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| U.S. EXPLOSIVE ORDNANCE |
| PART 6 - BOMBS AND BOMB FUZES |
| Chapter 17 - EXPLOSIVE BOMBS |
| Section 3 - "M" SERIES |
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4-pound Frag. "Butterfly" M83 |
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Over-all length, inches |
3.0 |
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Body length, inches |
3.0 |
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Body diameter, inches |
3.1 |
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Wall thickness, inch |
0.25 |
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Filling |
TNT |
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Weight of filling, pounds |
0.47 |
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Total weight, pounds |
3.2 |
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Charge/weight ratio |
15% |
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Fuzing: M129 Air or ground burst, M130 Time, maximum 30 minutes, or M131 Anti-dis-turbance. |
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Body construction: The bomb body is cylindrical in shape, cast in two halves and welded together. The fuze cavity is situated athwart-ships in the body, is 1¾ inches in diameter, and is threaded with a left-hand thread. The left-hand thread is to prevent unscrewing of the fuze while the bomb is in flight. |
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Arming vane assembly: The vane assembly consists of four pieces hinged together - two semi-cylindrical surfaces (wings) and two dics (propeller blades) inclined at a slight angle. While the bomb is still in the cluster, the vane assembly is folded around the bomb to form a cylindrical casing which can be closed against the pressure of the vane coil springs by means of a safety clip. The arming spindle projects through the bomb casing. |
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When the bomb are packed in the cluster adapter, the safety clips are removed but the bombs remain in their closed status because of their proximity to each other. When the bluster adapter bursts open, the bombs scatter and the vane assembly on each bomb is spread open by the force of its coil springs. The vane assembly is forced by air resistance to the top of the arming spindle, where the square head on the spindle enga-ges the square hole in the assembly. The two wings reduce the velocity of descent of the bomb. The two propellers, being set at angles to each other, cause the vane as-sembly to turn in a counterclockwise direction, thereby screwing the arming spindle out of the fuze body and permitting the fuze to arm. The arming spindle is not completely withdrawn from the fuze, being retained in the fuze by a collar on the spindle. |
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Markings: The bombs are painted olive drab, with a half-inch yellow band running ho-rizontally around the folded wings. |
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Figure 260. 4-pound Frag. "Butterfly" Bomb M83 |
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