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[7.0] US Battlefield UAVs (2)

v1.2.0 / 7 of 16 / 01 jan 03 / greg goebel / public domain

* This chapter completes the discussion of US battlefield UAVs.


[7.1] BAI AEROSYSTEMS BQM-147 DRAGON DRONE
[7.2] S-TEC SENTRY, SENTRY HP / LEAR ASTRONAUTICS SKYEYE
[7.3] RYAN MODEL 324 SCARAB, BQM-145A MEDIUM RANGE UAV
[7.4] SIKORSKY CIPHER / BELL EAGLE EYE / FREEWING SCORPION
[7.5] BOEING X-50 DRAGONFLY / FRONTIER SYSTEMS A160 / UCAR

[7.1] BAI AEROSYSTEMS BQM-147 DRAGON DRONE

* The BAI Aerosystems (BAIA) Dragon Drone, which as mentioned in an earlier chapter served in the Gulf War as the "Exdrone", is the product of over a decade of refinement and is now in widespread service.

The Dragon began life in 1986, when the US Marines Corps contracted with the Applied Physics Laboratory (APL), an offshoot of Johns Hopkins University in Baltimore, Maryland, that works on government technology development contracts, to build a small piston-powered UAV as an "expendable jammer" for battlefield electronics warfare. The program was logically named "ExJam". BAI Aerosystems was a subcontractor to APL and provided airframe parts.

A little "creeping featurism" infected the program as the Marines considered more applications for the little drone, and in 1987 the program was given the new name of "Expendable Drone" or "Exdrone". However, APL wasn't able to meet the schedule requested by the Marines for fielding the Exdrone, and so the program was passed on to BAI Aerosystems, with the Navy assisting by developing a video imaging system for tactical reconnaissance.

The NASA Langley Flight Research Center also assisted in the development effort, performing wind-tunnel tests and making recommendations for aerodynamic improvements, and after these changes the BQM-147A Exdrone went into service with the Marines in time to help them chase the Iraqis out of Kuwait City. A few years later, the UAV-JPO also bought several hundred Exdrones for demonstrations and training to help get tactical officers in tune with battlefield UAV capabilities.

The current "Dragon Drone" is an improved version of the Exdrone, obtained through a 1996 contract with the Marines. BAI renamed the UAV since the Exdrone wasn't really all that expendable, given that it carried a reasonably sophisticated sensor system and and flight avionics. The Dragon Drone is a flying wing with a single vertical tailplane that, as mentioned earlier, is symmetrically designed to allow it to fly with either side up.

The Dragon Drone is powered by a small piston engine. It can carry one of three different plug-in turrets, featuring daylight color TV with a laser rangefinder, daylight color TV, or infrared imager. It can also be fitted with an auxiliary fuel tank for increased range.

   BAIA DRAGON DRONE:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                2.44 meters         8 feet
   length                  1.52 meters         5 feet
   empty weight            25 kilograms        55 pounds
   max loaded weight       43 kilograms        95 pounds

   cruise speed            130 KPH             80 MPH / 70 KT
   service ceiling         3,000 meters        10,000 feet
   endurance               3 hours

   launch scheme           Pneumatic catapult.
   recovery scheme         Net capture or skid landing.
   payload                 Day / night imager or other payload.
   guidance system         Programmable with GPS & radio control backup.
   _____________________   _________________   _______________________

The US Coast Guard is now procuring a "navalized" version of the Dragon Drone under the name "Condor", and intends to use it with Coast Guard cutters and similar small ocean-patrol vessels. The Condor will be useful for missions such as search and rescue or hunting drug trafficers.

Launching and recovering a UAV off such small vessels is troublesome. Naval UAVs have traditionally been launched with a catapult or RATO boosters, and recovered using a net. Not only is this approach unsuited to smaller vessels, it is also not particularly reliable even on large vessels, with catapult launches causing drone damage, catapult failures leading to loss of the drone, and recoveries similarly leading to damage through collisions and unintended ditching.

