The AC-130 is the world's biggest flying artillery gunship - nicknamed 'Hell in the Sky.' With three side-firing weapons, a 25mm Gatling gun, a 40mm Bofors cannon, and a 105mm howitzer ...

The Army proposed to mount a 105 mm artillery gun on the chassis of a UH-1 Iroquois ... factored into its successful development of later flying artillery systems, such as the famed AC-130 gunship.