Northrop Grumman RQ-4 Global Hawk
|RQ-4/MQ-4 Global Hawk|
|An RQ-4 Global Hawk flying in 2007|
|National origin||United States|
|First flight||28 February 1998|
|Primary users||United States Air Force
United States Navy
|Program cost||US$1.635 billion|
|Unit cost||US$104 million (flyaway cost for FY2012)|
|Variants||Scaled Composites Model 396|
|Developed into||Northrop Grumman MQ-4C Triton|
The Northrop Grumman RQ-4 Global Hawk is an unmanned aerial vehicle (UAV) surveillance aircraft. It was initially designed by Ryan Aeronautical (now part of Northrop Grumman), and known as Tier II+ during development. In role and operational design, the Global Hawk is similar to the venerable Lockheed U-2. The RQ-4 provides a broad overview and systematic surveillance using high resolution synthetic aperture radar (SAR) and long-range electro-optical/infrared (EO/IR) sensors with long loiter times over target areas. It can survey as much as 40,000 square miles (100,000 km2) of terrain a day.
The Global Hawk is operated by the United States Air Force and Navy. It is used as a high-altitude platform for surveillance and security. Missions for the Global Hawk cover the spectrum of intelligence collection capability to support forces in worldwide military operations. According to the United States Air Force, the superior surveillance capabilities of the aircraft allow more precise weapons targeting and better protection of friendly forces. Each aircraft costs US$35 million on its own; including development costs and a planned fleet of 55 units, the unit cost is US$218 million.
The first seven aircraft were built under the Advanced Concept Technology Demonstration (ACTD) program, sponsored by DARPA, in order to evaluate the design and demonstrates its capabilities. Demand for the RQ-4's abilities was in high demand in the Middle East; thus, the prototype aircraft were actively operated by the U.S. Air Force in the War in Afghanistan. In an unusual move, the aircraft entered initial low-rate production while still in engineering and manufacturing development. Nine production Block 10 aircraft, sometimes referred to as RQ-4A, were produced; of these, two were sold to the US Navy and an additional two were deployed to Iraq to support operations there. The final Block 10 aircraft was delivered on 26 June 2006.
In order to increase the aircraft's capabilities, the airframe was redesigned, with the nose section and wings being stretched. The altered aircraft, designated RQ-4B Block 20, allow the aircraft to carry up to 3,000 pounds of internal payload. These changes were introduced with the first Block 20 aircraft, the 17th Global Hawk produced, which was rolled out in a ceremony on August 25, 2006. First flight of the Block 20 from the USAF Plant 42 in Palmdale, California to Edwards Air Force Base took place on 1 March 2007. Developmental testing of Block 20 took place in 2008.
The United States Navy took delivery of two of the Block 10 aircraft to be used to evaluate maritime surveillance capabilities, designated N-1 (BuNo 166509) and N-2 (BuNo 166510). The initial example was tested in a naval configuration at Edwards Air Force Base for several months, later ferrying to NAS Patuxent River on 28 March 2006 to begin the Global Hawk Maritime Demonstration (GHMD) program. Navy squadron VX-20 was tasked with operating the GHMD system.
The GHMD aircraft flew in the Rim of the Pacific (RIMPAC) exercise for the first time in July 2006. Although RIMPAC operations were in the vicinity of Hawaii, the aircraft was operated from Edwards, requiring flights of approximately 2,500 miles (4,000 km) each way to the operations area. Four flights were performed, resulting in over 24 hours of persistent maritime surveillance coordinated with USS Abraham Lincoln and USS Bonhomme Richard. As a part of the demonstration program, Global Hawk was tasked with maintenance of maritime situational awareness, contact tracking, and imagery support of various exercise operations. In operation, images from Global Hawks were transmitted to NAS Patuxent River for processing before being forwarded to the fleet operations off Hawaii.
