Thermobaric weapons under fire again

As a consequence of the positive results achieved by penetrating weapons against reinforced concrete bunkers during recent conflicts, many nations are moving their most valuable national assets into underground facilities, particularly tunnels. In many cases, the mission critical areas of tunnel facilities are practically invulnerable to physical destruction using current conventional weapons -- requiring a functional defeat of tunnel facilities.

ACTD scientists are addressing these deficiencies by developing a weapon that is capable of generating increased weapon effects to functionally defeat mission areas inside tunnels. The program will design a high-strength warhead case compatible with existing guidance kits and develop an explosive fill with improved air-blast capabilities. Additionally, the program will enhance guidance system and operational tactics to provide the warfighter with an improved capability to defeat tunnel targets.

The Bomb Live Unit (BLU)-118/B is a penetrating warhead filled with an advanced thermobaric explosive that when detonated generates higher sustained blast pressures in confined spaces such as tunnels and underground facilities. The U.S. Air Force fielded 10 of these new warheads compatible with the current Guided Bomb Unit (GBU)-15, GBU-24, and Air-launched Surface-attack Guided Missile (AGM)-130 weapon systems for employment by U.S. Air Force F-15E Strike Eagle aircraft.

The BLU-118/B uses the same penetrator body as the BLU-109 weapon, with the significant difference being the replacement of the high explosive fill with a new thermobaric explosive that provides increased lethality in confined spaces. The Defense Threat Reduction Agency (DTRA) is conducting a three-year Advanced Concept Technology Demonstration for a thermobaric weapon system to defeat hardened underground targets. The Sept. 11, 2001, terrorist attacks motivated changes in program priorities. On Oct. 11, 2001, DTRA organized a quick-response team that included Navy, Air Force, Department of Energy and industry experts to identify, test, integrate and field a rapid solution that would enhance weapons options in countering hardened underground targets.

The explosive experts at the Naval Surface Weapons Center, Indian Head, Md., responded with a developmental explosive that clearly provided enhanced blast effects. The Air Force Precision Strike Program Office at Eglin AFB, Fla., led the team performing the weapon system integration, safety and flight clearances, and produced a modified fuzing system for the new warhead. The Indian Head facility conducted static testing of the fuze to demonstrate reliable initiation of the new explosive. Both static and flight tests were then conducted at full-scale tunnel facilities at the Department of Energy's Nevada Test Site.

The fast-paced program culminated on Dec.14, 2001, with a successful flight test of the GBU-24 laser-guided weapon using the BLU-118B warhead launched by an F-15E. When compared to the standard BLU-109 explosive, results showed the new thermobaric weapon generated a significant improvement in overpressure and pressure-impulse in the tunnel complex.

The Air Force completed verification and validation of the technical data and operational flight clearances needed to deploy the BLU-118B warhead. Ten warheads were immediately made available to the U.S. Air Force for deployment.

The rules of war

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