Northrop Grumman RQ-4 Global Hawk

RQ-4 Global Hawk
Global Hawk 1.jpg
An RQ-4 Global Hawk flying in 2007
RoleSurveillance UAV
National originUnited States
ManufacturerNorthrop Grumman
First flight28 February 1998
StatusIn service
Primary usersUnited States Air Force
Number built42 RQ-4Bs as of FY2013[1]
Program costUS$10 billion (USAF cost through FY2014)[1]
Unit cost
US$131.4M (FY13)[1]
US$222.7M (with R&D)[1]
Developed intoNorthrop Grumman MQ-4C Triton

The Northrop Grumman RQ-4 Global Hawk is an unmanned (UAV) surveillance aircraft. It was initially designed by Ryan Aeronautical (now part of Northrop Grumman), and known as Tier II+ during development. The Global Hawk performs a similar role as the 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, which is an area the size of South Korea or Iceland.

The Global Hawk is operated by the United States Air Force. It is used as a high-altitude platform covering 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. Cost overruns led to the original plan to acquire 63 aircraft being cut to 45, and to a 2013 proposal to mothball the 21 Block 30 signals intelligence variants.[1] Each aircraft was to cost US$60.9 million in 2001,[2] but this had risen to $222.7 million per aircraft (including development costs) by 2013.[1] The U.S. Navy has developed the Global Hawk into the MQ-4C Triton maritime surveillance platform.



The Global Hawk took its first flight on 28 February 1998.[3] The first seven aircraft were built under the Advanced Concept Technology Demonstration (ACTD) program, sponsored by DARPA,[4] in order to evaluate the design and demonstrate its capabilities. Demand for the RQ-4's abilities was high 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.[5]

In order to increase the aircraft's capabilities, the airframe was redesigned, with the nose section and wings being stretched. The modified aircraft, designated RQ-4B Block 20,[6] can carry up to 3,000 lb (1,360 kg) 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 25 August 2006.[7] 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.[8]

United States Navy version

The prototype MQ-4C on its first flight

The United States Navy took delivery of two of the Block 10 aircraft to evaluate their maritime surveillance capabilities, designated N-1 (BuNo 166509) and N-2 (BuNo 166510).[9] The initial navalised example was tested at Edwards Air Force Base briefly, before moving to NAS Patuxent River in March 2006 for the Global Hawk Maritime Demonstration (GHMD) program, operated by Navy squadron VX-20.[10][11] In July 2006, the GHMD aircraft flew in the Rim of the Pacific (RIMPAC) exercise for the first time; although it was in the vicinity of Hawaii, the aircraft was operated from NBVC Point Mugu, requiring flights of approximately 2,500 mi (4,000 km) each way to the area. Four flights were performed, resulting in over 24 hours of persistent maritime surveillance coordinated with Abraham Lincoln and Bonhomme Richard. For the GHMD program, the Global Hawk was tasked with maintaining maritime situational awareness, contact tracking, and imagery support of exercise operations. Images were transmitted to NAS Patuxent River for processing and then forwarded to the fleet off Hawaii.[12]

Northrop Grumman entered a RQ-4B variant in the US Navy's Broad Area Maritime Surveillance (BAMS) UAV competition. On 22 April 2008, it was announced that Northrop Grumman's RQ-4N had won and that the Navy had awarded a US$1.16 billion contract.[13] In September 2010, the RQ-4N was officially designated the MQ-4C.[14] The Navy MQ-4C differs from the Air Force RQ-4 mainly in its wing. While the Global Hawk remains at high altitude to conduct surveillance, the Triton climbs to 50,000 ft to see a wide area and can drop to 10,000 ft to get further identification of a target. The Triton's wings are specially designed to take the stresses of rapidly decreasing altitude. Though similar in appearance to the Global Hawk's wings, the Triton's internal wing structure is much stronger and has additional features including anti-icing capabilities and impact and lightning strike protection.[15]

Cost increases and procurement

Development cost overruns placed the Global Hawk at risk of cancellation. In mid-2006, per-unit costs were 25% over baseline estimates, caused by both the need to correct design deficiencies as well as to increase its capabilities. This caused concern over a possible congressional termination of the program if its national security benefits could not be justified.[16][17] However, in June 2006, the program was restructured. Completion of an operational assessment report by the USAF was delayed from August 2005-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 was extended by two years to 2015.[18]

A maintenance crew preparing a Global Hawk at Beale Air Force Base

In February 2011, the USAF reduced its planned purchase of RQ-4 Block 40 aircraft from 22 to 11 in order to cut costs.[19] In June 2011, the U.S. Defense Department's Director, Operational Test and Evaluation (DOT&E) found the RQ-4B "not operationally effective" due to reliability issues.[20] 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."[21]

