page_title: Ryan Model 147
section_title: Ryan Model 147S Buffalo Hunter
hierarchical_section_title: Ryan Model 147 / Operational history / Ryan Model 147S Buffalo Hunter
caption_attribution_description: English: The U.S. Air Force Ryan AQM-34L Firebee drone "Tom Cat" of the 556th Reconnaissance Squadron flew 68 missions over North Vietnam before being shot down by anti-aircraft fire over Hanoi.
context_page_description: The Ryan Model 147 Lightning Bug is a jet-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 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.
context_section_description: The U.S. Air Force also pursued a refined solution for the low-altitude reconnaissance mission, and "refinement" meant balancing optimization for the mission against cost. Strategic Air Command's Buffalo Hunter program was implemented to conduct low altitude photographic reconnaissance in Southeast Asia using unmanned aircraft, particularly for time-sensitive targets such as military airfields and suspected SAM sites in North Vietnam. The initial low-altitude drone, the Model 147J, had been derived from the high-altitude Model 147B and retained the 147B's wide wings; these were a drawback because at low altitudes they reduced the drone's maneuverability. The new low-altitude optimized Model 147S had a J69-T-41A engine and featured the original Firebee wings with a 13-foot (4.0 m) span which were also lower cost to manufacture. The fuselage was stretched to a length of 29 feet (8.8 m).
  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 60 miles (96 kilometres) long with a resolution of up to 1 foot (30 centimetres), or even six inches (15 centimetres) 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 1,000 to 20,000 feet (300 meters to 6,100 meters), making it much more unpredictable. It also had improved gyros 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 navigation 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 150 feet (46 m) instead of 1,500 feet (460 m) 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. The picture was posted on the unit bulletin board with a caption provided by the commander: "The FAA frowns on this bullshit!"
  Losses were heavy at the 1,000 to 1,500 feet (300 to 450 meters) altitude set for early Model 147S missions, so the flight altitude was changed to 500 feet (150 m). The drones were used in missions over Hanoi and Haiphong which had powerful air defenses. One Model 147S took a picture of an SA-2 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 Lig
caption: U.S. Air Force AQM-34L (Ryan Model 147SC) "Tom Cat" of the 556th Reconnaissance Squadron flew 68 missions over North Vietnam before it was lost to anti-aircraft fire over Hanoi.
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