Birth of the AC-47 Gunship

By Henry M. Holden

 The airborne gunship was a totally new weapons system. Gunships are generally considered side-firing airborne weapons platforms. The concept of the gunship originated in 1926 with a .30-caliber Lewis machine gun mounted on the wing of a de Havilland DH-4 It flew “pylon turns” to keep the gun on target.

Stories of a missionary who had been able to air-deliver mail and supplies to remote villages by lowering them in a weighted pouch. The pouch remained stationary over a point on Earth at the end of a long rope as he flew pylon turns around the point. The straight line of the rope could translate into a straight line of gunfire at a single point on Earth if the gunship were flown in a similar pylon turn.

DC3, C47, Dakota, R4D, Gooney Bird, DAK, DST, C-53, C-117,C-49

Capt. Ronald W. Terry was a project pilot who was assigned to put the concept into practice. Terry is one of the few individuals in military history that helped create a totally new weapon system and tested it in combat himself.

 Terry began operations during December 1964. The Air Force had created two FC-47s (“FC” meant “Fighter Cargo,”) by 7.6 mm Gatling guns, a gun sight cobbled up from a crosshair reticle and a 16 mm camera reflex viewfinder, and a supply of flares. 

 Dec. 15 marked the first of several successful day missions. Eight days later, the first night mission had a double success. The first part of the sortie was flown at Thanh Yend, where the FC-47 dropped 17 flares and expended 4,500 rounds of ammunition, causing the Viet Cong to break off their assault. Then it was sent to Trung Hung, where, under a barrage of 4,500 rounds of ammunition, the Viet Cong again were forced to leave.

 There were challenges: A night illumination system was needed, and the flares, some dating to World War II, often did not work. The very sound and fury of the FC-47 raised South Vietnamese morale even as it “spooked” the VC, and the aircraft soon got affectionate nicknames such as “Puff” and “Dragonship.” The call sign “Spooky” was assigned to early gunship operations.

 The 7.62 miniguns were excellent weapons but were in short supply. Terry got authorization to take 300 old M-2 .30-caliber machine guns and install them, 10 at a time, in four C-47s.

 By the end of 1965, the Air Force had flown 277 combat missions-but had lost two aircraft. The gunships now designated AC-47s, had to operate low, slow, at night, and in bad weather. Forty-seven AC-47s went to Vietnam, and 12 were lost.

 Spooky’s mission expanded to include interdiction of roads, trails, and rivers, and this greatly increased the demand for its services. 

 Nonetheless, the US had to try to interdict the flow of supplies, and the best tool for the job was obviously an improved gunship. The goal was an aircraft that could carry more equipment for longer times with greater safety. A high wing was preferred for ease of gun and sensor installation.

 Terry proposed a converted C-130A with improved sensors and weapons, more ammunition, and improved performance. Four 7.62 miniguns and four M-61 Vulcan 20 mm cannons were installed in Gunship II, along with a side- and forward-looking radar, a Starlight scope night observation device, and a computerized fire-control system linking sensors and guns. Also installed were overt and covert illuminators, armor plate, and better navigation equipment. Fuel tanks were “inerted” against ground fire.

 Air Force Secretary Harold Brown had authorized the C-119G as the AC-47 replacement. Gen. John P. McConnell, Chief of Staff, continued to press for the AC-130, stressing it had a “search and destroy” capability in addition to a close-support mission. The two most telling arguments for the AC-130 were its survivability and its effectiveness. It cost $5,100, on average, for Gunship II to destroy or damage a truck. For an F-105, the cost per vehicle was $118,000.

The opposing views were ultimately reconciled in a costly compromise that led to the creation of three types of gunships in the fleet-AC-47s, AC-119s (Gs and Ks), and AC-130s.

 In December 1968, four AC-130s were pressed into combat and forced to adapt to a variety of missions, but they concentrated on night interdiction. Within three months, the four aircraft, with still-inexperienced crews, had destroyed 607 trucks, more than a quarter of the theater total.

