A top-secret, highly successful and still unheralded program in Vietnam presaged today’s drone victories in the war on terror.
At a surface-to-air missile site south of Hanoi on February 13, 1966, radar appeared to lock in on a lone incoming aerial reconnaissance aircraft. The North Vietnamese crew launched an SA-2 Guideline missile and within 30 seconds the intruder was blasted out of the sky. The men on the ground celebrated their score, never to know the Pyrrhic nature of their victory.
Indeed, they had been tricked into engaging a Model 147E“sniffer drone”that was launched to provoke their attack. In the seconds it took the SA-2 to reach its target, the drone detected, recorded and transmitted all of the missile’s vital electronic signals to an aircraft flying over the South China Sea. In an instant, U.S. intelligence had captured the deadly missile’s tracking, acquisition and guidance signals, and the sequence in which those signals appeared during an engagement. The drone also recovered the frequency and operating characteristics of the warhead’s proximity fuze.With that essential data in their hands, U.S. electronic warfare experts soon developed radar warning equipment and countermeasures to confound the Soviet-built missile system. It was the first of many intelligence breakthroughs the U.S. Air Force“drone reconnaissance”detachment achieved over more than a decade of operations in Indochina.
Although unmanned remotely piloted aircraft had been in limited use in the two world wars,Vietnam was the first war in which they were extensively employed. Because the U.S. drone program was top secret at the time, few even today know the role this innovative aircraft played in Vietnam. In fact, drones were among the first units deployed to the Indochina theater and the very last to leave.
On August 4, 1964, President Lyndon Johnson ordered the deployment of strategic reconnaissance assets to the Western Pacific just hours after the Gulf of Tonkin incident. Among those assets were the RF-101 photoreconnaissance plane, the U-2E high-altitude reconnaissance aircraft and remotely piloted vehicles of the 4080th Strategic Reconnaissance Wing. In the pre-satellite era, aerial reconnaissance aircraft were the only means of getting a picture of the ground situation in hostile areas. Air Force RB-47s, RB-57s, RF-101s and the CIA’s U-2s were the primary platforms for those missions.
The potential Chinese reaction to a U.S. buildup was of particular concern to the Johnson administration in August 1964. Senior leaders feared China might intervene as it had in the Korean conflict. And China’s air defenses were improving with the addition of the Soviet-made SA-2 SAM, which had proved its mettle by downing Gary Powers’ U-2 in 1960. Besides eliminating the risk to life and limb, flying unmanned aircraft over a country was regarded to be less provocative and politically sensitive than flying manned aircraft,making drones ideal recon platforms.
Just 48 hours after Johnson’s orders, the 4080th Strategic Reconnaissance Wing’s personnel quickly set up shop at Okinawa’s Kadena Air Force Base, and four days later began sending its Model 147B drones on missions over Southern China. The wing’s first sorties were disappointing as windy, wet conditions hampered the drones’ navigation systems, and damage on recovery was a significant problem.
The 4080th’s Drone Detachment consisted of two DC-130As and eight Fire Fly drones. The DC-130s were early C-130A cargo planes modified to carry four BQM-34 Firebee target drones or two Ryan Model 147 Fire Fly recon drones.
In today’s parlance, the Firebee was a remotely piloted vehicle (RPV) because it was flown entirely by remote control.A loss of signal, therefore, would result in the drone flying its last command or simply continuing in a straight line until its fuel ran out and it crashed. The reconnaissance models on the other hand, more closely approximated today’s unmanned aerial vehicles (UAVs). They had autonomous navigation equipment and generally flew a programmed flight for most of their mission, though they could be controlled remotely—and often were—during the flight’s launch and final recovery phases. The DC-130 carried two launch control officers and an airborne control officer and airborne technician. Unlike today’s UAVs, which rely on satellite links, the early air- and ground-based command guidance units used an Ultra High Frequency (UHF) transmitter to control the drones as required. The DC-130 was the perfect “mothership” platform. It was reliable and robust; it had great lift, range and endurance; and it had the internal power and roomy interior to host the command guidance equipment.
