OP 1664 - U.S. Explosive Ordnance (Vol. 2); Part 6 - Bombs and Bomb Fuzes; Chapter 20 - Bomb Fuzes; Section 2 - Army-Designed Bomb Fuzes: M112, M113, and M114 (Obsolescent), and A1 Modifications (Tail Mechanical Impact)

U.S. EXPLOSIVE ORDNANCE

PART 6 - BOMBS AND BOMB FUZES

Chapter 20 - BOMB FUZES

Section 2 - ARMY-DESIGNED BOMB FUZES

M112, M113, and M114 (Obsolescent), and A1 Modifications (Tail Mechanical Impact)

Bombs
M112A1	100-lb. G.P. AN-M30 250-lb. G.P. AN-M57
M113A1	500-lb. G.P. AN-M43, 64 500-lb. S.A.P. AN-M58 600-lb. G.P. M32
M114A1	1,000-lb. G.P. AN-M44, 65 1,000-lb. S.A.P. AN-M58 1,100-lb. G.P. M33 2,000-lb. G.P. AN-M34, 66 2,000-lb. S.A.P. M103
Functioning	Primer Detonators M16 and M16A1 with 4 to 5, 8 to 11, or 8 to 15 seconds delay are interchangeable
Fuzes used with	None
Armed data	18 - 21 vane revolutions; 100 feet of air travel
Vane span, inches	5
Body diameter, inches	1.5
Over-all length, inches	M112A1 - 9.6 M113A1 - 12.6 M114A1 - 16.6
Material	Cadmium-plated steel

General: These fuzes are designed for ship and masthead bombing by land-based pla-nes. The only difference in these three fuzes is in the length of the arming stem. Larger bombs require a longer arming stem, so that the vanes can catch the air slip from the bomb.

Opeation: As the vanes rotate, the arming stem is unthreaded from the plunger. There are no reduction gears in the vane assembly, the arming stem being secured to the vane nut by a cotter pin; and 18 to 21 revolutions of the vanes will free the plunger. A key pin riding in a groove in the plunger prevents it from rotating as the arming stem is withdrawn. On impact, the plunger compresses its creep spring and the spring-loaded firing pin forces the locking balls out into the enlarged part of the fuze cavity, freeing the firing pin. The cocked firing-pin spring forces the firing pin against the primer initiating the delay in the primer detonator.

Early designs: The original M112, M113, and M114 used the Primer Detonator M16, which is the same as the M16A1 except that the shoulder is lower. Hence, when the Pri-mer Detonator M16A1 was designed, it was necessary to alter the base of the fuze slightly to permit use of this primer detonator with the higher shoulder on its external surface. The alternative Primer Detonator M16 had delays of 4 to 5 or 8 to 11 seconds, whereas the longer-delay M16A1 has a range of from 8 to 15 seconds. This delay con-sists of a barium chromate silicon powder in place of the lead chromate silicon mixture used in the Primer Detonator M16. The M16, through no longer being manufactured, can still be used in the Tail Mechanical Impact Fuze M112A1, M113A1, and M114A1.

Remarks: This fuze will function on an impact angle of 3°, and gives positive action because of its cocked firing pin. This fuze is unsafe for carrier landings. Delay of 4 to 5 seconds should be used against sea targets, and delay of 8 to 15 seconds against land targets.

Never turn the vanes counterclockwise to render the fuze safe, as the arming stem may depress the plunger instead of engaging it.

These fuzes may have a groove around the top of the fuze body, or the top may be straight like the AN-M100 series fuzes. This groove is a distinguishing mark used by those manufacturers making both the M112 and AN-M100 series fuzes, and is not to be consi-dered a positive mark for fuze identification.

Figure 342. Tail Fuze M112A1