Northrop Grumman RQ-4A Global Hawk
The RQ-4A Global Hawk was originally developed by Northrop Grumman as an Advanced Concept Technology Demonstration (ACTD) vehicle to validate their design for a High-Altitude, Long Endurance Unmanned Aerial Vehicle (HAE UAV). The design was conceived to satisfy the Defence Airborne Reconnaissance Office (DARO) intention of providing an extended reconnaissance capability of enemy forces, day or night regardless of the weather, to a Joint Force commander. After a six-month competition between five competing companies to satisfy the DARO requirement for a conventional design, the Global Hawk was declared the winner in May 95. A complimentary Low Observable design competition was eventually won by the Lockheed Martin / Boeing DarkStar.
The Global Hawk is built by Northrop Grumman at the Teledyne Ryan Aeronautical centre in San Diego, California. The main sub-contractors are: Raytheon Systems who provide the sensors and mission control element, Rolls-Royce Allison who provide the AE 3006H turbofan engine, Vought Aircraft Industries who provide the 116.2ft carbon fibre wing and L3 who provide the communications system. The Raytheon System reconnaissance sensor suite includes a Synthetic Aperture Radar (SAR) together with Electro-Optical (EO) and Infra-Red (IR) sensors. With a 14,000-nm range, 42 hours endurance and the ability to cruise at 65,000ft, Global Hawk has the ability to direct its sensors over an area of 40,000 square miles in a single 24hr period.
The vehicles flight control, vehicle management software and navigation functions are controlled by two Integrated Mission Management Computers (IMMC) developed by Vista Control Corporation in California. The IMMC combines the data from a Global Positioning System (GPS) and an Internal Measurement Unit (IMU) and then sends control instructions to a Inertial Navigation System (INAS) supplied by Litton Systems of California. The accuracy and reliability of the IMMC was demonstrated in Apr 01 when a Global Hawk made the first non-stop flight by an unmanned aircraft across the Pacific Ocean, flying from Edwards AFB in California to the RAAF base at Edinburgh, South Australia, a distance of 7,500 miles, in 23 hours.
The sensor systems supplied by Raytheon enable the Global Hawk to have a 24-hr reconnaissance capability, regardless of the weather. A 10-inch reflecting telescope acts as the common optics for both the infrared and electro-optical sensors. The electro-optical/infrared sensor operates in the 0.4 to 0.8 micron visible waveband and the 3.6 to 5 micron infrared band. In spot mode the sensor can cover a total of 1900 spots, each one 2km by 2km to an accuracy of 20 meters. In wide area search mode, the sensor can cover an area 10 kilometers wide, giving a total coverage of 40,000 square miles per day. The SAR, incorporating a Ground Moving Target Indicator (GMTI) mode down to 4kts, operates in the X band with a 600 MHz bandwidth giving 3.5kW peak power and can achieve resolutions of 1 ft in spot mode and 3 ft in wide area search mode. The sensors give the Global Hawk a 200km slant range, enabling it to stand-off from highly defended targets.
The distinctive bulge on the top front surface of the fuselage of Global Hawk houses a 48 inch Ku-band wideband satellite communications antenna, part of a comprehensive communications system developed by L3. The system enables reconnaissance or control data to be transferred by either the Ku-band satellite communications system or X-band and UHF line-of-sight links. The onboard self-defence system includes an AN/ALR 89 radar warning receiver, a jamming system and an ALE 50 towed decoy system. The wing has a number of hard points capable of carrying up to 1,000lb each, enabling the vehicle to carry additional payloads externally when necessary.
The Mission Ground Control Station for Global Hawk, developed by GDE Systems who are part of Tracor Aerospace, is housed in an 8ft x 8ft x 24ft shelter. The shelter houses a variety of mission planning, command, communications and image processing computers with four workstations for the staff and is equipped with satellite and line of sight data links to the vehicle. A separate launch and recovery ground station is housed in an 8ft x 8ft shelter, containing two workstations which access the launch and recovery mission computers, and has its own satellite and line of sight data links to the vehicle. Both systems can be transported in a single C-5B or in two loads on a C-17.
The first of 7 development Global Hawks flew on 28 Feb 98 and the following year testing increased considerably, but was put back some months when a Global Hawk went out of control and crashed in Mar 99. During the formal development phase of testing, Global Hawks actually saw operational service in Operation Enduring Freedom in 2001 and Operation Iraqi Freedom in 2003. In total, over 3000 flight hours were logged during the development phase, more than half of which were operational sorties. The first of 48 production vehicles rolled off the assembly line on 1 Aug 03, with the USAF planning to acquire around 51 vehicles, in batches of approximately 10 a year. The USAF Global Hawks will be operated by the 9th Reconnaissance Wing, based at Beale AFB in California, alongside their U-2Ss, and are a complete contrast to the SR-71 formally operated by the unit.
