v1.4.1 / chapter 13 of 19 / 01 mar 08 / greg goebel / public domain
* After a slow emergence, endurance UAVs are now an important military asset. This chapter describes modern US endurance UAV technology.
* The first endurance UAV to be widely used in combat was the General Atomics "RQ-1 Predator", a derivative of the Gnat 750. The RQ-1 Predator resembles the Gnat 750 in general configuration, with some clear differences. While the Gnat 750's fuselage is straight and streamlined, the Predator's fuselage looks something like a plastic spoon turned upside down and faired over underneath, with the bulbous front containing forward-looking SAR peering out through a chin panel, and a Versatron Skyball turret containing electro-optic and infrared sensors under the nose.
The Predator's Westinghouse-built SAR, derived from a system developed for the cancelled US Navy A-12 strike aircraft, provides 30 centimeter (1 foot) resolution at operational altitudes. The Predator has carried a laser target designator, and has provisions for a stores pylon under each wing. The Predator is fitted with a number of datalink antennas, for control or data download via a direct RF or satellite link. The UAV can provide real-time data to other platforms, such as the J-STARS battlefield surveillance aircraft, or submarines.
The Predator takes off and lands under remote control, with the "pilot" using
a TV camera in the nose of the aircraft, but flies in a preprogrammed
pattern, using a GPS-INS guidance system. Like the Gnat-750, it is built
largely of composites and powered by a Rotax 912 piston engine, and has a
payload capacity of 225 kilograms (500 pounds).
GENERAL ATOMICS RQ-1 PREDATOR:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 12.7 meters 41 feet 8 inches
length 8.14 meters 26 feet 8 inches
loaded weight 686 kilograms 2,250 pounds
cruise speed 130 KPH 81 MPH / 70 KT
service ceiling 7,600 meters 25,000 feet
endurance 24 hours
_____________________ _________________ _______________________
The initial Predator system was designated "RQ-1A", but that designation
covered the ground systems as well as the aircraft, which had the more
specific designation of "RQ-1K". The distinction was confusing and the
Air Force finally abandoned it, now calling the UAV itself the "RQ-1A".
The Predator is designed to keep watch over a battlefield area for a long period of time. If a Predator were flown out of San Francisco, it would be able to operate into Nevada, southern Oregon, or northwestern Mexico and monitor a 185 x 185 kilometer (115 x 115 mile) grid. The Predator is almost completely silent, and is invisible to the eye at ranges of about 4 kilometers (2.5 miles) or more. Cost for an early production Predator was about $3.2 million USD.
The Predator was developed by the JPO. The first Predator flew in mid-1994, with the type evaluated by the US Air Force in exercises over New Mexico in the spring of 1995, and performing operational flights that summer. The US Navy operated two Predators on an experimental basis, and the UAV is now in service with, or being planned for service with, several European armed forces. General Atomics partnered with Alenia of Italy's Meteor subsidiary for a successful bid on an Italian Army endurance UAV requirement. Six Predators were ordered, with options for more, with the UAV going into service with the Italian Army at the end of 2004. Italian Predators were sent to Iraq in 2005 to help assist Italian occupation forces in that country.
Both the Gnat-750 and Predator continue to be refined. The US Sandia National Laboratory collaborated with General Atomics to develop an improved SAR, the "AN/APY-8 Lynx" that could be carried on the Gnat-750 or the Predator. The Lynx SAR gives the UAVs an all-weather, around the clock reconnaissance capability. Another new payload is the Raytheon "Multispectral Targeting System (MTS)", a replacement for the original EO/IR sensor turret. The MTS provides greater accuracy and the ability to cut through camouflage. A datalink was implemented as part of a quick-reaction program to allow Predator video to be sent to an AC-130 gunship. The Predator has also been fitted with a SIGINT payload.
* As mentioned, the Predator was introduced to operations in the summer of 1995. Three Predators were deployed over Bosnia that summer, flying out of Albania, with one command-destroyed after an engine failure and another apparently shot down. These aircraft were replaced. Initially, these Predators only had the Skyball turret payload, but they were withdrawn to the US for fitting the SAR payload, and then returned in the spring of 1996. The Predator was passed over to Air Force control after its Bosnian service. The Air Force promptly put the Predator into service in the air campaign against Yugoslavia in 1999.