Northrop Grumman entered a version of the RQ-4B in the US Navy's Broad Area Maritime Surveillance (BAMS) UAV contract competition. On 22 April 2008 the announcement was made that the Northrop Grumman RQ-4N had won the bid, with the Navy awarding a contract worth US$1.16 billion. In September 2010, the RQ-4N was officially designated the MQ-4C.
Cost increases and procurement 
Program development cost overruns had put the Global Hawk system at risk of cancellation. Per-unit costs in mid-2006 were 25% over baseline estimates, caused by both the need to correct design deficiencies as well as increase the system's capabilities. This caused some concerns about a possible congressional termination of the program if its national security benefits could not be justified. However, in June 2006, the Global Hawk program was restructured. Completion of an operational assessment report by the Air Force was delayed from August 2005 to November 2007 due to manufacturing and development delays. The operational assessment report was released in March 2007 and production of the 54 air vehicles planned has been extended by two years to 2015.
In February 2011, the Air Force reduced its planned purchase of RQ-4 Block 40 aircraft from 22 to 11 in order to cut costs. In June 2011, the U.S. Defense Department's Director, Operational Test and Evaluation (DOT&E) found the RQ-4B "not operationally effective" for its mission due to reliability issues.
In June 2011, the Global Hawk was certified by the Secretary of Defense as critical to national security following a breach of the Nunn-McCurdy Amendment; the Secretary stated: "The Global Hawk is essential to national security; there are no alternatives to Global Hawk which provide acceptable capability at less cost; Global Hawk costs $220M less per year than the U-2 to operate on a comparable mission; the U-2 cannot simultaneously carry the same sensors as the Global Hawk; and if funding must be reduced, Global Hawk has a higher priority over other programs."
On 26 January 2012, the Pentagon announced plans to end Global Hawk Block 30 procurement as the type was found to be more expensive to operate and with less capable sensors than the existing U-2. Plans to increase procurement of the Block 40 variant were also announced. The Air Force's fiscal year 2013 budget request said it had resolved to divest itself of the Block 30 variant, however, the National Defense Authorization Act for Fiscal Year 2013 mandated operations of the Block 30 fleet through the end of 2014.
The German Air Force (Luftwaffe) ordered a variant of the RQ-4B, to be equipped with a customized sensor suite, designated EuroHawk. The aircraft was based on the RQ-4B Block 20/30/40 and was to be equipped with an EADS-built SIGINT package; it was intended to fulfill Germany's requirement to replace their aging Dassault-Breguet Atlantique electronic surveillance aircraft of the German Navy (Deutsche Marine). The EADS sensor package is composed of six wing-mounted pods; reportedly these sensor pods could potentially be used on other platforms, including manned aircraft.
The EuroHawk officially rolled out on 8 October 2009 and the first flight took place on 29 June 2010. It underwent several months of flight testing at Edwards Air Force Base. On 21 July 2011, the first EuroHawk arrived in Manching, Germany; after which it was schedueled to receive its SIGINT sensor package and undergo further testing and pilot training until the first quarter of 2012. The Luftwaffe planned to station the type with Reconnaissance Wing 51.
Development of the type proved to be problematic. During the flight trials, problems with the EuroHawk's flight control system were exposed; the German certification process was also complicated by a refusal by Northrop Grumman to share technical data on the aircraft with which to perform evaluations. In May 2013, it was reported that the EuroHawk is not certifiable under ICAO rules without an anti-collision system; thus preventing any operations within European airspace or the airspace of any ICAO member; the additional cost of certification was reported to be more than €600 million (US$780 million).
On 15 May 2013, the German government announced the immediate termination of the program, attributing the cancellation to the certification issue. Reportedly, the additional cost to develop the EuroHawk to the standards needed for certification may not have guaranteed final approval for certification. German defense minister Thomas de Maizière called the project "a horror without end" in his Bundestag statement. The total cost of the project before it was canceled was €562 million.
