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BLU-136 Improved Lethality Warhead

The BLU-136 is a 2000-pound class bomb body with form factor and mass properties similar to the BLU-109. When combined with the joint direct attack munition tail kit, the BLU-136 is designated as the GBU-31v11. The loading of the weapons and delivery of the BLU-136/GBU-31v11 is the same as any other JDAM loading or delivery for the F-16, so if/when fielded, the weapon will be virtually ready from day one. This also means that the delivery of the GBU-31v11 from any other aircraft will likely require little to no changes in loading or delivery tactics.

The U.S. Air Force is developing a 2,000 lb.-class bomb called BLU-136 that will shower metal fragments on enemy forces as a replacement for cluster munitions, which are being phased out by the Pentagon because they leave unexploded ordnance. This weapon is four-times the size of the BLU-134/B Improved Lethality Warhead, which is now being put into production. The BLU-134 and BLU-136 are different designs. The weapon in the 2,000-pound bomb class is intended to replace the Pentagons existing cluster bomb arsenal, following a 2017 doctrinal change in which the US gave up its pledge to get rid of bombs or shells that deploy smaller exploding bomblets.

Ductile Iron (DI) castings are finding increasing applications for military hardware. The ability to produce complicated shapes, minimizing machining, yet providing performance characteristics equivalent to wrought steel components, are the drivers. As a plus, there is often considerable cost savings. These applications are in vehicles and armament hardware, and now, new opportunities have been identified by the DOD for DI applications in projectiles and bomb bodies. The latter offers potential for significant adding of tonnage to the ductile iron industry. Five hundred pound, 1000 pound and eventually 2000 pound conventional explosive type bombs are needed by the Navy and the Air Force.

Presently, steel bodies are produced by beginning with cut-to-length steel pipe, swedging to the desired profile, followed by machining and welding on aircraft suspension lugs. Steel aft end guidance wings (fins) are subsequently attached. The welded forging is heat treated. High cost, distortion and other quality problems make DI castings an attractive replacement.

As-cast ductile iron bombs (CDIB) were first evaluated in the late 1980s, but failed to meet a fragmentation requirement when detonated. In short, it did not duplicate the requirement for large, uniform fragments, a capability of the heat treated steel. A program initiated in 1994 at the Naval Air Warfare Center (NAWC) identified the excellent potential of DI for meeting all requirements, if the castings have good graphite morphology and were in the fully annealed condition. This structure produces the desired walnut or marble size fragmentation; plus, provides the structural strength and fracture toughness necessary for handling, transport and airborne dynamic load forces.

High casting soundness is necessary for meeting the elongation and impact requirements. The target is ASTM severity level 2 or less radiographic soundness throughout all sections. No gross shrinkage can be tolerated. This unsoundness is restricted to scattered microporosity that might occur in the matrix structure cell boundaries or at the mid center of any section. Other requirements are good as-cast surface finish and freedom from other types of casting defects. Surface finish is important because the only machining that is required is for the nose cone insert, threading for aircraft suspension lugs and an aft V-groove where the flight guidance steel wings are attached during final bomb casing assembly. The balance of the OD and the ID remain with as-cast finishes.

The 28th Test and Evaluation Squadron conducted a Force Development Evaluation to operationally test the BLU-136 Next Generation Area Attack Weapon from July 8-24, 2020 at the Nellis Test and Training Range. The fragmentation of the BLU-136 is non-explosive, making it a less-hazardous alternative to cluster munitions. The FDE consisted of seven missions flown by the 422nd Test and Evaluation Squadron, successfully dropping ten BLU-136s from F-16 Fighting Falcons. The operational tests were designed to gather data to determine the operational performance of the BLU-136, specifically in the areas of blast and fragmentation damage, said Lt. Col. Daniel Lambert, 28th TES Global Strike division chief. This data will help decision makers determine if the BLU-136 is a viable substitute for the Air Forces fleet of cluster bombs. The tests proved that the design of the BLU-136 was effective in area denial and would be very effective against light vehicles, light structures, and personnel. They also showed that the BLU-136 is capable of inflicting fragmentation damage on the equipment and simulated personnel targets at distances in excess of 225 ft. away from the target.

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Page last modified: 01-07-2021 17:59:58 ZULU