Lt Gen AKS Chandele (Retd),
Managing Editor – GeoIntelligence
<< Recent advancements in manned aircraft systems and in the field of computers have made UAVs not only a preferred aerial platform but also a potent weapon of choice among defence forces >>
The development of Unmanned Aerial Vehicles (UAVs) is redefining geointelligence as well as the very concept of air power to a large extent. Today, in an active military environment, a typical UAV unit may log upwards of 2,000 operational hours annually. In comparison, a manned fighter jet unit would barely log between 200 and 400 operational hours; and this gap is certainly going to widen in the future.
Today, UAVs possess almost all the characteristic strengths of manned aircrafts, besides overcoming some of the pilots’ physiological and physical limitations and completely avoids human risk. The absence of pilot from cockpit allows UAVs to be operated at the limit of their performance envelope, thus enhancing endurance, payload, altitude ceiling and maneuverability. Recent advancements in manned aircraft systems, such as stealth technologies, propulsion systems, payloads, GIS navigational resources and onboard weapon systems, have been integrated with the advancements in the field of computers, data links, control systems and optronics, to make UAVs not only a preferred aerial platform but also a potent weapon of choice. This has been amply demonstrated in the Gulf War, Arab-Israeli wars, Bosnia, Iraq and AfPak region, where extensive UAV usage provided near realtime information to military commanders across the continents. The successful firing of Predator UAV mounted Hellfire missiles against targets in Afghanistan amply demonstrated that these platforms, sensors and weapons technologies have matured sufficiently for UAVs to convert into unmanned combat aerial vehicles (UCAVs). Today, many countries, like USA, Israel, UK, Australia, Sweden and China, are actively pursuing the development of UCAVs capable of undertaking offensive roles typically reserved for manned aircraft. Also, advancements in micro electronics and proximity/visual sensors, coupled with availability of detailed GIS mapping has led to the development of micro UAVs, which can operate autonomously at very low altitudes in a dense urban environment and provide unbelievable intelligence. Some civil uses of UAVs are listed in Table 1. Let us explore the fascinating world of UAVs in some more detail.
Dr Samuel P Langley, the pioneering aviator, is credited with the first unmanned ‘heavier than air’ powered flight over the Potomac (1896).The US Navy converted trainer aircraft to make the first radio controlled UAVs (1917). Kettering Bug, costing USD 400 and capable of carrying a 300 lb bomb, was the first to be mass produced (1918). Queen Bee, an all-wooden radio controlled version of Tiger Moth aircraft was used by British Navy as an expendable target drone between 1934 and 1943. Fire Bee of US army followed suit in 1950s and fl ew more than 34,000 missions during the Vietnam war from 1964 to 1973. It was used for communication and electronic reconnaissance and for dropping propaganda leafl ets and taking photographs.
During the 1969 War of Attrition, Israel desperately needed to monitor Egyptian military movements across the Suez Canal. A team from military intelligence used masking tape to attach automatic still camera to remotecontrol planes. They then sent these planes over the canal to snap photos. This was Israel’s first experience with UAVs. Subsequently world’s first UAV squadron was raised by Israeli Air force (1971), using Fire Bee. Israeli Scout and Mastiff UAVs were extensively used during the 1973 war on the Syrian and Egyptian fronts and during the first Lebanon war in 1982 for ISR missions, and to trick enemy radars into activation, using radar enhancing lenses to transmit radar signals similar to combat aircraft. These radars were then attacked by anti-radiation missiles. US employed Pioneer and Pointer UAVs during the Gulf War, while Britain and France employed CL-289 and MART respectively. Predators carried out round-the-clock surveillance for NATO forces in Bosnia.
Since then, more than 100 state owned/ private companies across 25 countries have undertaken independent/ joint UAV development projects. Today, more than 500 different types of UAVs exist in the world. Israel and US have been leading the development with Israel producing many successful UAVs like Searcher I, Searcher II, Hermese 450, Hermese 900, Heron and Heron TP. Israeli UAVs are now used by more than 30 countries. US on the other hand, is more secretive about its UAVs like Hunter, Predators, X45s and the iconic Global Hawk. UAVs were primarily used mainly for ISR missions by military, but the employment of Hellfire equipped Predators in offensive role in Iraq, AfPak and Libya has been a ‘role changer’; and in their new avatar of UCAVs, UAVs have started to threaten the exclusive domain of fighter aircraft.
