W54
Encyclopedia
The W54 was the smallest nuclear warhead deployed by the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It was a very compact implosion-type nuclear weapon design
Nuclear weapon design
Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three basic design types...

, designed for tactical use and had a very low yield
Nuclear weapon yield
The explosive yield of a nuclear weapon is the amount of energy discharged when a nuclear weapon is detonated, expressed usually in the equivalent mass of trinitrotoluene , either in kilotons or megatons , but sometimes also in terajoules...

 for a nuclear weapon.

Development

The W54 was designed by Los Alamos Scientific Laboratory
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

 and built by the United States Atomic Energy Commission
United States Atomic Energy Commission
The United States Atomic Energy Commission was an agency of the United States government established after World War II by Congress to foster and control the peace time development of atomic science and technology. President Harry S...

. Around 400 units were manufactured from 1961 until early 1962, and they were deployed until at least 1971.

Preproduction testing

The earliest identified nuclear tests
Nuclear testing
Nuclear weapons tests are experiments carried out to determine the effectiveness, yield and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that have developed nuclear weapons have tested them...

 of devices corresponding to the W54 characteristics were the Pascal-A and Pascal-B test detonations in 1957, in the Operation Plumbbob
Operation Plumbbob
Operation Plumbbob was a series of nuclear tests conducted between May 28 and October 7, 1957, at the Nevada Test Site, following Operation Redwing, and preceding Operation Hardtack I...

 nuclear test series. These were both intended to be very low yield, but overshot to higher yields (tens and hundreds of tons).

These were followed by tests of the XW-51 design which evolved into the XW-54 in the Operation Hardtack I
Operation Hardtack I
Operation Hardtack I was a series of 35 nuclear tests conducted by the United States in 1958 in the Pacific Ocean.Operation Newsreel was a series of three high-altitude nuclear tests conducted as part of Hardtack I. The individual tests in the series were Orange‎, Teak‎ and Yucca‎.-Test Blasts:-...

 test series in 1958 (Hardtack Quince and Hardtack Fig). These were both described as fizzle
Fizzle (nuclear test)
In nuclear weapons, a fizzle occurs when the testing of a nuclear bomb fails to meet its expected yield. The reason for the failure can be linked to improper bomb design, poor construction, or lack of expertise. All countries that have had a nuclear weapons testing program have experienced fizzles...

s, or test failures.

A number of XW-51/XW-54 tests followed in the 1958 Operation Hardtack II
Operation Hardtack II
Operation Hardtack II was a series of 37 nuclear tests conducted by the United States in 1958 at the Nevada Test Site.With test moratoriums on the horizon, American weapons labs rushed out many new designs. After the conclusion of Hardtack II, the United States announced a unilateral testing...

 test series, including Hardtack II Otero, Bernalillo, Luna, Mora, Colfax, Lea, Hamilton, Dona Ana, San Juan, Socorro, Catron, De Baca, Chavez, Humboldt, and Santa Fe. By this time, the XW-51 / XW-54 design had been test fired more times than any preceding US nuclear weapon prior to its successful introduction in service, indicating the difficulty of successfully making this small and low yield design work reliably and safely.

Further testing followed in the 1961 Operation Nougat
Operation Nougat
Operation Nougat was a series of 45 nuclear tests conducted at the Nevada Test Site in 1961 and 1962, immediately after the Soviet Union abrogated a testing moratorium, with the US' "Mink" test shot taking place the day before the Soviets test-detonated the Tsar Bomba. Most tests were...

 test series, probably including Nougat Shrew, Boomer, Ringtail, and possibly others. By this time the W-54 design was performing consistently as expected at low yields.