The Air Force handed the Predator over to the service's Big Safari office after the Kosovo campaign in order to accelerate tests of the UAV in a strike role, fitted with reinforced wings and stores pylons to carry munitions, as well as a laser target designator to designate weapons for itself and other strike platforms. The Predator's service in the Kosovo campaign left something to be desired, since it was unarmed and operators of the UAV were not properly trained or equipped to direct strike aircraft pilots onto a target. The result was a comedy of errors, with one officer involved saying that with such clumsy methods it would 45 minutes to get a strike aircraft into the same zip code. The laser target designator allowed targets to be pinpointed for strike aircraft quickly and accurately, with the Predator firing its own munitions when a target was likely to be gone before a strike aircraft arrived.
This effort led to a series of tests in February 2001, in which the Predator fired three Hellfire anti-armor missiles, scoring hits on a stationary tank with all three missiles. The effectiveness of the scheme was a relief, because nobody was quite sure if firing a Hellfire from a Predator might not rip the UAV's wing right off. The configuration was put into service, with the armed Predators given the new designation of "MQ-1A". Given that a Predator is very unobtrusive and the Hellfire is supersonic, such a combination gives little warning of attack.
A new "Hellfire P" variant of the missile has been fielded, featuring an "off boresight" seeker that can be gimballed to get a target lock, eliminating the need to point the Predator at a target. This permits faster targeting and a wider missile launch envelope.
The Air Force is working on carriage of the Viper glide weapon. The Air Force has also investigated using the Predator to drop battlefield ground sensors, and (as discussed later) to carry and deploy the "Finder" mini-UAV. Over the long run, the USAF wants to use a 113 kilogram (250 pound) GPS-guided "small diameter bomb (SDB)", previously known as the "small smart bomb (SSB)", but the SDB is still in development and is not quite available yet. In the meantime, the Hellfire and the Viper are among the few effective weapons that are small enough to be carried by the Predator.
The Air Force has long been cautious about arming UAVs, since armed long-range UAVs are technically outlawed by the 1988 Intermediate Nuclear Forces (INF) treaty which prohibits ground-launched cruise missiles. Interestingly, the INF does not ban arming ship or submarine launched UAVs, nor short-range tactical UAVs. Since the USAF is now very enthusiastic about the armed Predator, since it is proving an excellent weapon in America's current "war on terror", the legal implications will likely become a matter of diplomatic discussion.
* The Hellfire experiments were quickly put to use. After attacks on America on 11 September 2001 by terrorists believed to be associated with Saudi dissident Osama bin Laden and his Afghanistan-based al-Qaeda terrorist network, in early October of that year the US military began a campaign against Afghanistan intended to root out Osama and the al-Qaeda.
The Predator was a particularly important element in the campaign, being used by the USAF to locate high-priority targets for air strikes. The Predators were armed with Hellfires to ensure that if Osama or other al-Qaeda leadership were spotted, they could be attacked immediately. On 18 November 2001, a Predator was supporting an attack on a Taliban site when the UAV's operators spotting enemy forces fleeing the site. A Hellfire was launched, killing dozens, including some Taliban leadership.
By the time of the Afghan campaign, the Air Force had acquired 60 Predators, and lost 20 of them in action. Few if any of the losses were from enemy action. The Predator was not a very mature machine, with one significant problem being that communications from friendly forces can break the command datalink, which resulted in the loss of at least one Predator. The fact that it has a limited operational ceiling means that it can't fly above storm conditions, and foul weather, particularly icy conditions, caused the lion's share of the losses.
In response to the losses caused by cold weather flight conditions, a few of the later Predators obtained by the USAF were fitted with de-icing systems, along with an uprated turbocharged engine and improved avionics. This improved "Block 1" version is referred to as the "RQ-1L", or the "MQ-1L" if it can carry munitions.
On 3 November 2002, an MQ-1L operating over Yemen spotted a car that was identified as carrying a high al-Qaeda official and five of his people. The Predator blasted the car with a Hellfire, killing all the occupants. The UAV was operated by the CIA, but was being flown by a USAF pilot from a French military base in Djibouti, in the horn of Africa. The attack was cued by observers on the ground. Osama bin Laden is believed to be hiding out in the mountains of Pakistan and Predators are also on patrol there, waiting for him to show himself. He is distinctive, being very tall and slender, making him a good target.
Of course, Predators were employed in the American invasion of Iraq in the spring of 2003. One fired a Hellfire at an antenna on the roof of the Iraqi propaganda ministry in Baghdad to get the propaganda minister, Mohammed Saeed al-Sahaf, off the air. The propaganda minister had acquired an international reputation for his colorful remarks, and was known as "Baghdad Bob" to American forces, but the decision was taken to finally shut him up. The Predator-Hellfire was used because the propaganda ministry was close to the grand mosque and nobody wanted to risk damaging it by using a larger munition.
