The B61 Family is a series of nuclear weapons based on the

B61 nuclear bomb The B61 nuclear bomb is the primary thermonuclear gravity bomb in the United States Enduring Stockpile following the end of the Cold War. It is a low to intermediate-yield strategic and tactical nuclear weapon featuring a two-stage radiation im ...

B61 nuclear bomb

Initial development

The B61 bomb was developed by Los Alamos Scientific Laboratory (LASL; now

Los Alamos National Laboratory Los Alamos National Laboratory (often shortened as Los Alamos and LANL) is one of the sixteen research and development laboratories of the United States Department of Energy (DOE), located a short distance northwest of Santa Fe, New Mexico, ...

) starting in 1960. The intent was to develop an aircraft bomb which was high yield (over 100

kiloton TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...

s) and yet was small enough and had low enough drag to carry under the wing of a fighter or fighter-bomber type aircraft. One major feature was Full Fuzing Option, allowing various air and ground burst usage options; free fall air burst, parachute retarded air burst, free fall

ground burst A ground burst is the detonation of an explosive device such as an artillery shell, nuclear weapon or air-dropped bomb that explodes at ground level. These weapons are set off by fuses that are activated when the weapon strikes the ground or som ...

, parachute retarded ground burst, and

laydown Laydown delivery is a mode of delivery found in some nuclear gravity bombs: the bomb's descent to the target is slowed by parachute so that it lands on the ground without detonating. The bomb then detonates by timer some time later. Laydown deliver ...

delivery. The B61 project started in 1960 with a study contract analyzing the potential of such a weapon. The official development program was funded in 1961, and the weapon was designated TX-61 (Test/Experimental) in 1963. The first TX-61 free fall ballistic test was held at

Tonopah Test Range The Tonopah Test Range (TTR, also designated as Area 52) is a highly classified, restricted military installation of the United States Department of Defense, and United States Department of Energy ( nuclear stockpile stewardship) located about ...

on August 20, 1963. The first War Reserve B61-0 was accepted by the AEC on December 21, 1966. The original models of B61 used PBX 9404, an HMX based

plastic bonded explosive Polymer-bonded explosives, also called PBX or plastic-bonded explosives, are explosive materials in which explosive powder is bound together in a matrix using small quantities (typically 5–10% by weight) of a synthetic polymer. PBXs are normally ...

to implode the fissile material in the primary stage. Newer models use

TATB TATB, triaminotrinitrobenzene or 2,4,6-triamino-1,3,5-trinitrobenzene is an aromatic explosive, based on the basic six-carbon benzene ring structure with three nitro functional groups (NO2) and three amine (NH2) groups attached, alternating aroun ...

based

PBX 9502 Polymer-bonded explosives, also called PBX or plastic-bonded explosives, are explosive materials in which explosive powder is bound together in a matrix using small quantities (typically 5–10% by weight) of a synthetic polymer. PBXs are normally ...

, which is an

insensitive high explosive Insensitive munitions are munitions that are designed to withstand stimuli representative of severe but credible accidents. The current range of stimuli are shock (from bullets, fragments and shaped charge jets), heat (from fires or adjacent the ...

(IHE) and will resist detonation in adverse conditions such as fire, shock and impact.

Design

The overall B61 bomb is in diameter and long, and weighs approximately across most mods. The

nuclear device A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bomb ...

within the outer B61 envelope is probably the same overall dimensions and weight as the W80 warhead, which is in diameter, long and weighs about .

Warheads

W69 The W69 was a United States nuclear warhead used in the AGM-69 SRAM ( Short-Range Attack Missile). It was designed in the early 1970s and entered the U.S. stockpile in 1972. The weapon was retired between 1991 and 1994. About 1,500 warheads were ...

The W69 missile

warhead A warhead is the forward section of a device that contains the explosive agent or toxic (biological, chemical, or nuclear) material that is delivered by a missile, rocket, torpedo, or bomb. Classification Types of warheads include: * Expl ...

was produced in the early 1970s for use in the

AGM-69 SRAM The Boeing AGM-69 SRAM (Short-Range Attack Missile) was a nuclear air-to-surface missile. It had a range of up to , and was intended to allow US Air Force strategic bombers to penetrate Soviet airspace by neutralizing surface-to-air missile de ...

Short Range Attack Missile The Boeing AGM-69 SRAM (Short-Range Attack Missile) was a nuclear air-to-surface missile. It had a range of up to , and was intended to allow US Air Force strategic bombers to penetrate Soviet airspace by neutralizing surface-to-air missile de ...

. The W69 was in diameter and long, weighed 275 pounds, and had a yield of 170-200 kilotons. 1,500 W69 warheads were produced.