Variants

There were four distinct models of the basic W54 design used, each with different yield, but the same basic design. These were:
  • Mk-54 (Davy Crockett) — 10 or 20 ton yield, Davy Crockett
    Davy Crockett (nuclear device)
    The M-28 or M-29 Davy Crockett Weapon System was a tactical nuclear recoilless gun for firing the M388 nuclear projectile that was deployed by the United States during the Cold War...

     artillery warhead
  • Mk-54 (SADM) — variable yield 10 ton to 1 kiloton, Special Atomic Demolition Munition
    Special Atomic Demolition Munition
    The Special Atomic Demolition Munition was a family of man-portable nuclear weapons fielded by the US military in the 1960s, but never used in actual combat. The US Army planned to use the weapons in Europe in the event of a Soviet invasion...

     device
  • W-54 — 250 ton yield, warhead for AIM-26 Falcon
    AIM-26 Falcon
    The AIM-26 Falcon was a larger, more powerful version of the AIM-4 Falcon air-to-air missile built by Hughes. It is the only guided U.S. air-to-air weapon with a nuclear warhead, though the unguided AIR-2 Genie was also nuclear-armed.-Development:...

     air to air missile
  • W72 — 600 ton yield, rebuilt W-54 (Falcon warhead) for AGM-62 Walleye
    AGM-62 Walleye
    The AGM-62 Walleye is a television-guided glide bomb which was produced by Martin Marietta and used by the United States armed forces during the 1960s. Most had a 250 lb high-explosive warhead, some had a nuclear warhead...


Specifications

All four variants share the same basic core: a nuclear system which is 10.75 inches diameter (270 mm), about 15.7 inches long (400 mm), and weighs around or slightly over 50 pounds (23 kg).

The W54 core, based on the available photos (particularly of the Davy Crockett
Davy Crockett (nuclear device)
The M-28 or M-29 Davy Crockett Weapon System was a tactical nuclear recoilless gun for firing the M388 nuclear projectile that was deployed by the United States during the Cold War...

) was neither spherical nor elliptical. The best interpolated photographic match to its external dimensions is a center cylindrical section 11 inches in diameter and 5 inches long, with roughly 5.5 inch radius hemispherical ends.

Known and theoretical uses

These small size devices were first intended for use by United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 ground soldiers in battle, and were in theory small enough to be delivered by a bazooka
Bazooka
Bazooka is the common name for a man-portable recoilless rocket antitank weapon, widely fielded by the U.S. Army. Also referred to as the "Stovepipe", the innovative bazooka was amongst the first-generation of rocket propelled anti-tank weapons used in infantry combat...

-style firing mechanism. Early known versions could destroy a two block area, with an estimated yield comparable to approximately 10 tons of TNT. Larger versions were later developed with a selectable yield of between 10 and 250 tons. Though small compared to most other nuclear weapons, whose yields are usually measured in the thousands of tons of TNT (kilotons), in human terms they are still extremely large. By comparison, the smallest yield version of the W54 (10 tons) is two to four times as powerful as the 1995 Oklahoma City bombing
Oklahoma City bombing
The Oklahoma City bombing was a terrorist bomb attack on the Alfred P. Murrah Federal Building in downtown Oklahoma City on April 19, 1995. It was the most destructive act of terrorism on American soil until the September 11, 2001 attacks. The Oklahoma blast claimed 168 lives, including 19...

, making the 250 ton version 50 to 100 times as powerful.

Several variations of the W54 are known to exist and they were used in weapons projects by every branch of the U.S. armed forces except the Coast Guard.

The W54 style warhead was known to be used on the M-388 Davy Crockett
Davy Crockett (nuclear device)
The M-28 or M-29 Davy Crockett Weapon System was a tactical nuclear recoilless gun for firing the M388 nuclear projectile that was deployed by the United States during the Cold War...

, a tactical nuclear recoilless rifle projectile that was deployed by the United States during the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...

.

The W54 is small enough to be deployed as a SADM (Special Atomic Demolition Munition
Special Atomic Demolition Munition
The Special Atomic Demolition Munition was a family of man-portable nuclear weapons fielded by the US military in the 1960s, but never used in actual combat. The US Army planned to use the weapons in Europe in the event of a Soviet invasion...

) or so called "Backpack Nuke". It was the closest thing the U.S. is known to have to developed to a so-called "suitcase bomb
Suitcase bomb
A suitcase nuke is a tactical nuclear weapon which uses, or is portable enough that it could use, a suitcase as its delivery method. Synonyms include suitcase bomb, backpack nuke, mini-nuke, pocket nuke and snuke....

".

