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The Ryan Model 147 Lightning Bug is a Jet engine-powered drone, or unmanned aerial vehicle, produced and developed by Ryan Aeronautical from the earlier Ryan Firebee target drone series.
Beginning in 1962, the Model 147 was introduced as a reconnaissance RPV (Remotely Piloted Vehicle, nomenclature of that era) for a United States Air Force project named Fire Fly. Over the next decade – assisted with secret funding from the recently formed National Reconnaissance Office along with support of the Strategic Air Command and Ryan Aeronautical's own resources – the basic Model 147 design would be developed into a diverse series of variants configured for a wide array of mission-specific roles, with multiple new systems, sensors and payloads used, modified and improved upon during the operational deployment of these drones in Southeast Asia. Missions performed by the Model 147 series RPVs included high- and low-altitude photographic and electronic aerial reconnaissance, surveillance, decoy, electronic warfare, signals intelligence, and psychological warfare.
The Ryan drones were designed without landing gear for simplicity and to save weight. Like its Firebee predecessor, the Model 147 could either be Air launch from a larger carrier aircraft or launched from the ground using a solid rocket booster; at completion of its mission the drone deployed its own recovery parachute which could be snatched in mid-air by a recovery helicopter (in a combat environment it was naturally not desired to recover the drone on, from or near enemy territory and ground or water impact could also cause damage to or loss of the drone or its payload).
At the end of the Vietnam War in 1975 the U.S. military's available funding and need for combat drones severely declined, even as Teledyne Ryan introduced further advanced developments of the Model 147 series such as the BGM-34 Interdictor and defense suppression RPVs. Costs of maintaining the Lightning Bugs at full readiness could no longer be justified. Only by the 1990s did substantial interest, organization and funding again emerge from the U.S. Air Force and intelligence agencies to develop, acquire and widely deploy combat UAVs.
Ryan presented its report on the studies to the U.S. Air Force in mid-April 1960. On 1 May 1960 an American Lockheed U-2 spy plane was shot down over the Soviet Union and its pilot, Francis Gary Powers, captured. On 1 July a Boeing RB-47H reconnaissance aircraft flying an electronic intelligence mission in international airspace near the Soviet border was shot down; four of its crew were killed and the other two captured. A few days later, the Air Force awarded Ryan a US$200,000 contract to perform further studies.
Ryan conducted radar measurements on sub-scale Firebee models and determined that their radar signature could be reduced by placing a wire screen over the jet intake, painting parts of the drone with non-conductive paint, and placing radar-absorbent material pads on both sides of the fuselage. Test flights of the modified Firebees were performed in September and October 1961. Flights were given a cover story, describing the drones as high-altitude targets for surface-to-air missiles (SAMs) in case one of them came down in a public area. The flights demonstrated that the modifications did not compromise the Firebee's performance.
Ryan actually wanted to build a completely new drone, the Ryan Model 136, for the reconnaissance mission. The Model 136, or Red Wagon, was optimized for the role with long straight wings for high-altitude flight, an engine set on the back of the fuselage to reduce its radar and infrared signatures as seen from below, and inward-canted twin tail fins to conceal the exhaust plume. The project stalled, however as the incoming Kennedy Administration was certain to reassess many military projects and Red Wagon was put on hold.
Ryan then proposed another drone project named "Lucy Lee" consisting of a highly modified Firebee intended to perform photographic and signals intelligence (SIGINT) reconnaissance from outside Soviet airspace. Lucy Lee seemed to be on track, but was then abruptly cancelled in January 1962.
The new reconnaissance drones were designated Model 147A and codenamed Fire Fly. Specifications dictated a range and a cruise altitude of .
