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Monday, January 09, 2017

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Weapons of the War in Afghanistan: Cluster Bombs

Weapons of the War in Afghanistan
Photo By: Lance Cpl. Graham J. Benson

In the world of war, weapons and technology are ever changing, each war is characterized by the weapons and tactics used to fight it. As new environments and enemies are encountered, the parties to those wars develop new - more effective tactics, technologies, and weapons to counter and defeat their adversaries. The ingenuity seen in war has existed since (and most certainly before) the first wars of recorded history and continue to this very day. 

Keeping with that theory, let’s take a look at the weapons that have characterized the wars and conflicts that the United States has been a party to over the course of it’s history. During the course of this series, I aim to breakdown the weapons used in each conflict by their classification, and to which party they were employed by. Having served in combat operations in Afghanistan’s Korengal Valley, I would like to start our series with the War in Afghanistan. 

For our twentieth installment let's take a look at the some of the common cluster bombs/munitions used in the War in Afghanistan.


Part I: The United States

CBU-100 / CBU-99 / Mk 20
Photo By: PH3 Mac M. Thurston, USN
The CBU-100 Cluster Bomb (also called the Mk-20 Rockeye II) is an American cluster bomb which is employed primarily in an anti-tank mode. It weighs 490 pounds and carries 247 Mk 118 Mod 1 bomblets. The Mk 20, CBU-99, and CBU-100 are used against armored vehicles.

The anti-tank cluster bomb is an air-launched, conventional free-fall weapon.

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 recently the FMU-140 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 which cut the dispenser case in half and disperse the bombs/bomblets. When the Mk 339 Mod 1 primary fuse 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 fail to function and be a dud.

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 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 7 Mod 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 (600 g) and has a 0.4-pound (180 g) shaped-charge warhead 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 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. During Desert Storm US Marines used the weapon extensively, dropping 15,828 of the 27,987 total Rockeyes against armor, artillery, 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 (WSESRB) established in the wake of the 1967 USS Forrestal fire, the cooking off time for a Rockeye CBU is approximately 1 minute 13 seconds.

The CBU-87 Combined Effects Munition is a cluster bomb used by the United States Air Force, developed by Aerojet General/Honeywell and introduced in 1986 to replace the earlier cluster bombs used in the Vietnam War. CBU stands for Cluster Bomb Unit.

The basic CBU-87 is designed to be dropped from an aircraft at any altitude and any air speed. It is a free-falling bomb and relies on the aircraft to aim it before it drops; once dropped it needs no further instruction, as opposed to guided munitions or smart bombs. The bomb can be dropped by a variety of modern-day aircraft. It is 7 feet 7 inches (2.31 meters) long, has a diameter of 16 inches (41 centimeters), and weighs roughly 950 pounds (430 kg). The price is US$14,000 per bomb

Each CBU-87 consists of an SUU-65B canister, a fuze with 12 time delay options and 202 submunitions (or bomblets) designated BLU-97/B Combined Effects Bomb. Each bomblet is a yellow cylinder with a length of 20 centimeters and a diameter of 6 centimeters. The BLU-97/B bomblets are designed to be used against armour, personnel and softskin targets and consist of a shaped charge, a scored steel fragmentation case and a zirconium ring for incendiary effects. The CBU-87 can also be equipped with an optional FZU-39/B proximity sensor with 10 altitude selections.

When dropped from an aircraft, the bomb starts spinning. There are 6 speeds that can adjust the bomb's rate of spin. After it drops to a certain altitude, the canister breaks open and the submunitions are released. Each bomblet has a ring of tabs at the tail end, these orient the bomblet and deploy an inflatable decelerator to decrease the falling speed of the bomblet. When the submunitions hit the ground, they will cover a large area and the CBU-87 can be adjusted so it can cover a smaller or wider area. Depending on the rate of spin and the altitude at which the canister opens, it can cover an area between 20x20 meters (low release altitude and a slow rate of spin) to 120x240 meters (high release altitude and a high rate of spin).

Manufacturers and the Department of Defense have claimed that the failure rate for each bomb is about 5%. This would mean that of the 202 bomblets dropped, about 10 will not explode on impact. Landmine Action has claimed the failure rate of the BLU-97/Bs used in the Kosovo campaign was higher, between 7 and 8 percent.

Photo By: Airman 1st Class Matthew B. Fredericks
When the CBU-87 is used in conjunction with the Wind Corrected Munitions Dispenser guidance tail kit, it becomes a precision-guided weapon, and is designated CBU-103.

The Wind Corrected Munitions Dispenser system is a US tail kit for use with the TMD (Tactical Munitions Dispenser) family of cluster bombs to convert them to precision-guided munitions. In 1997 the United States Air Force issued contracts to complete development and begin production of the WCMD, planning to modify 40,000 tactical munitions dispensers at a cost of US$8,937 per unit.

Guidance: INS updated with GPS data from launch platform before release.
Range: 9.9–12.4 mi.
Accuracy: 26 m (85 ft) CEP.

Shawn G in the Korengal Valley, Kunar Province, Afghanistan.

For more info on these and other weapons
Technical specs compiled from:

"The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement."

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Shawn in the Korengal Valley, Kunar Province, Afghanistan.

For more info on these and other weapons
Technical specs compiled from:

"The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement."


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