The Global Hawk UAV system comprises the RQ-4 air vehicle, which is outfitted with various equipment such as sensor packages and communication systems; and a ground element consisting of a Launch and Recovery Element (LRE), and a Mission Control Element (MCE) with ground communications equipment. Each RQ-4 air vehicle is powered by an Allison Rolls-Royce AE3007H turbofan engine with 7,050 lbf (31.4 kN) thrust, and carries a payload of 2,000 pounds (900 kilograms). The fuselage comprises an aluminum, semi-monocoque construction; the wings are made of lightweight high-strength composite materials.
System and ground facilities 
The Integrated Sensor Suite (ISS) is provided by Raytheon and consists of a synthetic aperture radar (SAR), electro-optical (EO), and infrared (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 transmitted from the aircraft to the MCE as individual frames, and reassembled during ground processing. A onboard inertial navigation system, supplemented by Global Positioning System updates, comprises the aircraft's onboard navigational suite. Global Hawk is intended to operate autonomously and "untethered" using a satellite data link (either Ku or UHF) for sending 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 compatible ground stations.
The ground segment consists of a Mission Control Element (MCE) and Launch and Recovery Element (LRE), provided by Raytheon. The MCE is used 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.
Sensor packages 
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, and is being sold on the international market. 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 and transmitted in real time at up to 50 Mbit/s to a ground station.
The SAR-MTI system operates in the X-band and provides a number of operational modes; such as the wide-area MTI mode with a radius of 62 miles (100 kilometers), combined SAR-MTI strip mode provides 20 foot (6 meter) resolution over 23 miles (37 kilometers) wide sections, and a SAR spot mode providing 6 foot (1.8 meter) resolution over 3.8 square miles (10 square kilometers).
The visible and infrared imagers share the same gimballed sensor package, and use common optics, providing a telescopic close-up capability. It can be optionally fitted with an auxiliary SIGINT package. To improve survivability, the Global Hawk is fitted with a Raytheon developed AN/ALR-89 self-protection suite consisting of the AN/AVR-3 Laser Warning System, AN/APR-49 Radar Warning Receiver and a jamming system. An ALE-50 towed decoy also aids in the Global Hawk's deception of enemy air defenses.
In July 2006, the US Air Force began testing the Global Hawk Block 30 upgrades in the Benefield Anechoic Facility at Edwards AFB; such as the Advanced Signals Intelligence Payload, an extremely sensitive SIGINT processor. In 2006, a specialist radar system, the Multi-Platform Radar Technology Insertion Program, or MP-RTIP, began testing on the Scaled Composites Proteus; one modified Global Hawk shall carry the radar following validation. In 2010, Northrop spoke on the sensor capabilities of the new Block 40 aircraft, including MP-RTIP radar, emphasising surveillance over reconnaissance.
Operational history 
U.S. Air Force 
Air Force Global Hawk flight test evaluations are performed by the 452nd Flight Test Squadron at Edwards AFB. Operational USAF aircraft are flown by the 9th Reconnaissance Wing, 12th Reconnaissance Squadron at Beale Air Force Base.
Global Hawk ATCD prototypes have been used in the War in Afghanistan and in the Iraq War. Since April 2010, they fly the Northern Route, from Beale AFB over Canada to South-East Asia and back, reducing flight time and improving maintenance. While their data-collection capabilities have been praised, the program lost three prototype aircraft to accidents, more than one quarter of the aircraft used in the wars. The crashes were reported to be 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 wars. The manufacturer stated that it was unfair to compare the failure rates of a mature design to that of a prototype aircraft. In June 2012, a media report described the Global Hawk, the MQ-1 Predator and the MQ-9 Reaper s "... the most accident-prone aircraft in the Air Force fleet."
On 11 February 2010, the Global Hawks deployed in the Central Command AOR accrued 30,000 combat hours and 1,500 plus sorties. Initial operational capability was declared for the RQ-4 Block 30 in August 2011. The Air Force does not plan to keep the RQ-4B Block 30 Global Hawk in service past 2014, in favor of the U-2 and other platforms that can more cheaply take over the mission. Congress wants the Air Force to keep flying the Block 30 Global Hawk through December 2016.