The first Model 147A was a standard Firebee with a new guidance system consisting of no more than a timer-programmer, a gyrocompass, and an altimeter. The Fire Fly could be programmed to fly in a certain direction at a certain altitude for a certain time, and then turn around and return the way it came. This aircraft was intended only as a demonstrator and to evaluate the new guidance system; it carried no cameras. Three test flights were performed in April 1962 and demonstrated the validity of the concept, with the drone performing a mission which ranged from New Mexico, north into Utah, and then back again with no guidance from the ground (though accompanied by a B-57 chase plane).
The second Model 147A had an "plug" inserted into the fuselage to carry an additional 68 US gallons (258 litres) of fuel, increasing overall length from to . It also had a new nose containing a camera from the U-2. After four successful test flights performed in April and early May 1962, the third and fourth Model 147As (which were almost identical to the second example) were declared operational and deployed at Holloman Air Force Base in New Mexico with a Lockheed DC-130 Hercules launch aircraft.
Tests conducted that summer showed the drone was almost invisible to ground radar, and interceptors that were scrambled to find it ended up chasing each other. The only problem was that the drone generated a contrail, which gave it away. A "no-con" (no-contrail) program was initiated to fix the problem in subsequent variants, though apparently it wasn't fitted to the Model 147A. The system injected chlorosulfonic acid into the engine tailpipe when the drone entered hostile territory, creating tiny ice crystals which formed a transparent contrail. An effective system, although the chlorosulfonic acid was very corrosive which required use of high-grade stainless steel plumbing.
During the Cuban Missile Crisis a Rudolf Anderson over Cuba on 27 October 1962 by an S-75 Dvina and its pilot killed. Afterwards the Model 147As were authorized for reconnaissance missions in place of the U-2. The drones were mounted under the wings of their DC-130 Hercules controller aircraft, its propellers turning, at ready on the runway when notification came from Air Force Chief of Staff Curtis LeMay that the mission was scrubbed. The U-2s were used for reconnaissance over Cuba instead, with missions resuming on 5 November 1962. LeMay wanted to reserve the Fire Fly for later.
The delivery schedule for the high-altitude Model 147B was several months out, so the Air Force also ordered seven Model 147Cs, a production version of the 147A, as an interim solution. The Model 147C had a wingspan extended to , and incorporated the no-contrail system.
Three of this batch of Model 147Cs were modified to become special-purpose Model 147Ds. The 147D combined the functions of reconnaissance and the original Ryan Firebee mission of aerial target: it was to be used as bait for S-75 Dvina SAMs to obtain data on signals associated with the S-75. The SAM was targeted by a radar codenamed Fan Song and it was simple enough to pick up its signals with a normal SIGINT aircraft. The S-75 was also radio-controlled to the target by a ground command guidance link, with the missile carrying a transponder that sent back a signal to the Fan Song radar to allow tracking. Picking up these radio command signals was hazardous, since they only came on when a missile was launched. The proximity fuze signal was the most dangerous because it would only be detected moments before the SAM detonated.
A special "SAM sniffer" Radar MASINT payload was installed on the Fire Fly to pick up these signals, with the drone relaying the data to an ERB-47H electronic warfare aircraft. An active radar enhancement device was installed to encourage the enemy to take shots at the drone. The three Model 147Ds were delivered in December 1962. The Fire Fly code name had leaked in the meantime, so the new drones were given the codename Lightning Bug.
In July 1963, the Lightning Bugs reached full operational status, though they had yet to fly an operational mission. In late December 1963, the Air Force ordered fourteen more Model 147Bs. By this time Fidel Castro was threatening to shoot down U-2s flying over Cuba, and a May 1964 study concluded that the Lightning Bug was the best alternative. After information about the proposal leaked to the press, the United States administration decided to back up the U-2s with the Lockheed A-12, precursor of the SR-71 Blackbird spy plane.
While the fledgling Ryan Model 147 drones had thus far played only backstage roles, United States relations with China and North Korea and events in Southeast Asia would significantly ramp up their operational involvement in the next decade. Ryan Aeronautical's engineering expertise and feedback from the USAF's operational experience with the drones would also cause them be continually modified, redesigned and optimized for better performance, and further developed to take on an array of new missions.
