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| U.S.N.B.D. - UNITED STATES - BOMBS AND FUZES; PYROTECHNICS |
| SECTION III - BOMB FUZES |
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DATA: |
U.S. - NAVY NOSE FUZE |
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Mk 221 |
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BOMBS USED IN |
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Mk 221 |
500 lb. G.P. Mk 12 | |
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1000 lb. G.P. Mk 13 | |
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Mk 239 |
AN-standard G. P. |
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bombs. |
MECHANICAL IMPACT |
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FUNCTIONING |
0.01 seconds delay |
(Rotor System Arming) |
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ARMED CONDITION |
When striker flange has |
(Obsolescent) |
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risen more than 5/16" | |
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from outer sleeve, and | |
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arming wire is gone. |
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FUZES USED WITH |
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Mk 221 |
Mk 223 | |
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Mk 239 |
AN-M100 Series in AN-M G.P. bombs. | |
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ARMING TIME |
Approximately 150 revolutions | |
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VANE SPAN |
5.3" (four vanes) | |
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MAX. BODY DIAMETER |
2.75" | |
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OVERALL LENGTH |
8.5" (with booster) | |
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MATERIAL |
Steel, aluminum alloy, and brass. |
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GENERAL: |
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The Mk 221 is essentially the same as the Mk 219, but it incorporates the following difference: |
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(1) The body is longer and larger. |
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(2) It incorporates a delay of .01 seconds. The delay element and percussion type firing pin are housed in the delay carrier. The delay carrier corres-ponds to the firing pin carrier in the Mk 219. |
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(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. |
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(4) There are three lock screws instead of one. |
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(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 delay carrier to the shaft extension nut, and thus preventing the parts from getting out of line before impact. |
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(6) The central spindle has a shear collar and a guide pin which permit the central spindle to teles-cope. The Mk 239 is a Mk 221 fuze modified by re-ducing the diameter of the fuze (extending from the booster cup to the fuze threads) from 1.875" (Mk 221) to 1.59". The Mk 239 was designed to utilize present stocks of Mk 221 fuzes in AN-standard G.P. bombs. |
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OPERATION: |
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The operation of the Mk 221 and Mk 239 are the same as the operation of the AN-Mk 219 on page 235. |
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REMARKS: |
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The delay element consists of a primer, delay pel-let of black powder and a special detonator of fulmi-nate of mercurry; the detonator consists of fulminate of mercurry mixture; and the auxiliary booster lead-in, booster lead-in, and booster consists of tetryl. |
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The Mk 221 will fit into the nose of the depth bomb, but the .01 second delay may allow the case of the bomb to be so damaged that a low order deto-nation may result. Therefore, it is not recommended that the Mk 221 be used with the depth bomb. |
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