Lockheed’s A-12 needed a powerplant that could sustain Mach 3 flight, leading to the Pratt and Whitney J58, a turbojet-ramjet ...

Lockheed’s engineers built the J58 engine to do the impossible, operate as both a jet and a ramjet. At Mach 3 and 85,000 feet, it pushed the SR-71 through temperatures that melted titanium and tested ...