The BLU-82B/C-130 weapon system, known under programme "Commando Vault" and nicknamed "daisy cutter" in Vietnam and in Afghanistan, is a 15,000 pound (6800kg) conventional bomb, delivered from an MC-130 transport aircraft. 225 were constructed.
Originally designed to create an instant clearing in the jungles of Vietnam, it was test-dropped from a CH-54 Tarhe "Flying crane" helicopter there. Later it has been used in Afghanistan as an anti-personnel weapon and as an intimidation weapon because of its very large lethal radius (variously reported as 100 to 300 meters/300 to 900 feet) combined with a visible flash and audible sound at long distances. It was the largest conventional bomb for several decades. That title is now held by the Russian-made Father of All Bombs, which contains 7.8 tons of high explosives, although both these weapons were outstripped in weight and size by the T12 Cloud Maker penetration or earthquake bomb developed from the British Grand Slam bomb of World War II. The T12 weighed 43,600 lb, almost twenty metric tons.
The BLU-82 uses conventional explosive incorporating both agent and oxidizer. In contrast, fuel-air explosives (FAE) consist only of an agent and a dispersing mechanism, and take their oxidizers from the oxygen in the air. FAEs generally run between 500 and 2000 pounds; making an FAE the size of a daisy cutter would be difficult because the correct uniform mixture of agent with ambient air would be difficult to maintain if the agent were so widely dispersed. Thus, the conventional explosive of a daisy cutter is more reliable than that of an FAE, particularly if there is significant wind or thermal gradient.
This system depends upon the accurate positioning of the aircraft by either a fixed ground radar or on-board navigation equipment. The ground radar controller, or aircrew navigator as applicable, is responsible for positioning the aircraft prior to final countdown and release. Primary aircrew considerations include accurate ballistic and wind computations provided by the navigator, and precision instrument flying with strict adherence to controller instructions. The minimum altitude for release due to blast effects of the weapon is 6,000 feet (1,800 m) above ground level (AGL). The warhead contains 12,600 pounds (5,700 kg) of low-cost GSX slurry (ammonium nitrate, aluminium powder and polystyrene) and is detonated just above ground level by a 38-inch (965 mm) fuse extender, optimized for destruction at ground level without digging a crater. The weapon produces an overpressure of 1000 pounds per square inch (psi) (7 MPa) near ground zero, tapering off as distance increases.
The BLU-82 was originally designed to clear helicopter landing zones and artillery emplacements in Vietnam. South Vietnamese VNAF aircraft dropped BLU-82 bombs on NVA positions in desperation to support ARVN troops in the Battle of Xuan Loc in the last days of the Vietnam War. Eleven BLU-82s were dropped during the 1991 Gulf War, all from Special Operations C-130s. The initial drops were believed to be intended to test the ability of the bomb to clear or breach mine fields; however, no reliable assessments of mine clearing effectiveness are publicly available. Later, bombs were dropped as much for their psychological effect as for their anti-personnel effects. The US Air Force dropped several BLU-82s during the campaign to destroy the Taliban and al-Qaeda terrorist networks in Afghanistan to attack and demoralize personnel and to destroy underground and cave complexes. On 15 July 2008, Airmen from the Duke Field 711th Special Operations Squadron, 919th Special Operations Wing dropped the last operational BLU-82 at the Utah Test and Training Range.