The Robin was the common design nuclear fission bomb core for several Cold War designs for American nuclear and thermonuclear weapons, according to researcher Chuck Hansen.

Primary is the technical term for the fission bomb component of a thermonuclear or fusion bomb, which is used to start the reactions going and implode and detonate the second, fusion stage.

The Robin design was used as the W45

W45

The W45 was a multipurpose American nuclear warhead developed in the early 1960s, first built in 1962 and fielded in some applications until 1988. It had a diameter of 11.5 inches , a length of 27 inches and weighed 150 pounds . The yields of different W45 versions were 0.5, 1, 5, 8, 10, and 15...

 nuclear and as the primary in the W38

W38

The W38 was an American thermonuclear warhead used in the early to mid 1960s as a warhead for Atlas E and F, and LGM-25 Titan I ICBMs. It was first built in 1961 and was in service from 1961 to 1965. 70 were deployed on Titan I missiles and 110 on Atlas missiles. It used the Avco Mark 4 reentry...

 and W47

W47

The W47 was an American thermonuclear warhead used on the Polaris A-1 sub-launched ballistic missile system. Various models were in service from 1960 through the end of 1974...

 thermonuclear weapons.

It has been associated with the W48

W48

The W48 was an American nuclear artillery shell, fired from a standard 155 mm howitzer e.g. the M114 or M198. It was manufactured starting in 1963, and all units were retired in 1992....

 nuclear warhead, but this is probably an error.

History

The Robin is apparently a weaponized version of the Swan

Swan (nuclear explosive)

Swan was a U.S. test nuclear explosive.It was tested standalone as a test nuclear device on June 26, 1956 in shot Redwing Inca. It was tested again as the primary of a test thermonuclear device on July 2, 1956 in shot Redwing Mohawk. Both tests were successful in all respects. It subsequently...

primary tested during operation Redwing

Operation Redwing

Operation Redwing was a United States series of 17 nuclear test detonations from May to July 1956. They were conducted at Bikini and Enewetak atolls. The entire operation followed Operation Wigwam and preceded Operation Plumbbob. The primary intention was to test new, second-generation...

 and shares its design features.

See also

• List of nuclear weapons
• Teller-Ulam design
  Teller-Ulam design
  The Teller–Ulam design is the nuclear weapon design concept used in most of the world's nuclear weapons. It is colloquially referred to as "the secret of the hydrogen bomb" because it employs hydrogen fusion, though in most applications the bulk of its destructive energy comes from uranium fission,...
  
  
• Python primary
  Python primary
  According to researcher Chuck Hansen, the W34 Python was a gas-boosted fission primary used in several designs of American thermonuclear weapons....
  
  
• Tsetse primary
  Tsetse primary
  The Tsetse was the common design nuclear fission bomb core for several Cold War designs for American nuclear and thermonuclear weapons, according to researcher Chuck Hansen....