More Bang for the Buck

A New Design and Manufacturing Method for Deep Penetrating Bomb Cases

The ∼4,450-pound BLU-122 deep penetrating bomb was developed by the U.S. Air Force in 2003, making improvements on the BLU-113 penetrator which would enable it to have significant penetration through hard targets. The weapon incorporates ∼780 lb of energetic explosive filling, a higher-strength case made from Eglin steel with an ultimate tensile strength of 245-255 ksi, an impact toughness of 11.5-15.5 ft-lb @ −40°F, and a modified nose shape for increased penetration. Despite the improved case, the BLU-122 possesses only 18-20 feet penetrability in 5.0 ksi strength reinforced concrete.

The U.S. Air Force is moving ahead to get a new 2,000-pound class bunker buster bomb filled with 530 lb of explosive material, built around an improved warhead called the BLU-137, which has a steel case made from the USAF-96 steel. This bomb will ultimately replace existing weapons in this category, which have already been a key part of recent engagements. The BLU-137 is intended to provide improvements in capability and survivability over the BLU-109 bomb. The BLU-109 has a steel case made from 4330 modified steel with an ultimate tensile strength of 245-255 ksi and an impact toughness of 20 ft-lb @ −40°F. The BLU-122, BLU-137, and BLU-109 bombs have monolithic and uniform steel cases.