v1.6.0 / chapter 8 of 19 / 01 mar 10 / greg goebel / public domain
* The US armed services are now in a new era in which UAVs are critical to combat operations, with the machines carrying imaging reconnaissance or SIGINT payloads, relaying the data over high-bandwidth data links in real time to ground, air, sea, and space platforms. This trend had been emerging before the American war in Afghanistan in 2001:2002, but was greatly accelerated by the use of UAVs in that conflict. This chapter describes contemporary American tactical UAV systems.
* After the collapse of the Outrider effort, the US Army went through a fourth attempt to procure a battlefield UAV. AAI followed up their Pioneer UAV with the similar but refined Shadow 200 UAV, and in late 1999, the Army selected the Shadow 200 to fill the tactical UAV requirement.
The Army requirement specified a UAV that used a gasoline engine, could carry an electro-optic / infrared imaging sensor turret, and had a minimum range of 50 kilometers (31 miles) with four hour endurance on station. The Shadow 200 offers at least twice that range.
The Shadow 200 looks something like a Pioneer, but has a sharper nose, a ring
around the pusher prop, and an inverted-vee tail mounted on twin booms. The
UAV is powered by a 28.5 kW (38 HP) rotary engine. The Army requirement
dictated that it be able to land in an athletic field.
AAI RQ-7 SHADOW 200:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 3.89 meters 12 feet 9 inches
length 3.41 meters 11 feet 2 inches
payload 27.2 kilograms 60 pounds
launch weight 149 kilograms 328 pounds
maximum speed 225 KPH 140 MPH / 123 KT
service ceiling 4,575 meters 15,000 feet
endurance > 5 hours
launch scheme RATO booster or runway takeoff.
recovery scheme Net or runway landing with hook.
payload Day / night imager or other payload.
guidance system Programmable with radio control backup.
_____________________ _________________ _______________________
The Army ordered a total of 44 Shadow 200 systems. The service felt that
since the Shadow 200 was basically a proven system, there wouldn't be any
hangups in evaluation, but the Army's "jinx" proved hard to break, with the
evaluation suffering from crashes and accidents. The problems were resolved
and the Shadow 200 went into LRIP in 2002.
* Each Shadow 200 system includes three UAVs, two ground stations, and support vehicles for equipment and personnel. The Army is now working to expand Shadow 200 capabilities, with Shadow 200s fitted with a high-resolution EO system from 2009. There has been talk of automatic target recognition capabilities, and a SIGINT payload is in development; it will swap out with the EO turret.
The Army has also considered arming the Shadow 200 with light munitions. Air-dropped acoustic / seismic ground sensors are another possible payload. In a particularly interesting application, the US Army Aviation & Missile Command (AMC) in Huntsville, Alabama, has developed a supply canister, named "Quick-MEDS (Medical Emergency Delivery System)", that can be carried in pairs by a Shadow 200 and parachuted to front-line troops to deliver medical supplies or other emergency gear.
Quick-MEDS looks like a little fat aerial bomb. It has a loaded weight of 9 kilograms (20 pounds), 75% of that being payload; dimensions of 81 by 20 centimeters (32 by 8); and four "lattice fins" on the tail. These are shaped like paddles, with the flat side facing the airstream, and contain a lattice of airfoils to provide the maximum flight surface in the smallest form factor. The fin concept was developed by the Russians and is licensed under Russian patents. Quick-MEDS has a crushable nose full of plastic foam and a parachute in the tail. Quick-MEDS could also be deployed by any helicopter or light aircraft. It has been designed to be scalable to 90 kilograms (200 pounds) and a GPS-guided version is being designed, for deliveries to troops in close contact with an enemy.
* It is unclear if the Shadow 200 saw service in the Afghanistan campaign of 2001:2002, but it did fly operational missions during the US occupation of Iraq in 2003. The operating conditions in Iraq proved hard on the UAVs, with heat and sand leading to engine failures, leading to a high-priority effort to implement fixes and improve operating procedures. Despite the difficulties, the RQ-7A Shadow 200 was enthusiastically received by field commanders, and regarded as an important asset in helping combat Iraqi insurgents fighting US occupation forces.