A Saint Louis, Missouri, company named Advanced Aerospace Technologies Incorporated (AATI) has come up with an alternative scheme for launching and recovering a Dragon Drone or other small UAV from small vessels. The scheme involves the use of a parasail and is referred to the "runway in the sky (RITS)".

In AATI demonstrations, a Dragon Drone is attached to a piggyback frame that harnesses the drone to the parasail. The parasail is reeled out into the wind until it reaches an altitude of about 250 meters (800 feet). The drone is then released, diving until it builds up enough speed for the operator to pull it out of the dive and sent it on its mission.

In recovery, the parasail is used to lift a tow line into the sky, with the tow line trailing a series of recovery lines hanging between the parasail and the ship. The drone is flown into the recovery lines, and a snaplock mechanism on the drone's wing grabs onto a line. The drone is then reeled back down to the ship. The tow line has more "give" to it than a recovery net, reducing the likelihood of damage.

The current RITS scheme can handle UAVs weighing up to 180 kilograms (400 pounds), but AATI thinks it can be scaled up to handle larger aircraft. AATI claims the system is inexpensive and easy to use. They also point out that the parasail could also be used to loft an antenna to allow over-the-horizon communications with a UAV. Whether the Coast Guard intends to use this scheme or not is uncertain, but it certainly is an interesting concept.

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[7.2] S-TEC SENTRY, SENTRY HP / LEAR ASTRONAUTICS SKYEYE

* S-TEC systems of Texas, now part of the British Meggitt Defence Systems organization, builds a battlefield mini-UAV named the "Sentry" in roughly the same class as the BAI Dragon drone. In fact, the Sentry looks something like an Exdrone with a twin-boom raised tail. It is powered by a 19.5 kW (26 horsepower) piston engine in a tractor configuration.

   S-TEC SENTRY:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                3.35 meters         11 feet
   length                  2.24 meters         8 feet
   payload                 27.2 kilograms      60 pounds
   empty weight            59 kilograms        130 pounds
   launch weight           109 kilograms       240 pounds

   maximum speed           175 KPH             110 MPH / 95 KT
   service ceiling         4,880 meters        16,000 feet
   endurance               8 hours

   launch scheme           Wheeled dolly or pneumatic catapult.
   recovery scheme         Parasail or skid landing.
   payload                 Day / night imager or other payload.
   guidance system         Programmable with radio control backup.
   _____________________   _________________   _______________________

S-TEC's main business is building autopilots for civil aviation, and small UAVs were a logical extension of that business. S-TEC introduced the Sentry in 1986, and has sold over 130 since that time.

S-TEC has now built a follow-on battlefield UAV, the "Sentry HP", which is a different design with a broad wing and a vee tail. The Sentry HP is larger, with greater payload capacity and an underwing stores capability. It is powered by a variant of the same 26 horsepower engine as the Sentry. It can be ordered with an option for fixed landing gear to permit conventional takeoff and recovery.

   S-TEC SENTRY HP:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                3.90 meters         12 feet 10 inches
   length                  2.57 meters         8 feet 5 inches
   payload                 34 kilograms        75 pounds
   empty weight            81.6 kilograms      180 pounds
   launch weight           147 kilograms       325 pounds

   maximum speed           185 KPH             115 MPH / 100 KT
   service ceiling         4,880 meters        16,000 feet
   endurance               8 hours

   launch scheme           Pneumatic catapult or runway takeoff.
   recovery scheme         Parasail, skid, or runway landing.
   payload                 Day / night imager or other payload.
   guidance system         Programmable with radio control backup.
   _____________________   _________________   _______________________

S-TEC is now teaming with TRW Corporation in the US and IAI of Israel to sell the Sentry HP on the international market.

* Lear Astronautics was one of the first US companies to investigate battlefield UAVs, flying the first prototype of their "SkyEye" series in 1973, leading to the first flight of the improved R4E variant in 1978. The R4E has been continuously refined since then in a sequence of subvariants.

