General

Because of the nature of their development, it is necessary to classify bomb fuzes in this publication as either Army or Navy items.

Explosive train

Typical firing trains employed in both Army and Navy fuzes use pointed strikers with sensitive primers for instantaneous action and blunt firing pins and percussion primers for delay action. The simple instantaneous explosive train in nose fuzes consists of a sensi-tive primer mixture of lead azide and lead styphnate, an upper detonator of lead azide, and a lower detonator ot tetryl.

For a short delay, the blunt firing pin initiates a mercury-fulminate percussion primer, which sends a flash through a chamber of compression to ignite a pressed black-powder delay. This, on completion of burning, flashes a relay pellet of lead azide and lead styph-nate, which detonates the lower detonator of tetryl.

The explosive train, including the booster, is usually incorporated in all Navy fuzes and Army nose fuzes; but in Army tail fuzes the explosive train does not include the booster, and may have the remainder of its explosive contained in an interchangeable primer de-tonator to allow optional selection of short delays.

Army tail fuzes contain the primer detonator, but the booster charge is housed in an adapter booster which is considered an integral part of the bomb base plug and should not be removed. The adapter booster also serves to seat the fuze.

The standard adapter boosters are found in the base plugs of Army bombs; the M102, M102A1, M115, and the M115A1. Since the inside thread diameter of the M102 and M102A1 is 1.5 inches, bomb fitted with these adapter booster receive Army-designed tail fuzes only, all of which have an outside thread diameter of 1.5 inches.

In AN G.P. bombs, the adapter booster is modfied to permit the insertion of Navy hy-drostatic tail fuzes (AN-Mk 230 Mods 4, 5, and 6) whose outside thread diameter is 2.0 inches, typical of all Navy-designed fuzes. The Adapter Booster M115 and M115A1, which are used in AN G.P. bombs incorporate an inner sleeve or ring, which gives the adapter booster an inside thread diameter of 1.5 inches, permitting Army-type fuzing only. When this sleeve is removed, the inside thread diameter of the adapter booster be-comes 2.0 inches, and the Navy hydrostatic tail fuzes may be inserted.

The A1 modification on the Adapter Booster M102 and M115 consists of the addition of tow base-plate locking pins and an adapter booster locking pin to prevent the removal of the base plate and adapter booster when anti-withdrawal tail fuzes are employed. See figure 317.

Figure 317. Army Fuze Seat Liners and Adapter Boosters

The nose fuze pocket of AN and other Army-designed bombs have an inside thread diameter of 2.0 inches and are designed to take the Nose Fuze AN-M103 (and variati-ons). No adapter booster is used, since the Nose Fuze AN-M103 has its booster built into the fuze body and the fuze is threaded directly into the fuze seat liner. The Nose Fuze M111 (and variations, particularly the M127), however, has an outside thread diameter of 1.5 inches and must be used in conjunction with an adapter booster when desired for employment in AN and other Army bombs. This adapter booster, the M117, has an inside thread diameter of 1.5 inches to receive the smaller fuzes and an outside thread diame-ter of 2.0 inches to fit the fuze seat liner. It converts the nose fuse pockets of G.P., S.A.P., L.C., 260-pound fragmentation, 90-pound fragmentation, 500-pound incendiary, and 500-, 1,000-, and 2,000-pound chemical bombs for use with the Nose Fuze M127.

The function of the Army adapter booster is performed in Navy bombs by the fuze seat liner and the auxiliary booster. The fuze seat liner is an integral part of the bomb, and the auxiliary booster is slipped into position as shown in figure 318. The Auxiliary Booster Mk 1 is used in the fuze seat liners of all Navy G.P., A.P., and depth bombs. One extra Auxiliary Booster Mk 1 is required to adapt the standard Navy nose fuze seat liner for the Fuze AN-Mk 219. The Auxiliary Booster Mk 2, which is designed primarily for inser-tion in rocket heads, can be adapted for Navy G.P. and depth bombs fuzed with the Hy-drostatic Fuze AN-Mk 230 by fitting a ¼-inch wooden disc spacer on the bottom of the fuze seat liner and placing two Auxiliary Boosters Mk 2 above the spacer. When it is desi-red to use the Nose Impact Fuze AN-Mk 219 in Army bombs, the Auxiliary Booster Mk 4 is inserted in the fuze seat liner.

Figure 318. Navy Fuze Seat Liner

Figure 319. Some Primer Detonators