The US Navy have also ordered 2 Global Hawks as testbeds for the development, integration and testing of future maritime UAV sensors and payloads, as well as helping to establish a concept of operations for their use. In the longer-term, the US navy is planning to acquire a Broad Area Maritime Surveillance (BAMS) UAV and, as many of their requirements will probably dovetail fairly neatly with Australia, I think it’s almost certain that the US Navy will end up operating a specialised version of Global Hawk from around 2009-2010. Given its huge radius of operation, 24 hrs at 3000nm from base, it would be feasible for the USN to operate Global Hawk from land bases, however, I suspect they would prefer a specialised version with folding wings capable of operating from their aircraft carriers. Australia already plan to purchase six Global Hawks, designed specifically for maritime surveillance but operating from land bases, to replace their AP-3C Orion maritime patrol aircraft, with the first vehicle becoming operational by 2009, and the final vehicle delivered in 2012.
Future developments for the B-Model Global Hawk include an increased 130ft wingspan and a new fuselage length of 47ft 7in, giving a 50% increase in payload-carrying capacity and the first B Models are scheduled for delivery between 2004-5. The B-Model will incorporate a SIGINT capability and an electronically scanned phased-array radar. The electronically scanned phased-array radar will be based on the system developed under the Multi-Platform Radar Technology Insertion Program (MP-RTIP). The first SIGINT system will be based on an off-the-shelf Hyperwide system for communication bands, followed by a High Band Subsystem initially developed for as part of the Joint SIGINT Avionics Family and finally a new low-band subsystem. The US Air Force Research Laboratory has funded at least two feasibility studies into nuclear powered versions of Global Hawk., which could extend the vehicles flight time from hours to months. However, given the potential drawbacks of using a conventional fission reactor, research is focused on a quantum nucleonic reactor that could generate gamma rays to produce a jet of heated air. Whether this system will ever enter service remains debateable.
A long-running debate has been going on in the US to determine whether to supplement their fleet of 31 U-2Rs with additional aircraft or allocate a bigger role to the Global Hawk. In 1997, Lockheed Martin unsuccessfully proposed an unmanned variant of the U-2S, known as the U-2U, to the USAF for long-duration, high-risk missions – presumably an attempt to kill development of the purpose built Global Hawk. Although the Global Hawk has a much greater range and endurance than the U-2S, the payload capability of the U-2S is twice that of the Global Hawk and is currently more versatile. The most likely solution is that both types will operate side-by-side, as currently each offer capabilities the other lacks. A debate has already taken place within the Department of Defence whether to publicly proceed with development of the next-generation spyplane, known as the U-X, or instead to concentrate ISR capabilities in UAVs. Given the USAF’s already clear preference for manned aircraft working alongside UAVs, I believe the U-X will be developed and in fact may already be in service, following a ‘black’ development programme.
The German Navy (Marineflieger) has had a long-standing requirement to replace, by around 2008, the four ageing Breguet Atlantic ELINT aircraft, of Marinefliegergschwader 3 (MFG3) Graf Zeppelin based at Nordholz, that began operations in the early 1970’s. Five ELINT aircraft initially conducted the 'Slow Coach' SIGINT mission, mainly over the Baltic and North Sea, although one aircraft was withdrawn from service in 1995. Various options have been considered, including an new version of the Atlantic and a refurbished and re-engined version of the P-3C Orion. However, Germany were also keen to investigate whether the operational requirement could be most easily be met by the employment of a HALE UAV, such as Global Hawk.
To display the capabilities of the Global Hawk to the German Ministry of Defence, Northrop Grumman decided to stage a series of demonstration flights in Germany. The first prototype RQ-4A Global Hawk 95-2001 left Edwards AFB California and flew across the Atlantic to the German Navy airbase at Nordholz, arriving at 0405hrs on 15 Oct 03 after a 20hr 53 min flight. The RQ-4A was equipped with an EADS developed ELINT sensor package which had already undergone testing in the USA.
The RQ-4A was based at Nordholz between 15 Oct and 6 Nov 03 during which it made a total of six demonstration flights over the North Sea, achieving a total of 29 hrs flight time. Using the EADS ELINT sensor package, the RQ-4A was able to detect and classify electromagnetic signals from aircraft, ships and land based systems, determining whether they were either tracking, guidance or surveillance radars, whilst relaying the information via a data link to an EADS ground station. If the RQ-4A is ordered to replace the Breguet Atlantic ELINT aircraft, it will also have the capability of carrying a SIGINT or COMINT package. After completing the final test flight on 6 Nov, the RQ-4A took off for the return flight to Edwards AFB, arriving the next day.
NATO has a proposal for the Alliance Ground Surveillance (AGS) programme which will almost certainly be filled by a mixed fleet of manned aircraft and UAVs. Northrop Grumman are leading the TIPs consortium to meet this requirement with a manned Airbus A321 and a version of the RQ-4A known as the EuroHawk.
The reconnaissance capability of Global Hawk is of a wholly different magnitude to any other previous system. For instance, during Operation Iraqi Freedom, a single Global Hawk flew a mere 3% of the image collection sorties mounted by coalition forces and yet collected an amazing 55% of all time-critical data on air defence targets. This one Global Hawk located at least 13 surface-to-air missile batteries, 50 SAM launchers, 300 canisters and 70 missile transporters as well as imaging 300 tanks, 38% of of Iraq's armoured force - an astonishing display of the vehicles.capability. Global Hawk will almost certainly be the most significant ISR UAV of this decade and given the developments planned to enhance its intelligence gathering capabilities, it could well be the pre-eminent ISR UAV of the next decade as well.