The R4E SkyEye is in service with a number of countries for battlefield surveillance, and has also been used commercially for pesticide spraying. In the late 1980s, McDonnell Douglas offered a variant of the SkyEye named the "Sky Owl" in response to a US Army competition, but the IAI/TRW Hunter won the award instead. Apparently a few stock R4Es were also purchased by the US Army's Central Command in Latin America and used for border patrols.

The SkyEye has the common pusher-propeller twin-tailboom configuration, but it has distinctive slightly-swept wings and antennas on top of the vertical tailplanes. It is powered by a UAV Engines Limited (UEL) 39 kW (52 horsepower) rotary engine. The SkyEye can carry two underwing stores along with its other payload.

   LEAR ASTRONAUTICS SKYEYE:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                7.32 meters         24 feet
   length                  4.1 meters          13 feet 5 inches
   payload                 82 kilograms        180 pounds
   launch weight           567 kilograms       1,250 pounds

   maximum speed           200 KPH             125 MPH / 110 KT
   service ceiling         4,570 meters        15,000 feet
   endurance               > 8 hours

   launch scheme           Catapult or runway takeoff.
   recovery scheme         Parachute, parasail, or runway landing.
   payload                 Day / night imager or other payload.
   guidance system         Programmable with radio control backup.
   _____________________   _________________   _______________________

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[7.3] RYAN MODEL 324 SCARAB, BQM-145A MEDIUM RANGE UAV

* In the 1980s, Ryan followed up on its long history of robot aircraft development with two jet-propelled UAVs for tactical reconnaissance and other roles, named the Model 324 Scarab and the similar BQM-145A.

The Scarab is a medium-range reconnaissance asset, similar in operational concept to the old Ryan FireFly UAVs, but implemented with improved technology. It was designed to Egyptian Air Force requirements, and was first flown in 1988. 56 were delivered and the type remains in service. It is a neat UAV with low-midbody-mounted swept wings, a twin-fin tail, and a rear-mounted Teledyne CAE 373-8C turbojet engine with the intake on the rear spine of the UAV.

   RYAN MODEL 324 SCARAB:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                3.35 meters         11 feet
   length                  6.12 meters         20 feet 1 inch
   max loaded weight       1,130 kilograms     2,500 pounds

   maximum speed           970 KPH             600 MPH / 520 KT
   service ceiling         13,100 meters       43,000 feet
   range                   2,250 kilometers    1,400 MI / 1,220 NM

   launch scheme           RATO launch.
   recovery scheme         Parachute recovery.
   payload                 Reconnaissance cameras.
   guidance system         Programmable with radio control backup.
   _____________________   _________________   _______________________

* The "Model 350 / BQM-145A" was developed in the early 1990s for a joint US Navy / Marine Corps and Air Force "Medium Range UAV" program, with the Navy developing the airframe and the Air Force working on the payload. The BQM-145A was designed to precede airstrike packages into a target area and relay reconnaissance information in real time.

Production BQM-145As were to have a metal airframes, but the initial two prototypes were built with plastic composites, with initial flight in May 1992. The program then collapsed in 1993 due to technical difficulties and funding cutbacks. However, six BQM-145As with plastic-composite airframes then under construction were completed, with first flight of a composite BQM-145A in 1997.

Apparently Northrop Grumman continues to use them for other experiments. Some sources claim they have been evaluated for unmanned strike missions, and paintings have been circulated showing a BQM-145A fitted with an "high-power microwave (HPM)" generator in the nose to fry adversary electronic equipment. It has been confirmed that BQM-145As have been flown in the US on test flights carrying HPM payloads.

The BQM-145A has some broad similarities to the Scarab, with a similar configuration except that it has twin air intakes on either side of the fuselage, just forward of the wing roots. Like the Scarab, it has no landing gear. It is powered by a Teledyne CAE 382-10C (F408-CA-400) turbojet engine, with 4.4 kN (455 kg / 1000 lb) thrust. Interestingly, it can be air-launched from a standard fighter such as the F-16R Falcon or the F/A-18 Hornet.

