Monday, Aug. 14, 1950

Guaranteed

Ever since they first went into action in Korea, U.S. troops had prayed for weapons powerful enough to pierce the heavily armored, Russian-made tanks of the North Korean Communists. The first successful new weapon against the Red tanks was the 3.5 inch bazooka (TIME, July 31), which quickly proved its worth. Last week, the Army took the wraps off a new artillery shell guaranteed by ordnance experts to "kill any tank in the world as far as a gunner can see it and hit it."

The new shell is a 90-mm. projectile which gets its deadliness from the same "shaped charge" that is built into the bazooka rockets. But the shell, designed for the 90-mm. guns of the U.S. 45-ton General Pershing tanks, has much greater velocity than the bazooka rockets, and an effective combat range of 1,000 yards, ten times that of the bazooka.

Long familiar to ordnance men, the shaped charge* is a mass of high explosive with a conical cavity in its front end; the cavity is lined with a cone of thin metal. When the charge explodes, the wave of detonation starts at the rear of the shell; when the explosive waves hit the point of the metal liner, the metal comes under immense pressure and acts like a thin fluid. Like a jet-propelled stream of toothpaste, the fluid metal spurts forward, at speeds up to 30,000 feet a second. The jet of liquid metal and gas can pierce more than eleven inches of armor plate. Shaped-charge shells are also equipped with rocket-like fins to give a steady flight without the spin of the standard artillery projectile.

The new shells will arrive in Korea this week but they will not be available in heavy supply for some time to come.

* Also known as the "Munroe effect," after Charles E. Munroe (1849-1938). Munroe, who also invented indurite, the first smokeless powder used by the U.S. Navy for large guns, noted the principle of the shaped charge in 1888, while chemist to the Naval Torpedo Station at Newport, R.I.

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