B61 nuclear bomb
Encyclopedia
The B61 nuclear bomb is the primary thermonuclear weapon in the U.S.
Enduring Stockpile
following the end of the Cold War
. It is an intermediate yield strategic
and tactical nuclear weapon
featuring a two-stage radiation implosion design.
The B61 is a variable yield
bomb (0.3 to 340 kiloton yield in various mods and settings) designed for carriage by high-speed aircraft. It has a streamlined casing capable of withstanding supersonic flight speeds. The weapon is 11 ft 8 in (3.58 m) long, with a diameter of about 13 in (33 cm). Basic weight is about 700 lb (320 kg), although the weights of individual weapons may vary depending on version and fuze
/retardation configuration.
The B61, known before 1968 as the TX-61, was designed in 1963. It was designed and built by the Los Alamos National Laboratory
in New Mexico
. It began from a program for a lightweight, streamlined weapon launched in 1961. Production engineering began in 1965, with full production beginning in 1968 following a series of development problems.
Total production of all versions was approximately 3,155, of which approximately 1,925 remain in service , and some 1,265 are considered to be operational. The warhead
has changed little over the years, although early versions have been upgraded to improve the safety features.
Nine versions (or 'Mods') of the B61 have been produced. Each shares the same 'physics package,' with different yield
options.
The newest variant is the B61 Mod 11, deployed in 1997, which is a ground-penetrating bunker buster
.
The B61 unguided bomb should not be confused with the MGM-1 Matador
cruise missile
, which originally was developed under the bomber designation B-61.
When the B61 was still classified, aircrew were not allowed to use the term "B61". Instead, it was referred to as a "shape", "silver bullet", or even "external delivery".
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The B61 has been deployed by a very wide variety of U.S. military aircraft
. Aircraft cleared for its use have included the B-58 Hustler
, B-1
, B-2
, B-52
, and FB-111 strategic
bomber aircraft; the F-100 Super Sabre
, F-104 Starfighter
, F-105 Thunderchief
, F-111
and F-4 Phantom II
fighter bombers; the A-4 Skyhawk
, A-6 Intruder
, and A-7 Corsair II
attack aircraft; the F-15 Eagle
and F-15E Strike Eagle
; British
, German
and Italian
Panavia Tornado
IDS aircraft. USAF, Belgian, Turkish Air Force
and Dutch
F-16 Fighting Falcon
can also carry the B61.
Since the F-22 Raptor
will not be used for the nuclear mission the B61 will instead be carried by the Lockheed Martin F-35 Lightning II.
Though exact numbers are hard to establish, research done by the Natural Resources Defense Council
suggests approximately 480 are deployed with United States Air Force
units in various European countries
.
, 180 tactical B61 nuclear bombs are deployed in Europe under the NATO nuclear sharing arrangement
.
The B61 is a variable yield
bomb designed for carriage by high-speed aircraft. It has a streamlined casing capable of withstanding supersonic flight speeds. The weapon is 11 ft 8 in (3.58 m) long, with a diameter of about 13 in (33 cm). Basic weight is about 700 lb (320 kg), although the weights of individual weapons may vary depending on version and fuze
/retardation configuration.
B61 administrative procedures performed by ground-based personnel are executed via an access panel located on the side of the bomb, which opens to reveal 9 dials, 2 sockets and a T-handle which manually triggers the "command disable" function. One of the sockets is a MC4142 "strike enable" plug which must be inserted in order to complete critical circuits in the safety/arming and firing mechanisms. The other socket is the PAL connector located in the top right hand corner of the arming panel, which has 23 pins marked with alphabetic letter codes. On at least one design of B61 warhead the destructive yield of the bomb is adjusted via a dial marked "Option", which allows 6 settings ranging from A to F. The B61 also features a "command disable" mechanism, which functions as follows: after entering the correct 3-digit numeric code it is then possible to turn a dial to "DI" and pull back a T-shaped handle which comes away in the user's hand. This action releases a spring-loaded firing pin
which fires the percussion cap
on an MC4246A thermal battery, powering it up. Electrical power from the thermal battery is sufficient to "fry" the internal circuitry of the bomb, destroying critical mechanisms without causing detonation. This makes the bomb incapable of being used. Any B61 which has had the command disable facility used must be returned to Pantex
for repair.
