As far back as in the 18th century, airborne vehicles were used for intelligence, surveillance and reconnaissance (ISR). That remains true of many airborne vehicles today. But unlike the balloons flown more than 200 years ago and the various types of aircraft that have flown since, pilotless aircraft now fly a growing number of ISR missions.
While the roles of unmanned air vehicles (UAVs) are expanding, their primary mission remains ISR–as we determine in this second article in our series on UAV electronics. Last month, we examined UAV development in the United States; here we look at UAVs in other parts of the world.
Toting a Camera
The fundamental UAV payload is a camera, weighing anything from a few ounces to several pounds. It provides outputs ranging from exposed film to real-time, high-resolution video imagery. Often, electro-optic (EO) systems are supplemented by thermal/infrared (IR) imagery for night/low-light vision. The EO/IR payload thus has become ubiquitous in ISR-dedicated UAVs, although they increasingly must make room for other mission avionics elements such as laser designators, radars and communications systems.
UAV payloads can sometimes be adapted from those developed for manned aircraft and helicopters. But, as most UAVs must be lighter and smaller, designers often have to start with a clean sheet.
UAV payloads also have to be remotely controllable, autostabilized and resistant to the shock and g forces imposed by unrestricted maneuvering and hard landings. And because UAVs tend to be more mishap-prone and disposable than piloted planes, their payloads must be affordable. More than 20 unmanned aircraft were shot down over Kosovo in 1999. Edward Bair, U.S. Army program executive officer for intelligence, electronic warfare and sensors, puts it neatly: "The problem if you have a $100,000 ‘attritable’ air vehicle, and you put a million-dollar payload on it, is that it kind of defeats the purpose of your attritable air vehicle."
The ability to reconfigure UAVs rapidly also has placed a premium on open systems architectures and simplified interfaces, which also minimize integration costs.
While the United States leads in UAV development, a number of countries outside North America have shown a knack for producing payloads that offer high performance yet are relatively affordable. Western European countries–notably the United Kingdom, France, Germany and Sweden–offer a range of UAV payloads. So do Israel and South Africa.
In the UK, BAE Systems (formerly GEC Marconi) has gained experience from its Phoenix battlefield surveillance, acquisition and targeting UAV. Phoenix, in service with the British Army, was deployed successfully in peacekeeping operations in Kosovo. BAE Systems in Basildon provides the payload pod to prime contractor BAE Systems in Rochester.
A two-axis stabilized sensor turret below the mission pod is mounted to Phoenix’s belly via stabilizing roll arms. The turret houses a thermal imaging common module (TICM II), providing a 60-by-40 degree field of view. The optical element is a Pilkington telescope with 2.5-to-10X magnification.
While orbiting a target, Phoenix’s sensor can lock onto it and maintain line of sight. Imagery is transmitted via a steered 360-degree, J-band video data link to a ground data terminal and then by cable to a control station, which can be located up to 0.62 miles (1 km) away. There, an operator can select a thermal image battlefield view or a map displaying the positions of the target and the UAV.
Thales Avionics UK (former Racal Defence Electronics), which long has worked with the British Army on thermal imaging, has studied payload concepts to meet UK intelligence, surveillance, target acquisition and reconnaissance (ISTAR) requirements. These concept payloads would be for the Sender battalion-level, tactical UAV and its larger brigade/divisional-level sister, designated Spectator. (Phoenix may or may not be part of the ISTAR solution.) ISTAR requirements call for advanced EO/IR technologies compatible with the Sender’s C4I (command, control, communications, computers and intelligence) architecture.
For the Sender element, Thales leads a team that includes UK companies Smiths Aerospace and Ultra Electronics, as well as Elbit Systems, UAV producer Silver Arrow, and Northrop Grumman Electronic Sensors and Systems. The team is conducting a study of possible Sender payloads. The results, due shortly, will outline the payload mix to support the Ministry of Defence’s needs for ISTAR.
In another effort, the UK Defence Evaluation and Research Agency (DERA) and Cranfield Aerospace have teamed to conduct trials of the short-range Observer UAV. It carries an IR sensor that requires no cooling unit and thus is smaller and lighter. The Observer UAV has been demonstrated to the U.S. Air Force.
In France Thales commands a range of sensor and electronics applicable to such UAV programs as Crecerelle, which was built by Sagem for the French army. Thales Optronique, for example, plans to integrate systems from W.Vinten, which it recently acquired from UK-based Avimo, into its reconnaissance pods.
