November 25, 2009: The U.S. Air Force is ordering five more RQ-4 Global Hawk UAVs for about $55 million each. This order includes two Block 30 and three Block 40 versions. The air force is also ordering another ground station, ground crew equipment for the five new UAVs, and two additional sets of sensor gear. One of the new aircraft will be equipped with the first new MP-RTIP AESA radar. This sensor does the same job as the E-8 JSTARS ground radar aircraft AESA, but is built to be mounted in the RQ-4. The air force had planned to build a replacement for the E-8, the E-10, but that has been cancelled because of the high cost. Meanwhile, an updated AESA (Active Electronically Scanned Array) radar for JSTARS enables them to spot smaller, man sized, objects.

AESA type radars have been around a long time, popular mainly for their ability deal with lots of targets simultaneously, and produce a more accurate picture of what is out there. AESA radar consists of thousands of tiny radars that can be independently aimed in different directions. An AESA radar made the JSTARS aircraft possible, as it enabled it to locate vehicles moving on the ground. The smaller MP-RTIP radar for the RQ-4 can also spot smaller objects on the ground. As a result of an RQ-4 UAV equipped with AESA, the air force has a choice between extending the life of the E-8 aircraft, or replacing them with the UAVs.

Two of the new RQ-4s will have the EISS (Enhanced Integrated Sensor Suite), which combines day/night cameras and synthetic aperture radar (which can provide photo like images in all weather). Two more EISS systems will be bought to equip existing RQ-4s. All of the aircraft and equipment will be delivered within three years.

Development of the RQ-4 began in the 1990s, as a DARPA research project. But by 2006, per-aircraft costs were 25 percent over the original price. By 2007, production had slipped as well. The air force and manufacturer Northrop Grumman disagreed over what has caused the problems. The air force blames it on poor management, Northrop Grumman says it's all about dealing with complex technology. The air force points out that the RQ-4 is not high tech. The sensors often are, but they are added to the aircraft after they come off the production line.

All nine of the RQ-4A ("Block 10") aircraft have been built (seven for the U.S. Air Force and two for the U.S. Navy). The ones in production are the larger RQ-4B (block 20, 30 and 40) models. Five RQ-4s were delivered in 2007, but the air force only had 16 in service, rather than the planned 20, by the end of last year.

The RQ-4 was still in development on September 11, 2001, but was rushed into action. The first production RQ-4A was not delivered until August, 2003. Although the RQ-4 could stay in the air for up to 42 hours, all of them have only amassed about 4,000 flight hours by 2004. But most of those 4,000 hours, which were originally planned to involve testing of a new aircraft, were instead used to perform combat missions. Global Hawk also got to fly under difficult conditions, something an aircraft still being developed, would not do.

Last year, an RQ-4A Global Hawk made the first non-stop crossing of the Pacific, flying 12,000 kilometers, from California to Australia, in 23 hours. The Global Hawk has previously crossed the Pacific in several hops, but it always had the endurance to do it non-stop. In the last seven years, RQ-4s have flown over 25,000 hours, most of that combat missions, and many of them from Persian Gulf bases. The latest models have been able to fly 20 hour missions, land for refueling and maintenance, and be off in four hours for another twenty hours in the sky. The RQ-4 has been very reliable, with aircraft being ready for action 95 percent of the time. The U.S. Air Force has been buying them at the rate of five a year, at a cost of $58 million each. An RQ-4 can survey about 4,000 square kilometers an hour.

The new B version is larger (wingspan is 15 feet larger, at 131 feet, and it's four feet longer at 48 feet) than the A model, and can carry an additional two tons of equipment. To support that, there's a new generator that produces 150 percent more electrical power. The B version is a lot more reliable. Early A models tended to fail and crash at the rate of once every thousand flight hours, mostly because of design flaws. The first three RQ-4Bs entered service in 2006. At 13 tons, the Global Hawk is the size of a commuter airliner (like the Embraer ERJ 145), but costs nearly twice as much. Global Hawk can be equipped with much more powerful, and expensive, sensors, than other UAVs. These more the double the cost of the aircraft. These spy satellite quality sensors (especially AESA radar) are usually worth the expense, because they enable the UAV, flying at over 60,000 feet, to get a sharp picture of all the territory it can see from that altitude.

The air force has stationed a squadron of seven Global Hawks on the island of Guam. These UAVs will begin arriving there next year, and undertake recon missions throughout the western Pacific.