W73

The W73 missile warhead was designed for the

AGM-53 Condor In 1962, the U.S. Navy issued a requirement for a long-range high-precision air-to-surface missile. The missile, named the AGM-53A Condor, was to use a television guidance system with a data link to the launching aircraft similar to the system of ...

air to ground missile An air-to-surface missile (ASM) or air-to-ground missile (AGM) is a missile designed to be launched from military aircraft at targets on land or sea. There are also unpowered guided glide bombs not considered missiles. The two most common p ...

. Other than being described as a derivative of the B61, details of the W73 design are poorly documented. Both the W73 and the Condor missile were cancelled and never entered service.

W80

Two versions of the W80 cruise missile warhead were designed and deployed. Both are the same basic size and shape and weight: 11.8 inches in diameter, 31.4 inches long, and weight of 290 pounds.

W80-0

The BGM-109 Tomahawk TLAM-N cruise missile was equipped with a W80-0 warhead. The W80-0 used

supergrade plutonium Plutonium-239 (239Pu or Pu-239) is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 is also used for that purpose. Plutonium-239 is also one of the three main ...

with less inherent radioactivity, due to missile storage in close proximity to submarine crew. The weapon lacks the metal attachment points featured on the Mod 1 variant and instead features a plastic guard of some sort. The W80-0 has a

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. For example, the Mod-10 ...

of 5 or 150 kilotons. 367 W80-0 warheads were produced.

W80-1

The

AGM-86 ALCM The AGM-86 ALCM is an American subsonic air-launched cruise missile (ALCM) built by Boeing and operated by the United States Air Force. This missile was developed to increase the effectiveness and survivability of the Boeing B-52H Stratofortre ...

and ACM cruise missiles used the W80-1 variant warhead. It has a yield of 5 or 150 kilotons. 1,750 W80-1 warheads were produced.

W81 The W81 was a planned American warhead to be mounted on the RIM-67 Standard, SM-2 surface-to-air missile used by the United States Navy. The W81 was believed to be derived from the B61 nuclear bomb which forms the backbone of the current US nuclea ...

The W81 missile warhead was designed for use on the SM-2 missile. An enhanced radiation version was proposed, but the final version was fission-only. Detailed dimensions and weight are unknown. Yields are described as 2-4 kilotons. The W81 was cancelled and never entered service.

W84

The W84 is a

LLNL Lawrence Livermore National Laboratory (LLNL) is a federal research facility in Livermore, California, United States. The lab was originally established as the University of California Radiation Laboratory, Livermore Branch in 1952 in response ...

design based on the B61, used in the Ground Launched Cruise Missile. It is slightly larger (13 inches diameter, 34 inches long) and heavier (388 pounds) than the otherwise similar W80 warheads, possibly to make it safer for ground handling in the field. Between 300 and 350 W84 warheads were produced. They remain in US inactive inventory.

W85

Used on the

Pershing II The Pershing II Weapon System was a solid-fueled two-stage medium-range ballistic missile designed and built by Martin Marietta to replace the Pershing 1a Field Artillery Missile System as the United States Army's primary nuclear-capable thea ...

IRBM missile, the W85 was a cylinder in diameter and long. It had a variable yield from 5 to 80 kilotons. 120 W85 warheads were produced. They were recycled into B61 Mod 10 bombs after Pershing II was scrapped.

W86 The W86 was an American earth-penetrating ("bunker buster") nuclear warhead, intended for use on the Pershing II intermediate-range ballistic missile (IRBM). The W86 design was canceled in September 1980 when the Pershing II missile mission shift ...

Some sources have described the W86 as being B61 derived,New bomb, no mission
Greg Mell
''Bulletin of the Atomic Scientists''
May/June 1997, pp. 28 but other sources have described the W86 as being in diameter, substantially smaller than the B61.

Gallery

Image:B-61 bomb (DOE).jpg, B61 nuclear bomb, assembled and disassembled. Image:B61internals.png, Internal nuclear components of the B61 bomb. Image:W80 nuclear warhead.jpg, A W80-1 ALCM cruise missile warhead Image:W80-0clr.jpg, A W80-0

SLCM A submarine-launched cruise missile (SLCM) is a cruise missile that is launched from a submarine (especially a SSG or SSGN). Current versions are typically standoff weapons known as land-attack cruise missiles (LACMs), which are used to attack ...

cruise missile warhead Image:W85 warhead (DOE).jpg, A DOE drawing of the W85 Pershing-II IRBM warhead.

References

B61
a
nuclearweaponarchive.org
{{Current U.S. nuclear weapons Nuclear weapons