Directory of U.S. Military Rockets and Missiles|
Appendix 2: Modern UAVs
|Copyright © 2004-2008 Andreas Parsch|
The Global Hawk is the U.S. Air Force's first operational UAV in the HAE (High Altitude Endurance) category. Its development began in 1994, when DARPA issued a request for proposals for their "Tier II+" HAE UAV requirement. In March 1995 an ACTD (Advanced Concept Technology Demonstration) contract was awarded to Teledyne Ryan Aeronautical (now part of Northrop Grumman), and in January 1997, the designation RQ-4A was officially allocated to the Global Hawk UAV. The first of five ACTD vehicles flew for the first time in February 1998. The EMD (Engineering and Manufacturing Development) phase of the program began in March 2001, and in February 2002, low-rate initial production was approved.
The RQ-4A is powered by a Rolls-Royce/Allison F137-AD-100 (model AE 3007H) turbofan. It takes off and lands on conventional runways using a retractable tricycle landing gear. The airframe has the typical layout of a high-endurance UAV, and the prominent nose bulge houses the wideband SATCOM antenna of 1.2 m (4 ft) diameter. The vehicle can reach an altitude of 19800 m (65000 ft) and has a maximum endurance of at least 36 (and possibly up to 42) hours. A Global Hawk system consists of two RQ-4A UAVs and two major ground stations, the RD-2A Mission Control Element (MCE) and the RD-2B Launch and Recovery Element (LRE). The LRE is used to load autonomous flight data into the UAV's GPS/INS navigation system, control the vehicle during take-off and landing, and monitor its flight performance. The MCE personnel controls and monitors the UAV's sensor systems. Both LRE and MCE can control three RQ-4As simultaneously. The main components of the RQ-4A's ISS (Integrated Sensor Suite) for its surveillance, reconnaissance and target acquisition missions are an SAR/MTI (Synthetic Aperture Radar/Moving Target Indicator) and IR/EO (Infrared/Electro-Optical) sensors. For self-defense, the UAV is equipped with an AN/ALR-69 radar warning receiver and AN/ALE-50 towed decoys.
|Image: Northrop Grumman|
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.
|Photo: Northrop Grumman|
In April 2003, the designation RQ-4B was assigned to an enlarged derivative of the RQ-4A. At the time of this writing, Northrop Grumman is building several RQ-4B aircraft for the USAF. The first one made its initial flight on 1 March 2007. 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 initial RQ-4B configuration is also known as Global Hawk Block 20 (Block 10 is the RQ-4A), and Block 30/40 upgrades are already defined. Future Global Hawk production contracts by the USAF will be for Block 20+ (i.e., using the larger airframe) versions only.
The U.S. Navy was evaluating the Global Hawk from 2005 on as an unmanned maritime surveillance platform under the GHMD (Global Hawk Maritime Demonstration) program. The first RQ-4A for the Navy flew in October 2004. In April 2008, the Navy selected the Global Hawk as the winner of its BAMS UAS (Broad Area Maritime Surveillance Unmanned Aircraft System) competition. The first BAMS Global Hawk, a variant of the RQ-4B informally known as the RQ-4N, is planned for delivery in 2011.
Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!
Data for RQ-4A/B:
|Length||13.53 m (44 ft 4.75 in)||14.50 m (47 ft 7 in)|
|Wingspan||35.42 m (116 ft 2.5 in)||39.90 m (130 ft 11 in)|
|Height||4.64 m (15 ft 2.5 in)|
|Weight||max: 12130 kg (26750 lb); empty: 6710 kg (14800 lb)||max: 14630 kg (32250 lb)|
|Speed||648 km/h (403 mph)||?|
|Ceiling||19800 m (65000 ft)||18300 m (60000 ft)|
|Range||21720 km (11730 nm)|
|Endurance||36 h||28 h|
|Propulsion||Rolls-Royce/Allison F137-AD-100 turbofan; 33.8 kN (7600 lb)|
 Kenneth Munson (ed.): "Jane's Unmanned Aerial Vehicles and Targets, Issue 15", Jane's, 2000
 Tom Kaminski: "The Future is Here", article in Combat Aircraft Vol. 4, No. 6, 2003
 Northrop Grumman Website
 "Unmanned Aircraft Systems Roadmap, 2005-2030", Office of the Secretary of Defense, August 2005
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