During this time operational deployment of Model 147 drones would be undertaken by the Air Force's Strategic Air Command and its reconnaissance wings, equipped with DC-130 launch aircraft and recovery helicopters. Continued behind the scenes support from the National Reconnaissance Office, which had allocated project funds from its outset via the classified Program D for developing airborne intelligence collection platforms, also ensured that the Lightning Bug project would grow into a full-fledged aerial reconnaissance program.
The Johnson Administration feared Communist ChineseUrdang, p. 1105 intervention in the widening war, and decided to use the Lightning Bugs to monitor Chinese activities. The drones were sent with their DC-130 director aircraft to Kadena Air Base on Okinawa Island to conduct overflights of southern China.
The first Lightning Bug mission took place on 20 August 1964, though there were problems. The DC-130 controlling the mission was loaded with a pair of Model 147Bs. One drone failed to launch, and was later lost when it fell off its underwing pylon. The second 147B successfully completed its mission over China, flew back to Taiwan, deployed its parachute and splashed down in a rice paddy. The drone, however was dragged over the ground by the parachute which badly damaged the machine. Its film payload was recovered intact and although the drone's navigation hadn't been as accurate as hoped, images of several primary targets were recovered.
A total of five Lightning Bug missions were performed over China into early September 1964, with only two of them successful. The Nationalist Chinese, however were very enthusiastic about the Lightning Bugs. They had been flying U-2 spy planes over mainland China on behalf of the Central Intelligence Agency and were experiencing increased losses from S-75 SAMs.
Lightning Bug overflights continued and so did Chinese efforts to intercept them. The Chinese succeeded in destroying five drones by mid-April, and on 20 April 1965 put the wrecks of three of them on public display. With every shoot-down, the Chinese issued verbose press reports praising China's "great victory" in shooting down "reconnaissance planes of the Imperialism United States."
Although self-destruct charges were considered for installation on overflight Lightning Bugs it was finally decided not to, and the United States simply adopted a policy of "no comment" when asked about the reconnaissance drones. With no American crews lost in the shoot-downs, the U.S. press paid very little attention to the Chinese reports.
On 13 February 1966 — the fourth Model 147E mission — the drone was destroyed by an S-75, but not before it relayed the vital signal data. The U.S. had been desperate to get this data ever since the deployment of the S-75, and officials claimed that this single flight justified the entire Model 147 program. The information was immediately put to use to develop a simple warning system that would tell the pilot when an S-75 command signal was turned on, meaning a missile launch was imminent; this device would go into production as the AN/APR-26.
The decoys were designated Model 147N, with the first mission performed by one alongside a Model 147G on March 3, 1966. The two drones followed a parallel path until they reached the target area, where they diverged. North Vietnamese air defenses tracked the "brighter" 147N instead of the 147G, which was recovered. As an added bonus the 147Ns resulted in a few "kills" of North Vietnamese fighter aircraft. One fighter ran out of fuel when the pilot chased the drone out to sea, and other fighters were lost due to "friendly fire" accidents while hunting the drones.
The decoys worked so well that the Air Force ordered another batch of ten with a few minor improvements, and designated them Model 147NX. The initial Model 147Ns had been programmed to turn back and head for home in order to simulate a normal operational drone flight profile, and a few of them surprisingly did make it back even with their limited fuel supply. They crashed since they were not designed to be recovered, but the recovery system was not expensive and so the Model 147NX was fitted with recovery parachutes and gear as well as a cheap camera. If the decoy survived the mission, it might provide useful intelligence.
The fast-moving 147J drones flew low, making them difficult targets and increasing their odds of returning from a mission. Up to then the drones had parachuted to the ground upon return, but were often damaged by the impact. The Air Force then devised a retrieval method using a Sikorsky CH-3E helicopter that snagged the parachute in mid-air and it in. Mid-air retrieval proved effective, with an eventual 2,655 successful recoveries in 2,745 attempts, a 97% recovery rate. A total of 105 drone missions were flown over North Vietnam and Communist China in 1966. Most of these were 147G flights, along with some 147Js, as well as the 147E and 147F SIGINT missions and the 147N and 147NX decoys. One of the 147Js actually took a picture of an S-75 SAM streaking past it.