Classification of UAVs
UAVs have, as yet, not been formally recognised as aviation machines and no common standard classification of UAVs has been used for certification/ standardisation. However, UAVs are mainly classified in three ways –
- On the basis of their performance characteristics – UAVs can be classified by weight, endurance, altitude or a combination of these
- On the basis of their role and employment – UAVs, nowadays, are used for various purposes like ISTAR (Intelligence, Surveillance, Target Acquisition and Reconnaissance), radar and communication relay, aerial delivery and resupply, multimission UAVs or for combat.
- Launch/ recovery model – Different UAVs follow different launch/ recovery mode, that is, hand/ catapult launched – parachute recovery, runway launched and recovery, or Vertical Take-Off and Landing (VTOL).
Based on characteristics such as flight altitude, endurance, speed, size etc, EUROUVS (European Association of Unmanned Vehicles Systems) have classified UAVs in the following categories (also see Table 2):
Micro/ Mini UAVs
These are short range, limited endurance smaller UAVs with limited payload and specific, generally ISR missions. US standards for micro/ mini UAV are given in Table 3. Micro UAVs generally measure only 15 cm or less in any dimension and can carry basic payload, avionics and communication links to perform the required mission. Due to weight limitations, these are usually not fitted with Inertial Navigation System (INS)/GPS, resulting in less accurate positional accuracy. This limitation is being overcome in newer generation UAVs, which is discussed later.
Tactical UAVs can further be subdivided into six categories – Close range (CR), Short range (SR), Medium range (MR), Long range (LR), Endurance (EN), and Medium Altitude Long Range (MALE). Close, short and medium range UAVs are limited in range by their communication line of sight (LOS). Small in size, with range up to a few hundred kilometers, maximum endurance of 12 hours, these UAVs operate with an altitude ceiling of 8,000m and are normally controlled by local commanders.
Long range UAVs, however, can use satellite communications (Satcom) or an intermediate relay mounted on another platform to enhance their range. For example, Predator MALE can operate for up to 40 hours with a maximum range of 3,700 km.
A further improvement over MALE UAV is High Altitude Long Endurance (HALE) UAV which is bigger-heavier platform usually used for high altitude, long endurance and long range purposes. HALE UAVs are strategic UAVs which can usually carry multimission payloads with a MTOW varying from 2,500 kg to 12,000 kg and a maximum altitude ceiling of about 20,000m. Apart from obvious military roles, HALE UAVs can be used for communications, mapping, atmospheric monitoring, earth observation augmenting and complementing remote sensing satellites. Electric/solar-powered Helios from Aerovironment operated by NASA is an example of a nonmilitary HALE UAV, which has set an altitude record of about 30,000 km and uses solar panels to power electrically driven propellers.
Special Task UAVs
Special task UAVs can be any of the above three categories which are used for a specific purpose. For example, raised communication relay platform, ELINT, COMINT, SAR or in combat role as UCAV.
VTOL technique can be used in mini, CR, MR, and MALE categories of UAVs. These vehicles feature a variety of rotary-wing designs and are suitable for naval and urban surveillance. They eliminate the need to have a runway for takeoff and landing, can fly at low altitudes and can hover over specific targets.
Components of a UAV System
A typical UAV besides its airframe and propulsion also requires a communication system and a control system. The control system can be fully autonomous, remotely and real-time monitored or remotely piloted/ controlled in real-time.
The UAV and payload controls are exercised through Ground Control Station (GCS) via data-links. The GCS can be a containerised station which can be ground-based, onboard a manned aircraft, ship, submarine or any other location or it can even be a laptop based portable station which can be used anywhere within the control range. In conventional UAVs, navigation and guidance systems may include GIS assisted INS/GPS, while more complex UAVs may employ Differential GPS (DGPS), and Terrain Contour Matching (TERCOM). Typical UAV payloads include Electro- Optical/Infra-Red (EO/IR) sensors, Synthetic Aperture Radar (SAR), Laser designators, EW pods and COMINT. Meanwhile, UCAVs may carry missiles, bombs, explosives, etc.
