Description
The Nose Mechanical Impact Fuze Mk 221 is essentially the same as the Mk 219, but it incorporates the following differences:
1. The body is longer and larger.
2. It incorporates a delay of 0.01 second. The delay element and percussion-type firing pin are housed in the delay carrier. The delay carrier corresponds to the firing-pin carrier in the Nose Mechanical Impact Fuze Mk 219.
3. A protecting cap is over the head. The vanes are screwed to the vane carrier by four screws which pass through the protecting cap to the vane carrier.
4. There arc three lock screws instead of one.
5. When the fuze is armed, a lock pin in the floor of the fuze body falls through an opening in the shaft extension nut, locking the rotor and the delay carrier to the shaft extension nut, and thus preventing the parts from getting out of line before impact.
6. The central spindle has a shear collar and a guide pin which permit the central spindle to telescope. The Nose Mechanical Impact Fuze Mk 239 is a Fuze Mk 221 modified by reducing the diameter of the fuze (extending from the booster cup to the fuze threads) from 1.875 inches (Mk 221) to 1.59 inches. The Mk 239 was designed to utilize present stocks of Fuzes Mk 221 in AN-standard GP bombs.
The delay element consists of a printer, a delay pellet of black powder, and a special detonator of fulminate of mercury; the detonator consists of fulminate of mercury mixture; and the auxiliary booster lead-in. booster lead-in, and booster consist of tetryl.
The Mk 221 will fit into the nose of the depth bomb, but the 0.01 second delay may allow the case of the bomb to be so damaged that a low order detonation may result. Therefore, it is not recommended that the Mk 221 be used with the depth bomb.
Functioning
The operation of the Mk 221 and Mk 239 is the same as the operation of the AN-Mk 219.
Hazardous Components
No information about hazardous components.
See Also
Source(s)
MIL-HDBK-146, Fuze Catalog (1982)
OP 1664, Volume 2 - US Explosive Ordnance (1947)
USNBD - Bombs and Fuzes, Pyrotechnics (1945)
