February 1, 2008:
Five U.S. RQ-4 Global Hawk UAVs were
delivered in 2007. Seventeen are in production, as well as six ground stations
for controlling and maintaining the aircraft.
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.
In the last seven years, RQ4s have
flown nearly 20,000 hours, over 70 percent of that combat missions, and many of
them from Persian Gulf bases. Some of the more recent 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. A year ago, the U.S.
Air Force has ordered five more RQ-4B Global Hawks, at a cost of $58 million
each, and, in effect, approved the new model. This 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 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 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.