Early unmanned reconnaissance drone projects had been canceled in the late 1950s because of costs, problems in testing and lack of organizational support, but Soviet deployment and sales of its SA-2 SAMs had rejuvenated UAV development efforts within a few weeks of Gary Powers’ shoot down in 1960. To save time and money, the Air Force modified the BQM-34 Firebee target drone for the reconnaissance role. It proved a smart choice as its small size and fiberglass construction gave it a minuscule radar cross-section. Also, since it was designed to fly as a target for fighter pilots, antiaircraft artillerymen and surface-to-air missile batteries, it was agile and robust. However, it did require some alteration for the reconnaissance role.
First efforts to develop a highly modified and far more expensive variant had failed, leading the Air Force to settle on a less extensive modification of the basic target drone, initially designated the Fire Fly. Because of its strategic reconnaissance mission, the entire BQM program and all operations were classified top secret and remained so throughout the program’s existence.
Four BQM-34s were taken in for modification in June 1960. For Fire Fly, the BQM-34 was enlarged by inserting a 35-inch plug into the fuselage to carry an additional 258 liters of fuel and a simple automated dead-reckoning navigation system. The nose was redesigned to carry the U-2’s Hycon A-1 camera system. The new Model 147 Fire Fly had a range of nearly 1,200 miles and a cruise altitude of 55,000 feet. Installing a mesh over the engine intakes and coating the fuselage with radar-absorptive material reduced the drone’s radar-detectability.
Early tests revealed it was almost invisible to the ground radars of the day and nearly undetectable by fighter aircraft radars. Its J-69 engine produced a contrail at cruising altitude, however, so engineers developed a contrail suppression system in which chlorosulfonic acid, which reduces water particles to an invisible size, was injected into the engine exhaust port when it was over enemy territory. That solved the problem and reduced the UAV’s infrared signature, but at a cost of more maintenance, as chlorosulfonic acid is highly corrosive. The early 147As were replaced in 1962 by B models with Doppler-radar-based state-of-the-art navigation systems and double the wingspan, allowing them to cruise at 62,500 feet. Installation of the contrail suppression system converted the 147As to Model 147Cs.
After a year of testing, the Fire Fly reached full operational status. But, at the same time, a press leak compromised the effort, forcing the program and drone to be renamed “Lightning Bug.”
The first DC-130/UAV Lightning Bug squadron joined the 4080th Strategic Reconnaissance Wing at Davis-Monthan Air Force Base in July 1963. Flights had proven the drones’ utility, but the greatest challenge was accurate navigation and recovery at the end of their flight. Typically, the drone was programmed or directed to fly toward the recovery airfield. If the drone’s control unit on the ground could establish contact, they would guide the aircraft in. Parachutes would deploy on command, or when the fuel ran out. In windy conditions, drones were often damaged upon impact and required days of repair.
End-of-mission recovery was a serious problem the 4080th faced in its early Kadena operations, as was serviceability and reliability. The first drone to fly from Kadena, a DC-130-mounted Model 147B, failed to launch and fell off its pylon into the sea. The second drone was badly damaged after completing its mission, when high winds caught its parachute and dragged it through hundreds of yards of rough terrain. The film payload was recovered, but the drone’s navigational accuracy was so poor that several key targets were missed. The first seven missions out of Kadena provided only two reels of usable film, a failure rate that nearly led the Air Force to cancel the entire program. Major General A.J. Beck and the 4080th’s commander, Colonel John Des Portes, were able to quickly correct the problems, however, vastly improving drone serviceability and performance.
Change came in October 1964, just as Washington’s focus shifted to North Vietnam and the area along the Sino-Vietnam border. At first, because its drones were still flying missions over southern China, the drone detachment made short deployments to Bien Hoa Air Base, where the 4080th’s RF-101s and U-2s had been moved in March 1965. However, as the air war over North Vietnam expanded, and with it drone missions, it became necessary to consolidate the aerial reconnaissance units close to the photo interpreters supporting the campaign. Film could now be walked over to the processing and interpretation center, accelerating the intelligence analysis and mission planning processes.