The newest variant is the B61 Mod 11, a hardened penetration bomb with a reinforced casing (according to some sources, containing depleted uranium
) and a delayed-action fuze
, allowing it to penetrate several metres into the ground before detonating, damaging fortified structures further underground. The Mod 11 weighs about 1,200 lb (540 kg). Developed from 1994, the Mod 11 went into service in 1997 replacing the older megaton
-yield B53 bomb, a limited number of which had been retained for anti-fortification use. About 50 Mod 11 bombs have been produced, their warheads converted from Mod 7 bombs. At present, the primary carrier for the B61 Mod 11 is the B-2 Spirit.
Most versions of the B61 are equipped with a parachute
retarder (currently a 24-ft (7.3 m) diameter nylon
/Kevlar
chute) to slow the weapon in its descent. This offers the aircraft a chance to escape the blast, or allows the weapon to survive impact with the ground in laydown mode. The B61 can be set for airburst, ground burst
, or laydown detonation, and can be released at speeds up to Mach 2 and altitudes as low as 50 feet (15 m).
The B61 is a variable yield, kiloton-range weapon called "Full Fuzing
Option"(FUFO) or "Dial-a-yield" by many service personnel. Tactical versions (Mods 3, 4, and 10) can be set to 0.3, 1.5, 5, 10, 60, 80, or 170 kiloton explosive yield (depending on version). The strategic version (B61 Mod 7) has four yield options, with a maximum of 340 kilotons. Sources conflict on the yield of the earth-penetrating Mod 11; the physics package or bomb core components of the Mod 11 are apparently unchanged from the earlier strategic Mod 7; however, the declassified 2001 Nuclear Posture Review states that the B-61-11 has only a single yield; some sources indicate 10 kt, others suggest the 340 kiloton maximum yield as the Mod-7.
The early Mods 0, 1, 2, and 5 have been retired (Mods 6, 8, and 9 were cancelled before production), and the Mod 10 has been moved to the inactive stockpile, leaving the Mods 3, 4, 7, and 11 as the only variants in active service.
The U.S. intended to refurbish the B61 bombs under its Life Extension Program with the intention that the weapons should remain operational until at least 2025.
However, the United States Congress ordered that this work be stopped pending reports from the National Academy of Sciences
and JASON defense advisory panel.
In May 2010 the National Nuclear Security Administration asked Congress for $40 million to redesign the bomb to enable the Lockheed Martin F-35 Lightning II to carry the weapon internally by 2017. This version is designated Mod.12. The four hundred B61-12 bombs will be used by both tactical aircraft (such as the F-35) and strategic aircraft (such as the B-2) and the Tail Subassembly (TSA) will give them Joint Direct Attack Munition
levels of accuracy, allowing the fifty kiloton warhead to have strategic effects from all carrying aircraft.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
Enduring Stockpile
Enduring Stockpile
The "Enduring Stockpile" is the United States's arsenal of nuclear weapons following the end of the Cold War.During the Cold War the United States produced over 70,000 nuclear weapons. By its end the U.S. stockpile was about 23,000 weapons of 26 different types...
following the end of 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...
. It is an intermediate yield strategic
Strategic nuclear weapon
A strategic nuclear weapon refers to a nuclear weapon which is designed to be used on targets as part of a strategic plan, such as nuclear missile bases, military command centers and heavily populated civilian areas such as large towns and cities....
and tactical nuclear weapon
Tactical nuclear weapon
A tactical nuclear weapon refers to a nuclear weapon which is designed to be used on a battlefield in military situations. This is as opposed to strategic nuclear weapons which are designed to menace large populations, to damage the enemy's ability to wage war, or for general deterrence...
featuring a two-stage radiation implosion design.
