Based on Lockheed’s four-engine turboprop transport and weaponized by Boeing, the deadly AC-130 “aerial battleship” had very humble beginnings.
Since its debut during the Vietnam War, the U.S. Air Force’s AC-130 gunship has played an integral role in close air support, air interdiction and force protection provided to U.S. ground troops. This includes not only close support of troops under fire and defending air bases, but also escorting convoys, specialized urban operations and interdiction missions conducted against preplanned targets. To accomplish these missions the gunship’s weaponry and electronic sophistication have evolved exponentially over the years.
The gunship program began in 1964 when U.S. Special Forces in Vietnam were in dire need of night firepower in their fight against localized attacks by Communist insurgents on the fortified hamlets and military outposts in the Mekong Delta. The gunship idea originated with an informal suggestion by a staff officer in the 1st Combat Applications Group, sister organization to the 1st Air Commando Wing based at Eglin Air Force Base in Florida. He suggested evaluating side-firing guns mounted in an aircraft that could circle its target at a constant airspeed at its pivotal altitude, putting continuous fire on the target as long as desired. (Pivotal altitude is based on ground speed and allows the target to remain fixed in place along a line parallel to the lateral axis of the aircraft.)
The idea was presented to the commander of the Special Air Warfare Center, Brig. Gen. Gilbert L. Pritchard, who immediately liked it. He had a Douglas C-47 transport modified with a .50-caliber M2 machine gun mounted on the floor by the left-side cargo door, pointing out parallel to the wing. Pritchard then piloted the C-47 out over the Gulf of Mexico and circled one of the raft targets maintained by Eglin’s Armament Development Division. Flying at 120 knots at the airplane’s 3,000-foot pivotal altitude, and using grease pencil crosshairs on the left-side window pane as a gunsight, he tried shooting at the raft. He had no problem hitting the target and reportedly had a ball in the process. Upon landing he made the gunship program a top-priority development project for the 1st Combat Applications Group.
The first fully modified C-47s were equipped with three 7.62mm General Electric miniguns—one in the cargo door and two mounted in the left-side rear windows. All three guns were triggered by a button on the pilot’s control yoke and could be fired individually or simultaneously.
The C-47 gunship could fly for hours in a counterclockwise orbit over a target area. A three-second burst from its miniguns provided suppressing fire over an elliptical area approximately 52 yards in diameter, with a round placed every 2.4 yards. The gunships also carried flares that were manually dropped to illuminate the area. The combination proved devastating.
Under the leadership of Captain Ron W. Terry from Air Force Systems Command, the project reached fruition on December 11, 1964, with the introduction of the FC-47. Operating with the call sign “Puff” (short for “Puff the Magic Dragon”), the gunship had its first significant success on the night of December 23 when it flew in support of a Special Forces outpost in the Mekong Delta that was under Viet Cong attack. The FC-47 arrived and illuminated the area with flares, then fired 4,500 rounds of 7.62 ammunition, breaking up the VC attack. The aircraft was then called to assist a second threatened outpost about 20 miles away. Once again, the FC-47 blunted the assault and forced the VC to retreat.
All of the gunships’ combat sorties that December proved successful. Then on February 8, 1965, an FC-47, flying for more than four hours over the Bong Son area in the Central Highlands, expended 20,500 rounds of 7.62 ammo at VC manning hilltop positions, killing an estimated 300 enemy troops.
To decrease vulnerability and increase munitions capability, the renamed AC-47 Spooky gunship concept pioneered in Project Gunship I was applied to a Lockheed C-130 Hercules transport. In 1967 JC-130A serial no. 54-1626 was converted to prototype AC-130A under Project Gunship II. New equipment included a night-vision telescope installed in the forward door and an early forward-looking infrared device mounted in the left wheel well. The miniguns were fixed facing down and aft along the left side. A prototype analog fire-control computer, handcrafted by Royal Air Force Wing Cmdr. Thomas C. Pinkerton at the USAF Avionics Laboratory at Wright-Patterson AFB, was also installed. In September 1967 the AC-130, call sign Spectre, was flown to Nha Trang Air Base in South Vietnam for a 90-day test program. It was an immediate success and in 1968 seven more airplanes were converted to the same configuration.
Despite the Spectre’s increased capability and awesome firepower, it’s difficult to believe what some brave American airmen experienced in that first iteration of the AC-130 gunship. The best description of its combat employment comes from Master Sgt. David M. Burns, who was assigned to the 16th Special Operations Squadron, based at Ubon Royal Thai AFB in Thailand, as a replacement aerial gunner during the “Palace Gun” program. When he joined the squadron in December 1969 there were six aircraft assigned to the program, each manned with a normal 11- or 12-man crew: pilot, copilot, flight engineer, table navigator, night-observation device operator, right scanner, forward gunner, aft gunner, two sensor operators, illuminator (IO) and a combat cameraman. “Each had a specific job and they all depended on each other for their very survival,” wrote Burns.