In July 1965, the drone detachment became the 4025th Reconnaissance Squadron, with its headquarters and maintenance crews stationed at Bien Hoa as Operational Location-20 (OL-20) and the Drone Recovery and Control Units stationed at Da Nang as OL-10. At this time its operations intensified as North Vietnam’s air defenses improved. Hanoi’s acquisition of MiG-17s in 1964 and MiG-21s in 1966 made manned reconnaissance missions much riskier, forcing U-2s to fly ever higher and avoid many areas of North Vietnam.Likewise,RF-101 missions had to be conducted away from the most densely protected areas. Consequently, the Lightning Bugs became increasingly important, flying more than 160 missions in the detachment’s first year in Vietnam.
The 4080th became the 100th Strategic Reconnaissance Wing in February 1966, and the drone unit became the 350th Strategic Reconnaissance Squadron. It was two days later, on February 13, that the squadron’s sniffer drone, an Electronic Intelligence (ELINT) Model 147E variant, lured the SA-2 missile above North Vietnam. That intelligence coup provided the key missing links in America’s knowledge of the SA-2, advancing development of electronic warning and countermeasures equipment that enabled pilots to contain and then defeat it.
For the ELINT collection missions, the drones often had wave guides attached to them to enlarge their radar cross sections, making them appear to be U-2s in order to draw a response. They also dropped expendable ELINT receivers that collected and relayed radar information until they crashed. In both types of ELINT missions, the drones’ onboard data link equipment transmitted the information back to the DC-130, an RB-47 or an RC-121. Communications Intelligence (COMINT) variants entered service in mid-1966, collecting vital details about North Vietnam’s and China’s air defense systems and tactics.
Missions typically involved the DC-130s, with Air Force or Navy fighter escorts, flying out over the South China Sea and launching the drones from points off the North Vietnamese coast. The drones generally flew a programmed flight, and most missions were high altitude. They were to be recovered at or near Da Nang, but if they crashed outside Da Nang, U.S. Army CH-37 helicopters recovered them. Depending on the extent of required repairs, Lightning Bugs were restored at Da Nang and delivered to Bien Hoa, usually by one of the squadron’s DC-130s.
In 1966 the squadron’s mission expanded to direct combat support. The Air Force used the drones to drop chaff, which creates a gigantic reflection that fills the radar scope to blind the operator, and even mounted AN/ALQ-51 deception jammers on one Lightning Bug to test its effectiveness against the SA-2 before installing it on a manned aircraft. Other drones carried radar-enhancement devices to deceive the North Vietnamese into believing they were attack planes and engaging them. Since the Lightning Bugs were smaller than the reconnaissance drones, the DC-130s could carry four.
In 1967 the squadron introduced a low-flying Lightning Bug equipped with a strobe light that activated over a chosen target area to illuminate it. Although it was not particularly successful in that role, its psychological effect on North Vietnamese defenders was considerable. The squadron often employed the strobe drones just to keep the North Vietnamese off balance. That year also saw more low-level missions using shortwinged 147Cs and Ds. The shift exposed the Lightning Bug’s primary weakness: its navigation system. The Doppler radar on the DC-130 was itself only accurate to within a few miles and the drone’s system was only accurate to within 3 percent of the distance traveled from the launch point; as a result, the drones often reported they were as much as 9 to 12 miles from their“real”position when they started their target run. The problem was not as critical when operating at high altitudes, as the camera’s wideangle lens captured most of the target area.
That coverage, however, diminished at lower altitudes. At 300 feet, it covered a mile on either side of its track. Efforts to improve the low-altitude navigation systems enhanced accuracy but not sufficiently to guarantee mission success. Less than 50 percent of the low-level missions successfully collected against their intended target.
