B41 nuclear bomb
Encyclopedia
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Strategic Air Command
Strategic Air Command
The Strategic Air Command was both a Major Command of the United States Air Force and a "specified command" of the United States Department of Defense. SAC was the operational establishment in charge of America's land-based strategic bomber aircraft and land-based intercontinental ballistic...
in the early 1960s. It was the most powerful nuclear bomb ever developed by the United States with a theoretical maximum yield of 25 megatons
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
. This project came about 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...
..
Development
The development of the Mk 41 began in 1955 with a USAF requirement for a Class B (high-yield, over 10,000 lb/4,545 kg) weapon. It was based on the "Bassoon" test device first fired in the Redwing ZuniOperation 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...
test of 27 May 1956. An ICBM warhead version of the weapon was cancelled in 1957.
Composition
The Mk 41 was the only three-stageTeller-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,...
thermonuclear weapon fielded by the U.S. It had a deuterium
Deuterium
Deuterium, also called heavy hydrogen, is one of two stable isotopes of hydrogen. It has a natural abundance in Earth's oceans of about one atom in of hydrogen . Deuterium accounts for approximately 0.0156% of all naturally occurring hydrogen in Earth's oceans, while the most common isotope ...
-tritium
Tritium
Tritium is a radioactive isotope of hydrogen. The nucleus of tritium contains one proton and two neutrons, whereas the nucleus of protium contains one proton and no neutrons...
boosted primary, probably with lithium-6
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
-enriched deuteride fuel for the fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
reaction. Two versions were deployed, Y1, a "dirty" version with a tertiary stage encased with U-238
Uranium-238
Uranium-238 is the most common isotope of uranium found in nature. It is not fissile, but is a fertile material: it can capture a slow neutron and after two beta decays become fissile plutonium-239...
, and Y2, a "clean" version with a lead-encased tertiary. It was the highest-yield nuclear weapon ever deployed by the United States, with a maximum yield of 25 megatons
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
(Mt), and weighing in at 4,850 kg. It remains the highest yield-to-weight ratio of any weapon created. The US claimed in 1963 that it could produce a 35 Mt fusion bomb, and put it on a Titan II (3,700 kg payload), almost doubling the yield-to-weight ratio of the B-41.
The Mk 41 was of the usual long cylindrical shape and weighed 10,670 lb (4,840 kg). The nuclear fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
warhead was of the Teller-Ulam type and used a 40–100 kiloton implosion type nuclear fission primary fueled by HEU to trigger the lithium-6 deuteride fusion fuel. Between 500 and 1,000 kg of lithium deuteride was used and was contained in a cylinder of natural uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
with an inner casing of U-238.
The Mk 41 was an example of a fission-fusion-fission type thermonuclear weapon, known by the term "thermonuclear triple threat". Such devices were so-called "dirty" H-bombs because when detonated they produced very large amounts of intensely radioactive fallout that would cause illness or death to those with whom it came into contact.
Physical characteristics
The weapon was 12 ft 4 in (3.76 m) long, with a body diameter of 4 ft 4 in (1.32 m). It weighed 10,670 lb (4,850 kg). It was carried only by the B-52 StratofortressB-52 Stratofortress
The Boeing B-52 Stratofortress is a long-range, subsonic, jet-powered strategic bomber operated by the United States Air Force since the 1950s. The B-52 was designed and built by Boeing, who have continued to provide maintainence and upgrades to the aircraft in service...
and B-47 Stratojet
B-47 Stratojet
The Boeing Model 450 B-47 Stratojet was a long-range, six-engined, jet-powered medium bomber built to fly at high subsonic speeds and at high altitudes. It was primarily designed to drop nuclear bombs on the Soviet Union...
. It could be deployed in free-fall or retarded (parachute) configuration, and could be set for airburst
Air burst
An air burst is the detonation of an explosive device such as an anti-personnel artillery shell or a nuclear weapon in the air instead of on contact with the ground or target or a delayed armor piercing explosion....
, groundburst, or laydown delivery.
Service life
The Mk 41 (designated B41 from 1968 on) entered service in 19611961 in aviation
This is a list of aviation-related events from 1961:-January:* January 3 – Aero Flight 311, a Douglas DC-3C, crashes near Kvevlax, Finland, killing all 25 people on board. An investigation finds that the captain and first officer both were exhausted for lack of sleep and drunk at the time of...
. About 500 of these weapons were manufactured between September 1960 and June 1962. The Mk 41 was progressively phased out of service from 1963
1963 in aviation
This is a list of aviation-related events from 1963:- Events :* Violating a 1959 requirement that all aircraft operating from the aircraft carrier Minas Gerais - which never has operated aircraft - belong to the Brazilian Air Force, the Brazilian Navy establishes an air group of its own for the...
in favor of the B53 nuclear bomb
B53 nuclear bomb
The Mk/B53 was a high-yield bunker buster thermonuclear weapon developed by the United States during the Cold War. Deployed on Strategic Air Command bombers, the B53, with a yield of , was the most powerful weapon in the U.S...
. The last B41s were retired in July 1976
1976 in aviation
This is a list of aviation-related events from 1976:-January:*January 1 - Middle East Airlines Flight 438, a Boeing 720, aircraft over Saudi Arabia when bomb exploded in the forward baggage compartment, aircraft destroyed killing 81.-March:...
.
Efficiency
During its operation, the Mk-41 was the most efficient known thermonuclear weapon in terms of yield to actual weight, with a 5.2 Megaton/ton ratio (based on a 25 Mt yield). Its blast yield was 25 to 50% that of the AN602 Tsar BombaTsar Bomba
Tsar Bomba is the nickname for the AN602 hydrogen bomb, the most powerful nuclear weapon ever detonated. It was also referred to as Kuz'kina Mat , in this usage meaning "something that has not been seen before"....
, which delivered a blast of 50 or 100 megatons of TNT, depending on its own configuration as a "clean" (lead encased) or dirty (uranium encased) bomb.