   RYAN BQM-145A:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                3.2 meters          10 feet 6 inches
   length                  5.6 meters          18 feet 4 inches
   payload weight          135 kilograms       300 pounds
   launch weight           900 kilograms       2,000 pounds

   speed                   1,115 KPH           690 MPH / 600 KT
   ceiling                 12,200 meters       40,000 feet
   range                   1,300 kilometers    810 MI / 705 NMI

   launch scheme           RATO or aircraft launch.
   recovery scheme         Parachute or parafoil.
   payload                 Reconnaissance or other payload.
   guidance system         Programmable with GPS-INS & radio control.
   _____________________   _________________   _______________________

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[7.4] SIKORSKY CIPHER / BELL EAGLE EYE / FREEWING SCORPION

* In the late 1980s, Sikorsky Aircraft flew a small UAV named "Cypher", with coaxial rotors inside a doughnut-shaped airframe. The doughnut-shaped shroud not only improved safety in handling the machine, it also helped increase lift.

The first proof-of-concept Cypher was 1.75 meters (5.75 feet) in diameter and 55 centimeters (1.8 feet) tall, weighed 20 kilograms (43 pounds), and was first flown in the summer of 1988. This design was powered by a four-stroke, 2.85 kW (3.8 horsepower) engine and had to be mounted on a truck for forward-flight tests.

It led to a true flight prototype Cypher that weighed 110 kilograms (240 pounds), had a diameter of 1.9 meters (6.2 feet) and was powered by a compact, 40 kW (53 horsepower) rotary engine. After an initial free flight in 1993, the Cypher prototype was used in flight tests and demonstrations through most of the 1990s, ultimately leading to a next-generation design, the Cypher II, which was a competitor in the US Navy VT-UAV competition.

Two Cypher II prototypes have been built for the US Marine Corps, which calls the UAV "Dragon Warrior". The Cypher II is similar in size to its predecessor, but has a pusher propeller along with its rotor and can be fitted with wings for long-range reconnaissance missions. In its winged configuration, the Cypher II has a range of over 185 kilometers (115 miles) and a top speed of 230 KPH (145 MPH).

* The Bell Eagle Eye tiltrotor, another one of the competitors in the Navy VT-UAV competition, performed its initial flight in 1993. The Eagle Eye is powered by a single Allison 250-C20 turboshaft engine mounted in the center fuselage, with a transmission system driving a tilting rotor at the end of each wing.

   BELL EAGLE EYE:
   _____________________   _________________   _______________________
 
   spec                    metric              english
   _____________________   _________________   _______________________

   wingspan                4.63 meters         15 feet 2 inches
   length                  5.46 meters         17 feet 11 inches
   rotor diameter          2.9 meters          9 feet 6 inches
   max loaded weight       910 kilograms       2,000 pounds

   maximum speed           322 KPH             200 MPH / 174 KT
   service ceiling         6,100 meters        20,000 feet
   endurance               8 hours
   _____________________   _________________   _______________________

Bell promoted the Eagle Eye for a decade without finding a buyer, but in the summer of 2002, the US Coast Guard ordered the UAV as part of the service's broad "DeepWater" re-equipment effort. It must have been a great relief to company officials.

* An interesting tactical UAV was developed by a company associated with the University of Maryland, Freewing Aerial Robotics Corporation. Working with well-known small-aircraft designer Burt Rutan, Freewing designed a series of piston-powered short-takeoff-and-landing UAVs, based on a design where the fuselage pivots relative to the wing surfaces. The "freewing" design also allows the UAV to operate as a stable observation platform during turbulent conditions.