His description of the gunship’s armament and the duties of his fellow crewmen shows how primitive those first few AC-130As were. The aircraft were painted all black for their night missions. Armament included four 20mm rotary cannons and four 7.62mm miniguns mounted in portals along the left side. In attack mode they would orbit the target in a 30-degree left bank, with the pilot varying their altitude to complicate the enemy’s anti-aircraft solution.
In describing operations, Burns told of one very large technical sergeant, 6-foot-5-inch Arthur Humphrey, who had been in the squadron for only a few months but was already a legend. Among his jobs as an IO was to hang out from the aircraft’s rear cargo door and drop flares when the pilot called for them. With his parachute harness attached by a cable hooked to the top of the aircraft interior, “he always hung out farther than other IOs.”
Humphrey was also tasked with calling out anti-aircraft fire directed at the aircraft. “On one mission he yelled ‘Accurate triple-A, break right!’” recalled Burns. “To escape the fire the pilot broke violently hard right and Arthur fell out of the aircraft. As he was hanging out of the aircraft by the cable he called on the ship’s intercom to the pilot and dutifully asked for permission to come aboard! The pilot quickly told him to get his big ass back in the aircraft….”
The Hercules gunship proved so effective as a truck-killer and in armed reconnaissance and interdiction of the Ho Chi Minh trail that the Air Force had difficulty keeping up with demand for an airplane that also provided vital troop and cargo transport. Thus, with a stock of Fairchild C-119 Flying Boxcar airframes available in the Air Force Reserve, in February 1968 Fairchild-Hiller converted 26 C-119Gs to AC-119Gs—call sign Shadow—under Project Gunship III. Their equipment included some of the most up-to-date electronic countermeasures and radar technology plus four GAU-2A/A 7.62mm miniguns and an LAU-74/A flare launcher.
Concurrently, another 26 C-119Gs were converted to AC-119Ks, referred to as Stingers. To boost the aircraft’s gross-weight-carrying capability the two piston engines were supplemented with underwing-mounted General Electric J85 turbojets. Designed specifically for the truck hunter role, the Stingers were equipped with two M61 Vulcan 20mm cannons in addition to the four miniguns already on the AC-119Gs. Both models eventually were taken over by the Republic of Vietnam Air Force until the fall of Saigon in 1975.
Today’s AC-130 gunships can best be described as cutting-edge in both weapons and electronic sophistication. The two primary versions still in use are the AC-130W Stinger II and AC-130J Ghostrider, which recently joined the fleet. The improved AC-130J, Block 20, is powered by four 4,700-hp Rolls-Royce turboprops, giving it a speed of 362 knots at 22,000 feet. Equipped with a Precision Strike Package, its armament includes an internal 30mm MK44 cannon and a trainable M102 105mm howitzer (first used in a Spectre in 1972 over Vietnam), combined with the capability to carry GBU-39 guided bombs and wing-mounted AGM-114 Hellfire missiles.
The Ghostrider’s electronic equipment includes a laser range finder, low-light TV camera, crew night-vision capability, night-vision radar and a moving-target indicator. The Block 20 configuration also includes large-aircraft infrared and radio frequency countermeasures. Like the MC-130J Commando II on which it is based, the Ghostrider has inflight refueling capability.
The Air Force reported that the first six AC-130Js achieved initial operational capability on September 30, 2017. The Ghostrider flew its first combat mission in late June 2019 over Afghanistan, replacing the retired AC-130U. Meanwhile, there are plans to replace the 30mm cannon of a few Ghostriders with a laser-like directed-energy weapon that could be used to engage ships, vehicles, aircraft and control towers. The Air Force currently has 37 AC-130Js ordered and they are expected to reach full operational capability by 2025.
Gunships have come a long way since the first FC-47 took to the skies more than 55 years ago. In essence they have become very effective and indispensable aerial battleships.
Retired U.S. Air Force Lt. Col. John Lowery is a Korean and Vietnam war veteran. For further reading, try: Spectre Gunner: The AC-130 Gunship, by Master Sgt. David M. Burns; and Gunships: The Story of Spooky, Shadow, Stinger and Spectre, by Wayne Mutza.
This feature originally appeared in the September 2020 issue of Aviation History. To subscribe, click here!