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.[22][23] Plans to increase procurement of the Block 40 variant were also announced.[24][25] 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.[26] The USAF plans to procure 45 RQ-4B Global Hawks as of 2013.[1] Before retiring in 2014, ACC commander, General Mike Hostage said of the U-2's replacement by the drone that "The combatant commanders are going to suffer for eight years and the best they’re going to get is 90 percent".[27]

From 2010-2013, costs of flying the RQ-4 fell by more than 50%. In 2010, the cost per flight hour was $40,600, with contractor logistic support making up $25,000 per flight hour of this figure. By mid-2013, cost per flight hour dropped to $18,900, contractor logistic support having dropped to $11,000 per flight hour. This was in part due to higher usage, spreading logistics and support costs over a higher number of flight hours.[28]


EuroHawk at the ILA 2012

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 Marineflieger (German Naval Air Arm). The EADS sensor package is composed of six wing-mounted pods;[29] reportedly these sensor pods could potentially be used on other platforms, including manned aircraft.[30]

The EuroHawk was officially rolled out on 8 October 2009 and its first flight took place on 29 June 2010.[31] It underwent several months of flight testing at Edwards Air Force Base.[32] On 21 July 2011, the first EuroHawk arrived in Manching, Germany; after which it was scheduled 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.[33] In 2011 the German ministry of defence was aware of difficulties with the certification for use within the European airspace.[34] During flight trials, problems with the EuroHawk's flight control system were found; the German certification process was also complicated by Northrop Grumman refusing to share technical data on the aircraft with which to perform evaluations.[30]

On 13 May 2013, German media reported that the EuroHawk would not be certifiable under ICAO rules without an anti-collision system; thus preventing any operations within European airspace or the airspace of any ICAO member.[35][36] The additional cost of certification was reported to be more than 600 million (US$780 million).[37] On 15 May 2013, the German government announced the immediate termination of the program, attributing the cancellation to the certification issue.[38] Reportedly, the additional cost to develop the EuroHawk to the standards needed for certification may not have guaranteed final approval for certification.[39] German defense minister Thomas de Maizière stated EuroHawk was "very important" for Germany in 2012,[34] then referred to the project as being "a horror without end" in his 2013 statement to the Bundestag. The total cost of the project before it was canceled was €562 million.[40][41] Northrop Grumman and EADS have described reports of flight control problems and high costs for certification as "inaccurate"; they have stated their intention to provide an affordable plan to complete the first EuroHawk's flight testing and produce the remaining four aircraft.[42][43]

On 8 August 2013, the EuroHawk set an endurance record by flying continuously in European airspace for 25.3 hours, reaching an altitude of 58,600 feet (17,900 m). It was the longest flight by an unrefueled UAS weighing more than 30,000 lb (14,000 kg) in European skies.[44] On 5 October 2014, German Minister of Defence Ursula von der Leyen was reportedly considering reactivating the EuroHawk program to test its reconnaissance abilities over a long period at altitudes of up to 20,000 m (66,000 ft). Attempting to test the recon system on Airbus aircraft and an Israeli drone as alternate platforms had proven unsuccessful. The Bundeswehr would use it to detect, decrypt, and potentially interfere with enemy communications signals. If tests prove successful, a carrier would be purchased, likely "similar" to the U.S. Global Hawk.[45] Germany is considering installing the EuroHawk's SIGINT payloads onto the U.S. Navy MQ-4C Triton Global Hawk derivative, as the electronic and communications intelligence sensors would be more difficult to place on other substitute aircraft. It already has icing and lightning-strike protection, and was built with certification over civilian airspace in mind, meeting the STANAG 4671 requirements that had ended the EuroHawk program.[46]

Universal Payload Adapter and new payloads

In January 2014, President Obama signed a budget that included a $10 million study on adapting the U-2's superior sensors for the RQ-4.[47] In April 2015, Northrop Grumman reportedly installed the U-2's Optical Bar Camera (OBC) and Senior Year Electro-Optical Reconnaissance System (SYERS-2B/C) sensors onto the RQ-4 using a Universal Payload Adapter (UPA). Successful testing indicated that all RQ-4s could be similarly retrofitted.[48]

On 14 July 2015, Northrop Grumman and the USAF signed an agreement to demonstrate an RQ-4B fitted with the U-2's OBC and SYERS-2C sensors; two Global Hawks are to be fitted with the UPA, involving the installation of 17 payload adapter fixtures and a new payload bay cover, as well as software and mission system changes for each sensor. The UPA can support 1,200 lb (540 kg) of sensors and will create a canoe-shaped sensor bay on the fuselage's underside. The RQ-4's ability to operate these sensors will likely influence the U-2's planned retirement by 2019. In addition, Northrop also expects to receive a contract to integrate the UTC Aerospace Systems MS-177 mulitspectral sensor used on the E-8C JSTARS onto the RQ-4;[49][50] the MS-177 will replace the SYERS-2 and includes modernized optronics and a gimbaled rotation device to increase field of view by 20 percent.[51] The RQ-4B flew with the SYERS-2 on 18 February 2016.[52]

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