After the 2011 Tōhoku earthquake and tsunami, the aircraft flew 300 hours over the affected areas in Japan. There were also plans to survey the No. 4 reactor at the Fukushima Daiichi Nuclear Power Plant.
By late November 2012, Northrop Grumman had delivered 37 Global Hawks to the U.S. Air Force.
On 21 March 2001, aircraft number 982003, the third ACTD aircraft produced, set an official world endurance record for UAVs, at 30 hours, 24 minutes and 1 second, flying from Edwards. During the same flight, it set an absolute altitude record of 19,928 meters (65,381 ft), which was later broken by the NASA Helios Prototype (although the absolute record was broken, the Global Hawk's record still stands in its FAI class category).
On 24 April 2001, a Global Hawk flew non-stop from Edwards in the US to RAAF Base Edinburgh in Australia, making history by being the first pilotless aircraft to cross the Pacific Ocean. The flight took 22 hours, and set a world record for absolute distance flown by a UAV, 13,219.86 kilometers (8,214.44 mi).
In December 2007, two Global Hawks were transferred from the U.S. Air Force to NASA's Dryden Flight Research Center at Edwards Air Force Base. Initial research activities beginning in the second quarter of 2009 supported NASA's high-altitude, long-duration Earth science missions. The three Global Hawks were the first, sixth and seventh aircraft built under the original DARPA Advanced Concept Technology Demonstration program, and were made available to NASA when the Air Force had no further need for them. Northrop Grumman is an operational partner with NASA and will use the aircraft to demonstrate new technologies and to develop new markets for the aircraft, including possible civilian uses.
According to an article in the March 2010 issue of Scientific American (p. 25-27), the Global Hawk aircraft belonging to NASA were in use for testing purposes as of October 2009, with science missions expected to start in March 2010. Initial science applications included measurements of the ozone layer and cross-Pacific transport of air pollutants and aerosols. The author of the Scientific American piece speculates that the aircraft could be used for Antarctic exploration while based in and operated from Chile.
In August and September 2010 one of the two Global Hawks was loaned for NASA's GRIP Mission (Genesis and Rapid Intensification Program), with its long-term on station capabilities and long range it was the best aircraft for the mission to monitor the development of Atlantic basin Hurricanes. It was modified to equip weather sensors including Ku-Band Radar, Lightning sensors and Dropsondes. It successfully flew into Hurricane Earl off the United States East Coast on September 2.
In 2009, NATO announced that it expects to have a fleet of up to eight Global Hawks by 2012. The aircraft are to be equipped with MP-RTIP radar systems. NATO has budgeted US$1.4 billion (€1 billion) for the project, and a letter of intent has been signed. NATO signed a contract for five Block 40 Global Hawks in May 2012.
Potential operators 
Australia considered the purchase of a number of Global Hawks for maritime and land surveillance. The Global Hawk was to be assessed against the MQ-9 Mariner in trials in 2007. The Global Hawk aircraft would have operated in conjunction with manned P-8A Poseidon aircraft by 10 and 11 Squadrons of the RAAF, as a replacement of aging AP-3C Orion aircraft. In the end, the Australian government decided not to proceed and canceled the order. In 2012, a procurement effort for seven UAVs by 2019 was initiated. In May 2013 the Australian government confirmed its interest in acquiring the MQ-4C Triton maritime surveillance variant.
Canada has also been a potential customer, looking at the Global Hawk for maritime and land surveillance as either a replacement for its fleet of CP-140 Aurora patrol aircraft or to supplement manned patrols of remote Arctic and maritime environments, before withdrawing from the joint effort in August 2011. Spain has a similar requirement, and has existing contacts with Northrop Grumman.