The Army has been seeking additional funding to buy more Shadow 200s. Production shifted to a generally improved "RQ-7B" variant in the summer of 2004. The RQ-7B features new wings increased in span by 91.4 centimeters (36 inches); the new wings are not only more aerodynamically efficient, they are "wet" to increase fuel storage for greater range and endurance. Endurance has been increased to 6 hours, and payload capability has been increased to 45 kilograms (100 pounds). Avionics systems have been generally improved, and the new wing is designed to accommodate a Tactical Common Data Link (TCDL).
As mentioned in the previous chapter, the US Marines decided to adopt the Shadow 200 in early 2007, replacing their Pioneer UAVs. Details of the Marine acquisition program are unclear, but since the Shadow 200 is already in US military service it is unlikely the Marines needed to perform any extensive evaluation of the machine, allowing it to be put into service quickly. By 2010, the Army and the Marines had a total of well over 400 Shadow 200s in service or on order. The US has also promised to provide a dozen Shadow 200s to Pakistan to help with the "war on terror".
* AAI has also built a scaled-up Pioneer derivative known as the "Shadow
600". It also resembles a Pioneer, except that the outer panels of the wings
are distinctively swept back. A number of Shadow 600s are in service in
several nations, including Romania.
AAI SHADOW 600:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 6.83 meters 22 feet 5 inches
length 4.70 meters 15 feet 5 inches
height 1.22 meters 4 feet
empty weight 163 kilograms 360 pounds
max loaded weight 272 kilograms 600 pounds
maximum speed 210 KPH 132 MPH / 115 KT
service ceiling 5,180 meters 17,000 feet
endurance 14 hours
launch scheme RATO booster, catapult, or runway takeoff.
recovery scheme Parachute, net, or runway landing.
payload Day / night imager or other payload.
guidance system Programmable with radio control backup.
_____________________ _________________ _______________________
BACK_TO_TOP
* While the Army was working on Outrider, the Navy was moving on to its second generation UAV, since the old Pioneers were being withdrawn from service. The Navy requirement specified a vertical takeoff & landing (VTOL) aircraft, with a payload capacity of 90 kilograms (200 pounds), a range of 200 kilometers (125 miles), an endurance on station of three hours at an altitude of 6 kilometers (20,000 feet), and the ability land on a ship in a 46 KPH (29 MPH) wind. The UAV was to fly 190 hours between maintenance.
There were three finalists in the competition, which was designated "VTOL-UAV" or "VTUAV". Bell, Sikorsky, and a collaboration of Ryan and Schweizer Helicopters submitted designs. The Ryan-Schweizer UAV was selected as the winner in the spring of 2000. The "RQ-8A Fire Scout", as it was named, was a derivative of the Schweizer three-passenger, turbine powered 330SP helicopter, itself a derivative of the Hughes 300 series helicopters. The Fire Scout featured a new fuselage, new fuel system, plus UAV electronics and sensors.
The initial prototype of the Fire Scout was piloted in early tests, flying autonomously for the first time in January 2000. Its Rolls Royce Allison 250 turbine engine ran on JP-5 and JP-8 jet fuel, which is nonvolatile and safe for shipboard storage. The Fire Scout was to be fitted with a sensor ball turret with electro-optic and infrared cameras and a laser range, and was to be controlled over a data link derived from the Northrop Grumman Global Hawk UAV, described later, capable of operating over a line of sight to a distance of 280 kilometers (172 miles). The control system was to be fitted onto a ship, or could be carried on a Hummer light vehicle for US Marine service.
* The Fire Scout program suffered a setback in November 2000, when the initial prototype crashed and was destroyed, leading to a schedule slip. Despite the accident, the Navy was expected to move quickly to begin production and introduction of the type, but then in late 2001 the program went into a holding pattern that made outside observers dizzy, and likely was even more unpleasant for those involved.
Although progress on the project had been regarded as satisfactory, the Navy decided the Fire Scout didn't meet their needs after all and cut funding for production in December 2001. However, the development program continued, and Northrop Grumman pitched a range of improved configurations to anyone who was interested. As it turned out, the US Army was very interested, awarding a contract for seven improved "MQ-8B" evaluation machines in late 2003.