Interestingly, some of the older Predators and Gnat-750s, as well as old Pioneer and Hunter UAVs, were stripped down to be used as decoys to provoke Iraqi defenses. After the occupation of Iraq, CIA-operated Predators and I-Gnats were launched from both Afghanistan and Iraq to probe Iran for evidence of a nuclear program, with one apparently lost in a crash in Iran in the summer of 2005.
Incidentally, USAF Predators in the Middle East are actually "piloted" from Nellis AFB and Creech AFB in Nevada. Only a relatively small service and handling team deals with the machines "in theater". One pilot flying the Predator from Nellis who had been on the battle lines says the experience is much the same: "Physically, we may be in Vegas [Nellis AFB is next door to Las Vegas], but mentally we're flying over Iraq. It feels real."
The Air Force had been hard-pressed to train personnel to fly the Predators, and the pilots have been badly overloaded, making retention troublesome. A "multiple aircraft" control system is being introduced, allowing one pilot to control up to four Predators, with three machines operating on autopiloted search patterns while one is under direct control. The USAF regards getting up the operational learning curve as a high priority, since the number of Air Force Predator squadrons is expected to expand rapidly.
One of the limitations of the Predator's EO system is that it has a narrow field of view. It works well enough to inspect a particular target, but it leaves much to be desired in keeping an eye on the "big picture". Two Predators have been flown in Iraq with a set of commercial off-the-shelf cameras mounted over the airframe to give a wide-area picture, the images from the different cameras being stitched together by software. They can only provide a frame or two per second and have no night / foul weather capability, but they have proven the concept and the Pentagon is interested in developing a more capable system.
* With the Predator proving so useful, in the summer of 2005 the US Army, having initiated an "Extended Range Multi-Purpose (ERMP)" UAV requirement a year earlier, formally decided to jump on board the bandwagon by awarding a contract to General Atomics for the "Sky Warrior", a Predator with a heavy fuel (diesel / jet fuel) engine, a slightly increased wingspan, and increased system redundancy. The Army had already operated I-Gnats in small numbers from 2003.
The Sky Warrior carries surveillance, communications relay, and strike payloads. The heavy-fuel engine is said to provide more horsepower, better fuel efficiency, and greater reliability than the Rotax 912 gasoline engine, though apparently the major driving force for adopting the new engine was the fact that Army vehicles are diesels, and having to support a gasoline engine in the field would have been logistically troublesome. The Sky Warrior features a Tactical Common DataLink (TCDL) along with its satellite comlink, and can carry a warload of four Hellfire missiles. Operational endurance is up to 36 hours.
The Army is definitely serious about the Sky Warrior, planning to obtain 11 systems, with 12 UAVs and 5 control stations per system. Combat in Iraq has obviously been a major driving force in the program, with ground forces in the theater relying on fighter jets with long-range targeting pods to provide real-time observation in support of ground combat operations. The Sky Warrior would be able to provide that capability with much more persistence and at much lower cost. Although the relationship between the Air Force and the Army over the close-support mission has been generally, if not always, good, the Army also likes to have their own air support assets.
Initial operational capability is expected in 2009, but the Army would like to move up that date if possible. Something of a "turf battle" has emerged between the Army and the Air Force over the Predator, with the Air Force attempting to take over control of relatively capable UAV assets such as the Sky Warrior from the Army. To no surprise, the Army has strongly resisted the idea.
* After a somewhat lengthy adolescence, the Predator has matured into a very useful system that has received a good deal of public attention. Unsurprisingly, General Atomics has developed an improved "Predator B" series.
General Atomics began development of the Predator B with the "Predator B-001", a proof-of concept aircraft, which performed its initial flight on 2 February 2001. The B-001 was powered by a Honeywell / Allied-Signal TPE-331-10T turboprop engine providing 712 kW (950 SHP). The Predator B-001 had a standard Predator airframe, except that the wings were stretched from 14.6 meters (48 feet) to 19.5 meters (64 feet). The B-001 had a speed of 390 KPH (240 MPH), compared to 220 KPH (135 MPH) for the Predator A, and could carry a payload of 340 kilograms (750 pounds) to an altitude of 15.2 kilometers (50,000 feet) with an endurance of 25 hours.