In 2011, South Korea's Defense Acquisition Program Administration (DAPA) expressed interest in acquiring at least four RQ-4B and support equipment to increase intelligence capabilities following the exchange of the Wartime Operational Control from the U.S. to the Republic of Korea. Government officials debated on the topic of the Global Hawks and its own domestic UAV programs. In September 2011, the US and South Korea discussed aircraft deployments near its border with North Korea to view North Korea and the North Korea–China border. In January 2012, DAPA announced that it would not proceed with a purchase due to a price rise from US$442M to US$899M, and that other platforms such as the Global Observer or the Phantom Eye were being investigated. However, in December 2012, South Korea notified Congress of a possible Foreign Military Sale of 4 RQ-4 Block 30 (I) Global Hawk UAVs with the Enhanced Integrated Sensor Suite (EISS) at an estimated cost of $1.2 billion.
The New Zealand Defence Force is keeping a "watching brief" over Global Hawk, which has the range to conduct surveillance in the Southern Ocean around Antarctica, and in the Pacific Islands. The acquisition process has not moved beyond an expression of interest. Also being looked at are the IAI Heron and the "Kahu", an indigenously developed hand-thrown drone.
- Initial production version for the USAF, 16 built.
- Improved version with increased payload, wingspan increased to 130.9 ft (39.8 m) and length increased to 47.7 ft (14.5 m). Due to the increased size and payload the range is reduced to 8,700 nmi.
- RQ-4E Euro Hawk
- Version for Germany based on RQ-4B and equipped with an EADS reconnaissance payload for SIGINT. Germany canceled its order in May 2013; it received one of five Euro Hawks originally ordered.
- MQ-4C Triton
- For USN Broad Area Maritime Surveillance (BAMS) role; previously known as the RQ-4N; 4 ordered, 68 total planned.
- Equipped with the Battlefield Airborne Communications Node (BACN) system.
Autonomous tanker variant 
Model 396 
Scaled Composites and Northrop Grumman also offered a 50% proportional shrink of the RQ-4A, known as the Model 396, as part of the USAF Hunter-Killer program. The aircraft was rejected in favor of the MQ-9 Reaper.
- United States Air Force
- Air Combat Command
- 9th Reconnaissance Wing – Beale Air Force Base, California
- 53d Wing
- Air Force Reserve Command
- Air Combat Command
- United States Navy
Specifications (RQ-4B) 
Data from USAF
- Crew: 0 onboard (3 remote: LRE pilot; MCE pilot and sensor operator)
- Length: 47.6 ft (14.5 m)
- Wingspan: 130.9 ft (39.9 m)
- Height: 15.3 ft (4.7 m)
- Empty weight: 14,950 lb (6,781 kg)
- Gross weight: 32,250 lb (14,628 kg)
- Powerplant: 1 × Rolls-Royce F137-RR-100 turbofan engine, 7,600 lbf (34 kN) thrust
- Cruise speed: 357 mph (310 kn; 575 km/h)
- Range: 8,700 mi (7,560 nmi; 14,001 km)
- Endurance: 28 hours
- Service ceiling: 60,000 ft (18,288 m)
See also 
- Related development
- Aircraft of comparable role, configuration and era
- Related lists
This article contains material that originally came from the web article Unmanned Aerial Vehicles by Greg Goebel, which exists in the Public Domain.
- "Analysis of the Fiscal Year 2012 Pentagon Spending Request"
- "FY 2011 Budget Estimates", p. 4–111. US Air Force, February 2011.
- "$143M for Global Hawk Cost Overruns". Defense Industry Daily, 25 April 2005.
- "Costly Drone Is Poised to Replace U-2 Spy Plane" New York Times, 2 August 2011.
- NASA Dryden Receives Two Early Global Hawk Aircraft
- "Last Block 10 Global Hawk Arrives For Check Flights."
- "RQ-4 Global Hawk fact sheet". US Air Force. 27 January 2012. Retrieved 25 August 2012.
- "Northrop unveils next generation Global Hawk", Aerotech News and Review, 1 September 2006.
- McGee, Chris, "Global Hawk in demand, passes 10,000 flight hours milestone", Aerotech News and Review, 11 August 2006.
- Northrop Grumman Press Release, 13 June 2005.
