Heralded as the replacement for the venerable U-2 spyplane, the heavy UAV has also been kind of a white elephant...

Type: high altitude, long-endurance recce UAV



Powerplant: 1 x 33.8 kN (7600 lb) RR/Allison
                    F137-AD-100 (model AE 3007H) turbofan

First flight: 28 February 1998

The RQ-4 Global Hawk is used by the US Air Force as a surveillance aircraft. In role and design, it is somewhat similar to the Lockheed U-2, the venerable 1950's spy plane. It was neither designed nor developed or built by Scaled Composites, and in fact was the direct competitor of two unfortunately undocumented designs that Scaled was associated with. However, Scaled is currently involved in the development of a smaller scale combat variant, and it is therefore important to tell the Global Hawk's story so as to know what the new aircraft comes from.

Defined as a High-Altitude, Long-Endurance Unmanned Aerial Vehicle (HAE UAV) program, it started off as an Advanced Concept Technology Demonstration (ACTD) designed to satisfy the Defense Airborne Reconnaissance Office's (DARO) goal of providing extended reconnaissance capability to the Joint Force commander. Extended reconnaissance was defined as "the ability to supply responsive and sustained data from anywhere within enemy territory, day or night, regardless of weather, as the needs of the warfighter dictate." Two complementary HAE UAV systems were developed under this program; a conventional design (Tier II Plus) and a Low Observable configuration (Tier III Minus).

The Tier 2+ program, initially funded to the tune of $115 million, attracted a variety of big-name defense companies. Boeing and Lockheed were jointly developing the Tier III-Minus behind closed doors (this became the RQ-3 Darkstar). The first phase of the Tier II-Plus project was also underway with five rival designs from Loral, Raytheon, Teledyne Ryan, Northrop Grumman, and Orbital Sciences Corp., the latter two each teaming with Scaled Composites (Scaled's Model 260 designation being applied to the fomer of these collaborations). Northrop's and OSC's projects lost out to Teledyne Ryan's Global Hawk, but ironically, Northrop Grumman not only would later receive a contract to uphaul the Teledyne Ryan UAV, but would soon absorb that very company and appropriating its once competitor design; in a further twist of irony, Scaled Composites will now be the prime contractor for the Global Hawk's Model 396 combat version.

The Tier II Plus air vehicle was to be capable of standoff, sustained high altitude surveillance and reconnaissance. It had to operate at ranges up to 3000 nautical miles from its launch area, with loiter capability over the target area of up to 24 hours at altitudes greater than 60,000 feet. It also had to be capable of simultaneously carrying electro-optical (EO), infra-red (IR), and synthetic aperture radar (SAR) payloads, and capable of both wideband satellite and Line-Of-Sight (LOS) data link communications. Finally, it had to be capable of long dwell, broad area coverage, and continuous spot coverage of areas of interest with high resolution sensors. Global Hawk's 24-hour operationally persistent dwell was to support persistently viewing and tracking targets like critical mobile targets. During the 1996-1998 development phase, two vehicles, two sets of payloads, and a ground control station were to be procured and field tested.

The Global Hawk is focused on the radar integrated into the system for all-weather, wide-area and spot capability that can provide high quality imagery with targeting accuracy. It is a theater commander's asset to both provide a broad overview and systematically target surveillance shortfalls. The Global Hawk air vehicle is to provide high resolution Synthetic Aperture Radar (SAR)—that can penetrate cloud-cover and sandstorms—and Electro-Optical/Infrared (EO/IR) imagery at long range with long loiter times over target areas. Potential missions for the Global Hawk cover the spectrum of intelligence collection capability to support forces in worldwide peace, crisis, and wartime operations. According to the Air Force, the capabilities of the aircraft will allow more precise targeting of weapons and better protection of forces through superior surveillance capabilities.

The Global Hawk is the first UAV to be certified by the FAA to file its own flight plans and use civilian air corridors in the United States with no advance notice. This potentially paves the way for a revolution in unmanned flight, including that of unmanned civil passenger airliners. The Global Hawk UAV system comprises an air vehicle segment consisting of air vehicles with sensor payloads, avionics, and data links; a ground segment consisting of a Launch and Recovery Element (LRE), and a Mission Control Element (MCE) with embedded ground communications equipment; a support element; and trained personnel.

