The SR-71’s JP-7 fuel—which also had to be carried onboard specialized KC-135Q tankers to refuel the Blackbird—was designed to be a safe, high-flashpoint fuel that would not vaporize or blow up under extreme heat and pressure. It had such low volatility that one could supposedly extinguish a match in a puddle of JP-7. But that also meant that the fuel was difficult to ignite using the convention systems, which meant Lockheed had to develop a triethylborane-based chemical ignition system for the SR-71’s engines—adding to the jet’s complexity and maintenance costs.
Capable of cruising at speeds in excess of Mach 3.2, the Lockheed SR-71 Blackbird was the fastest air-breathing manned aircraft to ever to see operational service. But even though its performance has never been matched, the SR-71 was retired as the Cold War drew to a close.
The Blackbird was initially retired in 1990, even before the fall of the Soviet Union. Eventually, however, three of the jets were reactivated by the Air Force—at the insistence of Congress—for a brief period between 1995 and 1998. Meanwhile, NASA flew research missions with the aircraft until 1999. In the end, the Blackbird was retired without a true replacement. But why?
Recommended: 5 Places World War III Could Start in 2018
Recommended: How North Korea Could Start a War
Recommended: This Is What Happens if America Nuked North Korea