The MQ-8B featured four-blade main and tail rotors, in contrast to the larger-diameter three-blade rotors of the RQ-8A, with the four-blade rotors reducing noise while improving lift capacity and performance. The four-blade rotors had already been evaluated on Fire Scout prototypes. They boosted gross takeoff weight by 225 kilograms (500 pounds) to 1,428 kilograms (3,150), with payloads of up to 317 kilograms (700 pounds) for short-range missions. The MQ-8B was fitted with stub wings as well. The wings serve an aerodynamic purpose, but their primary use was for carrying armament, or for supply pods like Quick-MEDS. A variety of sensor payloads was envisioned.
However, while the Army was very enthusiastic about the Fire Scout at the outset, in 2009 the service's far-ranging Future Combat Systems program, which was intended to provide a full spectrum of integrated weapons, was cancelled. That led to a reevaluation of the Army's UAV efforts, and somewhat surprisingly to the cancellation of the MQ-8B in early 2010. Army spokesman commented that the Shadow 200 would be able to do the job. Since the Fire Scout was supposed to include an armed capability, that hints at use of the Shadow 200 as a weapons platform, carrying small smart munitions.
* The dizziness continued, because the Army cancellation did not kill off the Fire Scout program. Ironically, Army work on the machine had revived Navy interest in the program, with the Navy ordering eight Sea Scout MQ-8B derivatives for evaluation and committing to full production. The Navy version has a FLIR turret with laser rangefinder and target designator, with the primary mission defined as target inspection and, presumably, guided-munition direction. A set of radios are carried to provide an over-the-horizon communications relay capability as a secondary mission. A battlefield targeting / mine detection system that can be swapped with the FLIR is in development, and a multimode maritime radar has been evaluated as well. Of course, the naval version also has shipboard recovery gear. Initial operational capability is expected in 2011.
Northrop Grumman sees possible sales of up to 73 RQ-8Bs to the Navy & Marine Corps, and sees more possible sales to the US Coast Guard -- which has evaluated a Fire Scout -- and to Britain.
* After failing to sell their BRAVE series of tactical UAVs, Boeing developed a twin-prop pogo UAV named the "Heliwing" that took off and landed standing on its tail. The prototype crashed on its sixth flight in 1995, and the project was abandoned. However, Boeing did end up scoring a success in the tactical UAV business, though in a roundabout way.
In July 1998, a small long-range piston-powered UAV, named the "Aerosonde",
made history by crossing the Atlantic non-stop, and they have made a number
of research flights into the deep Arctic. The Aerosonde was designed to
provide a low-cost weather observation platform. It was designed by
Aerosonde LTD of Australia, with design consulting by the Insitu Group of
Bingen, Washington, in collaboration with the University of Washington. It
has a high-mounted wing, twin tailbooms with a standup inverted vee tail, is
powered by a 0.75 kW (1 HP) engine, and is built from wood and composite
materials.
AEROSONDE LTD AEROSONDE:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 2.9 meters 9 feet 6 inches
length 1.74 meters 5 feet 8 inches
payload weight 2 kilograms 4.4 pounds
empty weight 15 kilograms 33 pounds
maximum speed 103 KPH 64 MPH / 56 KT
service ceiling 4,880 meters 16,000 feet
range 2,500 kilometers 1,550 MI / 1,350 NMI
launch scheme Launched from cartop.
recovery scheme Belly landing.
payload Meteorological and other sensors.
guidance system Programmed with GPS & radio command backup
_____________________ _________________ _______________________
Four Aerosondes were sent on the flight from Nova Scotia to Scotland, but
only one completed the trip. It was named "Laima", after the Latvian goddess
of good luck, in tribute to University of Washington aeronautics professor
Juris Vagners, who was heavily involved with the project and is from Latvia.
These four Aerosondes appear to have been configured for extra fuel, since
the total trip distance was 3,270 kilometers (2,044 miles). The flight time
for the aircraft that made the crossing was almost 27 hours.
