The Soviets physicist who invented stealth

 

 Lockheed engineer Denys Overholser found the math behind the F-117 stealth fighter in a Soviet paper. It was written in 1962 by physicist Pyotr Ufimtsev and called "Method of Edge Waves in the Physical Theory of Diffraction." Ufimtsev's government saw no military value in it and let him publish it openly.

Ufimtsev had worked out how to calculate the way radar bounces off an object's edges. It meant shape mattered more to radar than size. Angle the surfaces right, and even a big aircraft could almost vanish from a radar screen.

The US Air Force translated the paper in 1971. When Overholser read it a few years later, he realized it could predict how visible a plane would be on radar before anyone built it. He took it to Ben Rich, head of Lockheed's secret Skunk Works.

Computers back then could only handle flat surfaces, so Overholser developed a program called Echo 1 around flat panels. Many engineers doubted the strange shape it produced and nicknamed it the "Hopeless Diamond." In a radar test, the operator couldn't find a 10-foot wooden model of it. The radar picked up a black bird sitting on top instead.

The shape was so unstable that only a fly-by-wire computer could keep it in the air. The team built 2 secret test planes, codenamed Have Blue, and flew them from Area 51 in Nevada. Both crashed, but they proved stealth worked. The program became the F-117 Nighthawk, and Overholser wrote its patent. It first flew in 1981 and stayed secret until the Air Force admitted it existed on November 10, 1988.

In the 1991 Gulf War, it hit many of Iraq's most heavily defended targets without losing a jet. One was shot down over Serbia in 1999, and the pilot was rescued. The Air Force retired the F-117 in 2008.
The same math went on to shape the B-2 bomber, the F-22, the F-35 and the new B-21 Raider. Ufimtsev later moved to the United States and taught at UCLA.

Overholser spent decades working far from public view, and much of his work is still classified. He died on April 28 this year, at 86.