The B61 is a variable yield
Variable yield
Variable yield — or dial-a-yield — is an option available on most modern nuclear weapons. It allows the operator to specify a weapon's yield, or explosive power, allowing a single design to be used in different situations...
bomb (0.3 to 340 kiloton yield in various mods and settings) designed for carriage by high-speed aircraft. It has a streamlined casing capable of withstanding supersonic flight speeds. The weapon is 11 ft 8 in (3.58 m) long, with a diameter of about 13 in (33 cm). Basic weight is about 700 lb (320 kg), although the weights of individual weapons may vary depending on version and fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
/retardation configuration.
Development
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...
in New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
. It began from a program for a lightweight, streamlined weapon launched in 1961. Production engineering began in 1965, with full production beginning in 1968 following a series of development problems.
Total production of all versions was approximately 3,155, of which approximately 1,925 remain in service , and some 1,265 are considered to be operational. The warhead
Warhead
The term warhead refers to the explosive material and detonator that is delivered by a missile, rocket, or torpedo.- Etymology :During the early development of naval torpedoes, they could be equipped with an inert payload that was intended for use during training, test firing and exercises. This...
has changed little over the years, although early versions have been upgraded to improve the safety features.
Nine versions (or 'Mods') of the B61 have been produced. Each shares the same 'physics package,' with different 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...
options.
The newest variant is the B61 Mod 11, deployed in 1997, which is a ground-penetrating bunker buster
Nuclear bunker buster
Bunker-busting nuclear weapons, also known as earth-penetrating weapons , are a type of nuclear weapon designed to penetrate into soil, rock, or concrete to deliver a nuclear warhead to a target. These weapons would be used to destroy hardened, underground military bunkers buried deep in the ground...
.
The B61 unguided bomb should not be confused with the MGM-1 Matador
MGM-1 Matador
The Martin MGM-1 Matador was the first operational surface-to-surface cruise missile built by the United States. It was similar in concept to the German V-1, but the Matador included a radio link that allowed in-flight course corrections. This allowed accuracy to be maintained over greatly extended...
cruise missile
Cruise missile
A cruise missile is a guided missile that carries an explosive payload and is propelled, usually by a jet engine, towards a land-based or sea-based target. Cruise missiles are designed to deliver a large warhead over long distances with high accuracy...
, which originally was developed under the bomber designation B-61.
When the B61 was still classified, aircrew were not allowed to use the term "B61". Instead, it was referred to as a "shape", "silver bullet", or even "external delivery".
Deployment
Military aircraft
A military aircraft is any fixed-wing or rotary-wing aircraft that is operated by a legal or insurrectionary armed service of any type. Military aircraft can be either combat or non-combat:...
. Aircraft cleared for its use have included the B-58 Hustler
B-58 Hustler
The Convair B-58 Hustler was the first operational supersonic jet bomber capable of Mach 2 flight. The aircraft was designed by Convair engineer Robert H. Widmer and developed for the United States Air Force for service in the Strategic Air Command during the 1960s...
, B-1
B-1 Lancer
The Rockwell B-1 LancerThe name "Lancer" is only applied to the B-1B version, after the program was revived. is a four-engine variable-sweep wing strategic bomber used by the United States Air Force...
, B-2
B-2 Spirit
The Northrop Grumman B-2 Spirit is an American heavy bomber with low observable stealth technology designed to penetrate dense anti-aircraft defenses and deploy both conventional and nuclear weapons. The bomber has a crew of two and can drop up to eighty -class JDAM GPS-guided bombs, or sixteen ...
, B-52
B-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 FB-111 strategic
Strategic bomber
A strategic bomber is a heavy bomber aircraft designed to drop large amounts of ordnance onto a distant target for the purposes of debilitating an enemy's capacity to wage war. Unlike tactical bombers, which are used in the battle zone to attack troops and military equipment, strategic bombers are...
bomber aircraft; the F-100 Super Sabre
F-100 Super Sabre
The North American F-100 Super Sabre was a supersonic jet fighter aircraft that served with the United States Air Force from 1954 to 1971 and with the Air National Guard until 1979. The first of the Century Series collection of USAF jet fighters, it was the first USAF fighter capable of...