Aerosonde LTD, now part of Textron AAI, continues to improve and build the Aerosonde, with the latest models featuring largely composite construction and generally improved systems. During the ferocious hurricane season of 2005, NASA used an Aerosonde as a "hurricane hunter", sending one into Hurricane Ophelia to perform observations for several hours. AAI is also trying to promote the Aerosonde as a tactical UAV for military requirements.
* Following the success of the Aerosonde, the Insitu Group worked with Boeing to develop a more sophisticated UAV, the "ScanEagle". The ScanEagle is a tailless machine, with long, slightly swept wings ending in fins and attached to a tubular fuselage. It is driven by a pusher propeller and has a sensor dome in front, containing visible or infrared cameras. It is designed in a modular fashion to permit easy upgrade of avionics and sensor subsystems, and in fact has been successively upgraded with improved sensors in production.
The ScanEagle has a wingspan of 3.05 meters (10 feet), a length of 1.22 meters (4 feet), a weight of 18.1 kilograms (40 pounds), a maximum speed of 125 KPH (68 knots), and up to 15 hours endurance. It is launched by pneumatic catapult and recovered by a "Skyhook" scheme, in which the UAV snags a rope hanging from a tower. The ScanEagle can be carried on small vessels, such as coastal patrol cutters; a "SeaScan" system includes two ScanEagles, as well as launch, control, and recovery gear. Initial flight of the ScanEagle was in June 2002.
In 2004, the US Marines ordered two "mobile deployment units" based on the ScanEagle, with each unit including a number of the UAVs and associated control and support gear, with Marine ScanEagles quickly seeing service in Iraq. The ScanEagle was regarded as an interim solution pending evaluation of another UAV, but a follow-on evaluation of the MTC Technologies "XMQ-17 SpyHawk" UAV did not lead to a production order, and for the time being the Marines are still making intensive use of the ScanEagle.
The US Navy began operating ScanEagles in 2005, using it in antipiracy operations off the coast of Somalia from 2008. The US Special Operations Command (SOCOM) acquired the UAV as well in 2009. In late 2004, the British Royal Navy also ordered the ScanEagle as part of an experimental investigation, with Thales of France fronting the deal and providing systems integration. The Australian Army has obtained the ScanEagle and used it operationally. It has also been used on a semi-experimental basis to track wildfires in Alaska.
* Boeing bought out Insitu in 2008 and has been energetically improving the ScanEagle, with machines now featuring a heavy-fuel engine. The company is very enthusiastic about the ScanEagle, selling dozens every month, though of course the profit on the little UAV doesn't compare with that of a jetliner. Boeing has developed a "NightEagle" payload, consisting of a FLIR imager in a bulbous nose module, and the company has demonstrated a ScanEagle carrying a "NanoSAR" radar payload, developed by the ImSAR company and with a weight of only 600 grams (2 pounds), in addition to an EO imager. Work is currently underway to get the NanoSAR into operational service.
Boeing is now developing on company funds a "ScanEagle Compressed Carriage (SECC)" UAV, intended for air or container launch and with folding wings. It has an entirely different airframe than the ScanEagle itself, the name being leveraged into SECC mainly for association with a successful brand name, though the two UAVs do share subsystems. SECC is 1.2 meters (4 feet) long and has a wingspan of 3.35 meters (11 feet) with wings deployed; it has a launch mass of 34 kilograms (75 pounds) in a surveillance configuration and 47.6 kilograms (105 pounds) when carrying a strike payload.
SECC began life as a program named "Dominator" for an expendable multirole UAV, but SECC is seen as a generally reusable platform that can carry a number of different payloads: EO/IR imager, SAR, laser designator, communications relay, or submunitions. The US Navy is planning to use one carrying a magnetic anomaly detector (MAD) system as a demonstration of the usefulness of UAVs to hunt submarines.
Boeing is also now working on the "Integrator" UAV, which is similar to the ScanEagle but has a twin-boom tail assembly and, at 61 kilograms (134 pounds), over three times the weight. The Integrator has a length of 2.2 meters (7 feet 2 inches) and a span of 4.8 meters (15 feet 9 inches). Endurance with an 11.3 kilogram (25 pound) payload is roughly 24 hours; doubling the payload reduces the endurance to eight hours.
