No one at the Lockheed Skunk Works would ever have envisioned the U-2 still being the cutting-edge platform for Air Force Intelligence, Surveillance and Reconnaissance (ISR) missions more than half a century after its first flight. But over the years, the Air Force has invested close to $2 billion on enhancements to both the airplane and its various cameras and sensors. Those upgrades have kept the U-2 operational and relevant longer than any plane in the USAF except the B-52.
The big change was in the aircraft itself. In 1968, the U-2C, which had an 80-foot wingspan, was revised into the U-2R, which was significantly larger than the original U-2 design, with a 104-foot wingspan. In 1981, a structurally identical "Tactical Reconnaissance" version of the U-2R design, designated the TR-1, went into production, and 33 were built between then and 1989. In 1992, all TR-1s and U-2s were redesignated U-2Rs. In 1994, the U-2Rs were re-engined with General Electric F-118-101 engines and redesignated the U-2S.
The surveillance and navigation equipment on board the U-2 has also improved vastly over time. Originally, the U-2 pilots navigated and lined up their cameras using a periscope drift sight that displayed the view directly beneath the airplane. Various avionics and power upgrades took place over the years, and in 2002, the Block 20 U-2S upgrade finally eliminated the periscope and replaced it with glass cockpit technology.
Currently, the U-2 can be outfitted with any one of three kinds of imagery sensors: Radar (Synthetic Aperture Radar, or SAR), which can see through clouds and at night; Electro-Optical/Infrared sensors that provide a detailed look at a specific geographic area; or an Optical Bar Camera (OBC), which carries two full miles of wet film and delivers broad-area images in breathtakingly sharp detail. The U-2S can also "listen" to signal intelligence (SIGINT, in military acronym terminology).
But no platform lives forever. And while the U-2 is still a critical part of the U.S. reconnaissance community, there is a new kid on the block. In 2001, Northrup Grumman was awarded a contract for a possible replacement: an unmanned aerial vehicle known as the RQ-4 "Global Hawk." The USAF "high-altitude transition plan" calls for the RQ-4 to eventually replace the U-2 sometime after 2012.
At the moment, however, the U-2 and Global Hawk have different, but complementary, capabilities. The currently deployed Global Hawk (Block 10) does imagery only, and lacks the wide swath capability of the U-2's OBC wet-film camera. But the technology is improving, and the Block 30 versions of the RQ-4, which are expected to become operational two to three years from now, are slated to have signal intelligence capability, as well. In the meantime, the U-2 has been funded through at least 2012.
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