, F-104 Starfighter
F-104 Starfighter
The Lockheed F-104 Starfighter is a single-engine, high-performance, supersonic interceptor aircraft originally developed for the United States Air Force by Lockheed. One of the Century Series of aircraft, it served with the USAF from 1958 until 1969, and continued with Air National Guard units...
, F-105 Thunderchief
F-105 Thunderchief
The Republic F-105 Thunderchief, was a supersonic fighter-bomber used by the United States Air Force. The Mach 2 capable F-105 conducted the majority of strike bombing missions during the early years of the Vietnam War; it has the dubious distinction of being the only US aircraft to have been...
, F-111
General Dynamics F-111
The General Dynamics F-111 "Aardvark" was a medium-range interdictor and tactical strike aircraft that also filled the roles of strategic bomber, reconnaissance, and electronic warfare in its various versions. Developed in the 1960s by General Dynamics, it first entered service in 1967 with the...
and F-4 Phantom II
F-4 Phantom II
The McDonnell Douglas F-4 Phantom II is a tandem two-seat, twin-engined, all-weather, long-range supersonic jet interceptor fighter/fighter-bomber originally developed for the United States Navy by McDonnell Aircraft. It first entered service in 1960 with the U.S. Navy. Proving highly adaptable,...
fighter bombers; the A-4 Skyhawk
A-4 Skyhawk
The Douglas A-4 Skyhawk is a carrier-capable ground-attack aircraft designed for the United States Navy and United States Marine Corps. The delta winged, single-engined Skyhawk was designed and produced by Douglas Aircraft Company, and later McDonnell Douglas. It was originally designated the A4D...
, A-6 Intruder
A-6 Intruder
The Grumman A-6 Intruder was an American, twin jet-engine, mid-wing attack aircraft built by Grumman Aerospace. In service with the U.S. Navy and U.S. Marine Corps between 1963 and 1997, the Intruder was designed as an all-weather medium attack aircraft to replace the piston-engined A-1 Skyraider...
, and A-7 Corsair II
A-7 Corsair II
The Ling-Temco-Vought A-7 Corsair II is a carrier-based subsonic light attack aircraft introduced to replace the United States Navy's Douglas A-4 Skyhawk, initially entering service during the Vietnam War...
attack aircraft; the F-15 Eagle
F-15 Eagle
The McDonnell Douglas F-15 Eagle is a twin-engine, all-weather tactical fighter designed by McDonnell Douglas to gain and maintain air superiority in aerial combat. It is considered among the most successful modern fighters with over 100 aerial combat victories with no losses in dogfights...
and F-15E Strike Eagle
F-15E Strike Eagle
The McDonnell Douglas F-15E Strike Eagle is an all-weather multirole fighter, derived from the McDonnell Douglas F-15 Eagle. The F-15E was designed in the 1980s for long-range, high speed interdiction without relying on escort or electronic warfare aircraft. United States Air Force F-15E Strike...
; British
Royal Air Force
The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...
, German
Luftwaffe
Luftwaffe is a generic German term for an air force. It is also the official name for two of the four historic German air forces, the Wehrmacht air arm founded in 1935 and disbanded in 1946; and the current Bundeswehr air arm founded in 1956....
and Italian
Aeronautica Militare
The Italian Air Force is the air force of the Italian Republic. It has held a prominent role in modern Italian military history...
Panavia Tornado
Panavia Tornado
The Panavia Tornado is a family of twin-engine, variable-sweep wing combat aircraft, which was jointly developed and manufactured by the United Kingdom, West Germany and Italy...
IDS aircraft. USAF, Belgian, Turkish Air Force
Turkish Air Force
The Turkish Air Force is the aerial warfare service branch of the Turkish Armed Forces. It ranks 3rd in NATO in terms of fleet size behind the USAF and Royal Air Force with a current inventory of 798 aircraft .-Initial stages:...
and Dutch
Royal Netherlands Air Force
The Royal Netherlands Air Force , Dutch Koninklijke Luchtmacht , is the military aviation branch of the Netherlands Armed Forces. Its ancestor, the Luchtvaartafdeling of the Dutch Army was founded on 1 July 1913, with four pilots...