* Despite the failure of the Heliwing, Boeing continued work on vertical takeoff UAVs. Boeing developed two "X-50A Dragonfly" demonstrators with funding from a three-year DARPA contract awarded in late 1998. The Dragonfly featured 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. On takeoff and landings, the rotor wing would spin using jet exhausts in the wingtips, but once in flight the rotor wing was fixed in place to act as an auxiliary wing. The demonstrators were powered by a Williams Research F-112 small turbofan and had a weight of about 660 kilograms (1,460 pounds).
Initial flight of the first demonstrator was in late 2003; it crashed the following spring and was written off. The second demonstrator took to the air in the fall of 2005, only to be lost in another crash in the spring of 2006, effectively killing the program.
* Boeing had another ace up the sleeve, however. In the spring of 2004, Boeing bought out Frontier Systems of Irvine, California, where a team under Frontier Systems boss Abraham Karem was working on demonstrator for a helicopter UAV designated the "A160" for DARPA. Karem stayed with the program as a consultant.
The A160 was 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 "Optimum Speed Rotor (OSR)" 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. Mating the OSR system with a fuel-efficient 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.
The first true A160 demonstrator, named the "Hummingbird", performed its first flight on 29 January 2002. The machine weighed about 1,800 kilograms (4,000 pounds), had three rotor blades 5.2 meters (17 feet) long, and featured retractable landing gear. The demonstrator was powered by a six-cylinder commercial automobile engine built by Subaru providing over 225 kW (300 HP), and had a payload capacity of more than 135 kilograms (300 pounds). Two more demonstrators were built, with these machines featuring four-blade rotors of the same diameter as the original rotor. The third crashed in October 2003, forcing a flight halt for a year. The program resumed, with Boeing's Phantom Works building five more demonstrators with the four-blade rotors.
One crashed in the summer of 2005, imposing another delay on the program. However, by the fall of 2007, Hummingbirds were performing endurance flights in excess of 12 hours. By this time, the baseline configuration had moved on to the "A160T", powered by a Pratt & Whitney Canada PW207D turboshaft engine. Although at least five new-build A160Ts were produced, it appears some of the older demonstrators were also upgraded to the A160T spec.
A second crash in December 2007 threw yet another delay into the program but did not halt it. The US Army and SOCOM were very interested in the project, with the SOCOM considering uses such as extracting troops trapped behind enemy lines, as well as typical UAV applications such as reconnaissance, targeting, and communications relay. The US Marines are also interested in its use for field resupply.
Work has been done on a wide-area visual surveillance sensor, the "Autonomous Realtime Ground Ubiquitous Surveillance Imaging System (ARGUS-IS); and a UHF SAR, the "Foliage Penetration Reconnaissance, Surveillance, Tracking, & Engagement Radar (FORESTER)", with a long SAR antenna carried under the fuselage. Apparently there is longer-range work being done on integrating SAR receiving antennas into the rotors themselves, though the transmit antenna will be mounted conformally in the fuselage. Although the Army gave up on the Fire Scout, the A160 remains very attractive to the service in the surveillance role -- a fact that may have influenced the cancellation of the Army Fire Scout program.
Other work has involved development of a cargo pod with a capacity of 450 kilograms (1,000 pounds) and carriage of Hellfire antitank missiles. Boeing produced a thoroughly warlike black-painted mockup of an operational Hummingbird, with EO turret between the main landing gear, and stub wings with eight Hellfires. The DARPA program was supposed to end in 2007, but given good progress it is ongoing, with ten new machines obtained at the end of 2008 for a joint DARPA-SOCOM evaluation. They were given the formal designation of "MQ-18".
While the A160 demonstrators were not intended for operational service, the intent being to field a much more refined and capable derivative, it appears that the demand for the Hummingbird is such that it is likely production machines will be straightforward refinements of the demonstrators. A more sophisticated derivative would be built as a follow-on effort.
