Old Articles Series Part-6. This article was published in a late 2003 issue of the Defence Journal (of Pakistan). Please note that no jingoism was meant, the author wrote it from defence point of view. Author supports peace and cordial relations among countries of the South Asia. Also the information contained should be viewed in the context of the time period in which the article was written or published.
Unmanned Air Vehicles (UAVs)
Columnist Syed Imran Shah makes a thorough study of UAVs
The Need for UAVs
Military commanders have always wanted to observe the movements and deployments of enemy formations. Timely intelligence about the activities of the opponent and situational awareness have always been the key to success. For this purpose, many arrangments were done throughout human history like the construction of observation towers, use of air balloons, manned aircraft of first generation, dedicated reconnaissance aircraft, space satellites and unmanned or uninhabited air vehicles.
UAVs are nowadays used for surveillance and observation, artillery fire direction for naval guns and army batteries, maritime patrol, border patrol, checking illegal immigration and drug smuggling, electronic intelligence, communications relay, search and resuce operations and weather data collection.
Classification of UAVs
The US nomenclature for UAVs is RQ-X, in which 'R' stands for reconnaissance and 'Q' stands for drone. RF-4 means the surveillance version of the F-4 fighter aircraft and QF-4 means an F-4 converted into a drone. Some examples of tactical UAVs are US RQ-2 Poineer, RQ-5 Hunter, Brevel, Sagem Crecerelle and Sprewer, CL-289 etc. According to the distinction adopted by the US, UAVs can be classified into two major categories, Tactical UAVs and Endurance UAVs. Tactical UAVs are those having a maximum operation range of 200 km and are mostly intended for the direct support of the ground forces. They also include short-range UAVs (less than 50 km range). Endurance UAVs have ranges in excess of 200 km. They are further divided into Medium and High Altitude Long Endurance (MALE and HALE or MAE and HAE in US parlance) UAVs, with an endurance of 10-30 hours and more than a day, respectively. The Northrop Grumman RQ-4 Global Hawk is a premier US Air Force HALE UAV and General Atomics RQ-1 Predator is a MALE UAV.
Vertical Take-Off and Landing UAVs (VTUAVs) are mostly intended for naval roles featuring a variety of rotary-wing and tilt-rotor solutions. The Northrop Grumman RQ-8 FireScout designed for US Navy is a VTOL UAV. Hand-Launced UAVs (HLUAVs) are intended for use by individual soldiers and for deployment at company or even squadron level. AeroVironment's Pointer is an example of HLUAV.
The third important category is of small UAVs, also called Micro Air Vehilces (MAVs). By definition, UAVs having a wingspan of less than 15 cm are called MAVs. These MAVs carry special miniaturized day/night cameras.
An example of such MAV is the 6-inch long Black Widow of AeroVironment having a 2-gram video camera the size of a sugar cube, and flies at about 65 kilometers per hour with a range of 10 kilometers. The AeroVironment's MAV team was given the 1999 award for outstanding performance by DARPA (Defence Advanced Research Projects Agency). In the recent past, DARPA has funded various UAV projects. Since 1995, the US Department of Defence has spent $5 billion on cancelled Army and Navy TUAV projects.
UAVs Today
Israel was the first country to utilize the full potential of the UAVs in the Bekaa valley conflict in 1982, especially against SAM sites. After this war, UAVs have become standard military equipment. It was argued that it was far better to use and even lose a comparatively cheaper UAV on highly dangerous reconnaissance missions than to lose a pilot and a multi-million dollar plane.
Israeli Defence Force (IDF) has over 25 years experience in operating indigeneous UAVs, not only in Lebanon but also along its borders with Syria and Jordan. More recently, Israel has been using UAVs against HAMAS fighters. Current production versions of Israeli UAVs like Searcher, Hunter and Heron UAVs are all being offered with enhanced payload packages that include SATCOM (Satellite Communication) links and ELTA EL/M-2055 Synthetic Aperture Radar (SAR).
The Persian Gulf War later marked the coming of age of UAVs as serious players in the military strategy of many nations. The US Navy's Poineer played a crucial role as a spotter for US battleships. They were so effective that Iraqi troops began to associate the sound of the little aircraft's engine with an imminent devastating bombing. This eventually led to the first instance of human soldiers surrendering to a robot.
India has bought Searcher-I, Searcher-II TUAVs and Heron-II MALE UAVs from Israel in addition to the Harpy anti-radar drones. This was a $300 million deal for 6 Searcher-IIs, 4 Herons and Harpy drones. Sri Lanka has also acquired IAI (Israel Aircraft Industries) Searcher to aid in its long running fight against Tamil Tigers. From the start of the Operation Enduring Freedom in Afghanistan, the USAF deployed Predator systems to Uzbekistan and Pakistan.
