Genesis of the Predator UAV

Leading Systems' Amber UAV, grandfather of the Predator

In the mid-1970s, Abraham Karem, a designer of high-tech weaponry for the Israeli Defense Forces, emigrated to the United States but despite his credentials working with the Israeli military, found himself unable to get employment with any of the major American defense contractors. Karem had some innovative ideas for unmanned aerial vehicles (UAVs), so ended up starting his own company, Leading Systems, in the garage of his home in Irvine, California, to pursue his UAV concepts. In 1982, the Defense Advanced Research Projects Agency, DARPA, was providing seed money to small companies that offered innovative solutions to problems outlined by the US military. One such problem was a need for an advanced UAV that could provide reconnaissance imagery while having a long endurance but be both inexpensive and reliable. The classified DARPA program TEAL RAIN was established to study the technology for long-endurance UAVs. The problem at the time was that previous long endurance UAVs exemplified by the Boeing Condor as well as the Compass Cope program were large and prohibitively expensive. Two years after he founded Leading Systems, Abraham Karem secured seed money from DARPA to develop his concepts and in 1984, he received a contract to develop a classified reconnaissance UAV code-named Amber. While most competing companies adapted existing piston engines from snowmobiles and motorcycles for their designs, Karem used the DARPA seed money to hire engineers willing to design and build engines custom tailored for the Amber program. 

The first Amber UAV flew in 1986 (just two years after Karem got the DARPA contract!). Karem designed Amber to fold up and be fired from a standard torpedo tube- the US Navy was one of the backers of the Amber project- as a result, it had a slender fuselage with a parasol wing and an inverted-V tail with a pusher prop. Two types of Amber UAVs were planned- the "A" version had a pointed nose section carrying a warhead and was to be a low-cost cruise missile- approaching its target, the wing was to be jettisoned, hence the need for a parasol-type wing. The "B" version replaced the warhead section of the "A" version with a slightly bulged nose compartment that housed imaging sensors and datalinks to act as a reconnaissance UAV. The "B" version had a stalky retractable landing gear as well. The use of an inverted-V tail was to protect the pusher prop during landing and takeoff. By 1988, Amber had demonstrated a flight endurance of nearly 40 hours when competing companies were barely getting 12 hours out of their designs. Not only was Karem's design outflying its competitors, it was also proving to be immensely reliable as well. Thirteen Amber UAVs were built by 1990. 

In the same year that Amber was breaking records in 1988, Congress began to get impatient with the Pentagon's slow pace of UAV development. By 1990 the Pentagon was forced by Congressional mandate to consolidate the UAV research efforts of the different armed services into a single Joint Program Office (JPO). The JPO, however, wasn't budgeted any funds for research, which meant that only big defense contractors could stay in the running where internal corporate funding was plentiful. At the same time, and in its infinite wisdom, Congress banned DARPA from supporting UAV projects outside of the jurisdiction of the Pentagon JPO and as a result, Leading Systems' funding dried up overnight and Amber had to be canceled despite its achievements. 

Leading Systems/General Atomics Gnat 750

To try and stay afloat, Abraham Karem and his small team at Leading Systems developed a UAV based on Amber that was less-complex and used a standard Rotax piston engine for propulsion. This UAV was named the Gnat 750. Since the Gnat was planned for the export market, it was larger and didn't have as many of the advanced features of Amber, but it retained the overall layout with the difference that the wing was now directly attached to the fuselage instead of high-mounted on a pylon. The inverted-V tail was still there as well as a pusher prop and the stalky retractable undercarriage. The Gnat 750 first flew in 1989 and despite being "less high-tech" than Amber, boasted a significant number of design improvements. However, the loss of DARPA funding was too much for Leading Systems and Karem was looking at shutting down the company. However, San Diego-based defense contractor General Atomics was looking in 1990 to diversify its holdings outside of its core business of nuclear reactor technologies. One of its corporate directors was a former US Navy rear admiral, Thomas Cassidy, who joined General Atomics in 1987. He thought Karem's operation would be a good fit for what General Atomics was looking for and in 1990, General Atomics acquired Leading Systems and set up Abraham Karem and his team in a subsidiary General Atomics Aeronautical Systems to continue the development of the Gnat 750 UAV. 

