U-2R aircraft in ROC possession were flown from Taoyuan Air Base in Taiwan to Edwards AFB, California, US, and turned over to the USAF."Thou Shalt Not Fly ... Ever." Taiwan Air Power, 1 August 2009. Retrieved: 14 September 2009 Variants Primary list Subsection source: Aerospaceweb.orgU-2A Initial production, single-seat; Pratt & Whitney J57-P-37A engine; 48 built U-2B Proposed missile warning patrol aircraft; not built. U-2C Enhanced single-seat model with Pratt & Whitney J75-P-13 engine and modified engine intakes U-2D 2 seat used for various IR detection programs, not a trainer aircraft. U-2CT Enhanced two-seat trainer. U-2E Aerial refueling capable, J57-powered U-2F Aerial refueling capable, J75-powered U-2G C-models modified with reinforced landing gear, added arresting hook, and lift dump spoilers on the wings for U.S. Navy carrier operations; three converted U-2H Aircraft carrier capable, aerial refueling capable U-2R Re-designed airframes enlarged nearly 30 percent with underwing pods and increased fuel capacity; 14 built U-2RT Enhanced two-seat R-model trainer; one built U-2EPX Proposed U.S. Navy maritime surveillance R-model; two built TR-1A A third production batch of U-2R aircraft built for high-altitude tactical reconnaissance missions with side-looking radar, new avionics, and improved ECM equipment; 33 built. Re-designated U-2S after the fall of the Soviet Union TR-1B Two TR-1A airframes completed as two-seat conversion trainers TU-2S New redesignated TR-1B two-seat trainer with improved engine; five converted ER-2 Two TR-1A airframes, AF Ser. No. 80-1063, and Ser. No. 80-1097, modified as Earth resources research aircraft, moved from USAF to NASA and operated by the NASA High-Altitude Missions Branch, Ames Research Center. NASA flies Ser. No. 80-1097 as N809NA and Ser. No. 80-1063 as N806NA. U-2S Redesignation of the TR-1A and U-2R aircraft with updated General Electric F118 engine, improved sensors, and addition of a GPS receiver; 31 converted WU-2 Atmospheric/weather research WU-model U-2E/F/H details In May 1961, in an attempt to extend the U-2's already considerable range, Lockheed modified six CIA U-2s and several USAF U-2s with aerial refueling equipment, which allowed the aircraft to receive fuel from either the KC-97 or from the KC-135. This extended the aircraft's range from approximately and extended its endurance to more than 14 hours. The J57-powered U-2Bs were re-designated U-2E and the J75-powered U-2Cs were redesignated U-2F. Each modified U-2 also included an additional oxygen cylinder. However, pilot fatigue was not considered, and little use was made of the refueling capability. The only U-2H was both air refueling-capable and