W58

The W58 was an American thermonuclear warhead used on the Polaris A-3 submarine-launched ballistic missile. Three W58 warheads were fitted as multiple warheads on each Polaris A-3 missile.

The W58 was 15.6 in in diameter and 40.3 in long, with a basic weight for the warhead of 257 lb. The yield was 200 kilotons.

The W58 design entered service in 1964 and the last models were retired in 1982 with the last Polaris missiles.

Researcher Chuck Hansen claims based on his US nuclear program research that the W55 and W58 warheads shared a common Primary or fission first stage, and that this design was nicknamed the Kinglet primary by Hansen in 2001.