In 1993, the Pentagon issued a requirement to rapidly field a surveillance UAV to support UN peacekeeping forces in the former Yugoslavia. The Gnat 750 was selected, but because the need was immediate and existing military acquisition procedures were too slow, the program was transferred to the CIA under the code name LOFTY VIEW. Since the CIA would be operating the Gnat 750 in secret, it fell outside of the purview of the Congressional mandate the created the UAV JPO that inadvertently killed off the Amber program. By 1994 the first Gnat 750s were deployed to a CIA operating base in Albania for operations throughout the Balkans. The UAVs provided overhead surveillance for UN convoys as well as spotting artillery emplacements and the operating locations of the various belligerents in the wars that wracked the region through the latter half of the 1990s. The bad weather of the Balkans and the limited range of the Gnat's datalink proved to be the main issues that affected operations. 

While the CIA was getting the Gnat 750 operational over the Balkans, General Atomics Aeronautical Systems had secured funding under an advanced concept technology program. At the time, UAV development had been stratified into "Tier" levels based on endurance and performance. I had reviewed these Tiers a year ago in a previous blog posting that covered the development of top-secret stealthy Quartz UAV: 

In the 1990s, there were three "tiers" of UAV development based on operational capability. "Tier I" was for a low-altitude system that became the Gnat-750 UAV. "Tier II" was for a more capable medium altitude system based on the Tier I craft and that became the current Predator UAV family. The specification for "Tier III" would have been filled by the Quartz project, but with its cancellation, Tier III was split into two- Tier II+ was for the Quartz's performance without stealth and this became the RQ-4 Global Hawk UAV. Tier III- ("Tier III Minus") was stealthy but without the performance and payload of Tier II+. This design became the RQ-3 DarkStar. DarkStar, a joint effort between Boeing and Lockheed, had little in common with Quartz and itself would be canceled in 1999 in favor of further development of the Global Hawk.

General Atomics RQ-1/MQ-1 Predator

The Pentagon was issuing contracts for UAVs at each Tier. General Atomics's funding was for development of a Tier II UAV. The new design took the Gnat 750 and stretched the fuselage and lengthened the wings. The inverted-V tail, stalky retractable undercarriage, and pusher prop were retained (though with a more powerful Rotax piston engine). Since one of the weaknesses of the Gnat 750 was the limited range of its datalink, the new UAV had an enlarged nose section that had the imaging payload on the underside of the nose similar to what the Gnat 750's layout, but incorporated a satellite communications dish in a bulged radome as the new datalink. Use of a satcom datalink now meant that the UAV operators and pilots didn't even have to be in the same region as the UAV's area of operations. It was now possible for the crews to fly the UAVs from stateside bases using the satcom datalinks to fly the Tier II UAV anywhere in the world it was needed. 

Named Predator, the new Tier II UAV made its first flight in June 1994. Less than a year later during the Roving Sands 95 exercise at Fort Bliss, Texas, the Predators were used for the first time in an operational demonstration. They were so successful at Roving Sands that year that the USAF established its first UAV squadron, the 11th Reconnaissance Squadron at Indian Springs Auxillary Airfield in Nevada (later renamed Creech AFB in 2005) shortly after the exercise in Texas and just one month after Roving Sands, the first Predators were deployed to the Balkans under Operation Nomad Vigil. From July to November that year the 11th RS operated its Predators out of Gjader in Albania in support of Operation Deliberate Force, the NATO air campaign against Bosnian Serb forces. While more capable than the Gnat 750s operated by the CIA, the need for overhead surveillance was so great in the Balkans that both the Predator and the Gnat 750s operated simultaneously in theater. 