Air Force can use UAVs for its BDA (Battle Damage Assessment) missions, determining whether the target requires more strikes or not. The EW (Electronic Warfare) squadrons can also use UAVs for monitoring communications and electronic emissions of the air defence radars. This information can be useful for updating the threat libraries of the ESM (Electronic Support Measures) systems. UAVs of the EW squadrons can be used for quickly finding those operational frequencies of the air defence radars that are used only in the wartime. Another important job of the UAVs is the reconnaissance of the air bases. That shall provide the real time imagery and latest developments on those air bases. The movement and deployment of various fighter squadrons and air defence units can thus be monitored. This information shall be vital for the success of any air operation.
Sensors and Systems of UAVs
Today, UAVs carry a combination of sensors for accomplishing the task of surveillance. These sensors include video CCD day camera, Infra-red (IR) night camera, Synthetic Aperture Radar, Laser Range Finder, Laser Designator and possibly some EW payload. FLIR (Forward Looking IR) sensors allow UAVs to gather intelligence by day or by night. Radar remains the only all-weather sensor and is therefore used in all-weather image gathering. The focus and zoom of the cameras is controlled via data link from the ground.
All sensors that allow the UAV to provide real-time imagery to the commanders on the ground require some form of data link. A data link would almost certainly use direct line-of-sight radio, limiting the range at which UAV can be used. The data link should used some form of encryption to prevent an enemy from eavesdropping on the information coming from the UAV or interfering with the commands being sent from the Ground Control Station (GCS). Creating a jam-resistant, secure communications link for UAVs is not easy.
No nation has invested more heavily in the development of secure data links for the UAVs than the United States. Under the Common Data Link (CDL) and the newer Tactical Common Data Link (TCDL) programmes, lightweight standardised, wideband, digital secure data links have been developped for use on the UAVs. Intended to allow air-to-surface transmission of radar, video and other sensor data over ranges of upto 200 km,TCDL will operate at rates of upto 45 Mbps (Mega Bytes Per Second).
UAVs having only line-of-sight communication system cannot go beyond 150-200 km in a plane area like Punjab and Rajhistan desert and much less in a hilly or rough terrain like Kashmir, Kargil, Siachen etc. In these hilly areas, an important task for the UAVs can be the location of enemy artillery positions, which is traditionally fullfilled by the OP of artillery. Indian Army has acquired new artillery locating radars and thus we also need effective and redundant methods for locating enemy artillery positions.
For operations in these remote areas, our UAVs must be capable of RATO (Rocket-Assisted Take-Off) or catapult launch, because it shall be very difficult to make airstrips along the LoC and other eastern or western borders, especially if the UAVs are of short endurance.
A UAV should have an endurance of at least one hour if it is to be used behind the enemy lines. The 155 mm heavy guns and Smerch rocket systems (90 km range) are kept far behind the front line and a UAV may be forced to fly indirectly towards these positions because of the anti-aircraft defences, thus entailing a long endurance capability. Further, a UAV going beyond 200 km in a plane area or even 50 km in a hilly area shall require satellite communication systems to relay back the live imagery.
The US forces and agencies like CIA extensively used RQ-1 Predator and Gnat in the Operation Enduring Freedom in Afghanistan and the Predator even sent live imagery to commanders sitting in Pentagon using satellite communication. SATCOM enables a UAV to transmit target detection data at non-line-of-sight ranges. The RQ-1 Predator uses a traditional line-of-sight data link for take-off and landing but can switch to a Ku-band, 1.5 Mbps satellite communication system, which is usable over the Predautor's full range of 900 km.
If the communication link is lost between the Ground Control Station (GCS) and the UAV, then the autopilot of the UAV should bring it back to its site, as is done in some UAVs. This feature is very important for operations in a hilly terrain like Kashmir, where the chances of losing the line-of-sight communications are more.
Another interesting and important feature of the modern UAVs is the command destruction. If a UAV is flying over the hostile territory and develops a serious fault or gets damaged due to anti-aircraft fire, then its better to destroy it rather than leaving it to the enemy hands.
Laser range finders are installed on UAVs to find the range of targets being observed and laser designators or laser illuminators are used for the guidance of laser-guided bombs or laser-guided missiles like the Hellfire missiles fitted on the Predator system.
