W80 (nuclear warhead)

The W80 is a small thermonuclear warhead (fusion or, more descriptively, two-stage weapon) in the U.S. with a variable yield of between 5 and 150 kt of TNT.

It was designed for deployment on cruise missiles and is the warhead used in the majority of nuclear-armed US Air Force ALCM and ACM missiles, and their US Navy counterpart, the BGM-109 Tomahawk. It is essentially a modification of the widely deployed B61 weapon, which forms the basis of most of the current US . The very similar W84 warhead was deployed on the BGM-109G Gryphon GLCM.

The W80 is physically quite small: the "physics package" itself is about the size of a conventional Mk.81 250-pound (110 kg) bomb, 11.8 inches (30 cm) in diameter and 31.4 inches (80 cm) long, and only slightly heavier at about 290 pounds (130 kg).

Armorers have the ability to select the yield of the resulting explosion in-flight, a capability referred to as variable yield. The minimum yield, perhaps using just the boosted fission primary, is around 5 kilotons of TNT; the highest yield is equivalent to around 150 kt.

The Los Alamos National Laboratory began development on the W80 in June 1976, with the brief of producing a custom weapon for the cruise missiles then under construction. The main differences between the W80 and W61 appear to relate to the physical packaging of the device, and to the removal of the 0.3 kt yield mode; the W61 apparently needed this feature when deployed as a depth charge, a role for which the W80 was not intended.

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