Nuclear weapon

A nuclear weapon is a weapon which derives its destructive force from the nuclear reactions of nuclear fission and/or fusion. As a result, even a nuclear weapon with a small yield is significantly more powerful than the largest conventional explosives, and a single weapon is capable of destroying an entire city.

Weapons delivery

The term strategic nuclear weapons is generally used to denote large weapons which would be used to destroy large targets, such as cities. Tactical nuclear weapons are smaller weapons used to destroy specific military, communications, or infrastructure targets. By modern standards, the bombs that destroyed Hiroshima and Nagasaki in 1945 may perhaps be considered tactical weapons (with yields between 13 and 22 kilotons (54 to 92 TJ)), although modern tactical weapons are considerably lighter and more compact.

Related Topics:
Hiroshima and Nagasaki - 1945

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Basic methods of delivery for nuclear weapons are:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Gravity bombs

No nuclear weapon qualifies as a "wooden bomb" — US military slang for a bomb that is trouble-free, maintenance-free, and danger-free under all conditions. Gravity bombs are designed to be dropped from planes, which requires that the weapon can withstand vibrations and changes in air temperature and pressure during the course of a flight. Early weapons often had a removable core for safety, installed by the air crew during flight. They had to meet safety conditions, to prevent accidental detonation or dropping. A variety of types also had to have a fuse to initiate detonation. US nuclear weapons that met these criteria are designated by the letter "B" followed, without a hyphen, by the sequential number of the "physics package" it contains. The "B61", for example, was the primary bomb in the US arsenal for decades.

Related Topics:
Physics package - B61

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Various air-dropping techniques exist, including toss bombing, parachute-retarded delivery, and laydown modes, intended to give the dropping aircraft time to escape the ensuing blast.

Related Topics:
Toss bombing - Parachute - Laydown

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The first gravity nuclear bombs could only be carried by the B-29 Superfortress. The next generation of weapons were still so big and heavy that they could only be carried by bombers such as the B-52 Stratofortress and V bombers, but by the mid-1950s smaller weapons had been developed that could be carried and deployed by simple fighter-bombers.

Related Topics:
B-29 Superfortress - Bomber - B-52 Stratofortress - V bomber - 1950s - Fighter-bomber

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Ballistic missile warheads

Missiles using a ballistic trajectory usually deliver a warhead over the horizon. Some ballistic missiles may have a range of tens to hundreds of kilometers, while larger ICBMs or SLBMs may use suborbital or partial orbital trajectories for intercontinental range. Early ballistic missiles carried a single warhead, often of megaton-range yield. Due to accuracy considerations, this kind of high yield was considered necessary in order to ensure a particular target's destruction.

Related Topics:
Missile - Ballistic - Warhead - Ballistic missile - ICBM - SLBM - Megaton

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Since the 1970s modern ballistic weapons have seen the development of far more accurate targeting technologies. This set the stage for the use of "Multiple Independently-targettable Re-entry Vehicles" (MIRVs) with up to a dozen independently targetable warheads, usually in the hundreds-of-kilotons-range yield, on one ballistic platform. This allows for a number of advantages over a missile with a single warhead. It allows a single missile to strike a variety of apparently unrelated targets, or it can inflict maximum damage on a single target by encircling the target with warheads, as well as providing such an onslaught of warheads in conjunction with other tactical weapons that any form of defensive technology would be rendered useless. Soviet plans in the '70s were said to entail dropping one MIRV based warhead every ninety seconds to three minutes on major US targets for up to an hour.

Related Topics:
1970s - MIRV - Warhead - Kiloton

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Missile warheads in the American arsenal are indicated by the letter "W"; for example, the W61 missile warhead would have the same physics package as the B61 gravity bomb described above, but it would have different environmental requirements, and different safety requirements since it would not be crew-tended after launch and remain atop a missile for a great length of time.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Cruise missile warheads

A jet engine or rocket-propelled missile that flies at low altitude using an automated guidance system (usually inertial navigation, sometimes supplemented by either GPS or mid-course updates from friendly forces) to make them harder to detect or intercept could carry a nuclear warhead. Cruise missiles have shorter range and smaller payloads than ballistic missiles, so their warheads are smaller and less powerful. Rather than multiple warheads, which would have to be dropped separately as though the cruise missile were itself a bomber, each cruise missile carries its own warhead, although the B-1 Lancer bomber was designed to carry in its bomb-bay a rotating fixture for cruise missiles which resembles a set of MIRV warheads. Conventional cruise missiles sometimes use cluster munition payloads, though. Cruise missiles may be launched from mobile launchers on the ground, from naval ships, or from aircraft.

Related Topics:
Jet engine - Rocket - Missile - Inertial navigation - GPS - Mid-course updates - Cruise missile - B-1 Lancer - Cluster munition

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

There is no letter change in the US arsenal to distinguish the warheads of cruise missiles from those for ballistic missiles.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Other delivery systems

Other potential delivery methods include artillery shells, mines such as Blue Peacock, and nuclear depth charges and torpedoes for anti-submarine warfare. An atomic mortar was also tested. In the 1950s the U.S. developed small nuclear warheads for air defense use, such as the Nike Hercules. Further developments of this concept, some with much larger warheads, showed promise as anti-ballistic missiles. Most of the United States' nuclear air-defense weapons were out of service by the end of the 1960s, and nuclear depth bombs were taken out of service by 1990. However, the USSR (and later Russia) continues to maintain anti-ballistic missiles with nuclear warheads. Small, two-man portable tactical weapons (erroneously referred to as suitcase bombs), such as the Special Atomic Demolition Munition, have been developed, although the difficulty of balancing yield and portability limits their military utility.

Related Topics:
Artillery - Blue Peacock - Depth charge - Anti-submarine warfare - 1950s - Nike Hercules - Anti-ballistic missiles - 1960s - 1990 - Suitcase bomb - Special Atomic Demolition Munition

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

See list of nuclear weapons for a list of the designs of nuclear weapons fielded by the various nuclear powers.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~