The Integrated Sensor Suite (ISS) consists of a synthetic aperture radarSynthetic aperture radar (SAR) is a form of radar in which sophisticated post-processing of radar data is used to produce a very narrow effective beam. It can only be used by moving instruments over relatively immobile targets, but it has seen wide applic (SAR), electro-optical (EO), and infraredInfrared IR radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. The name means "below red" (from the Latin infra "below"), red being the color of visible light of longest wavelength. (IR) sensors. Either the EO or the IR sensors can operate simultaneously with the SAR. Each of the sensors provides wide area search imagery and a high-resolution spot mode. The SAR has a ground moving target indicator (GMTI) mode, which can provide a text message providing the moving target's position and velocity. Both SAR and EO/IR imagery are processed onboard the aircraft and transmitted to the MCE as individual frames. The MCE can mosaic these frames into images prior to further dissemination.

Navigation is via inertial navigation with integrated Global Positioning Systemsatellites such as this NAVSTAR have been launched since 1978. The Global Positioning System usually called GPS (the US military refers to it as NAVSTAR , is a satellite navigation system used for determining one's precise location and providing a highly updates. Global Hawk is intended to operate autonomously and "untethered" using a satellite data link (either Ku or UHF) for sending sensor data from the aircraft to the MCE. The common data link can also be used for direct down link of imagery when the UAV is operating within line-of-sight of users with compatible ground stations.

The ground segment consists of an MCE for mission planning, command and control, and image processing and dissemination; an LRE for controlling launch and recovery; and associated ground support equipment. (The LRE provides precision differential global positioning system corrections for navigational accuracy during takeoff and landings, while precision coded GPS supplemented with an inertial navigation system is used during mission execution.) By having separable elements in the ground segment, the MCE and the LRE can operate in geographically separate locations, and the MCE can be deployed with the supported command's primary exploitation site. Both ground segments are contained in military shelters with external antennas for line-of-sight and satellite communications with the air vehicles.

The contract for Phase II (development and flight test) of the Tier II+ program was awarded in May 1995 to Teledyne-Ryan Aeronautical. The Global Hawk system was built by a team comprised of Teledyne Ryan Aeronautical in San Diego, E-Systems in Falls Church, Virginia, Hughes, Loral, and a number of other companies that were working on various subsystems within the aircraft. Several integrated product-team reviews were held as progress was made towards system roll out. Teledyne-Ryan completed fabrication of Global Hawk air vehicle #1 in August 1996. It underwent ground-vibration testing at full gross weight with active flight controls in preparation for its first flight, due in 1997. Global Hawk's first flight was from Edwards Air Force Base, California, on February 28, 1998. Global Hawk flying quality flights were flown, and military utility flights were to commence in April 1999. However, in March, 1999, a Global Hawk vehicle, with its sensors, went out of control and was destroyed. This crash delayed the Global Hawk military utility study at least two months. Finally, on 16 February 2000 Northrop Grumman Corp. of San Diego, California, was awarded a $71,999,635 modification to a cost-plus-award-fee contract, MDA972-95-3-0013, to provide for two prototype Global Hawk unmanned aerial vehicles, associated system modification, and engineering support., with expected contract completion date being March 31, 2002.

Northrop Grumman's main customer for Global Hawk is the U.S. Air Force, which has taken delivery of 10 air vehicles and is buying 48 more. The Global Hawk is available in two major variants, the RQ-4A, which is the original variant, and the RQ-4B, which is somewhat larger, and has a 50% greater payload capacity. The U.S. Air Force has begun focusing on this newer version. Scaled Composites and Northrop Grumman are also offering a 50% proportional shrink of the RQ-4A, currently known as the Scaled Composites/Northrop Grumman Ryan Model 396, as part of the USAF Hunter-Killer program.

Global Hawk prototypes have been used in the 2003 invasion of Iraq and in Operation Enduring Freedom. While their data-collection capabilities have been praised, the aircraft did suffer a high number of accidents, with two of the aircraft, more than one quarter of the aircraft used in the conflicts, being lost (implying that there were seven Global Hawks used in this program). According to Australian press reports, the crashes were due to "technical failures or poor maintenance", with a failure rate per hour flown over 100 times higher than the F-16 fighters flown in the same conflicts. The manufacturers stated that it was unfair to compare the failure rates of a mature design to that of a prototype plane, and pointed to a lack of trained maintenance staff and spare parts. There is also something to be said for the fact that no pilot was placed at risk.

