Air Force Lockheed SR-71 Blackbird’s Pratt & Whitney J58 Engines Ran at Full Afterburner for Hours at a Time With Exhaust Temperatures Near 3,400 Degrees. At Mach 3.2 Cruise, Roughly 80 Percent of the Thrust Came From the Inlet, Not the

Automatically curated summary from 19FortyFive.

Expert Steve Balestrieri argues that the Pratt & Whitney J58 engine, rather than the airframe, made Lockheed's SR-71 Blackbird the fastest air-breathing manned jet. At Mach 3.2 cruise, approximately 80 percent of total thrust was generated by the movable inlet and ejector nozzle, with the engine functioning like a turbo-ramjet. The J58 continuously operated in full afterburner, consuming roughly 8,000 gallons of specialized JP-7 fuel hourly with exhaust temperatures reaching nearly 3,400°F. High maintenance demands and operational expenses, estimated at $200,000 per flight hour, led to the aircraft's final retirement in 1998.

Context and limitations

Specific flight cost estimates ($200,000 per hour) and detailed engine unit pricing rely on unverified historical estimates and retrospective commentary, as official unit-cost records for classified defense contracts remain unpublished.