OP 1664 - U.S. Explosive Ordnance (Vol. 1); Part 1 - Projectiles, Propellants, and Projectile Fuzes; Chapter 3 - Projectile Fuzes; Section 4 - V.T. Fuzes: Mk 32 Mods 0-20, Mod 30, and Mod 40 (Obsolete)

U.S. EXPLOSIVE ORDNANCE

PART 1 - PROJECTILES, PROPELLANT,
AND PROECTILE FUZES

Chapter 3 - PROJECTILE FUZES

Section 4 - V.T. FUZES

Mk 32 Mods 0-20, Mod 30, and Mod 40 (Obsolete)

Projectiles used in	5"/38/25/51* A.A. Common
Over-all length, inches	12 (approx.)
Diameter at base ogive, inch	3.3 (approx.)
Threaded length, inch	0.6 (approx.)
Threads	6 R.H.
Material	Steel base rings, black plastic nose ogive, aluminum nose cap or button tip
Weight, pounds	6.81
Minimum range, yards	Mods 0-20, 40 - 600
	Mod 30 - 1,000
Energizer	Mods 0-20, 40 - dry
	Mod 30 - Wet
Wave-suppression feature	Mod 40 only
Self-destruction feature	None

Description: This fuze was designed to initate detonate when passing within the maximum influence radius of about sixty feet. The Mod 40 has reduced sensitivity against low-flying aircraft because of the wave-supression feature (vor values, see V.T. Fuze Mk 40). Burst heights above water for all Mods without the wave suppression feature will be high at most ranges, averaging 130 feet at 12,200 yards in the 5"/38 projectile, with burst heights over water will average lower at shorter ranges, but a wide dispersion in heights will occur. These fuzes are especially affected by water surface conditions. Burst heights of the Mod 40 above water (WSF) will vary between 10 and 50 feet.

Random premature bursts of rounds assembled with this fuze will occur along the traj-ectory after the fuze is armed but before it approaches a target. With targets at longe range, 20 per cent of the rounds may burst before approaching the target, and a some-what smaller percentage of prematures will occur at shorter ranges. If a target at long range is approached within the sensitivity limits of the fuze, 65 per cent of the rounds should function at the most critical point to throw fragments against the target. The percentage of proper functions at shorter ranges is higher by the amount of decrease in premature functions. The remainder of the rounds will be duds. Because of ageing of the dry energizer, only about 50 per cent of the rounds will function properly after eignt months. The dry energizers are changed about every six months by Bureau of Ordnance personnel. Production has been suspended on this item.

Employment: This fuze was used for anti-aircraft work from 600 yards minimum ran-ge to extreme range. The Mod 40, with WSF, has normaly sensitivity above about 200 feet from the water, but has automatically reduced sensitivity below this level. Mods 0-20 and 30 are not ordinarily used against surface craft, because bursts at long range are too high for effective fragmentation damage, and those on low trajectory have a large dispersion in range. These Mods might be used with reduced effectiveness against low-flying planes.

Remarks: The Auxiliary Detonating Fuze Mk 54, replacing the Auxiliary Detonating Fu-zes Mks 17 and 46, is used in conjunction with this fuze.

This fuze is currently being replaced by the V.T. Fuze Mk 53 in new projectiles; Mk 53 cavity is smaller.