Thales is not alone in developing UAV payloads in France, however. Sagem, for example, offers OLOSP, a steerable line-of-sight payload incorporating a "near-IR day camera," which detects infrared wavelengths that are close to the visible spectrum.
Meanwhile, the European Aeronautic Defence and Space Company (EADS) is integrating a comprehensive payload for its medium-altitude, low-endurance Eagle UAV. This unmanned vehicle, in development, is based on the Israeli Aircraft Industries Ltd. (IAI) Heron UAV, which beat out General Atomics’ Predator in a competition.
According to Jean-Georges Brevot, EADS International senior vice president of defense affairs, the Eagle’s payload will include a TV camera, IR sensor, laser illuminator, synthetic aperture radar with moving target indicator (MTI), satellite communications and electronic intelligence (ELINT) systems. The Eagle, with its twin tailboom configuration and retractable landing gear, can carry a 550-pound (250-kg) payload.
In Sweden, Polytech AB has developed gyrostabilized payload options in which EO and IR sensors are interchangeable. The options include a Sony EVI CCD (charged coupled device) camera with a 12-to-1 zoom ratio and a minimum illumination threshold of 6 lux. Another option is a Sony three-chip digital color camera with a 20-to-1 zoom ratio, minimum 4-lux illumination, and horizontal resolution of more than 500 TV lines, plus a one-hour recording capability. Its EO sensor range is designated Pixel, the IR series is called Kelvin, and the latest stabilized solution combining EO and IR capability is named Shark.
Italy is an early European customer for the sizable and highly capable General Atomics RQ-1 Predator UAV. Predators are to arrive in Italy starting late next year. Initially to be used for training, the vehicles will join a UAV squadron scheduled for full operational readiness in 2005. With an EO/IR payload, Italy’s Predators will serve in ISTAR and battle damage assessment roles.
Northrop Grumman and General Atomics have proposed advanced sensor options on the Predator, such as two-color, daylight TV with variable zoom, high-resolution IR with six fields of view between .075 and 20 inches (0.19 and 51 cm), laser rangefinder/designator, and electronic support and countermeasures. There also is talk of adding foliage penetration radars and hyperspectral imaging, which would have helped in the Balkan theaters. This extra capability becomes possible with larger UAVs, like Predator, with payloads of some 450 pounds (204 kg).
Australia is thinking even bigger, however. The country is considering Northrop Grumman’s mammoth RQ-4 Global Hawk for coastal surveillance. It can shoulder a payload weighing some 1,950 pounds (885 kg). Global Hawk, therefore, can carry extremely sophisticated EO/IR combinations with advanced on-board central signal processing for sensor fusion, panoramic imaging, target acquisition and tracking, data networking and relay, mapping and other capabilities.
Australia is particularly keen on using UAVs for environmental imaging. In this area companies like Kingfisher Unmanned Aviation Systems Australia (KUASA) have significant technical capability.
At the other extreme in size are micro air vehicles (MAVs), which can be smaller than a man’s hand and potentially useful for urban warfare. They accommodate payloads weighing little more than half an ounce, about the weight of a packet of peanuts. BAE Systems’ Sanders Division is just one integrator working to develop daylight camera and communications relay capability within this constraint.
If any country has advanced in developing UAVs as much as the United States, it is Israel. It represents the vanguard of UAV technology, rooted in the exigencies of war. Companies like ELOP, Elbit Systems and the Tamam Division of IAI have learned to stabilize sensor packages to within a few milliradians of angle. They also have learned to steer the packages accurately over a limited range, for "pilot view" sensors located in the vehicle’s nose, and to survey plots of land, over a wider range, for primary surveillance devices positioned under the UAV’s belly.
Tamam has delivered hundreds of optronic payloads worldwide. It supplied the baseline sensor for the U.S. Navy’s and Marine Corps’ selected vertical takeoff and landing UAV (VTUAV). Built by Northrop Grumman-Ryan Aeronautical of San Diego and called the Fire Scout, the VTUAV is essentially an unmanned Schweitzer 333 helicopter designed to take off and land on warships such as cruisers and frigates. Tamam’s first UAV multimission optronic stabilized payload (U-MOSP) has been delivered to the prime contractor’s Ryan Aeronautical Center for integration into the Fire Scout and preparation for the vehicle’s maiden flight with payload next spring.