There is no risk of crew casualties, and political exploitation of aircrew as POW/ hostage by enemy is avoided. UAV ground crew does not suffer from much fatigue and combat stress, resulting in enhanced endurance and efficiency. Endurance is limited only by fuel. The base cost of UAV is a fraction compared to a fighter jet, for example, Reaper drone costs just USD 10.5 million, 14 times less than an F-22 Raptor fighter jet. UAVs enjoy the advantage of more space, greater design freedom, more agility and fl exibility and greater payload carrying capability. They are most suited for D3 – dull missions like naval surveillance, dirty missions like attacking or monitoring nuclear, biological and chemical (NBC) warfare, and dangerous missions like attacking heavily defended targets. Use of UAVs for longendurance ISTAR and D3 missions releases manned aircraft for other more important tasks.
Due to non-availability of direct UAV communication with ATC, sharing civil and military manned aircraft airspace with UAVs is a serious ATC challenge, especially for long range UAVs going beyond the airspace of take off location. In the absence of on-board aircrew, UAVs lack situational awareness. Thus, a UAV flight needs to be continuously monitored by external means like radars or additional sensors which are placed on the air vehicle and design interfaces to incorporate the same in downlink. Most of the current UAVs are yet to become all weather air vehicles, imposing limitations on their utilisation. Data-link controls and downlinks make UAVs vulnerable to interference, jamming and bandwidth limitation. UAVs require specifically trained personnel in the form of operating crew, payload controller and maintenance personnel. Long endurances would entail multiple shifts or continuous operation for these personnel causing fatigue and loss of efficiency. Being unmanned, UAVs need redundancy in almost every system which affects flight safety, for example, command links, onboard computers, navigational sensors and systems, servos or landing systems.
Main challenges in the development of mini and micro UAVs are in situational awareness. These UAVs have limited MTOW and hence existing INS/GPS are unsuitable for them. Also for low-altitude close proximity flight in urban environment, they require vision based/ proximity sensors, detailed GIS interface and autonomous flight control.
The development of Micro-Electro- Mechanical System (MEMS) may help overcome these constraints. For tactical UAVs, challenges are lack of self protection, replicating situational awareness, reducing radar cross section, vulnerability of data links, bandwidth limitations and multiple payload integrations. Another major challenge is having automatic take off and landing (ATOL) or incorporating VTOL.
Apart from challenges mentioned above (for tactical UAVs), the biggest challenge for strategic UAVs is to have unlimited or very high endurance. Mid-air refuelling or uses of newer technologies/ unconventional energy resources are solutions but these are yet to be perfected. The other challenges include ATC integration and integration of warheads.
Unmanned Combat Aerial Vehicles (UCAVS)
Much like nuclear energy, we have quickly found a destructive role for UAVs as well, turning them into UCAVs. When US Air Force fitted its unmanned Predator with hellfire missiles, they quickly changed its military nomenclature prefix from RQ (Reconnaissance) to MQ (Multi-mission). UCAVs are fitted with sensitive reconnaissance electronics like Laser designator and powerful precision weapons like MK-82 bombs, maverick anti-surface missiles, shrike anti-radiation missiles or hellfire missiles. They are capable of carrying out precise, deadly strikes without endangering human lives. Existing UCAVs can be classified in two main categories:-
These are reusable UAVs fitted with missiles and precision guidance system for these missiles. For example, Predator `A’ is fitted with two Hellfire missiles while larger version Predator `B’ can carry eight such missiles. The capability of armed UAVs to eliminate the time gap between detection and precision guided strike makes them invaluable.
Strike or Killer UCAVs
These are expendable drones which act like missiles and strike the chosen target. These are however different from missiles, as they carry onboard intelligent system capable of selecting and identifying desired or opportunity target. The target can be some radiating radar, a microwave station or such similar location. The UAV can loiter stealthy, waiting for the radar to come on, and home on to it like an anti-radiation missile. If the radar switches off before the strike, the UAV, instead of continuing on strike path, will climb to a safe altitude and continue to monitor the target again.