Although General Atomics originally considered a Predator B variant powered by a Williams FJ-44-2A turbofan engine providing 10.2 kN (1,040 kgp / 2,300 lbf) thrust, there was more interest in the turboprop configuration at the time, and the production Predator B machines retain the TP-331-10T engine. The production machines have a maximum ceiling of 15.8 kilometers (52,000 feet), and an endurance of 36 hours. The higher ceiling allows the Predator B to fly above bad weather conditions. The turboprop engine was not only more powerful than the Rotax piston engine, it also had a much longer mean time between failures. The ground system remained much the same as that of the original RQ-1 / MQ-1 Predator.
General Atomics had originally funded Predator B development with company money in anticipation of government interest and contracts, and they weren't disappointed. In October 2001, the US Air Force signed a contract with the company to purchase an initial pair of Predator Bs for evaluation, with follow-up orders for production machines; the USAF designated the type the "MQ-9B Hunter-Killer" or "Reaper". Cost is on the order of about $5 million USD each, more than a Predator A, but still a fraction of the cost of a piloted combat aircraft. Reapers were quickly fielded, performing combat evaluations in Afghanistan in late 2007, with flight control performed from the USA over satellite comlinks.
The MQ-9B is fitted with six stores pylons, with a maximum external load of 1,360 kilograms (3,000 pounds). The inner stores pylons can carry a maximum of 680 kilograms (1,500 pounds) each, and are "wet" to allow carriage of external fuel tanks. The midwing stores pylons can carry a maximum of 270 kilograms (600 pounds) each, while the outer stores pylons can carry a maximum of 90 kilograms (200 pounds) each. An MQ-9B with two 450 kilogram (1,000 pound) external fuel tanks and 450 kilograms of munitions has an endurance of 42 hours. An improved targeting system, with greater range and resolution, has also been fitted.
The Reaper gives the service an enhanced "deadly persistence" capability, with the UAV hanging over a combat area night and day, waiting for a target to present itself. In this role, an armed UAV neatly complements piloted strike aircraft. A piloted strike aircraft can be used to dump larger quantities of ordnance on a known target, while a cheaper UAV can be kept in operation almost continuously, with ground controllers trading off in shifts, carrying a light warload to engage targets of opportunity.
The current Hellfire may not be the preferred munition, since it isn't qualified for operation at cold temperatures found at high altitudes, nor does it have the range to hit targets from such altitudes. An improved Hellfire would be one armament option, as are the SDB and Viper, or even the 225 kilogram (500 pound) version of the Joint Direct Attack Munition (JDAM) GPS-guided bomb for larger targets.
The Stinger AAM has also been evaluated as a store, but it does not appear that this configuration has been fielded since there has been no operational need for it to this time. There has been some thought of carriage of the bigger Sidewinder, or even the long-range AIM-120 AMRAAM, as stores. The AMRAAM would require that the Reaper carry an improved radar with AMRAAM targeting and control capabilities. General Atomics has published ads showing the Reaper armed with twin 225 kilogram guided bombs, eight Hellfires, and two Sidewinders, demonstrating just how much of a punch the machine can pack.
The Reaper complements and doesn't replace the smaller, cheaper, Predator A; the Reaper is primarily a loitering strike asset, while the Predator A is primarily a surveillance and reconnaissance asset. The plan is for squadrons to operate one Reaper for about three Predator As, with a total force of at least 250 UAVs spread over 15 squadrons. Britain has also obtained three Reapers, for an urgent operational requirement in Afghanistan, and would like to acquire more, with some intent to use them for surveillance. The Royal Air Force would like to use the Reaper to provide security at the 2012 Olympic Games in London.
In addition, the US Forest Service (USFS) has evaluated a Reaper in a collaborative program with NASA and the US Federal Aviation Administration (FAA). The USFS and NASA conducted some trials in 2006 with a leased Predator B, leading to operations in 2007 with a Reaper obtained from the USAF. This machine was renamed "Ikhana", from the Chocktaw word for "intelligent" or "aware"; the name "Reaper" seemed a bit too warlike for a civil application. The Ikhana carried a NASA-designed infrared sensor package for fire mapping: although a standard Reaper can carry an infrared imager as a normal payload, it's too sensitive to be used to observe big, hot fires. The sensor package relayed imagery back to a ground station in real-time to allow warnings to be sent to fire-fighters.
NASA not surprisingly is also considering a range of other missions for the Ikhana. The US National Oceanographic & Atmospheric Administration (NOAA) is planning collaborative UAV efforts with NASA for weather and climate research. The two agencies have long collaborated on weather satellites and UAVs would only be an extension of existing practice.