   FREEWING SCORPION:
   _____________________   _________________   ___________________
 
   spec                    metric              english
   _____________________   _________________   ___________________

   wingspan                4.9 meters          16 feet
   length                  3.60 meters         11 feet 10 inches
   payload weight          23 kilograms        50 pounds
   maximum speed           235 KPH             146 MPH / 130 KT
   service ceiling         4,570 meters        15,000 feet
   endurance               5 hours
   _____________________   _________________   ___________________

The Scorpion will be offered for a US Army short-range UAV requirement, and is being proposed by Matra of France for use on French navy frigates and patrol boats. The Matra version is named "Marvel" and will carry a Matra-designed electro-optical day-night camera system initially, but the French navy has expressed interest in extending the payload to include communications relay, electronic warfare, and antisubmarine warfare equipment.

Freewing is also offering the similar but smaller "Scorpiette", with a payload of up to 6.8 kilograms (15 pounds) for commercial, third-world military, and law enforcement organizations.

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[7.5] BOEING X-50 DRAGONFLY / FRONTIER SYSTEMS A160 / UCAR

* After failing to sell their BRAVE series of tactical UAVs, Boeing developed a twin-prop "tailsitter" or "pogo" UAV named the "Heliwing" that took off and landed standing on its tail, but this aircraft crashed on its sixth flight in 1995, and the project was abandoned.

Boeing is now working a very interesting UAV, the "X-50A Dragonfly", with funding from a three-year DARPA contract awarded in late 1998. DARPA is providing $12 million USD of government money, while Boeing is providing matching company funds. The Dragonfly features a "canard-rotor wing (CRW)" configuration, with a slender fuselage, a wide twin-fin canard wing in back, canard fins up front, and a "rotor wing" on top.

The CRW configuration provides true vertical take-off capability, with much better flight performance than a helicopter. On takeoff and landings, the rotor wing spins using jet exhausts in the wingtips, but once in flight the rotor wing is fixed in place to act as an auxiliary wing.

The DARPA contracts specifies the construction of two prototypes. While the first flight was to be in the spring of 2001, the program schedule has slipped and initial flight is now expected to be in early 2003. As currently envisioned, the Dragonfly prototypes will each weigh about 590 kilograms (1,300 pounds) and have a length of 5.4 meters (17 feet 8 inches). Boeing feels the design can be directly scaled up to as much as 2,500 kilograms (5,510 pounds).

The X-50s will be powered by a Williams Research F-112 turbofan, as developed for the USAF Advanced Cruise Missile. The Dragonfly's engine exhaust will be switched through a diverter through titanium pipes to the rotor wingtips for VTOL and hoverflight, or to provide rearward thrust through a tailpipe. Some of the engine output will be directed through thrusters to assist in flight control in hovering flight.

The rotor uses a simple gimballed hub, which is locked in place after the aircraft transitions to forward flight. The CRW has no tail rotor, which is not required since the rotor jet-exhaust system does not transfer torque to the airframe, and the scheme also eliminates much of the complicated drive system of a conventional helicopter. However, the small rotor leads to high "disk loading", and the type is not expected to be very efficient in sustained hover. Top speed is expected to be about 700 KPH (430 MPH).

The two X-50 prototypes are demonstrators only and will not have an operational payload capacity. If a production version follows, it will likely have an engine better optimized for its unique flight behavior. Boeing is also considering an 11 tonne (12.1 ton) piloted version for scout, light attack, or air escort operations, with considerable interest from the US Navy and Marine Corps.

* Another unusual UAV now in development is the A160 helicopter demonstrator, built by Abraham Karem and his team at Frontier Systems of Irvine, California, under contract to DARPA.

The A160 is intended to have range, endurance, and altitude capabilities unprecedented in the history of helicopter design. The A160 has a conventional main-tail-rotor helicopter configuration, but the conventional appearance is misleading. A contemporary helicopter features lightweight flexible rotors that are connected to the rotor hub through articulated joints. Such rotors are designed to provide smooth flight operation with little vibration and good control authority.

However, they can only do so within a limited range of speeds, normally at as high an RPM as possible below that where the rotor tips break the sound barrier, and so the helicopter's rotor RPM is roughly constant while the aircraft is in flight. This is inefficient, particularly when the helicopter is flying below maximum speed or with a non-optimal load.