Major UCAVs Under Development
The US and Israel, and many other countries like the UK, France, Sweden, Australia and China are developing UCAVs. Apart from Predators and its successors Avenger and Reaper, Boeing is developing X-45A, X-45B and X-45C UCAVs. Boeing, along with Northrop Grumman, is developing X-46A and X-46B. At the Zhuhai Air Show last year, China demonstrated Soaring Dragon, Dark Sword and WJ-600. Though officially not confirmed, Israel’s Heron TP is said to be capable of carrying ballistic missiles.
Manned-Unmanned Systems Integration
Due to the limited range of missiles it can carry or the precision guidance system, a UCAV has to be close to the target while engaging it. As lack of situational awareness is one of the biggest challenges of a UCAV, and a limited visual range is a serious shortcoming of a manned aircraft, the latest concept that is being tried is Manned Unmanned Systems Integration Concept (MUSIC). As per this concept, one GCS console of a UAV along with a communication unit is fitted to a manned combat aircraft. The crew in manned aircraft then directly controls the unmanned aircraft and receives real-time sensor data while both are in air.
This way, the combat aircraft becomes aware of the battlefield much beyond its limited visual range and much prior to actually getting into it. On the other hand, due to its ability to look into battlefield from a standoff distance, UAV need not get into the battlefield. Also, the requirement of integration of warheads to UAV is also eliminated. During a recent flight test, the cockpit of an AH-64D Apache Block III helicopter, equipped with the new Unmanned Aerial Systems Tactical Common Data Link Assembly (UTA), controlled the payload and flight path of a Gray Eagle (MQ-1C) UAV, while both were in flight (details in news section).
UCAVs Vs Fighter Jets
It is debatable whether UCAVs will ever completely eliminate the need of manned fighter jets. UCAVs, however, carry distinct advantages over manned jets. Some of them are – no risk of life to operating crew, elimination of physical and psychological limitations of crew resulting in improvement in technical profiling of aircraft, higher endurance and more space which in turn leads to lighter weight and higher payload carrying capabilities, multi-mission capabilities and an ability to extend combat zone to beyond visual range. However disadvantages include lack of situational awareness and requirement of continuous external monitoring (discussed earlier). Also, though UCAVs are well-suited for surgical strikes, theyse weapons are not effective for use against large forces.
2020 is merely eight years away but the pace of advancement in technology is so fast that it is predicted that by 2020, present day UAVs will become outdated. The major changes anticipated are:-
To make UAVs runway independent, VTOL will become a norm. A number of rotary wing designs are already being adopted, but VTOL is likely to be limited to micro UAVs and unmanned helicopters. IAI, Malat of Israel and HAL of India are developing Chetak helicopter based Naval Rotary UAV (NRUAV). NRUAV will offer weather independent helicopter operation for ships at sea, enabling crew to launch missions even in high wind or rough sea. NRUAV will also have twice the mission endurance capabilities as compared to similar manned helicopters.
Apart from micro UAVs and the unmanned helicopters, most of the other mini and tactical UAVs will be Horizontal or Vertical Takeoff and Landing (HOVTOL). Such a vehicle will be a fixed wing tilt-rotor UAV. IAI’s first tilt-rotor UAV, Panther, is one such example. Weighing about 65kg, Panther is fitted with three small electric motors and can stay airborne at 10,000 feet for six hours. A smaller version, called Mini Panther, weighs merely 12 kg and can stay airborne for approximately two hours.
To enable seamless integration of UAVs into civil air traffic, UAVs will incorporate Communication Relay (Com Relay) and Interrogator Friend/ Foe (IFF) modules. Com Relay will facilitate direct communication between GCS and ATC through command data link of UAV enabling an aircraft to receive, process and respond to ATC instructions, flight plan and keep zone just as a manned aircraft does. Beyond the ATC integration, the Com Relay will also have military advantages. It can extend Line of Site (LOS) communications to provide an airborne radio and control over a large area, overcoming mountainous terrain or other interference, supporting ground units with efficient and reliable communications. Airborne relay can also support maritime operations, improving communications with ships and central control and intelligence center.