The W54 was tested for use in a U.S. Navy SEALs project that was demonstrated as feasible in the mid-to-late 1960s, designed to attack a harbor or other strategic location that could be accessed from the sea. The SEALs version would be delivered into water by parachute along with a two man team, then floated to the target, set in place and armed by hand.

The United States Air Force
United States Air Force
The United States Air Force is the aerial warfare service branch of the United States Armed Forces and one of the American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947 under the National Security Act of...

 also developed a project using the W54, the Hughes Electronics AIM-26 Falcon
AIM-26 Falcon
The AIM-26 Falcon was a larger, more powerful version of the AIM-4 Falcon air-to-air missile built by Hughes. It is the only guided U.S. air-to-air weapon with a nuclear warhead, though the unguided AIR-2 Genie was also nuclear-armed.-Development:...

. This was a larger, more powerful version of the AIM-4 Falcon
AIM-4 Falcon
The Hughes AIM-4 Falcon was the first operational guided air-to-air missile of the United States Air Force.-Development:Development of a guided air-to-air missile began in 1946. Hughes Aircraft was awarded a contract for a subsonic missile under the project designation MX-798, which soon gave way...

 air-to-air missile. It is notable for being the only U.S. guided air-to-air
Air-to-air missile
An air-to-air missile is a missile fired from an aircraft for the purpose of destroying another aircraft. AAMs are typically powered by one or more rocket motors, usually solid fuelled but sometimes liquid fuelled...

 weapon with a nuclear warhead. It was intended to destroy formations of Soviet bombers at a time when guided missiles were not accurate enough to produce high-probability kills with small conventional warheads.

W72

After the AIM-26 Falcon was retired, 300 units were rebuilt into an improved configuration with a higher yield and redesignated the W72. These warheads were then used to produce a number of nuclear versions of the AGM-62 Walleye
AGM-62 Walleye
The AGM-62 Walleye is a television-guided glide bomb which was produced by Martin Marietta and used by the United States armed forces during the 1960s. Most had a 250 lb high-explosive warhead, some had a nuclear warhead...

 television guided glide bomb system. The W72 variant had a yield of around 600 tons of TNT.

The 300 W72 units were produced between 1970 and 1972, and were in service until 1979.

Documented testing

Stockpiled W54 warheads were test fired
Nuclear testing
Nuclear weapons tests are experiments carried out to determine the effectiveness, yield and explosive capability of nuclear weapons. Throughout the twentieth century, most nations that have developed nuclear weapons have tested them...

 at the Nevada Test Site
Nevada Test Site
The Nevada National Security Site , previously the Nevada Test Site , is a United States Department of Energy reservation located in southeastern Nye County, Nevada, about northwest of the city of Las Vegas...

 on July 7 and July 17, 1962. In Little Feller II (July 7), the warhead was suspended only three feet above the ground and had a yield equivalent to only 22 tons of TNT. In Little Feller I (July 17), the warhead was launched as a Davy Crockett device
Davy Crockett (nuclear device)
The M-28 or M-29 Davy Crockett Weapon System was a tactical nuclear recoilless gun for firing the M388 nuclear projectile that was deployed by the United States during the Cold War...

 from a stationary 155 millimeter launcher and set to detonate between 20 and 40 feet above the ground around 1.7 miles from the launch point, with a yield of 18 tons. This test was the last atmospheric test at Nevada Test Site and was performed in conjunction with Operation IVY FLATS, a simulated military environment, and was observed by Attorney General Robert F. Kennedy
Robert F. Kennedy
Robert Francis "Bobby" Kennedy , also referred to by his initials RFK, was an American politician, a Democratic senator from New York, and a noted civil rights activist. An icon of modern American liberalism and member of the Kennedy family, he was a younger brother of President John F...

 and presidential adviser General Maxwell D. Taylor
Maxwell D. Taylor
General Maxwell Davenport "Max" Taylor was an United States Army four star general and diplomat of the mid-20th century, who served as the fifth Chairman of the Joint Chiefs of Staff after having been appointed by the President of the United States John F...

. Footage of Operation IVY FLATS was declassified by the United States Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...

 on December 22, 1997. Limited operational details of early SADM projects were published prior to this declassification.
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