General Atomics has designed a navalized version of the Reaper, named the "Mariner", for carrier operations and has flown a demonstrator. The production Mariner would be turboprop-powered, with folding wings for carrier storage; shorter and more rugged landing gear; an arresting hook; cut-down or eliminated ventral flight surfaces; and six stores pylons with a total load of 1,360 kilograms (3,000 pounds). General Atomics and Lockheed Martin are pitching the Mariner for the US Navy "Broad Area Maritime Surveillance (BAMS)" program, discussed below, with the UAV fitted with a belly radome for sea-search radar such as the Raytheon SeaVue, complementing other sensors, and featuring a saddle tank to improve endurance.
Although General Atomics did backtrack on development of a turbofan-powered Predator B variant, the idea didn't die out. The company has acknowledged work on a "Predator C" with turbofan propulsion and improved stealth, but has not released details.
* The Gnat 750 and Predator were the first in a series "Tier UAVs" considered by the US Air Force. In the USAF plan, the Gnat 750 was known as "Tier 1", while the Predator was known as "Tier 2". The original expectation was that the series would then move on to a very large and powerful long-range UAV known as "Tier 3", something along the lines of a B-2 Stealth bomber. This was not exactly a new idea, there having been work in the late 1980s and early 1990s on a comparable UAV codenamed "Quartz", but it was too ambitious, being cancelled in 1992. Although Quartz designs were dusted off for Tier 3, that program ran into exactly the same problems and was canned in turn.
In place of Tier 3, the USAF decided to develop a smaller "Tier 3-" UAV designated the "Darkstar", and a "Tier 2+" UAV, something like a "super Predator", the Teledyne-Ryan "Global Hawk".
The Lockheed Martin / Boeing Tier 3- Darkstar was a stealthy design that resembled a big pumpkin seed with a long straight wing at the rear. It was to send real-time still images produced by either SAR or EO sensors, though it didn't have the capacity to carry both sensors at the same time. Data was to be returned using a satellite communications link with a bandwidth of 1.5 megabits per second (MBPS). The Darkstar was intended to penetrate protected airspace to observe high-value targets for a limited amount of time. Range and endurance were intended to be similar to that of the Predator, though the Darkstar's sensor suite could cover over twice the area, and of course it was harder to detect.
The Darkstar was powered by a Williams Research FJ-44-1A turbofan engine with
8.46 kN (862 kgp / 1,900 lbf) thrust, and could carry a 450 kilogram (1,000
pound) payload. The UAV was to cost about $10 million USD each.
LOCKHEED MARTIN / BOEING RQ-3A DARKSTAR:
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spec metric english
_____________________ _________________ _______________________
wingspan 21 meters 69 feet
length 4.6 meters 15 feet
height 1.5 meters 5 feet
empty weight 1,980 kilograms 4,360 pounds
max loaded weight 3,900 kilograms 8,600 pounds
cruise speed 555 KPH 345 MPH / 300 KT
service ceiling 15,200 meters 50,000 feet
endurance 12 hours
_____________________ _________________ _______________________
The Darkstar was unlucky. On its second takeoff in the spring of 1996, it
stood up on one wing and slammed into the runway, bursting into fire and
smoke. An analysis of the failure showed flight software and takeoff
procedures to be faulty.
The Air Force and the contractors didn't give up right away, and a redesigned Darkstar, now formally designated "RQ-3A", flew in the early summer of 1998. However, the program was still unhealthy, and the Darkstar was cancelled in early 1999. Although flight tests were generally satisfactory, the Darkstar was by no means close to being a useful operational system. Building an actual operational UAV based on the Darkstar would have required major redesign and improvement, and the costs were more than the Air Force was willing to spend.
* At least that was the official line. In the summer of 2003, confirming rumors that had been in circulation for some time, Air Force officials announced that Lockheed Martin's "Skunk Works" had developed several prototypes of a stealthy reconnaissance UAV similar to the Darkstar but larger, and that this machine had been used in an operational evaluation over Iraq during the American invasion of that country in the spring of 2003.
The unnamed UAV's payload was described as less than that of a Lockheed U-2, featuring a "low probability of intercept (LPI)" SAR and electro-optic sensors, along with a satcom datalink. Range was less than that of the Global Hawk, described below, though cost is described as several times greater. The Air Force wanted to conduct the operational evaluation to see if putting the new machine into production was worthwhile. The most likely operational base for the UAV was Al Udeid Air Base in Qatar, which has extensive and well-developed facilities, is near to Iraq, and was off-limits to reporters during the invasion of Iraq.