The A160's carbon-fiber composite rotor blades are tapered, and their cross-section varies from root to tip. They are light but stiff to avoid vibration, and their stiffness also varies from root to tip. The rotor system is rigid and hingeless, and features a larger diameter and lower disk loading than that of a conventional helicopter with the same lift capacity. The A160 rotor can be spun from 140 to 350 RPM. Coupled with a fuel-efficient piston engine results in a helicopter that not only has unbelievable fuel efficiency, but good speed, unprecedented altitude capability, and is very silent.

The A160 project began in early 1998, with Frontier Systems modifying a light commercial Robinson R22 helicopter to a UAV configuration, named the "Maverick", to test flight-control systems. The R22 was lost in an accident in early 2000, but not before it had flown for 215 hours under autonomous control. Program officials believe the A160's advanced flight control system will allow it to operate in weather that would ground most other helicopters.

The A160 demonstrator performed its first flight on 29 January 2002. The machine weighs about 1,800 kilograms (4,000 pounds), has rotor blades 5.2 meters (17 feet) long, and features retractable landing gear. The demonstrator is powered by a commercial automobile engine with over 225 kW (300 horsepower), and has a payload capacity of more than 135 kilograms (300 pounds).

Possible payloads include EO/IR imaging and SAR sensors. Apparently there is work being done on integrating SAR receiving antennas into the rotors themselves, though the transmit antenna will be mounted on the fuselage.

The demonstrator, which was given the name "Hummingbird", is designed for a top speed of 260 KPH (160 MPH), 40 hours endurance, 4,625 kilometer (2,875 mile) range, and a flight ceiling of 9,150 meters (30,000 feet). Two more demonstrators are planned under the DARPA contract, with all three machines completed by the summer of 2002. The program will experiment with alternate configurations, with possible options including a four-bladed propeller, lighter engine, or improved flight control system.

The A160 is a technology development exercise and is not being designed for a specific operational mission, but its general design concept envisions a UAV that could deploy itself from the US to a combat area, or perform deep penetrations into hostile territory. A production version could have an endurance of up to 48 hours and a ceiling of 16,800 feet (55,000 feet), and would feature multiple-redundant systems for operational reliability.

The US Army and the US Special Operations Command (SOC) are interested in the project, with the SOC considering uses such as extracting troops trapped behind enemy lines. Other uses under consideration are typical UAV applications such as reconnaissance, targeting, and communications relay.

The Army's interest in the Hummingbird took a big step up with the US military involvement in Afghanistan that began in late 2001. Although the services sometimes are reluctant to pick up DARPA programs, the Army has stepped up their schedule for taking over the A160 effort, with the transfer to take place in late 2003. Given that the evaluation of the demonstrators goes well, the Army then wants to fly a militarized version, with sensors, datalink, and weapons.

* DARPA is also working with the Army on development of prototypes for an "Uninhabited Combat Armed Rotorcraft (UCAR)", originally given the snappy name of "Robotic Rotary Wingman". A requirement was issued in the spring of 2002, specifying a robot rotorcraft to be armed with missiles, unguided rockets, guns, and nonlethal subsystems, and with the capability of attacking masked targets autonomously. The UCAR is to cost 60% to 80% less than an RAH-66 Commanche scout-gunship helicopter, and have operating costs 60% to 80% those of an AH-64 Apache.

Major US aerospace firms are submitting proposals, with four to be chosen for a year-long concept development phase, to be winnowed down to two contractors to conduct a nine-month preliminary design phase. A single contractor will be chosen to develop two X-vehicle prototypes, which should lead to a "B-model" that will be close to an operational machine. DARPA expects to hand the program over to full Army control in 2009.

In the meantime, the Army hopes to convert two Bell AH-1 Cobra helicopter gunships to optionally-piloted UAVs to evaluate the usefulness of armed helicopter UAVs.

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