Lockheed AC-130 Specter gunship. The M61 Vulcan is a hydraulically or pneumatically driven, six-barrel, air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm rounds at an extremely high rate (typically 6,000 rounds per minute).
Vietnam War: USAF F-4 Phantom fighter bombers in the skies of Southeast Asia. The Phantom is a large fighter with a top speed of over Mach 2.2. It can carry over 18,000 pounds (8,400 kg) of weapons on nine external hardpoints, including air-to-air missiles, air-to-ground missiles, and various bombs. The F-4, like other interceptors of its time (mid-sixties), was designed without an internal cannon. Later models incorporated a M61 Vulcan rotary cannon. (USAF photo)