- Selinger, M. "U.S. Navy To Receive First Global Hawk Next Week." Aviation Week & Space Technology. 1 October 2004.
- First Unmanned Global Hawk Delivered to U.S. Navy – U.S. Department of Defense Transformation News Story
- "Navy Global Hawk Performs in RIMPAC", Aerotech News and Review, 18 August 2006.
- Navy Awards Northrop Grumman Unmanned Aircraft System Contract
- BAMS given MQ-4C designation
- "Navy drone crashes in Maryland"
- "Investigators Look Into BAMS-D Loss"
- "Navy UAV crashes in Md.; no injuries reported"
- "Cost overruns put Global Hawk at risk"[dead link]. Flight International, 18 April 2006.
- "Cost overruns put Global Hawk at risk", SBAC.com
- http://www.flightglobal.com/Articles/2006/11/21/Navigation/196/210621/Global+Hawk+costs+soar+to+%2410bn.html[dead link] Flight International, 21 November 2006.
- Putrich, Gayle. "Northrop: Global Hawk not slowing down even with cuts". Flight International, 22 February 2011.
- "Pentagon Says Northrop Drone Isn’t ‘Effective’." Bloomberg News, 6 June 2011.
- "Nunn-McCurdy Certification Acquisition Decision Memorandum for the Restructured RQ-4A/B Unmanned Aircraft System Global Hawk." Memorandum for Secretary of the Air Force, 14 June 2011.
- "Defense Budget Priorities and Choices", p. 11. US DoD, January 2012.
- Clark, Colin. "Air Force To Cut 10,000; Global Hawks Get Warehoused." Aol Defense, 27 January 2012.
- Stephen, Trimble. "Pentagon slashes fighter squadrons, airlifters in new budget proposal". Flightglobal. Retrieved 30 January 2012.
- "USAF Cancels Block 30 RQ-4 Global Hawk". Defense Update, 29 January 2012.
- "Global Hawk Program Manager Plans For Early Deliveries, Budget Cuts". InsideDefense. 22 January 2013.
- "RQ-4 Euro Hawk UAV Readying for Takeoff". Defense Industry Daily. 15 May 2013.
- Gubisch, Michael (16 May 2013). "Germany pulls plug on Euro Hawk UAV programme". Flight International.
- "Northrop Grumman and EADS Defence & Security's Euro Hawk Unmanned Aircraft Completes Successful First Flight". GlobeNewswire. 30 June 2010.
- Norris, Guy (12 October 2009). "Northrop Grumman Unveils Euro Hawk". Aerospace Daily and Defense Report.
- "Germany axes Euro Hawk drone program". Defense News, 14 May 2013.
- "German government culls costly Euro Hawk drone project". Deutsche Welle, 15 May 2013.
- "De Maiziere defends Bundeswehr reforms and Euro Hawk halt". Deutsche Welle, 15 May 2013.
- "Germany will not buy Euro Hawk drones." Reuters, 14 May 2013.
- "Euro Hawk" (in German). German Air Force (Luftwaffe). 15 May 2013. Retrieved 16 May 2013.
- Gubisch, Michael. "Germany pulls plug on Euro Hawk UAV programme". Flight International, 16 May 2013.
- "RQ-4 Block 20 Global Hawk". Retrieved 2010-08-16.
- "Hughes Integrated Surveillance & Reconnaissance (HISAR)". Jane's Information Group
- Aerotech News and Review, vol 21, issue 27, August 4, 2006
- AN/ALQ to AN/ALT – Equipment Listing
- "Next generation of Global Hawks ready to roll". Retrieved 2010-08-16.
- Global Hawk Crashes: Who’s to Blame?. May 2003.
- Global Hawk crash unlikely to hurt program. Aerospace Daily via globalsecurity.org, 8 January 2002.
- High-Altitude American Spy Plane Crashes in Pakistan; Engine Failure Cited. 10 July 2002.
- McGarry, Brendan (18 June 2012) Drones Most Accident-Prone U.S. Air Force Craft: BGOV Barometer. Bloomberg, Retrieved 4 February 2013.