In 2005, the Skunk Works did unveil a UAV named the "Polecat" that could, in development, be used as a high-altitude stealthy reconnaissance platform along the lines of the Darkstar, as well as for other missions such as strike. The Polecat was a tailless delta, something like a "mini-B-2", powered by twin Williams Research FJ44-3E turbofans, with a 4,080 kilogram (9,000 pound) takeoff weight and a span of 27.4 meters (90 feet). It had a centerline payload bay for 450 kilograms (1,000 pounds) of sensors or munitions, and a ceiling of 18,300 meters (60,000 feet).
Lockheed Martin officials said the machine was strictly a demonstrator, intended to validate technologies for future military requirements, and was not designed in response to any specific current requirement. However, the Polecat crashed in December 2006 after only three flights. It is unclear if another will be built.
* With the death of the Darkstar, the Ryan RQ-4A Global Hawk became the Air Force's great hope for a strategic UAV reconnaissance platform. With the purchase of Ryan by Northrop Grumman in July 1999, the aircraft became the Northrop Grumman Global Hawk.
The Global Hawk is not particularly stealthy, but it has sophisticated long-range sensors to allow it to operate outside of hostile air defenses, and can survey as much as 100,000 square kilometers (40,000 square miles) of terrain a day. In comparison to the Predator, if a Global Hawk were flown out of San Francisco, it would be able to operate in Maine for 24 hours, observe a 370 x 370 kilometer (230 x 230 mile) grid, and then fly back home.
A Global Hawk costs about $10 million USD, is powered by an Allison Rolls-Royce AE3007H turbofan engine with 31.4 (3,200 kgp / 7,050 lbf) thrust, and carries a payload of 900 kilograms (2,000 pounds). The fuselage is mostly of conventional aluminum airframe construction, while the wings are made of carbon composite.
The Global Hawk carries the "Hughes Integrated Surveillance & Reconnaissance (HISAR)" sensor system. HISAR is a lower-cost derivative of the ASARS-2 package that Hughes developed for the Lockheed U-2. HISAR is also fitted in the US Army's RC-7B Airborne Reconnaissance Low Multifunction (ARLM) manned surveillance aircraft. HISAR integrates a SAR-MTI system, along with an optical and an infrared imager. All three sensors are controlled and their outputs filtered by a common processor. The digital sensor data can be transmitted at up to 50 MBPS to a ground station in real time, either directly or through a communications satellite link.
The SAR-MTI system operates in the X-band and provides a number of operational modes:
The visible and infrared imagers share the same gimballed sensor package, and
use common optics, providing a telescopic close-up capability. The Global
Hawk is also fitted with a "self-protection" countermeasures suite to help it
frustrate adversary air defenses, and can be optionally fitted with an SIGINT
package.
NORTHROP GRUMMAN RQ-4A GLOBAL HAWK:
_____________________ _________________ _______________________
spec metric english
_____________________ _________________ _______________________
wingspan 35.4 meters 116 feet 2 inches
length 13.5 meters 44 feet 5 inches
height 4.6 meters 15 feet 2 inches
empty weight 3,850 kilograms 8,490 pounds
max loaded weight 10,400 kilograms 22,900 pounds
cruise speed 650 KPH 404 MPH / 350 KT
service ceiling 20,000 meters 65,000 feet
endurance 34 hours
_____________________ _________________ _______________________
First flight of the Global Hawk was on 28 February 1998. Five prototypes
were built, and put through a thorough flight test program. Beginning in the
spring of 1999, the Global Hawk performed a series of operational evaluation
flights, some of which were remarkable demonstrations of the aircraft's
capability. One of the prototypes flew from Eglin Air Force Base in the
Florida panhandle to Alaska and back again, nonstop and unrefueled, in just
under 25 hours.
In May 2000, a prototype flew up the Atlantic coast of the US from Eglin AFB, transmitting radar images to a US Army ground station at Fort Bragg, North Carolina, and the aircraft carrier USS GEORGE WASHINGTON, at dock at Norfolk, Virginia. The RQ-4A then proceeded across the Atlantic, monitoring shipping movements, and reached its final target, an amphibious landing exercise near Setubal, Portugal. Once done, the Global Hawk retraced its steps and landing at Eglin, 28 hours after its departure.