Accuracy, reliability and survivability improved in consonance with advancing technology. The high-altitude Model 147H boasted the longest wingspan yet, and could operate at 69,000 feet. It also had two automated self-defense systems. The Rivet Bounder electronic countermeasures system fed false data to the SA-2 fire control system. More important was its flight navigation computer, which included a program that sent the drone into a series of tight evasive maneuvers when engaged by SAM tracking or fighter interceptor radars.
The squadron also received regular BQM-34 target drones modified into Model 147N and 147NC expendable decoys, designed to precede strike missions into the densest defended areas and draw fire away from the reconnaissance drones. The navigation system was also improved in the Model 147J, with better inertial guidance and a more precise Doppler navigation radar.
An unheralded, less high-tech but critical squadron improvement came in 1966 with the arrival of two CH-3 Jolly Green Giants and the introduction of the Mid-Air Recovery System (MARS). Developed by Ryan Engineers in San Diego, MARS required the Jolly to fly above the descending drone and extend a cable down through a hole in the fuselage. The recovery cable was connected to a harness with three hooks, two of which were at the end of poles that could be “telescoped” about 8 feet. A 3- to 4-foot flying hook connected the two poles. The hook snagged the drone’s small engagement parachute, and a winch operator then reeled the drone up until it could be secured to the load line. At the recovery base, the Lightning Bug was gently lowered onto a fuel bladder or other comparatively soft material. The MARS recovery method significantly reduced damage, improving drone readiness rates. From its introduction in March 1966 to its final recovery in 1975, 2,745 MARS attempts resulted in 2,655 “catches,” a 96.7 percent success rate. Average turnaround time for a MARS-caught drone was 1.5 working days versus 2 to 10 days for the ground-recovery methods.
Recognizing the Air Force success, the Navy also experimented with using Lightning Bug reconnaissance drones, embarking three 147SKs aboard the USS eras and a closed-circuit television that sent imagery Ranger on Oct. 14, 1969. The SK had film camback to the carrier. The Navy’s Operation Belfry Express conducted 24 operational flights, with mixed results. Most of the early missions were very successful,using a water recovery method with Navy H-3 helicopters. However, lack of training and experience with the drones led to serious problems. One E-2 Airborne Warning and Control System (AWACS) aircraft crew lost track of a drone and, without knowing its actual location, tried to fly it back to the ship. The drone eventually ran out of fuel and crashed on China’s Hainan Island. China claimed its air defense forces shot it down and made several propaganda broadcasts about the “latest example of American Imperialist aggression.” The 15 missions the Navy conducted after that were plagued by “recovery failures.” Subsequent investigations revealed that saltwater corrosion impeded parachute deployment, leading to highspeed impacts and destruction of the drones. Considering its drone experiment a failure, the Navy canceled the program.
Meanwhile, Viet Cong mortar and rocket attacks on Bien Hoa were intensifying in 1969, leading to the 350th’s final relocation in July 1970 to Thailand’s U-Tapao Royal Thai Air Force Base, where it joined the 100th Strategic Reconnaissance Wing. With the move, more missions began to be launched from Cambodian or Laotian air space.
Improved electronics and computers continued to refine the drones. Various S models started arriving in 1969, their vastly upgraded inertial navigation systems solving the “missed coverage” problem that had bedeviled low-level missions. Better, lighter cameras and more sensitive film further expanded drone mission capabilities, as did TV-camera-equipped models and the Microwave Guidance Control System, which enabled mission controllers to monitor and guide the drones at a range of up to 600 nautical miles. With these advancements and the changing political environment of the war came a range of new missions.
The high-altitude 147T series carried a variety of collection systems, but their most important addition was new, high capacity communications intelligence equipment. Flying above 70,000 feet and equipped with radar signal suppression and deception systems, the Ts could copy Chinese and North Vietnamese High Frequency (HF) and Very High Frequency (VHF) communications from as far as 570 nautical miles and relay it to electronic intelligence aircraft. Supported by lower flying Model 147N jamming and chaff-dropping drones and equipped with an automated evasive maneuver program for the H models, the 147T was extremely difficult to shoot down. With the introduction of these new drones, virtually every North Vietnamese communications system could now be detected and analyzed.