While Ryan was working on the Model 147NP, the Air Force also came forward with an urgent requirement for a low-altitude night reconnaissance drone. Four Model 147NPs were pulled from production and modified as Model 147NREs, where "NRE" stood for "night reconnaissance electronic". The Model 147NREs had a dual-camera payload synchronized to a bright white strobe light fitted into the drone's belly. The strobe lit up the sky when it went off.
Both the 147NREs and 147NPs went into action in Vietnam in spring of 1967. The first 147NRE mission was in late May, with the first 147NP mission following a week later. The Model 147NREs were painted black as appropriate to their night mission, while the Model 147NPs were painted in jungle camouflage colors.
The Model 147NPs performed as desired, but the Model 147NREs did not quite meet expectations. The "footprint" of the strobe light was fairly small, and the drone's navigation system lacked the accuracy to put the cameras precisely on target. Despite these drawbacks the Air Force did obtain useful intelligence from the drone's cameras even when they were not on target, as well as some minor psychological warfare effect from the startling bright strobe flashes, and felt that the concept was worth further development.
Another low-altitude reconnaissance variant was derived from the Model 147NP, the Model 147NQ. Its main distinction: instead of using an automatic guidance system, it was radio-controlled by a crewman on its DC-130 launch aircraft.
The Model 147NC, which entered service in 1969 with the 11th Tactical Drone Squadron was generally similar to the Model 147NA, with the addition of endplate auxiliary fins on its tailplane. It had been designed a few years earlier to fly at medium altitude carrying AN/ALE-2 chaff dispensers under each wing to counter enemy radar systems. The Model 147NC had originally been intended to support bombing raids over North Vietnam under Compass Bin and Combat Angel, but air strikes on North Vietnam were scaled back in March 1968 and stopped completely by November so the 147NC was not deployed in its intended role. When bombing resumed in 1972, chaff was dropped by piloted F-4 Phantom Fighter aircraft instead. Model 147NCs did get into action during the "political offensive" of 1972 by dropping propaganda leaflets. The project was codenamed Litterbug, but the troops called them "bullshit bombers".
A medium altitude training version of the 147NC designated the Model 147NC(M1) lacked underwing pylons and was operated for reconnaissance RPV training with the 11th Tactical Drone Squadron. Some of these were later updated to AQM-34V ( Ryan Model 255) standard in the mid-1970s.
"Stealthy" features that had been built into the original Lightning Bugs were becoming less and less effective, so the Model 147H was designed with new features to improve survivability, including a radar warning receiver (RWR) to alert the drone if it was illuminated by Fighter aircraft or SAM radars, an improved guidance system that sent it into a right turn when alerted by the RWR, an ECM box named "Rivet Bouncer" to jam the S-75 SNR-75 radar, a coating in the jet intake to reduce radar reflectivity, and an improved no-contrail system.
Older Model 147Gs continued to fly high-altitude missions in parallel with the Model 147H drones until the 147Gs were phased out in August 1967. Despite losses, the survivability of Model 147H drones did prove to be better than that of the 147B and 147G.
The Model 147S carried a single camera that cost less but provided better coverage than the earlier dual-camera payloads. At typical operating altitudes the camera system of the 147S could image a strip of land long with a resolution of up to 1-foot (30 centimetres), or even under optimum conditions. Cost of a production Model 147S was about $160,000 USD in contemporary dollars, which was about 60% of the cost of a Model 147G or 147H.
The Model 147S drones were built in a number of different production "blocks". The initial 147S block was designated the Model 147SA, and the subtype performed its initial operational flight in December 1967.
