: Its Pratt & Whitney J58 engines acted as a turbojet-ramjet hybrid, becoming most efficient at speeds above Mach 3.
The Blackbird was engineered to outrun surface-to-air missiles by cruising at the edge of space. : Mach 3.3 (2,193 mph / 3,529 km/h). Service Ceiling : 85,000 feet (approx. 26,000 meters).
: The aircraft used its fuel as a heat sink to cool the air-conditioning system and internal components before the fuel was burned. Legacy and Successors Aircraft Report: Lockheed SR-71 Blackbird
: Roughly 85% of the airframe was titanium, which could withstand the 600°F (315°C) surface temperatures.
To survive the extreme heat generated by friction at Mach 3+, the aircraft required radical design solutions: