UAVs Come Of Age

UAVs Come Of Age

ISRJ (Intelligence Surveillance Reconaissance Journal) [a U.S. military journal]
March, 2002
http://www.afji.com/ISR/Mags/2002/Issue2/UAVs_3.html

Last October, the Air Force purchased, and is testing, two Predator B air vehicles. Predator B, designated the MQ-9, is larger than the basic Predator and is powered by a Honeywell TPE-331-10T turboprop engine. The 10,000-lb (formerly 6,400-lb) Predator B is 36 feet long. It has a 66-foot wingspan, a 750-lb internal sensor payload, endurance up to 24 hours, speed in excess of 220 knots, and can fly at altitudes of 45,000 to 52,000 feet. It will be able to carry eight Hellfire missiles (or up to 3,000 lbs externally, compared with two Hellfires for the MQ-1 Predator) as well as larger sensors.

The Air Force is buying six MQ-9 Predator Bs along with 16 MQ-1 Predators this year. The Service believes that the Predator B could fill an altitude and payload niche between the MQ-1 Predator and the higher altitude Global Hawk.

GLOBAL HAWK
While Predator is a tactical UAV with focused sensor coverage, Northrop Grumman Integrated Systems' long-endurance RQ-4A Global Hawk is designed to provide near-real-time imagery of large geographic areas. The largest operational UAV ever produced, Global Hawk began as an ACTD program in 1995, had its first flight in February 1998, and was taken over by the Air Force in October 1998. Global Hawk entered low-rate initial production in February 2002.

The 44-foot-long, 25,600-lb air vehicle is about as large as a medium-size corporate jet, but with a sailplane-like 116-foot wingspan and a V-tail. The vehicle's distinctive bulbous nose houses a 4-foot-diameter, steerable, Ku-band wideband satellite antenna.

Global Hawk flies at nearly twice the altitude of commercial airliners and can stay aloft at 65,000 feet for as long as 35 hours without refueling. Last April, a Global Hawk flew autonomously from California to Australia on a nonstop flight lasting nearly 24 hours, then matched the feat in June when it returned to the US. The air vehicle cruises at a speed of 342 knots and has a range of 12,500 nm. Powered by a single Rolls-Royce Allison AE3007H commercial turbofan engine, it can fly to a target area 1,200 nm away and loiter at 60,000 feet while monitoring an area the size of the state of Illinois for 24 hours, then return.

The Global Hawk's 2,000-lb internal payload is an integrated suite of sensors that is much larger than those on the Predator air vehicle. They consist of an all-weather SAR with Moving Target Indicator (MTI) capability, an E-O digital camera, and an IR sensor, which produce high-resolution still-frame images. The sensor operator can select among radar, IR, and visible wavelength modes, and can even use the SAR/MTI simultaneously with either of the other two sensors. The operator can observe large areas of coverage, select smaller areas of interest, and zoom in on specific target areas, no matter what the weather conditions are on the ground.

The gimballed SAR antenna scans from either side of the air vehicle to obtain 10-km swath-width radar images with 1-meter resolution in the wide-area search mode, 0.3-meter (1-foot) resolution images in the spot mode, and a 4-knot minimum detectable [vehicle] velocity in the MTI mode-all from ranges up to 200 km from the target area. Both the 612-lb SAR and the 300-lb E-O/IR receiver unit can search a 40,000 square-nautical-mile area (about the size of Virginia) in just 24 hours in the wide-area search mode, or can obtain 1,900 2-km-square spot images in the same amount of time. (The E-O camera is most effective at a range of 60 km and the IR sensor at 30 km.) The sensors collect this data at a high rate. Three to five Global Hawks reportedly could monitor all of Afghanistan, which is roughly the size of Texas. Raytheon Electronic Systems' division in El Segundo, CA produces the Global Hawk's SAR, while its McKinney, TX division makes the E-O/IR sensor unit.

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