CBU-55

The CBU-55 was a cluster bomb Fuel Air Explosive that was developed during the Vietnam War, by the United States Army, and was used only once in warfare. Unlike most incendiaries, which contained napalm or phosphorus, the 750 pound CBU-55 was fueled primarily by propane. Described as a "the most powerful non-nuclear weapon in the U.S. arsenal," the device was one of the more powerful conventional weapons designed for warfare.

Design
The device had three main compartments, with propane, a blend of other gases, perhaps chlorine triphospate, or another oxidizing agent, and an explosive.

The CBU-55 had two variations. The CBU-55/B consisted of 3 BLU-73A/B fuel-air explosive sub-munitions in a SUU-49/B Tactical Munitions Dispenser, and the CBU-55A/B had 3 BLU-73A/B sub-munitions in a SUU-49A/B dispenser). The SUU-49/B dispenser could be carried only by helicopters or low-speed aircraft, whereas the SUU-49A/B was redesigned with a strongback and folding tailfins, so that they could also be delivered by high-speed aircraft as well.

History
The first generation of the CBU-55 was used during the Vietnam War. By April 21, 1975, South Vietnam had largely been conquered by the military from the north. Earlier in the month, a single CBU-55 had been flown from Thailand to the Bien Hoa airbase. The senior military officer in Vietnam, Major General Homer Smith, cleared the way for the Saigon government to use the weapon against the North Vietnamese Army. A Vietnamese C-130 transport plane circled Xuan Loc at 20000 ft, then dropped the bomb. The contents exploded in a fireball over a 4 acre area. Experts estimated that 250 soldiers had been killed, primarily by the immediate depletion of oxygen rather than from burns. The CBU-55 was never used again in the war, and South Vietnam's government surrendered on April 30.

A second-generation of the CBU-55 (and CBU-72) fuel-air weapons entered the United States military arsenal after the Vietnam War, and were used by the United States in Iraq during Operation Desert Storm.