- Deployed Global Hawks surpass 30,000 combat flying hours, 1,500 sorties
- USAF details plan to halt Block 30 Global Hawk use - Flightglobal.com, April 19, 2013
- Lawmakers: Keep flying Global Hawk Block 30 through 2016 - Militarytimes.com, May 22, 2013
- Seth Robson (September 12, 2011). "Global Hawk invaluable after Japan disasters". Stars and Stripes.
- "Military Helicopters Finally Dump Seawater on Over-Heating Fukushima Reactors".
- Northrop Grumman Delivers 37th Global Hawk to US Air Force – Deagel.com, January 7, 2013
- FAI World Record data base
- FAI Aviation World Record database
- "Aviation history as Global Hawk completes US-Australia flight." Australian Ministry of Defence press release. 24 April 2001.
- FAI Aviation World Record database
- NASA DFRC web description of aircraft
- "Northrop plans civilian market Global Hawk demonstrations" FlightGlobal.com January 23, 2009
- "NASA GRIP Homepage"
- "GRIP Global Hawk Modifications and Capabilities" (PDF)
- "NASA GRIP News Hurricane Earl News Release". NASA
- Trimble, Stephen. "NATO plans to deploy first RQ-4s in 2012". Flight International, 14 January 2009.
- Hoyle, Craig. "NATO inks $1.7 billion Global Hawk order". Flight International, 21 May 2012.
- Australia funds study. Flight International 09/05/06.
- "Govt scraps plan for military drones" – ABC news
- "Australia moves to buy $3b spy drone fleet."
- Australia issues Triton Letter of Request, May 16 2013 Australian Aviation
- Trimble, Stephen (18 August 2011). "AUVSI: Canada withdraws from NATO RQ-4 program". Flightglobal. Retrieved 18 August 2011.
- Northrop negocia la venta de diez aviones espía a España CincoDias.com
- Japan may buy US drones to spy on China military 5 October 2010, The China Post of Taiwan
- "High costs could ground aerial reconnaissance activities." asahi.com, 23 February 2011.
- "S. Korea vows swifter deployment of spy drones, stealth fighters."
- Global Hawk deploy plan to South Korea, targeting North Korea and China
- Lee, Tae-hoon. "Seoul drops plan to buy Global Hawk UAV". Korea Times.
- South Korea Seeks Four RQ-4 Block 30 Global Hawks – Deagel.com, 24 December 2012.
- Gower, Patrick (2009-09-30). "Spy drones on NZ defence wish list". The New Zealand Herald (APN News & Media). Retrieved 26 February 2012.
- "Indian Navy Interested in Northrop Grumman MQ-4C Maritime Surveillance Unmanned Aircraft Systems". India Defence. February 8, 2011.
- "India will purchase the MQ-4C BAMS drone aircraft". 2012-04-02.
- Air Force Factsheet
- "Roll-out of a marine UAV Global Hawk will be held in June" (Automatically translated into English by Google)
- "U.S. Air Force Officially Designates Aircraft Flying Battlefield Airborne Communications Node System"
- Article: DARPA testing Global Hawk drones as aerial tankers
- "BBC News Technology Unstaffed drone refuelling test 'successful'"
|Wikimedia Commons has media related to: RQ-4 Global Hawk|
|Northrop Grumman RQ-4A Global Hawk Block 10 Cutaway|
|Northrop Grumman RQ-4A Global Hawk Block 10 Cutaway from Flightglobal.com|
- RQ-4 Global Hawk U.S. Air Force fact sheet
- "RQ-4A Global Hawk (Tier II+ HAE UAV)". Federation of American Scientists
- "Global Hawk RQ-4A-B High Altitude Long Endurance UAV". Defense Update
- Raytheon product page on the Global Hawk Integrated Sensor Suite
- Luftwaffe Euro Hawk page, Bundeswehr Euro Hawk page
- Results of Global Hawk accident investigation board
- RQ-4 Global Hawk profile on Air Attack