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.