Networked Ground Control Stations (NGCS)
With the TCP IP based networks being used in UAVs, the existing GCS may become a thing of the past or it may not remain a standalone station. There may be a central control facility having a number of control stations; and intelligence gathered from all the UAVs will be instantaneously integrated into one system, thus making it possible for commanders (or systems) to take decisions based on comprehensive inputs. It may be possible to transfer the control of UAV(s) to any control station in the network, irrespective of the UAV’s physical location. It will also be technically feasible to control some of the functions of a UAV in-flight through a smart phone, implying that in future, it may be possible to operate a UAV or its payload from anywhere in the world. One thing is sure though, in future, the intelligence gathered (video, SAR image or other data) will certainly be available on a handheld device like iphone.
Conversion from Manned to Unmanned
For all applications, proven and certified, manned aerial platforms already exist. Instead of redesigning every platform again, the approach being adopted is to convert the most suitable existing manned platform to an unmanned one by retrofitting the requisite modules. For example when completed, IAI-HAL NRUAV will be offered as a flyaway kit for installation in specific helicopters. Similarly, airframe of twin-engine light plane AD-42, made by Austria’s Diamond Aircraft Industries GmbH, is being converted into Dominator 2 UAV that will weigh two tons, can carry a variety of payloads up to a range of 450 km, spend up to 30 hours in air and reach an altitude of 30,000 feet. The platform already has all the necessary certifications, and systems are simply being added to make it unmanned using the flight control system that has been developed.
Fuel Cell UAVs
Long endurance missions will typically require large and heavy platforms, while persistent platforms that have to remain operational over long time in hostile area, should be designed to be more redundant. Both these requirements mean higher energy consumption implying more fuel. One solution can be solar panels but that requires large wing span, making it unsuitable for military purposes. By 2020, however, fuel cell technology is expected to have matured and we may see strategic UAVs based on fuel cells, remaining in air for months together.
Autonomous Micro UAVs
Micro UAVs are likely to become intelligent fully autonomous thinking machines. On the one hand, miniaturisation of airframe and components, new concepts in propulsion, and energy storage coupled with secure and robust communications are making ‘micro’ a possibility, on the other hand, models based on flying insects, new navigation and collision-avoidance techniques have developed. CMOS cameras and improved digital imaging have promoted the development and application of ‘camera images’. Data from existing sensors, such as MEMS accelerometers and piezoelectric rate gyro, when combined with the information obtained from sequences of ‘camera images’ can significantly increase situation awareness.
Future Belongs to UAVs
With their unmatched surveillance and reconnaissance capabilities even from a standoff distance, comparatively cheaper costs and cost effectiveness to perform multi-missions in a single flight, capability to carry multiple payloads including weapons, unbelievable endurance coupled with unlimited range achieved through SATCOM, UAVs have become the focus of aviation industry, including military aviation. Though the operation and use of UAVs is still considered less intrusive and threatening, there are no rules of engagement for UCAVs unlike manned aircraft. And a world with a proliferation of UCAVs and a few rules, can quickly turn into a world of lawlessness and chaos. There are also reports that development of deadly drones which can be carried in a backpack and are capable of identifing individual targets and attacking them is already on. If such weapon systems fall into the hands of terrorist groups, it will be catastrophic. Nevertheless, whatever be the potential dangers, it is a fact that today US Air Force trains more pilots for UCAV operations than for fighter jets. US has also increased its military expenditure on UCAVs from around USD 550 million in 2002 to nearly USD 5 billion in 2011. Cumulative flying hours of UAVs of just one Israeli company, IAI, have reached more than 900,000 hours, and are about to touch a million. Israeli companies sold USD 1 billion worth of UAVs and associated equipment around the world in 2010. It is estimated that global UCAV sales in the coming decade will be around USD 94 billion.
Future belongs to UAVs, and there is every possibility that in the coming years, all types of aircraft will become unmanned – fighter aircraft, followed by cargo planes and eventually, perhaps, commercial flights. The director of marketing and sales of one of the biggest aerospace companies in the world said, “Automated systems are better than people, they don’t get sick and they’re never in a bad mood.” And who knows, come 2050, instead of autos (popular 3-wheeler among Indians), we may have unmanned VTOL taxis flying (not plying) between Delhi and Noida (Uttar Pradesh)!