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The W33 (also known as the Mark 33, T317 and M422) was an American
nuclear artillery Nuclear artillery is a subset of limited- yield tactical nuclear weapons, in particular those weapons that are launched from the ground at battlefield targets. Nuclear artillery is commonly associated with shells delivered by a cannon, but in ...
shell designed for use in the
M110 howitzer The 8 inch (203 mm) M110 self-propelled howitzer is an American-made self-propelled artillery system consisting of an M115 203 mm howitzer installed on a purpose-built chassis. Before its retirement from US service, it was the largest a ...
and
M115 howitzer The M115 203 mm howitzer, also known as the M115 8-inch Howitzer, and originally the M1 8-inch Howitzer was a towed heavy howitzer developed and used by the United States Army during World War II, the Korean War, and the Vietnam War. Histor ...
. A total of 2,000 W33 projectiles were produced, with the first production warheads entering the stockpile in 1957. The W33 remained in service until 1992. The warhead used
enriched uranium Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U ...
(code named ''oralloy'') as its nuclear fissile material and could be used in two different yield configurations. This required the assembly and insertion of different pits, with the amount of fissile materials used controlling whether the destructive yield was low or high. The highest-yield version of the W33 may have been a
boosted fission weapon A boosted fission weapon usually refers to a type of nuclear bomb that uses a small amount of fusion fuel to increase the rate, and thus yield, of a fission reaction. The neutrons released by the fusion reactions add to the neutrons released ...
.


History

Development of the W33 was authorized by the Army Ordnance Corps in June 1953. It was believed that a shell capable of being fired by a standard mobile field howitzer would be more effective while also providing a psychological effect in ground warfare. The design would also include consideration for being fired from navy guns, and would use nuclear components from the W9 nuclear artillery shell. The initial army designation for the weapon was Shell, AE, 8-inch, T317 and the Atomic Energy Commission (AEC) nomenclature was Mark 33. The army were assigned the task of designing, constructing and stockpiling the non-nuclear components of the weapon, while the AEC were assigned the design and construction of the nuclear components. The design remained in the research and development phase until funds were assigned to the project in February 1954. In April it was decided the weapon needed to be in service by July 1955, so the program was placed on a crash basis. The first Emergency Capability (EC) weapons entered the stockpile in July 1955. Production (non-EC) weapons were produced from January 1957 to January 1965. Approximately 2000 weapons were produced and all were retired by September 1992.


Design

The weapon used nuclear components from the W9 nuclear artillery shell, and these in turn were derived from the nuclear components in the
Mark 8 nuclear bomb The Mark 8 nuclear bomb was an American nuclear bomb, designed in the late 1940s and early 1950s, which was in service from 1952 to 1957. Description The Mark 8 was a gun-type nuclear bomb, which rapidly assembles several critical masse ...
. From official sources, the weapon was of the gun-type design and had a range of . Information regarding the W33 has suggested that it was either a double gun and/or that it may have used an annular barrel assembly. The device's internal mechanism was apparently code-named ''Fleegle''. A double gun mechanism reduces the required velocity of each projectile by half, which reduces the gun system weight by a factor of 8. An annular bore may allow a larger projectile which remains subcritical by itself (a hollow projectile has lower effective density, and critical mass scales with the square of density).
Titanium Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resista ...
was used to reduce weight of some components. Judging by the remaining photographic evidence, it is likely that the exterior casing of the artillery shell itself was made of titanium. This is plausible, given that the copper-alloy driving band around the base of the shell is the only part of the shell which engages with the rifling on the
artillery Artillery is a class of heavy military ranged weapons that launch munitions far beyond the range and power of infantry firearms. Early artillery development focused on the ability to breach defensive walls and fortifications during siege ...
piece's barrel. The W33 mechanism has been reported to have comprised two critical nuclear parts which were required to assemble a complete W33 warhead. The initial disassembly of stockpiled W33 warheads in 1992 proceeded first by disassembling all existing parts for one of the components, and then disassembling the other one in following years. The weapon had four yield variants, known as the Y1 through Y4, and written using the standard nomenclature in the form of W33Y1 etc. The yield of each type remains classified, but it has been alleged that the Y2 version had a yield of and the other versions were . Use control to prevent unauthorized firing of the weapon was provided by a cover fitted to the rear of the weapon with a combination lock. The cover prevented loading of the weapon into a gun.


Tests

The W33 is the third known model of
gun-type fission weapon Gun-type fission weapons are fission-based nuclear weapons whose design assembles their fissile material into a supercritical mass by the use of the "gun" method: shooting one piece of sub-critical material into another. Although this is someti ...
s to have been detonated, and the second as a test explosion. The W33 was tested twice, first in Operation Plumbbob Laplace, on September 8, 1957 with a yield of , and the TX-33Y2 in Operation Nougat Aardvark on May 12, 1962, with a yield of . Neither test involved firing a W33 from an actual howitzer. Plumbbob Laplace was test fired with the device hanging from a balloon at an altitude of . Nougat Aardvark was test fired underground at a depth of . Prior gun-type detonations were the
Little Boy "Little Boy" was the type of atomic bomb dropped on the Japanese city of Hiroshima on 6 August 1945 during World War II, making it the first nuclear weapon used in warfare. The bomb was dropped by the Boeing B-29 Superfortress ''Enola Gay'' p ...
Mark-2 nuclear weaponSandia 1967 History of Mk 4 bomb
Document, Sandia Laboratories; Accessed Nov. 10, 2019
used on Hiroshima in
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
, and a test firing of the W9 nuclear artillery shell in test shot Upshot-Knothole Grable on May 25, 1953.


See also

*
List of nuclear weapons This is a list of nuclear weapons listed according to country of origin, and then by type within the states. United States US nuclear weapons of all types – bombs, warheads, shells, and others – are numbered in the same sequence starting wi ...
* W79 Artillery-Fired Atomic Projectile


References


External links


Allbombs.html
list of all US nuclear weapons models a
nuclearweaponarchive.org


at GlobalSecurity.org {{United States nuclear devices Nuclear warheads of the United States Gun-type nuclear bombs Nuclear artillery Military equipment introduced in the 1950s