The RQ-4A has already been used operationally during Operation Enduring Freedom in Afghanistan. Despite the loss of one of the two deployed vehicles, the operations were considered a success. By mid-2005, the USAF had received a total of 12 Global Hawk UAVs, and the current requirement is for up to 58 aircraft (including the later RQ-4B model, q.v.). The designation YRQ-4A has been assigned to RQ-4A aircraft which are modified to evaluate new technologies and components for the general improvement of the performance of the Global Hawk system. Similarly, modified MCEs and LREs have been designated YRD-2A and YRD-2B, respectively. In April 2003, the designation RQ-4B was assigned to an enlarged derivative of the RQ-4A. Northrop Grumman is currently building three RQ-4B aircraft for delivery in 2006. Compared to the RQ-4A, the RQ-4B has a 50% higher payload capability and will carry additional SIGINT (Signal Intelligence) and ELINT (Electronic Intelligence) payloads.

The U.S. Navy has ordered two examples of the Global Hawk in 2005 to be used to evaluate maritime surveillance capabilities under the GHMD (Global Hawk Maritime Demonstration) program. The first RQ-4A for the Navy was delivered and flown in October 2004 from a Northrop Grumman production plant in Palmdale, Calif., where the Navy formally accepted the air vehicle, to Edwards Air Force Base, Calif. The vehicle then underwent testing at Edwards for several months before heading to Naval Air Station Patuxent River, Md. to prepare for a future maritime demonstration. The second one was delivered several months later. The Navy RQ-4A Global Hawk was flown The maritime demonstration is intended to help the Navy determine how to use UAVs for reconnaissance.

International customers have also expressed interest in the Global Hawk. As of February 2004, Australia has committed to 5-6 Global Hawk airframes for maritime and land surveillance, to replace their Lockheed Martin P-3 Orion patrol aircraft and English Electric Canberra reconnaissance aircraft, with deliveries in 2004-2005. Joint USAF/ RAAF exercises in 2001 demonstrated the utility of the Global Hawk in Australian waters. In addition, Australia increased their requirements from merely a maritime role to a land surveillance role after observing American usage in 2003. Reports state that the cost of Australia's purchase of the planes has increased at least fivefold (from 150 million AUD to between 750 and 1000 million AUD) over initial estimates, though no explanation was given for the extra cost and the plans may involve the purchase of extra aircraft. Germany is strongly considering a variant of the RQ-4B (dubbed "Euro Hawk") equipped with an EADS SIGINT package to fulfill their desire to replace their aging Dassault-Breguet Atlantique electronic surveillance aircraft. Canada is also a potential customer.


General specifications:
Contractor: Northrop Grumman, with EADS participation in European models.
Landing Type: runway
Launch Type: runway

RQ-4A specifications:
Length: 13.53 m (44 ft 4.75 in) (RQ-4A)
Wingspan: 35.42 m (116 ft 2.5 in)
Height 4.64 m (15 ft 2.5 in)
Maximum weight: 12130 kg (26750 lb)
Empty weight: 6710 kg (14800 lb)
Top speed: 636 km/h 648 km/h (403 mph)
Cruise speed:250 km/h
Ceiling: 19,800 m (65000 ft)
Range: 21,720 km (11730 nm)
Endurance: 24 to 36 hours

RQ-4B specifications:
Length 14.50 m (47 ft 7 in)
Wingspan: 39.90 m (130 ft 11 in)
Height 4.64 m (15 ft 2.5 in)
Maximum weight: 14630 kg (32250 lb)
Ceiling: 18,300 m (60000 ft)
Range: 21,720 km (11730 nm)
Endurance: 28 hours

Crew/passengers: none

Main sources:
- Masterliness - The World Knowledge Library
- FAS Intelligence Resource Program
- Crash and burn: $1bn spy plane disaster
- Innovative Management in the DARPA High Altitude Endurance UAV Program
- The Spyflight Website