View source for Python (nuclear primary)

{{Short description|Gas-boosted fission primary used in some American thermonuclear weapons}}
{{No footnotes|date=August 2024}}
According to researcher [[Chuck Hansen]], the '''W34 Python''' was a gas-boosted fission [[Nuclear weapon design#Two-stage thermonuclear weapons|primary]] used in several designs of American [[thermonuclear weapon]]s.
Hansen's research indicates that the [[W34 (nuclear bomb)|W34]] '''Python''' primary was used in the US [[B28 nuclear bomb]], [[W28 (nuclear warhead)|W28]], [[W40 (nuclear warhead)|W40]], and [[W49]], and as a boosted fission warhead without a thermonuclear second stage in several other weapons. These were the [[Mark 45 torpedo|Mark 45 ASTOR]] wire-guided {{convert|19|in|cm|adj=on}}, submarine-launched heavyweight torpedo; the [[Mk 101 Lulu]] [[nuclear depth bomb]]; the [[Mk 105 Hotpoint]] laydown bomb.
Additionally, an anglicised [[W34 (nuclear bomb)|W34]] Python known to the British as 'Peter' was manufactured in Britain as the primary for [[Red Snow]], itself an anglicised [[W28 (nuclear warhead)|W28 warhead]]. Peter was also proposed as a replacement for the [[Red Beard (nuclear weapon)|Red Beard]] warhead housed in a Red Beard carcass, and as the [[Violet Mist]] [[nuclear land mine]] for the British Army in Germany.
The W34 used the melt-cast [[high explosive]] [[Octol]], a variant of [[HMX]] and [[TNT]] as the material for its implosion lenses, and this relatively unsophisticated explosive that pre-dated [[Polymer-bonded explosive|PBX]] was perhaps a reason why the British adopted this warhead, since they were attempting to deploy a thermonuclear warhead for their strategic bombers quickly, and the British were well-versed in the manufacture, storage and use of these melt-cast explosives.
Declassified British military documents also refer to a 'Low-Yield-Python' and the [[AIR-2 Genie]] [[air-to-air rocket]] being considered by the UK for their interceptors, suggesting that there was a design linkage with the [[W25 (nuclear warhead)|W25]] low-yield warhead of the Genie. There is no hard evidence as yet, but the 11&nbsp;kt yield of the W34 Python would degrade to a figure comparable with the W25 without the gas-boosting.
Historical evidence indicates that these weapons shared a reliability problem, which Hansen attributes to miscalculation of the reaction cross section of [[tritium]] in fusion reactions. The weapons were not tested as extensively as some prior models due to a mid-1960s nuclear test moratorium, and the reliability problem was discovered and fixed after the moratorium ended. The flaw was apparently common with the W44 [[Tsetse primary]] design.
Characteristics of these weapons are:
{| class="wikitable" style="border-collapse: collapse;"
! style="background-color: #F8EABA;" colspan="5" | Python primary based nuclear weapons
|-
|Model
|Max yield (kt)
|Diameter
|Length
|Weight
|-
|B28
|1,450
|{{convert|22|in|cm|abbr=on}}
|{{convert|170|in|m|abbr=on}}
|{{convert|2,300|lb|kg|abbr=on}}
|-
|W-28
|1,450
|{{convert|20|in|cm|abbr=on}}
|{{convert|60|in|m|abbr=on}}
|{{convert|1,725|lb|kg|abbr=on}}
|-
|W-40
|10
|{{convert|18|in|cm|abbr=on}}
|{{convert|32|in|m|abbr=on}}
|{{convert|385|lb|kg|abbr=on}}
|-
|W-49
|1,440
|{{convert|20|in|cm|abbr=on}}
|{{convert|58|in|m|abbr=on}}
|{{convert|1,610|lb|kg|abbr=on}}
|-
|W-34
|11
|{{convert|17|in|cm|abbr=on}}
|{{convert|32|in|m|abbr=on}}
|{{convert|320|lb|kg|abbr=on}}
|-
|!  style="background-color: #F8EABA;" colspan="5" | Possible family members
|-
|W25
|1.7
|{{convert|17.4|in|cm|abbr=on}}
|{{convert|26.6|in|m|abbr=on}}
|{{convert|221|lb|kg|abbr=on}}
|}
==See also==
* [[List of nuclear weapons]]
* [[Robin primary]]
==External links==
*[http://journals.sagepub.com/doi/full/10.2968/057002015 Beware the old story] by [[Chuck Hansen]], [http://thebulletin.org Bulletin of the Atomic Scientists], March/April 2001 pp.&nbsp;52–55
*Various Ministry of Defence and Ministry of Aviation declassified files  lodged in the National Archives, London.
*[http://nuclearweaponarchive.org/Usa/Weapons/Allbombs.html Complete List of All U.S. Nuclear Weapons]
*[http://nuclearweaponarchive.org/Library/Brown/B28bomb.gif Richard Brown's sectioned b/w line drawing.]
*[http://nuclearweaponarchive.org/Library/Brown/B28cut.jpg Richard Brown's sectioned colour drawing.]
*[http://nuclearweaponarchive.org/Library/Brown/B28outsd.jpg Richard Brown's colour exterior drawing.]
{{United States nuclear devices}}
[[Category:Nuclear bombs of the United States]]