The program has suffered some setbacks. On 29 March 1999, the second prototype fell out of the sky over the US Navy China Lake military training area in California and was destroyed. The third prototype was badly damaged during a landing on 6 December 1999 when a software bug told the aircraft to taxi at 290 KPH (180 MPH), leading to the grounding of the survivors for three months.
The Global Hawk was scheduled to reach operational service in late 2001, and this timeframe coincided with the US intervention in Afghanistan. Four Global Hawks were available at the time, though only three were regarded as suitable for operations. These three UAVs were operated in the war, though specific details of their missions are unclear. One crashed on 30 December 2001 due to a malfunction.
Global Hawks also served in the invasion of Iraq in the spring of 2003. Although details of their service there are sketchy for the moment, apparently their SAR payload came in very handy for pinning down targets during intense sandstorms. Ironically, despite the service of the Global Hawks in these conflicts, none of them that flew these operations were actually regarded as production machines. The first production RQ-4A, the eighth Global Hawk built, was finally rolled out in the summer of 2003. A base for Global Hawks has been built in the United Arab Emirates to help keep a better eye on the region.
* The Global Hawk is a very high priority program for the Air Force. The initial version, the "Block 5", was more or less an evaluation machine, though it was used operationally as well. It was followed by the "Block 10", which features an improved sensor and self-protection suite, and more electrical power.
The improved self-protection suite includes an AN/ALE-50 towed decoy, an AN/ALR-89 radar-warning receiver, and a new self-defense jammer being designed by Raytheon. The UAV autonomously acts on the information from the self-protection system, deciding whether to abort the mission, take evasive action, or continue with the towed jammer deployed. The remote operator can override whatever decision is taken.
Northrop Grumman is now producing the "Block 20" or "RQ-4B" Global Hawk, with the first rolled out in August 2006. This variant features an uprated engine; a wingspan stretch from 35.4 meters (116 feet) to 39.9 meters (130 feet 10 inches); and a fuselage stretch from 13.5 meters (44 feet) to 14.5 meters (47 feet 7 inches). The RQ-4B provides 50% more electrical power than the RQ-4A and carry a larger payload, of up to 1,360 kilograms (3,000 pounds) as opposed to 910 kilograms (2,000 pounds), and also has an improved communications system and an "open architecture" that makes updates simpler.
* One high-profile update for the Global Hawk is now being pursued under the "Mult-Platform Radar Technology Insertion Program (MP-RTIP)", which will give the UAV an advanced "active electronically scanned array (AESA)" multifunction radar.
MP-RTIP originally started out as an upgrade program for the "E-8 Joint-STARS" manned battlefield reconnaissance aircraft, which is based on the Boeing 707-320 jetliner, but the scope of the program expanded to envision the development of an AESA that could be adapted for use on a range of platforms.
An AESA can be thought of as a radio-frequency (RF) "array processor", composed of a grid of interconnected "transmit-receive" modules, each with its own RF, processing, and control electronics. The modules can work with each other to perform a wide variety of tasks. The AESA is scalable, allowing the fit of more or fewer modules as allowed by the size of the platform, with capability proportional to size. The AESA can perform communications, jamming, and sensing functions in parallel through juggling the use of its modules. Current thinking on the Global Hawk AESA is also placing increased emphasis on providing airborne search functions to the system to allow the UAV to operate as an "airborne early warning (AEW)" platform.
Raytheon and Northrop Grumman were awarded a contract for the MP-RTIP system in late 2000, with Raytheon to build the AESA and Northrop Grumman to perform systems integration. The Global Hawk was selected as the initial target system for MP-RTIP, with initial flight tests in 2005.
* Yet another high-priority update that is being considered for the Global Hawk is to fit it with a SIGINT payload. This option was being considered as a long-term program until the spring of 2001, when a Chinese F-8 fighter trying to "spook" a US Navy EP-3 Aries SIGINT aircraft cruising off the Chinese coast collided with it instead. The F-8 and its pilot were lost, and the EP-3 was forced to make an emergency landing on Tainan Island. The result was a protracted, nasty-tempered diplomatic quarrel, with the Chinese holding the aircraft and the crew while demanding that the US end surveillance of Chinese territory. The crew was returned unharmed, but the Chinese refused to let the EP-3 fly out, forcing the Americans to retrieve it with a leased Antonov Condor transport.