By 2001, the USAF had taken delivery of 68 Predator UAVs. Due to the steep learning curve in operating such a radically different type of aircraft, 19 were lost, but only 4 were confirmed to have been shot down over the Balkans. But it was only the beginning of how the Predator began to change the way air campaigns were fought. And that is subject matter for a future posting on this blog!

Sources: Birds of Prey: Predators, Reapers and America's Newest UAVs in Combat by Bill Yenne. Specialty Press, 2010, p37-40.

 Popular Science, September 1994. "Drones: Invented and Forgotten" by Bill Sweetman, p34.

Designation-Systems.net by Andreas Parsch. "Leading Systems Amber" and "General Atomics Gnat".

Photos: Federation of American Scientists, United States Air Force.

The Ground-Breaking Boeing Condor UAV

The Condor in flight

In the 1960s as the technology for unmanned aerial vehicles (UAVs) progressed, the USAF initiated two programs that would provide unmanned analogues to the premier airborne reconnaissance aircraft of the day, the Lockheed SR-71 Blackbird and the U-2. Both aircraft had their strengths and weaknesses and the USAF hoped to expand upon their capabilities with adjunct UAV reconnaissance aircraft. The companion program to the SR-71 Blackbird originated from the Lockheed Skunk Works as the D-21/Tagboard reconnaissance drone for the CIA. Possessing the same Mach 3 performance as the Blackbird, the D-21 was originally launched from the back of a modified A-12 Cygnus. However, after a disastrous fourth airborne launch that cost the launching aircraft and one of its crew, the D-21/Tagboard was moved over to the Boeing B-52 Stratofortress as the launching aircraft. After four failed operational missions in which the D-21 was lost, the program was canceled in 1971, at which time the second program which would have been a companion to the Lockheed U-2 was getting under way. Being a large jet-powered glider-like aircraft not too dissimilar in performance to the U-2, in 1971 the USAF initiated the Compass Cope program with Boeing and Teledyne Ryan producing prototypes- Boeing's design being the YQM-94 Gull (Compass Cope B) and Ryan's competing design being the YQM-98 Tern (Compass Cope R). After a competitive evaluation, Boeing's Gull was chosen in August 1976, to which Ryan lodged a protest. It was pointless at that juncture as the USAF canceled Compass Cope in 1977 before any production Gulls were built. 

But it wasn't the end of the story for Boeing's work for a high-altitude, long-endurance (HALE) UAV. The Defense Advanced Research Projects Agency (DARPA) was still interested in the idea of a HALE UAV for strategic reconnaissance. DARPA wanted to go one step further than the Compass Cope program, though. A contract was issued to Boeing for a HALE UAV that could operate for days at high altitudes carrying reconnaissance payloads that ranged for optical camera systems to electronic intelligence collection arrays to even an airborne synthetic aperture radar for all-weather/day-night surveillance. Boeing contracted with Burt Rutan who was using an all-composite structure in his record-breaking long-distance aircraft, Voyager. Boeing's design, aptly named Condor, used a predominantly composite structure with a wingspan of 200 feet, the same as that of the Boeing 747. The fuselage was only 68 feet long but was slab sided to facilitate the mounting of either an ELINT or SAR antenna array. Designed to be disassembled into sections and transported by a Lockheed C-5 Galaxy, the Condor's fully loaded weight was 60% fuel. 

Comparing the Condor and the 747

The wing's airfoil section was extremely efficient and provided natural laminar flow at altitudes in excess of 50,000 feet. Since the Condor was to be autonomously controlled, the wing had to have benign stall characteristics to simplify the control of the UAV. The wing was so efficient that it had twice the lift-drag ratio of the U-2- 40:1 compared to 20:1 for the spyplane. Since the wing would be highly flexible, a fuel transfer system was used to move fuel between wing tanks to reduce flexing in flight. The use of composites resulted in a wing that weighed only 2 lbs/square foot- an impressive feat considering that a commercial jetliner's wing comes in at approximately 30 lbs/square foot. 