The Air Force was impressed by the results of the Model 147SA missions and ordered a second batch of Model 147SBs. The Model 147SB carried a "multiple altitude control system" (MACS) that allowed it to shift in flight between three preprogrammed altitudes ranging from , making it much more unpredictable. It also had improved gyrocompass to permit tighter turns. Initial flights began in March 1968, with the Model 147SAs then being phased out by attrition.
The next block of 147S family was the Model 147SRE, intended for the night reconnaissance role. Instead of the white-light strobe used on the Model 147NRE, the 147SRE used an infrared strobe which was barely noticeable from the ground, and infrared film. The 147SRE also featured an improved guidance system with Doppler radar and flew its first mission in November 1968. Although the Model 147SRE performed well, photo interpreters found the infrared images difficult to inspect and sometimes failed to spot targets.
The low-level 147S flights were "exciting" by the standards of robot warfare. One suffered a malfunction in its flight-control computer and decided to fly at an altitude of instead of as planned. The drone made it back safely, though photo interpreters were startled to find out that the images included a picture of a power line tower, taken from underneath the power lines.
Losses were heavy at the altitude set for early Model 147S missions, so the flight altitude was changed to . The drones were used in missions over Hanoi and Haiphong which had powerful air defenses. One Model 147S took a picture of an S-75 streaking past, followed by a picture of the missile exploding; then — due to an autopilot programming error — the drone skirted a ridgeline, just missing the treetops.
The fourth production variant of the Model 147S family was the Model 147SC, which featured an improved Doppler radar navigation system with digital controls for greater flight accuracy. Initial operational flight of the Model 147SC Buffalo Hunter (its program codename as known to USAF crews) was in January 1969. Of the hundreds of Model 147S drones procured by the Air Force most were Model 147SCs, which would eventually fly almost half the total number of Lightning Bug missions.
A modified version, the Model 147SC/TV, was introduced in the spring of 1972. This featured a TV camera that relayed imagery to the DC-130 drone controller aircraft.
The low altitude-optimized 147S series continued to be developed even as the war drew to a close. The Model 147SD (AQM-34M) which saw service in 1972 and later featured external underwing tanks for extended range, a substantially more accurate navigation system, and a new cooling system to deal with tropical environmental conditions. The SD was externally similar to its SC predecessor with a slightly different nose shape and systems package; 87 of the Model 147SD were built under the Air Force's Compass Bin and Buffalo Hunter programs.Taylor and Munson, Jane's Pocket Book 13 — RPVs: Robot aircraft today. p. 203 Some 147SDs were converted to the Model 147SDL which featured a navigation system that obtained position information from the LORAN radio location network, providing the drone with greater accuracy. One Model 147SD served as a testbed for the USAF's Compass Robin program, which aimed to develop expendable radio frequency sensors that could be covertly ejected from RPVs or drones in areas defended by Soviet Union S-75 Dvina Fan Song radars and thus provide the capability to collect electronic intelligence information.
Despite the general decline in high-altitude reconnaissance RPV use, new mission roles would emerge. In April 1969 a Lockheed EC-121 Super Constellation SIGINT aircraft was shot down in international airspace by North Korean fighters, killing all 31 crew members on the aircraft. This incident led to consideration of using an unmanned drone to do the SIGINT job, resulting in the Model 147TE or Combat Dawn RPV. The Model 147TE's first operational flight was in February 1970, although this flight and those that followed over two months were really just evaluation tests. The tests proved successful and an order for fifteen production Model 147TE drones followed, with the first operational flight of a production 147TE in October 1970.
The Model 147TEs did not overfly hostile airspace; they stayed well out to sea at relatively high altitude, or cruised along the border between North and South Korea. They could fly under their own guidance or be controlled by their DC-130 launch aircraft. The drones relayed SIGINT data over a data link to ground stations for analysis. This data link technology would be developed for use in other reconnaissance aircraft, such as the Lockheed U-2 and the Beechcraft RC-12 Guardrail.
