The SR-71's speed record has stood since 1976

On 28 July 1976, a Lockheed SR-71 Blackbird screamed over Beale Air Force Base in California and set an absolute speed record of 2,193.2 mph (3,529.6 km/h) — roughly Mach 3.3, more than three times the speed of sound. Half a century later, that record for an air-breathing manned aircraft still stands unbroken.

The Blackbird routinely cruised at Mach 3.2 above 85,000 feet, and almost everything about it was shaped by heat. Air friction pushed surface temperatures past 300 degrees Celsius, so the airframe was built mostly from titanium that expands as it warms. The panels were therefore fitted deliberately loose on the ground — which is why a parked Blackbird sat in a puddle, leaking its JP-7 fuel onto the tarmac. Only once it heated up in flight did the metal swell and the seams seal shut.

The ironies ran deep. To get enough titanium, the U.S. quietly bought much of it from the Soviet Union — the very country the plane was built to spy on. Its J58 engines burned special high-flashpoint JP-7, so stable it had to be lit with a squirt of triethylborane.

It could fly faster than the missiles fired to shoot it down.

That wasn’t bravado. Of about 32 Blackbirds, not one was ever lost to enemy fire, despite an estimated 3,500-plus missiles launched at them. The standard evasive maneuver was almost comically simple: accelerate and climb.