But by this time, the air war was already winding down and more prosaic missions came to dominate drone operations. In addition to their reconnaissance and deception operations, the drones were used to drop leaflets and ground sensors on North Vietnam from March 1971 to late January 1972. After that, the bulk of the squadron’s missions were over Laos and Cambodia, and along the Ho Chi Minh Trail. Finally, in spring 1975, the squadron tracked the North Vietnamese buildup before its offensive, during their advance across South Vietnam and the seizure of Saigon in April 1975. For what it was worth, the Lightning Bugs provided thousands of feet of film showing the extent of the North Vietnamese violations of the Paris Peace Agreement. The squadron flew its final drone mission in June 1975 and began to withdraw from Southeast Asia shortly thereafter.
During 11 years of service, drones had flown 3,435 sorties over China and North Vietnam. Of the 544 Lightning Bugs lost, mechanical failures brought down about one-third, while antiaircraft artillery, SAMs and MiGs claimed the rest. Interestingly, the North Vietnamese lost seven fighters to Lightning Bugs: one fighter ran out of fuel while in pursuit over the sea, but the other MiGs were hit with friendly fire when they chased the drone into antiaircraft or another fighter’s fire. One drone even achieved “ace” status by being involved in the crashes of five MiGs.
The Lightning Bugs made an invaluable contribution to the war, providing intelligence about the SA-2’s technical operations and North Vietnamese tactics that saved many aircrew lives. They also discovered countless enemy bases, SAM sites, North Vietnamese ground control communication sites—even the Son Tay POW camp. They took the first close-up photographs of North Vietnam’s MiG-21Ds and Es, and discovered evidence of Soviet helicopters in North Vietnam. More important, they conducted the first ever real-time remotely controlled communications intelligence of an enemy, enabling American commanders to warn pilots in the air about enemy air and air defense activity. They also provided the only daily low-level battle damage assessment of B-52 raids during Linebacker II, the bombing campaign that drove Hanoi to the bargaining table.
The BQM-34 Lightning Bug proved the worth of UAVs during the Vietnam War, and serious consideration was given to expanding the drone program. The Air Force did experiment with using drones as bombers and missile platforms, but the secrecy precluded its winning the broad support required to survive the severe budget cuts that followed the Vietnam War. Drone research would have had to come out of the same budget pool as new manned aircraft, so the program died, even though at least one BQM-34 was tested as a bomber and another as a Maverick Missile platform—similar to today’s UAV mission in the war on terror.
Interest in unmanned aerial vehicles would not resurface until the 1980s, when advancing technology, miniaturization, reduced computer costs and vastly improved navigational systems made UAVs practical and cost-effective. Today’s wars would be far more difficult and expensive to conduct without UAVs such as the Predator, Hunter and Reaper.Armed versions of these UAVs have taken out hundreds of terrorists, denying them safe havens.
Fear of drone attacks may have been what drove Osama bin Laden to hide in Abbottabad, several hundred miles from the Afghanistan-Pakistan border and tribal areas where his operatives and the Taliban risk death every time they step out into the open. There are areas of Pakistan and Afghanistan where American drones provide almost constant surveillance. Even infantry patrols enjoy UAV surveillance support. High-altitude Global Hawks have taken over the large-area surveillance mission that the Model 147Hs, SC/TVs and Ts introduced in Vietnam—only with vastly better television cameras and imagery systems. As to the Firebee drones, on which five decades of development was based, they continue to serve as targets and were even used to lay chaff corridors during the 2003 invasion of Iraq.
Although neither recognized nor credited for it in contemporary media reporting, the UAVs and drone operations of today are the progeny of the 350th Strategic Reconnaissance Squadron and its pioneering efforts in Southeast Asia.
Captain Carl O. Schuster retired as an intelligence officer in 1999 after 26 years serving on a variety of U.S. and allied ships and submarines. He teaches military history at Hawaii Pacific University.
Originally published in the February 2013 issue of Vietnam. To subscribe, click here.