The strong air defence of the air bases will be a problem for the UAVs and for this purpose, high-speed UAVs would be more suitable than the low-speed ones. Presently Mirage aircraft is used by PAF (Pakistan Air Force) for high-speed reconnaissance. Therefore, the requirement is of a medium-endurance tactical UAV that can fly a low-level, high-speed, all-weather and round-the-clock reconnaissance missions. For low-level flight, the camera of the vehicle should have a wide-angle Field-of-View (FoV) to cover enough area.
UAVs can also be used to collect weather conditions data from remote and inaccessible areas. Tactical UAVs fitted with meteorological sensors can be used for finding accurate wind-speed and wind direction data in the target area.
Wind-speed and direction data in the target area is important information before launching an air strike or missile strike in that area. Wind shall determine the direction in which the smoke shall rise after the first aircraft bombing run and if the rest of aircrafts in the strike formation are coming against the wind direction, they would be unable to see the target due to smoke clouds. Wind speed and direction in the target area can also affect the accuracy of ballistic missiles. Tomahawk cruise missiles seems almost immune to this wind factor due to its terminal guidance system, which corrects any deviation in the missile trajectory till impact on target. Block 4 Tomahawk cruise missiles are now equipped with data links for in-flight re-targeting
and video display of the target. A UAV can be used for communication with the cruise missile too.
Originally the external signals or data link to the cruise missile were avoided to eliminate the potential for jamming the missile guidance and navigation system. However, as the threat of conflict with the Soviet Union waned and the possibility of regional conflicts grew, policy-makers re-examined the benefits offered by data links. The UHF (Ultra High Frequency) data link when fed through a UAV, manned aircraft or satellite, will allow the controllers abroad a ship or aircraft to monitor a cruise missile in flight, if necessary. For example, a missile en-route to a secondary target could be redirected in flight to a primary target if the later remained intact after a strike.
The UAV Pilots
The UAV pilots should be thoroughly trained like pilots and trained for all emergencies like engine failure, control loss, fuel leakage and emergency landings etc. For the training of UAV operators, flight simulators that are made and developped by the UAV manufacturer shall be very economical and effective. Also an important consideration is the sequencing of UAVs with manned aircrafts. During the Balkans conflict, some civil traffic had to be curtailed or rerouted because of UAV operations. During this conflict, UAVs were flying all over Balkans, and the UAV operators complied with all the rules and regulations like a manned airplane. UAV pilots communicated with air traffic controllers as if they were on the aircraft, and even made ILS (Instrument Landing System) approaches at military airfields.
Vulnerability of UAVs
The current problem with UAVs is their vulnerability to anti-aircraft defences. Even the US RQ-1 Predator UAV was shot down several time, including in Afghanistan. In the Balkans conflict, eight RQ-5 Hunters were lost. Many programs around the world are now underway to design and produce jet and stealthy UAVs so that their survivability in the modern battlefield can be improved.
The propeller-driven UAVs can't escape interception because of their slow speed and almost no situational awareness, thus they can't shake off the pursuing jet fighters. In June 2002, a PAF F-16 shot down an Indian Searcher-II UAV at night. Also on 28th January this year, an Indian UAV was shot down near Haji Pir area on the LoC.
UAVs are certainly cheaper than large planes but four to five modern tactical UAVs alongwith a Ground Control Station cost almost near to a modern jet fighter. Therefore, survivability is an important design consideration for tactical and endurance UAVs.
The operating height of the UAV shall be governed by the height at which its various cameras can take a clear high-resolution image, which in turn depends upon the sophistication of the camera, e.g., its zoom levels etc.
But this operating height may well be within the range of anti-aircraft guns and MANPADS (Man Portable Air Defence System). The most lethal anti-aircraft guns with India are the 23 mm ZSU-23 and 30 mm Tunguska systems. The fire of ZSU-23 is effective upto 6000 feet altitude. But going above 6-7000 feet altitude may deteriorate the image quality, especially if the camera does not possess enough zooming power. UAVs also present an easy target for various Indian short-range air defence systems (e.g., SA-8, SA-13, SA-15) because normally UAVs dont carry any countermeasures. But UAV can also be programmed to do evasive manoeuvering when under fire and the US Pioneer used this feature.
The operating altitude of the UAV can be increased by fitting a SAR (Synthetic Aperture Radar), which can take imagery at more height than cameras can do. But SAR imagery is different from CCD daylight and IR night cameras. Also, fitting a SAR along with other cameras shall make a UAV too costly to be easily lost.
The advantage of SAR is that it provides surveillance in all-weather conditions. SAR allows the UAV to fly above the clouds and still get imagery of the terrain. Also the SAR can feature MTI (Moving Target Indication), which rejects the static background and displays moving ground objects. MTI technology is an essential hardware for the movement intelligence.
