or perhaps even the results of battle may be determined. In the consideration of high-explosive loading, it is well to note that once a suitable bursting charge has been developed the next important step is to load it into the bomb cavity at the proper density. Low or non-uniform density of the charge will possibly leave a void around the fuze or booster and result in a dud or low-order detonation. Voids or areas of low density within the explosive charge may cause a "dying out" of the detonating wave, resulting in the explosion of only a portion of the charge. This is also generally referred to as a "low order" detonation. It may be said that practically all loading operations are made with a definite aim in view, to completely fill the bomb cavity with high explosive to a predetermined satisfactory density in a safe and uniform manner.

The empty bomb body is procured from the commercial manufacturer, and in order to make it truly a weapon of modern warfare, it is sent to an ordnance depot.

The bomb body, with the shipping bands around the suspension lugs, is rolled onto an inspection table. Here the nose plug and the rear cap or base plug are removed. The interior of the bomb is then inspected for paint, and is repainted if necessary. All of the grease is removed from the bomb and threads, and a liner is inserted in the nose of the bomb with a wrench. After assembling the fuze seat liner, the surplus glue is removed from the nose threads, and the assembled liner is gauged. The nose plug is cleaned and given a light coat of shell grease; then assembled in the nose of the bomb with a wrench.

The tail threads of the bomb body and cap are also cleaned and all grease removed. The rear cap or base plug is then assembled to the bomb and the bomb is given one coat of Olive Drab paint with the shipping bands remaining on the bomb.

After the paint dries (approximately 30 minutes), the shipping bands are removed and another coat of Olive Drab paint is applied. The loading rack is then brought under the bomb, which is placed on the loading rack to dry.

When dry, the bomb is ready to receive the M-104 Auxiliary booster.

The booster is that part of the explosive train between the detonator and bursting charge. The detonator sets up a high-explosive wave when initiated by the stab action of a firing pin or flame. This detonation is so small and weak that it will not initiate a high order detonation in the bursting charge unless a booster is placed between the two. The booster picks up the small explosive wave from the detonator and amplifies it to such an extent that the bursting charge is properly initiated.

An M-104 Bakelite auxiliary booster sleeve is slipped on the M-104 auxiliary booster, and this assembly is placed in a tool. The tool is grasped in the hand so that pressure is exerted on a lever-like handle. Together with a round, hardwood rod, the tool is let down into the bomb body. The Bakelite sleeve is slipped over the fuze seat liner with the hardwood rod held on top of the auxiliary booster so that the tool can be extracted from the bomb.

The bomb is now ready for its TNT "Down Pour," or "Nose Surround." This charge of TNT will serve to prevent exudation (a deterioration during storage evidenced by the emission of an oily, tarry material) of the bomb during periods of storage.

While this "Nose Surround" is being poured, it is essential that the TNT be continuously stirred. After pouring, the TNT is broken down approximately every half hour until it has become stiff.

The main bursting charge of Amatol is now ready to be poured into the bomb. The Amatol is hot when it comes out of the tub. and cooled to the proper temperature of 179.6°F. When ready, it is poured from the tub into a 12 quart commercial aluminum pail without lips. This pail holds about 30 pounds of Amatol, which is poured into the bomb. It is essential that the Amatol in the tub be stirred continuously during both the cooling and the pouring operations.

Beginning with the Amatol pour, the operation is continuous until the top of the riser is filled. Each pour will be made when the preceding one has become quite stiff, but before it has set. Constant breaking down of the crust by puddling is required for Amatol pours in the early stages. When the Amatol becomes slushy, the crust and pellets that form should be pushed or vibrated down into the charge.

Just before the second pour is to be made, the Auxiliary booster is inserted in the tail end of the bomb (on all bombs except the 100 lb bomb), by using a forming plug and auxiliary booster guide. The auxiliary booster guide is placed over the tail end of the bomb, and the forming plug with the auxiliary booster in position is placed through the hub guide. The second pour is made through the guide to the proper height. The breaking down of the Amatol is done around the plug and auxiliary booster, taking care not to disturb the booster.

A portion of the Amatol is allowed to solidify in this stage of the operation in order to form a bridge of the two legs between core and bomb wall. This insures the core of remaining centered and in proper relation with the vertical distance. When the breakdown is completed, the forming plug is removed by inserting an aluminum rod through the center hole.

When the bomb is ready for the "Top Off" or "Tail Surround," all Amatol or TNT splashes are removed from the surfaces at the tail end of the bomb, and the proper size steel plate is centered over the partially formed adapter booster cavity. This plate must be preheated to a temperature of 120°F. A brass forming plug, which has been preheated to a temperature of 190°F-194°F is inserted in the hole in the steel plate.

The TNT is poured in the forming plug from a one quart cast aluminum dipper and constantly stirred while pouring, to prevent lumping. This insures a positive flow of TNT through the two 3/8-inch diameter holes in the brass forming plug.

The brass forming plug remains in all sizes of bombs from seven to ten minutes, after which time it is removed with a special extractor tool by a slight twisting movement and an upward pull. Then a cork gasket is glued to the inner surface of the rear cap or base plug, and the threads are coated with animal glue. The rear cap or base plug is screwed into the bomb body and tightened with a standard commercial strap wrench. A cork gasket is glued to an M-102 adapter booster, which is screwed into the rear cap or base plug and tightened with a special wrench. The adapter booster closing plug is then screwed into the adapter booster FINGER TIGHT.

The bomb is marked, touched up with Olive Drab paint, and placed in ammunition cars for shipment or storage.

This article was originally published in the November, 1944, issue of Air Tech magazine, vol 5, no 5, pp 38, 43, 52.
Photos credited to Firestone Tire & Rubber Co, Press Association, Inc.
The PDF of this article is illustrated with several photos of the bomb-loading procedure and a photo of a large stack of bombs.