The CBU-100 Cluster Bomb (also called the Mk-20 Rockeye II) is an American cluster bomb

Cluster bomb

A cluster munition is a form of air-dropped or ground-launched explosive weapon that releases or ejects smaller sub-munitions. Commonly, this is a cluster bomb that ejects explosive bomblets that are designed to kill enemy personnel and destroy vehicles...

 which is employed primarily in an anti-tank mode. It weighs 490 pounds and carries 247 Mk 118 Mod 1 bomblets.

The anti-tank cluster bomb is an air-launched, conventional free-fall weapon. The Mk 20, CBU-99, and CBU-100 are used against armored vehicles.

Design

When the Mk 20 bomb cluster is released from the aircraft, the arming wires (primary and/or optional arming) are pulled sufficiently to arm the Mk 339 fuse

Fuse (explosives)

In an explosive, pyrotechnic device or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately...

 (and recently the FMU-140 fuse) and release the fins. The positive armed fin release arming wire frees the fin release band, and the movable fins snap open by spring-force. Functioning of the fuse initiates the linear shaped-charges in the dispenser that cut the dispenser case in half and disperse the bombs/bomblets. When the Mk 339 Mod 1 primary fuse arming wire is pulled, the fuse will function 1.2 seconds after the arming wire has been extracted. If the pilot selects the option time (4.0 seconds), both the primary and option arming wires must be pulled. If the pilot selects the option time and the primary arming wire is not pulled, the fuse will be a dud.

Deployments

The CBUs are delivered to the fleet as completely assembled all-up-rounds (AURs). Fuzes, suspension lugs, arming wires, wire extractors, and all other necessary components are installed.The information on configuration, functional description, and shipping and storage containers of the Mk 7 bomb dispenser and its associated components can be found in NAVAIR 11-5A-3, also information on decanning, preparation for use, and recanning procedures are found in NAVAIR 11-140-9. MK 20 MODS/CBU-99/CBU-100, BOMB CLUSTER CONFIGURATIONS The configurations of the Mk 20 Mods/ CBU-99/CBU-100 are listed in the table below. Mk 7 and Mods Bomb Dispenser The cargo section of the Mk 7 bomb dispenser is the main structure of the weapon and contains the bombs/bomblets. A nose fairing is attached to the forward end of the cargo section for aerodynamics and fuze installation. It has an observation window for viewing the safe/arm indicator on the installed fuze. The dispenser has two linear-shaped charges secured longitudinally inside the walls. When initiated, these shaped charges cut the dispenser in half, from front to rear, and the bombs/bomblets spread in free-fall trajectories.
To stabilize the weapon after release from the aircraft, a tail cone assembly is attached to the aft end of the cargo section. The tail cone assembly houses four, spring-actuated folding fins. The fins are spring-loaded to the open position and secured in the closed position during ground handling by a fin release-band assembly. The fin release band is secured in the closed position by a safety cotter pin and by the fin release wire. A yellow band around the forward end of the cargo section indicates the explosive content of the weapon. The Mk 7 Mods 3, 4, and 6 bomb dispensers have the Mk 339 Mod 1 fuze, which provides the pilot with in-flight selection of the fuze function time. The Mk 7 Mod 4 bomb dispenser differs from the Mk 7 Mod 3 by modifying the dispenser and giving interface capabilities with a wider range of military aircraft. The Mk 7Mod 6 bomb dispenser is the same as the Mk 7 Mod 3 except that the outside of the Mod 6 cargo section is coated with a thermal protective coating and has an additional yellow band around the forward end of the cargo section. The addition of the thermal coating increases the overall weight of the Mod 6 to 505 pounds

Each bomblet weighs 1.32 pounds (598.7 g) and has a 0.4 pounds (181.4 g) shaped-charge 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...

 of high explosives, which produces up to 250,000 psi (1.7 GPa) at the point of impact, allowing penetration of approximately 7.5 inches (190.5 mm) of armor. Rockeye is most efficiently used against area targets requiring penetration to kill. Fielded in 1968, the Rockeye dispenser is also used in the Gator air-delivered mine system

GATOR mine system

The GATOR mine system is a US system of air-dropped anti-tank and anti-personnel mines, that was developed in the 1980s to be compatible with existing cluster dispensers. It is used with two dispenser systems — the Navy 500 lb CBU-78/B and the Air Force 1,000 lb CBU-89/B...

. During Desert Storm US Marines

United States Marine Corps

The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...

 used the weapon extensively, dropping 15,828 of the 27,987 total Rockeyes against armor, artillery

Artillery

Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

, and personnel targets. The remainder were dropped by Air Force (5,346) and Navy (6,813) aircraft.

According to a test report conducted by the United States Navy's Weapon System Explosives Safety Review Board

Weapon System Safety

The United States Navy formed the Weapon System Explosives Safety Review Board in 1968 as a result of the tragic fire on the USS Forrestal . The subsequent investigation recommended an independent review process be established...

 (WSESRB) established in the wake of the tragic 1967 USS Forrestal fire

1967 USS Forrestal fire

The 1967 USS Forrestal fire was a devastating fire and series of chain-reaction explosions on 29 July 1967 that killed 134 sailors and injured 161 on the aircraft carrier , after an unusual electrical anomaly discharged a Zuni rocket on the flight deck...

, the cooking off

Cooking off

Cooking off refers to ammunition exploding prematurely due to heat in the surrounding environment. It can also refer to a technique used when throwing grenades to achieve a controlled, predictable explosion....

time for a Rockeye CBU is approximately 1 minute 13 seconds.