The flight performance of the UAV can take it out of the danger zone. A high climb rate can take a UAV out of the range of AAA fire. A good agility can also save the UAV from the devastating ground fire, provided that there is some means of knowing that it is about to come under fire. An arrangement in this regard can be the installation of the Radar Warning Receiver (RWR) with its display at the Ground Control Station. RWR shall give a timely warning of any air defence radar that has locked on the UAV. This arrangement is suitable for costly and complicated UAVs. The AAA units can also be seen through camera and thus proper precautions can be taken but the SAM units may target the UAV from a longer distance beyond the camera range.
For the surveillance of a target defended by a SAM site, the UAV should possibly be flown in a position that represent a minimum RCS (Radar Cross-Section), which is usually the head-on position for a pusher-propeller configuration.
For increasing the survivability of UAVs, a few more things can also be done like an intelligent autopilot, a quiet engine to reduce the aural signature, heat shielding of the engine to reduce thermal signature, composite material airframe to reduce radar signature, a low-visibility camoflauge color scheme that matches the sky from below and terrain or sea-surface from above, fuel dumping system for making safe emergency landings etc.
Future Prospects
Another feature, which shall become prominent in future, is the capability of UAVs to carry guided weapons, like the Predator, which destroyed the Al-Qaida vehicle in Yemen using the Hellfire missiles. RQ-1 Predator carried two Hellfire anti-armour missiles in the Operation Enduring Freedom. This capability to carry guided weapons caused the development of Unmanned Combat Air Vehicles (UCAVs), which are designed from the onset to carry guided weapons.
The capability of carrying guided weapons waste added in the Predator to immediately attack the targets of opportunity, which can otherwise escape till dedicated strike platforms arrive at the spot. In the Balkan's conflict, once the UAV sighted a target, the information was transferred to air operations center in Italy and by the time fighter jets arrived, those targets had enough time to escape.
UAVs shall also constitute an element of future air-to-ground strike missions. In the NATO air operations over Kosovo, the Predator UAVs (with laser designators) were used below the clouds for illuminating the target with laser and manned strike fighters were used above the clouds.
UAVs can also provide real-time imagery directly to fighter cockpits. During the NATO air campaign over Kosovo, imagery from the Predator UAVs was sent directly to the rear cockpits of F-15E Strike Eagles and to a multi-functional display on the F/A-18 Hornets. The pilots could see their target at the start of the strike and also immediately after the strike, thus observing the effects of their weapons. The Kosovo campaign ended in June 2000.
The RQ-1 Predator has now been equipped with de-icing and IFF (Identification Friend or Foe) equipment, turbocharged engines and all other modifications for carrying guided weapons. The further derivative of the proven Predator-A UAV, called RQ-9 Predator B is intended to have turboprop powerplant, giving it a higher speed and more service ceiling.
Jet-powered stealth UAVs shall soon be operational with the US forces. One example of such programmes is the X-45 of Boeing. X-45 is developped by Phantom Works, which is an elite R & D unit of Boeing (like the Skunk Works of Lockheed). First task envisioned for the X-45 is the SEAD (Suppression of Enemy Air Defences) and other dangerous missions. Passive stealth techniques can also be used in the structural design of the UAV for minimizing the RCS, requiring some compromise in its aerodynamics.
In the USAF (United States Air Force), RQ-4 Global Hawk has complemented the U-2 aircraft in high-altitude reconnaissance role. Global Hawk is also being considered for SIGINT (Signals Intelligence) role and information warfare. Information warfare consists of picking up and penetrating enemy audio, video and data communications.
The confrontation between US and China over the US Navy EP-3 SIGINT aircraft in the spring of 2001 increased the priority of a new, large surveillance UAV. Many defence officials are now promoting the acquisition of a large and capable UAV with stealthy characteristics that can fly at altitudes above the ceiling of piloted interceptors.
But one thing is clear that the payload capacity of the current tactical UAVs is limited and therefore they cannot presently replace the dedicated maritime patrol, surveillance and SIGINT aircraft like Atlantic of Pakistan Navy, E-8 AWACS of the USAF or EP-3 of US Navy.
Pakistan can also operate a mix of imported high-tech and indigenous medium-tech UAVs for the surveillance and reconnaissance roles. All the indigenous UAV programmes should emphasize on the good handling and flying qualities of the air vehicle, secure and encrypted data link with the Ground Control Station, survivability of the vehicle, efficient and intelligent autopilot, an endurance that matches the mission requirements, zero length take off like RATO or short take-off like catapult launching.
For Pakistan, UAVs can complement other dedicated assets and also operate independently in the high threat environments or where there are no other dedicated reconnaissance platforms available.
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