F-16 Fighting Falcon
F-16 Fighting Falcon
The General Dynamics F-16 Fighting Falcon is a multirole jet fighter aircraft originally developed by General Dynamics for the United States Air Force . Designed as an air superiority day fighter, it evolved into a successful all-weather multirole aircraft. Over 4,400 aircraft have been built since...
can also carry the B61.
Since the F-22 Raptor
F-22 Raptor
The Lockheed Martin/Boeing F-22 Raptor is a single-seat, twin-engine fifth-generation supermaneuverable fighter aircraft that uses stealth technology. It was designed primarily as an air superiority fighter, but has additional capabilities that include ground attack, electronic warfare, and signals...
will not be used for the nuclear mission the B61 will instead be carried by the Lockheed Martin F-35 Lightning II.
Though exact numbers are hard to establish, research done by the Natural Resources Defense Council
Natural Resources Defense Council
The Natural Resources Defense Council is a New York City-based, non-profit, non-partisan international environmental advocacy group, with offices in Washington DC, San Francisco, Los Angeles, Chicago, and Beijing...
suggests approximately 480 are deployed with 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...
units in various European countries
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
.
, 180 tactical B61 nuclear bombs are deployed in Europe under the NATO nuclear sharing arrangement
Nuclear sharing
Nuclear sharing is a concept in NATO's policy of nuclear deterrence, which involves member countries without nuclear weapons of their own in the planning for the use of nuclear weapons by NATO, and in particular provides for the armed forces of these countries to be involved in delivering these...
.
Design
Variable yield
Variable yield — or dial-a-yield — is an option available on most modern nuclear weapons. It allows the operator to specify a weapon's yield, or explosive power, allowing a single design to be used in different situations...
bomb designed for carriage by high-speed aircraft. It has a streamlined casing capable of withstanding supersonic flight speeds. The weapon is 11 ft 8 in (3.58 m) long, with a diameter of about 13 in (33 cm). Basic weight is about 700 lb (320 kg), although the weights of individual weapons may vary depending on version and fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
/retardation configuration.
B61 administrative procedures performed by ground-based personnel are executed via an access panel located on the side of the bomb, which opens to reveal 9 dials, 2 sockets and a T-handle which manually triggers the "command disable" function. One of the sockets is a MC4142 "strike enable" plug which must be inserted in order to complete critical circuits in the safety/arming and firing mechanisms. The other socket is the PAL connector located in the top right hand corner of the arming panel, which has 23 pins marked with alphabetic letter codes. On at least one design of B61 warhead the destructive yield of the bomb is adjusted via a dial marked "Option", which allows 6 settings ranging from A to F. The B61 also features a "command disable" mechanism, which functions as follows: after entering the correct 3-digit numeric code it is then possible to turn a dial to "DI" and pull back a T-shaped handle which comes away in the user's hand. This action releases a spring-loaded firing pin
Firing pin
A firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...
which fires the percussion cap
Percussion cap
The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...
on an MC4246A thermal battery, powering it up. Electrical power from the thermal battery is sufficient to "fry" the internal circuitry of the bomb, destroying critical mechanisms without causing detonation. This makes the bomb incapable of being used. Any B61 which has had the command disable facility used must be returned to Pantex
Pantex
The Pantex plant is America's only nuclear weapons assembly and disassembly facility and is charged with maintaining the safety, security and reliability of the nation’s nuclear weapons stockpile. The facility is located on a 16,000 acre site 17 miles northeast of Amarillo, in Carson County,...
for repair.
The newest variant is the B61 Mod 11, a hardened penetration bomb with a reinforced casing (according to some sources, containing depleted uranium
Depleted uranium
Depleted uranium is uranium with a lower content of the fissile isotope U-235 than natural uranium . Uses of DU take advantage of its very high density of 19.1 g/cm3...
