The antitank bomb cluster is an air-launched, conventional free-fall weapon. The Mk 20, CBU-99, and CBU-100 are used against armored vehicles. 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 Mk 20 bomb cluster weighs 490 pounds and contains 247 Mk 118 antitank bombs. 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.

The purpose of the Mk 339 Mod 1 mechanical time fuze is to initiate the linear-shaped charges located in the cargo section walls. 1-35

The antitank bomblets Mk 118 Mod 0 consists of a Mk 1 Mod 0 fuzing system, a shaped-charge warhead, and fixed stabilizing fins. It is loaded in the Mk 20 Mod 3 bomb clusters only. In the antitank bomb Mk 118 Mod 1, the fuzing system is a Mk 1 Mod 1, and the bombs are loaded in the Mk 20 Mod 6 bomb clusters only.

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 fuze 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 fuze initiates the linear-shaped charges in the dispenser; that cut the dispenser case in half, and disperses the bombs/bomblets. When the Mk 339 Mod 1 primary fuze arming wire is pulled, the fuze 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 fuze will be a dud.

When the Mk 118 bomb separates from the dispenser case, the base fuze-arming vane rotates and the fuze is armed. If the bomb strikes a hard target, such as concrete or armor, the electric detonator ignites the shaped-charge warhead immediately. If the bomb strikes a soft target, such as earth or sandbag, the bomb penetrates the targets until deceleration lets the inertia firing pin strike and initiate the stab detonator, causing warhead denotation.

The Mk 427 Mod 0 and Mod 1 shipping and storage containers encase one fully assembled Mk 20 bomb cluster. The reusable containers consist of metal upper and lower shell assemblies that are secured with either 16 quick-release latches (Mod 0) or 18 "T" latches (Mod 1). A rubber gasket provides an environmental seal when the upper and lower shells are mated. External framemembers are welded to each half of the container so the containers can be stacked six high and provide the necessary fittings for ground-handling equipment. The reusable weapon cradle Mk 18 Mod 0 is used to ship and store two fully assembled Mk 20 bomb clusters. The cradle consists of plastic upper and lower shell assemblies, which are shock-mounted on a metal cradle assembly. The weapon cradle has forklift guides, lifting eyes; hand truck brackets, and lifts devices to permit the use of handling equipment. Four supports are provided on each cradle to aid in stacking the cradle assemblies.

CBU-78/B and B/B GATOR

The CBU-78/B and B/B GATOR weapon is delivered as an all-up-round (AUR) (fig. 1-33). The weapon consists of the SUU-58/B dispenser, Mk 339 Mod 1 fuze, Kit Modification Unit KMU-428/B, and 60 mines (45 BLU-91/B and 15 BLU-92/B). The fuze initiation time is preset and is activated upon weapon release from the aircraft. Fuze time settings are primary mode (1.2 seconds) and option mode (4.0 seconds). The KMU-428/B adapts the mines to the dispenser; it also provides mine activation/self-destruct time selection.

The SUU-58/B consists of a cargo section with a nose fairing assembly attached, a tail cone assembly, and fuze arming wires with extractors. There are two observation windows—one for viewing the safe/arm indicator and the other to observe the fuze time-setting dials. The cargo section houses the BLU-91/B and BLU-92/B mines. The tactical weapons have two yellow bands around the nose cone fairing.