 On May 24 the Air Force lost its first Spectre. Severely hit by 37-mm anti-aircraft, the AC-130 crashed on landing at Ubon. Two crewmembers were killed, and the aircraft was destroyed.

 They did so with heavier armament, a digital fire-control system, an air-to-ground moving target indicator system, and a low-light-level television to improve target acquisition at night. The four 7.62 miniguns were replaced by two 20 mm Gatling guns and two 40 mm Bofors guns. A two-kilowatt illuminator and a Paveway I laser designator were added to facilitate cooperation with tactical aircraft. The location of detected targets could be stored in an inertial navigation system, for later use.

 The advanced AC-130 was less vulnerable because it was able to operate at higher altitudes and was better armored. Its 40-mm guns and laser designators made it far more lethal.

 Estimates were that about 200 trucks per day were sent down the trail. Previous interdiction efforts peaked at 30 truck kills per day. Now, a force of 18 AC-130s and 26 AC-119K aircraft could kill 100 to 200 trucks per night.

As experience was gained, the success of the gunships continued to rise; by March 1971, they were destroying an average of 13 trucks per sortie, with as many as 3,240 destroyed and 787 damaged per month, almost 90 percent of the number attacked. By June, a total of almost 14,000 trucks had been destroyed and damaged, three times as many as in the previous year. 

 A contract was awarded in 1968 for project Combat Hornet, for a total of 52 additional gunships. The first 26 were to be AC-119Gs, equipped with four 7.62 GAU-2B/A miniguns, gun sight, armor, night observation sight, DPN-34 and SPR-3 radars, 20 kw airborne illuminator, and an LAU-74/A flare launcher. The second 26 were to be AC-119Ks, with similar equipment plus two 20 mm Vulcan guns, AN/APQ-133 beacon tracking radar, FLIR, and a Doppler navigation system. The AC-119Ks were almost five times as expensive as the AC-119Gs.

 The Gunship III program was not without its difficulties, but four AC-119G Shadows arrived at Nha Trang by the end of December 1968, along with advance elements of the 71st SOS, whose personnel were largely called up from reserve units. Combat operations began Jan. 5, with the Shadows operating in South Vietnam. All 18 aircraft assigned arrived by March 1, and the AC-119Gs proved acceptable in all the roles accomplished by the AC-47 except for that of forward air control. (In June 1969, the 71st SOS became the 17th SOS.)

 In 1969, the AC-119Gs would fly more than 3,700 sorties over 14,251 combat hours, fire almost 35 million rounds of ammunition, and expend 22,000 flares. They killed some 1,500 enemy troops and, most important, had allowed no outpost to be overrun while they were overhead. Flying the Shadow was not without hazard; many recorded hits from AAA. One was lost to ground fire, and another crashed on takeoff.

 By the end of 1970, 33 AC-119s were spread over four bases: 

In March 1972 two AC-130s were shot down in the Steel Tiger area in Laos. In May, the brand new SA-7 Strela was introduced. This SAM was a shoulder-fired weapon with an infrared seeker for which there was no immediate defense. Airpower became increasingly important as North Vietnam began its spring 1972 offensive. The most sophisticated methods were employed to oppose it. The Spectres and Stingers worked from their Thai and South Vietnamese bases against targets in Cambodia, South Vietnam, and Laos. As North Vietnam stepped up its efforts, the work of the gunships expanded to provide more close support of the South Vietnamese army. The Pave Aegis AC-130s were particularly successful, using their 105 mm gun to destroy tanks and the increasingly heavy artillery being deployed. There were many instances when the heavy fire from gunships halted overwhelming assaults on South Vietnamese positions, as in the defense of An Loc.

©Copyright Henry M. Holden 1996 2013

For the complete story on the Douglas DC-3 see “Legacy of the DC-3″

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