U-MOSP combines TV and forward-looking IR (FLIR) with a laser rangefinder/designator in a 200-pound (91-kg) payload. The third-generation FLIR has a high-resolution, 3-to-5-micron (mid-wave) indium/antimonide (InSb) thermal sensor. (Mid-wave thermal detectors suit many UAVs and are better than the 8-to-12-micron band at penetrating hot, humid atmospheres. Typically, the InSb sensor also can deliver 2.5 times the resolution of long-range devices with optics of the same size.) The FLIR on the U-MOSP provides three fields of view, from 0.75 to 13.5 degrees, and the TV camera has a broadly overlapping zoom capability.
The Navy and Marine Corps are considering other equipment for the Fire Scout, including synthetic aperture radar/moving target indicator (SAR/MTI) and signals intelligence (SIGINT).
IAI/Tamam’s technology first impressed U.S. military authorities when its Plug-in Optronic Payload (POP) 200 was used in an Alliant Techsystems Outrider UAV demonstration during a fly-off at Fort Huachuca, Ariz. POP 200 combines daylight color TV from a 320-by-240-pixel InSb focal plane array with FLIR (but no laser) on an 11-inch (28-cm) gimbal. The off-the-shelf, 60-pound (27-kg) payload proved it could meet U.S. Army detection requirements at 1.8 miles (3 km). It probably will equip the Army’s Shadow Tactical UAV (TUAV) when it enters service, although a more advanced, 40-pound (18-kg) payload developed by Wescam may replace the POP 200 as an upgrade.
Tamam has supplied payloads for the Seeker, Hunter, Hermes, Ranger and other unmanned vehicles. The company can configure payloads to client requirements from a range of monochrome or color cameras and FLIRs mounted on four-gimbal stabilized platforms.
Controp Precision Technologies offers another product family for UAVs. It includes turreted EO systems, the FSP-1 high-resolution, stabilized FLIR system, and the DSP-1 compact, dual-sensor day/night observation system.
The DSP-1 features a 786-by-494-pixel color, daylight TV camera with a 22.5X zoom lens and a focal plane array detector for night operations. The thermal camera reportedly has sufficient resolution to detect trucks at 15.5 miles (25 km) and identify them at 4.7 miles (7.5 km). The DSP-1’s two sensors are mounted on a stabilized platform, which can be tilted to +10 and —105 degrees and rotated through 360 degrees. The DSP-1 turreted system weighs some 57 pounds (25.8 kg) and can withstand 15g shocks.
Meanwhile, ELOP-Electronics Industries, known for its IR and ultraviolet (UV) expertise, has flown EO/IR payloads on IAI Pioneer short- and medium-range surveillance and intelligence gathering UAVs. Its Compass system combines color-zoom CCD with FLIR and a laser rangefinder/designator on a four-axis platform, all within a 75-pound (34-kg) package. A heavier (220-pound [100-kg]), military-capable, multisensor integrated system (MSIS) has day/night, all-weather capability for search and tracking of land and sea targets.
Elbit Systems, another Israeli player noted for its UAV payload integration, recently acquired ELOP. Elbit builds tactical, medium-altitude, long-endurance (MALE) UAVs and civilian UAVs. It partners with electronics manufacturers to supply Israeli defense forces with vehicles such as the short-range Hunter 450.
The UK government selected Elbit as part of a Thales-led team to undertake the risk-reduction conceptual study for that country’s Sender UAV program. The UK military intends Sender for tactical use at the battalion level.
South Africa, too, has considerable UAV experience. Kentron, for example, produces observation and reconnaissance systems, and the Cumulus business unit of Denel offers the Goshawk family of sensors. The latter comprises TV cameras, a 3-to-5-micron or 8-to-12-micron imager, laser rangefinder and automatic tracker, all of which can be configured to serve various requirements. The gyro-stabilized, turreted system weighs 53 to 77 pounds (24 to 35 kg), depending on the sensors chosen.
Denel also develops UAVs and has designed a stealthy high-altitude craft that is meant to fly at subsonic speeds. Called the Seraph, it is a version of Denel’s Skua reconnaissance UAV. The manufacturer seeks international partners for the Seraph program, which is in a very early stage.
Russia, too, has developed UAV payloads, some of which have seen active duty. A dual-sensor payload carried by Pchela-1T aerial vehicles, for example, delivered round-the-clock EO/IR surveillance for Russian forces in Chechnya. The UAV package combines a TV camera that transmits real-time imagery with a field of view that is remotely controlled between 3 and 30 degrees. An IR sensor with 3-milliradian resolution and linear scanning served Russian forces for night surveillance.