) and a delayed-action fuze
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
, allowing it to penetrate several metres into the ground before detonating, damaging fortified structures further underground. The Mod 11 weighs about 1,200 lb (540 kg). Developed from 1994, the Mod 11 went into service in 1997 replacing the older megaton
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...
-yield B53 bomb, a limited number of which had been retained for anti-fortification use. About 50 Mod 11 bombs have been produced, their warheads converted from Mod 7 bombs. At present, the primary carrier for the B61 Mod 11 is the B-2 Spirit.
Most versions of the B61 are equipped with a parachute
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...
retarder (currently a 24-ft (7.3 m) diameter nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
/Kevlar
Kevlar
Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...
chute) to slow the weapon in its descent. This offers the aircraft a chance to escape the blast, or allows the weapon to survive impact with the ground in laydown mode. The B61 can be set for airburst, ground burst
Ground burst
A groundburst is the detonation of an explosive device such as an artillery shell, nuclear weapon or air-dropped bomb that explodes upon hitting the ground...
, or laydown detonation, and can be released at speeds up to Mach 2 and altitudes as low as 50 feet (15 m).
The B61 is a variable yield, kiloton-range weapon called "Full Fuzing
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
Option"(FUFO) or "Dial-a-yield" by many service personnel. Tactical versions (Mods 3, 4, and 10) can be set to 0.3, 1.5, 5, 10, 60, 80, or 170 kiloton explosive yield (depending on version). The strategic version (B61 Mod 7) has four yield options, with a maximum of 340 kilotons. Sources conflict on the yield of the earth-penetrating Mod 11; the physics package or bomb core components of the Mod 11 are apparently unchanged from the earlier strategic Mod 7; however, the declassified 2001 Nuclear Posture Review states that the B-61-11 has only a single yield; some sources indicate 10 kt, others suggest the 340 kiloton maximum yield as the Mod-7.
The early Mods 0, 1, 2, and 5 have been retired (Mods 6, 8, and 9 were cancelled before production), and the Mod 10 has been moved to the inactive stockpile, leaving the Mods 3, 4, 7, and 11 as the only variants in active service.
The U.S. intended to refurbish the B61 bombs under its Life Extension Program with the intention that the weapons should remain operational until at least 2025.
However, the United States Congress ordered that this work be stopped pending reports from the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
and JASON defense advisory panel.
In May 2010 the National Nuclear Security Administration asked Congress for $40 million to redesign the bomb to enable the Lockheed Martin F-35 Lightning II to carry the weapon internally by 2017. This version is designated Mod.12. The four hundred B61-12 bombs will be used by both tactical aircraft (such as the F-35) and strategic aircraft (such as the B-2) and the Tail Subassembly (TSA) will give them Joint Direct Attack Munition
Joint Direct Attack Munition
The Joint Direct Attack Munition is a guidance kit that converts unguided bombs, or "dumb bombs" into all-weather "smart" munitions. JDAM-equipped bombs are guided by an integrated inertial guidance system coupled to a Global Positioning System receiver, giving them a published range of up to...
levels of accuracy, allowing the fifty kiloton warhead to have strategic effects from all carrying aircraft.
See also
- List of nuclear weapons
- B61 FamilyB61 FamilyThe B61 Family is a series of thermonuclear bombs and thermonuclear warheads based on the B61 nuclear bomb.-Initial development:The B61 bomb was developed by Los Alamos Scientific Laboratory starting in 1960...
- Weapon Storage Security System (WS3)
External links
- "Developing and Producing the B-61", official AEC film
- B61 information at Carey Sublette's NuclearWeaponArchive.org
- B61 information at GlobalSecurity.org
- B61-11 Concerns and Background from the Los Alamos Study Group, an anti-nuclear weapons organization
- Low-Yield Earth-Penetrating Nuclear Weapons by Robert W. Nelson, Federation of American Scientists, January/February 2001, Volume 54, Number 1
- B61 Nuclear Bomb Preflight Controller Unit