View source for W9 (nuclear warhead)

{{Short description|American nuclear artillery shell (1952–1957)}}
{{No footnotes|date=September 2022}}
[[File:W9 AFAP.jpg|thumb|W9 280mm Artillery Fired Atomic Projectile]]

The '''W9''' was an American [[nuclear artillery]] shell fired from a special {{val|280|u=mm}} [[howitzer]]. It was produced starting in 1952 and all were retired by 1957, being superseded by the [[W19 (nuclear artillery shell)|W19]].

==Description==

The W9 was {{convert|280|mm|order=flip}} in diameter, {{convert|54.8|in|abbr=on}} long, and weighed {{convert|850|lb|abbr=on}}. It had an explosive yield of {{convert|15|ktonTNT|abbr=on|lk=on}}.

The W9 was a [[gun-type fission weapon|gun-type]] nuclear weapon, using around {{convert|50|kg|abbr=on}} of [[enriched uranium|highly enriched uranium]] in one large rings assembly and one smaller ''bullet'', which was fired down a tube by conventional explosives into the rings assembly to achieve [[critical mass]] and detonate the weapon.{{Citation needed|date=December 2010}}

The W9 units which were retired in 1957 were recycled into lower yield [[T-4 Atomic Demolition Munition]]s. These were the first (semi) man-portable nuclear weapons.

==Tests==

The W9 is only the second gun-type nuclear weapon known to have been detonated; the first was the [[Little Boy]] nuclear weapon used in World War II.

The W9 artillery shell was test fired once, fired from the "Atomic Annie" [[M65 Atomic Cannon]], in ''[[Upshot-Knothole Grable]]'' on May 25, 1953 at the [[Nevada Test Site|NTS]]. Yield was the expected 15 kilotons.

Subsequently, the [[W33 (nuclear weapon)|W33]] nuclear artillery shell was test fired twice (not in a gun) during its development (shots [[Operation Nougat|Nougat]]/Aardvark and [[Operation Plumbbob|Plumbbob]]/Laplace). These four detonations are the only identified gun-type bomb detonations.

==Gallery==
<gallery class="center" widths="220">
File:UpshotKnotholeGrable.gif|The W9 nuclear artillery shell was tested during the [[Upshot-Knothole Grable]] shot in 1953 with a yield of 15 kilotons, about the same strength as the [[Little Boy]] bomb dropped on [[Hiroshima]] during [[World War II]]
File:Upshot_Knothole_Grable.gif|Full uncut detonation of Upshot Knothole Grable, launched out of the ''[[M65 Atomic Cannon|Atomic Annie]]'' device on 5/25/1953. The footage at normal speed is about 2 and a half minutes.
File:uk-grable2.jpg|A closeup of the [[mushroom cloud]] and fireball.
M65_Atomic_canon_1.jpg|M65 Atomic Cannon; the artillery piece of which the projectile was first test-fired from.
</gallery>

==See also==

* [[Nuclear artillery]]
* [[List of nuclear weapons]]

==External links==

* [http://nuclearweaponarchive.org/Usa/Weapons/Allbombs.html Allbombs.html list of all US nuclear weapons models at nuclearweaponarchive.org]

{{United States nuclear devices}}

[[Category:Nuclear warheads of the United States|W09]]
[[Category:Gun-type nuclear bombs|W09]]
[[Category:Nuclear artillery]]
[[Category:Military equipment introduced in the 1950s]]