The 1969 shootdown of an EC-121 SIGINT aircraft by the North Koreans led to the development of the "Combat Dawn" Firefly variant, and the 2001 incident led to widespread discussion of adopting a similar strategy to ensure that the problem wouldn't arise again. While the Global Hawk does not have the payload capability to replace a large SIGINT aircraft like the EP-3, it would provide an interim solution if nothing else were available. The Global Hawk SIGINT payload is now a high priority.
Other upgrades are also being considered, such as a fast-track effort to add stores pylons for external payloads, including improved electro-optic / infrared and multispectral sensors; or jamming pods. While a Global Hawk configuration carrying two 225 kilogram (500 pound) or four 112 kilogram (250 pound) GPS-guided bombs has been considered, senior Air Force brass are not enthusiastic about arming the type, since that would make it politically more difficult to use in peacekeeping operations or to obtain overflight permission from friendly nations.
Another possible role is for "Information Warfare (IW)", picking up and penetrating enemy voice, video, and data communications, but currently no miniaturized IW payload suitable for the Global Hawk is available. Northrop Grumman is promoting schemes where several Global Hawks with different but complementary payloads could be used to perform a single mission.
Current USAF plans project 40 to 45 Global Hawks in service by 2010 and 78 in service by 2020, with 40 carrying EO payloads and the other 38 carrying SIGINT payloads. The Air Force expects to retire the aging U-2 reconnaissance aircraft no later than 2011, and have focused on the Global Hawk as the replacement. Lockheed Martin promoted a UAV version of the U-2 designated the "U-2U" as an alternative to the Global Hawk, but nobody was interested.
* NASA is planning to obtain two Global Hawks for research purposes, and following the conflict in Afghanistan, the US Navy also became interested in the Global Hawk, ordering two Block 10 machines. The two UAVs have been used to evaluate concepts for a naval endurance UAV under the Broad Area Maritime Surveillance (BAMS) program, mentioned above. BAMS would complement manned maritime patrol aircraft, and the Navy would like to field BAMS by 2008.
The Navy wants BAMS to have an operational radius of 2,775 kilometers (1,500 NMI) and an on-station time of 12 hours. It would carry an extensive payload suite, with EO/IR imaging sensors; a radar with sea-air-land wide-area search, high-resolution spot beam, MTI, and SAR imaging modes; and a SIGINT package with emitter identification and targeting capabilities. Payload systems will be modular, and it may not be possible to carry a complete suite on a single machine.
BAMS would operate from land bases, but it could be controlled by airborne and maritime platforms as well. Navy officials say they have not selected the Global Hawk for the application, but have also indicated they basically want to modify an off-the-shelf UAV instead of building one from scratch, and so the Global Hawk is a high-profile candidate. However, General Atomics and Lockheed Martin are aggressively pursuing the BAMS requirement as well, offering the Predator B / Mariner subvariant as a solution. The BAMS requirement remains completely up in the air for the moment.
Northrop Grumman has been trying to sell the Global Hawk internationally. Germany is now planning to buy a fleet of five "Eurohawks", which will be Global Hawks fitted with an EADS-built SIGINT suite. The plan is to introduce to service in 2010. NATO is planning to acquire a fleet of eight Global Hawks as well; the Germans are offering to host the NATO Global Hawks, saying the NATO machines would be able to leverage off the support infrastructure the Germans have in place for their Eurohawks. There has also been Middle Eastern interest in a "GulfHawk". Australia and Japan are considering the type; the Japanese wanted to build their own endurance UAV to keep an eye on the North Koreans, but common sense prevailed and the decision was made to obtain an available solution.
* Northrop Grumman has conducted preliminary investigations for the USAF Research Lab of a follow-on HALE vehicle, known as the "Sensor Craft", which would have greater endurance and payload. One Northrop Grumman concepts features a diamond-shaped "joined wing" airfoil, with long conventional airfoil extensions. Boeing has also produced Sensor Craft concepts, featuring a pure joined-wing airfoil.
Sensor Craft appears to be a purely experimental program, but the confrontation between the US and China over the EP-3 SIGINT aircraft in the spring of 2001 helped increase interest in a new, large surveillance UAV. Many defense officials are now promoting acquisition of a large, capable UAV designated the "U-X" with stealthy characteristics that can fly at altitudes above the ceiling of a piloted interceptor. The UAV would not necessarily be designed to overfly protected airspace. One or two dozen such UAVs would be bought at a minimum total price of $1.5 billion USD. Ironically, if the new UAV is built, it will bring the US full circle, back to the "Tier 3" UAV that was cancelled early in the 1990s.