Late in the Model 147TE program, underwing external tanks were added to improve time on-station from five to eight hours. In 1973 an updated version, the Model 147TF, with external tanks as standard and improved SIGINT gear went into operation. Almost 500 missions were flown by Model 147TE and 147TF Combat Dawn RPVs between 1970 and 1975.
By 1970 the Model 147 program was beginning to become public knowledge. Aviation Week magazine carried an article on the drones that November, though it was based on informal and unconfirmed information. The following spring, the Air Force released pictures of the drones along with a very general statement that they were used for reconnaissance. No technical or operational details were released.
The number of drone continued to increase through 1971 and 1972. The Model 147SC was the workhorse for low-altitude reconnaissance during this period; in December 1972 during Operation Linebacker II the USAF depended almost entirely on the Buffalo Hunter AQM-34L/M RPVs for bomb damage assessment due to bad weather. High altitude flights by the 147T series continued. The Model 147H was on the way out by this time, performing its last mission in September 1972. The Soviets had updated the S-75's electronics, thus American electronic countermeasures needed to be updated as well. Cameras were replaced by a "SAM sniffer" payload, and a Model 147H flight on September 28 was able to obtain the necessary data before the drone was destroyed by an S-75.
The North Vietnamese conducted an Easter Offensive in the spring of 1972 which was broken by American air power. U.S. President Richard Nixon then retaliated with a renewed bombing campaign against North Vietnam, codenamed Operation Linebacker, to persuade the North Vietnamese to negotiate. The two sides seemed to be close to an agreement, but in December 1972 the talks collapsed and President Nixon ordered the Operation Linebacker II campaign which continued into the final days of 1972. The bombing stopped completely after the January 1973 peace agreement.
Reconnaissance flights continued after signing of the peace treaty in order to ensure that the North Vietnamese were honoring their side of the bargain. By this time drone technology and operational practice had been well refined. While the Model 147SC drones had been designed to survive an average of 2.5 missions, in practice the average was much higher. One example, nicknamed "Tom Cat", performed a record 68 missions.
The Lightning Bug program had proven highly successful. A series of fast-track adaptations of an existing target drone resulted in a system whose effectiveness was beyond expectations, even with guidance technology that was extremely crude by 21st century standards. Despite this, Lightning Bugs could not affect the course of Vietnam War. Drone reconnaissance clearly showed that the North Vietnamese were violating their agreement with the Americans on a massive scale, but the U.S. leadership was unwilling to commit to ending its "endless war". When the North Vietnamese began their last offensive in early 1975 the U.S. did little to stop it; Saigon fell on April 30, 1975, and the war was over.
The Lightning Bug program also came to an end. The last Model 147S low-altitude drone flight occurred on the day Saigon fell. AQM-34R / Model 147TF Combat Dawn flights continued until June 1975, and then most of the surviving drones were stockpiled.
Five BQM-34-53 Extended Range Firebees were also used to lay chaff corridors during the 2003 invasion of Iraq. The drones were modernized by Northrop Grumman in a fast-response program earlier that year, being fitted with chaff dispensers and other improvements including GPS-based programmable waypoint guidance systems (which may or not have been added by the upgrade program). These Firebees were delivered for service in charcoal-black paint schemes. Only one DC-130 drone launcher aircraft remained in the U.S. military's inventory at the time and was not immediately operational due to a malfunction. Two Firebees were ground-launched on the first night of the operation; the other three were air-launched by the DC-130 on the second night of the operation. The drones flew until they ran out of fuel and crashed. Iraqi TV broadcast footage of the wrecks while describing them as piloted aircraft.
Almost half of the missions were flown by the Model 147SC, of which about a thousand were built. 578 drones of all types were lost, with over half shot down and the rest lost in various accidents. It is something of a compliment to the usefulness of the Model 147 that the Chinese used the Lightning Bugs shot down over their territory to copy the basic Firebee design and produce it themselves.
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