The J58 engine—with its 30,000 pounds of
thrust—was the most powerful of Pratt & Whitney's final two turbojets.
The J58 was the exclusive engine for the Air Force's SR-71 Blackbird surveillance and reconnaissance aircraft. Manufactured by Lockheed, it could fly at speeds in excess of Mach 3 and routinely cruised at altitudes of 80,000 feet and higher. After more than 3,550 missions during a 25-year career, the small Blackbird fleet was retired in March 1990.