That cover story was destroyed when the Soviets produced the pilot, Francis Gary Powers, alive and in Soviet custody.

The SR-71, which followed the U-2, could fly at Mach 3 and above 80,000 feet — so fast that if a missile was fired at it, the SR-71 could simply accelerate away from the missile’s flight path.

Its design involved aerodynamic and thermal engineering at the absolute edge of what the known physics would permit, because at Mach 3 the airframe becomes hot enough to glow.

These were the kinds of problems — at the edge of the physical envelope, requiring mathematics that had not previously existed, developed in conditions of secrecy that prevented public acknowledgment — that the engineers and mathematicians at Lockheed’s most advanced units were working on.