The Condor was powered by two Teledyne Continental 175-horsepower six-cylinder piston engines that were superturbocharged for operation at very high altitudes. Each wing-mounted engine drove a three-bladed propeller 16 feet in diameter. Since the propellers were optimized for high-altitude cruise, at lower altitudes they would cause a significant amount of fuel burn and drag- as a result, a two-speed gearbox was used- one gear ratio for low-altitude flight and a different gearing for high altitude cruise. 

The flight control computer of the Condor was groundbreaking in that the Condor was the first UAV designed and flown autonomously without external control input from a remote pilot. Two Delco Magic 3 series computers were used as the brains of the Condor- the Magic 3 series computers were also used in the guidance systems for the Titan II ballistic missiles and the Delta family of rocket launchers. One computer acts as the primary computer with the second one operating in standby and ready to takeover should the primary computer fail. The control software consisted of only 60,000 lines of Fortran code- minuscule when one considers that today's RQ-4 Global Hawk reconnaissance UAV uses several million lines of software code! The Condor's computers were responsible for vehicle functions, flight control, and navigation using inputs from an inertial navigation system (this was in the days before GPS). The computer system was even designed to not only handle inflight emergencies but also prevent an enemy from taking electronic control of the UAV. Should that happen, the system was designed to recognize it was being taken over and immediately direct the Condor back to friendly territory. 

A microwave landing system was adopted to provide control of the Condor during takeoff as well as landing. Using a dolly, once the Condor reached 65 knots, it lifted off the ground and left its takeoff dolly behind. It would take anywhere from two to three hours for the Condor to reach its cruising altitude of over 50,000 feet. At cruise altitude, the Condor cruised at 200 kts, but its all composite construction made it a very small radar target and its piston engines had a very low infra-red signature- so despite its size and apparent leisurely cruise speed, it was a difficult target to track on most radars of the day. Descent for landing took two to three hours as well, and an extendable nosewheel and landing skids were used for landing. To save weight, instead of doors covering the skids and wheel, a replaceable Mylar sheet was used that the skids and nosewheel broke through on landing.

The Boeing Condor today at the Hiller Aviation Museum 

The Condor was developed in secret and its rollout in March 1986 was its unveiling to the world. It made its first flight on 9 October 1988 from Boeing's test facility at Moses Lake, Washington (the former Larson AFB). Since the rules on UAV operations in controlled airspace had yet to be fully written, a manned chase plane had to accompany the Condor during its transit through any controlled airspace. Only eight test flights were made with the last one on 28 November 1989, but the Condor set two world records- one for record altitude for a piston-engined aircraft at 67,028 feet on the fourth test flight and one for unmanned aircraft endurance at an impressive 58 hours, 11 minutes on the final test flight. Given that the test flights occurred over eastern Washington state, it's unlikely any operational reconnaissance payloads were carried, but to this day the exact nature of the payloads to have been carried- or even if they were carried- on the Condor remain classified. With a cost of $300 million, the Condor program did prove the viability of autonomous UAV flight as well as advanced composite construction and ultra-lightweight structures, but it lacking in military flexibility as well as its slow speed resulted in its cancellation after the final test flight. Only one Condor was built and flown, and in 1998 it was acquired by the Hiller Aviation Museum in the Bay Area where it can be seen on display today. It's the largest aircraft to be suspended in an interior museum display in the world. Not bad, even just sitting in the museum it still sets a record!

Sources: Birds of Prey: Predators, Reapers and America's Newest UAVs in Combat by Bill Yenne. Specialty Press, 2010, p20-32. 
Condor photo in the Hiller Museum by Joe May @ Travel for Aircraft- "Photo Funday- Boeing's Condor"