F-117 Nighthawk: The Stealth Fighter That Started a Revolution

Key point: It successfully penetrated enemy air defenses for a time.

The F-117 Nighthawk, America's original stealth plane with a deeply sinister appearance, is an example of a weapon system designed around the limitations imposed by a promising new technology. The Nighthawk was revolutionary when it entered service in 1983-not that many could appreciate that, as the plane was kept secret from the public for five years.

Ironically, the Pentagon had a Russian researcher named Pyotr Ufimtsev to thank for first elaborating in a 1964 paper the concept that visibility on radar was not based purely on the size of an object, but also the angle at which radar waves reflected off its edges. Ufimtsev devised a method for calculating the Radar-Cross Section of objects, determining how visible they are on radar.

Ufimtsev's research attracted attention in the United States rather than Russia, and in the late 1970s Lockheed Martin began working on the Have Blue project to design a plane with the smallest radar cross section possible. The key was to employ flat surfaces that reflected radar waves away from the transmitter.

When Lockheed rolled out the first two prototypes in 1977, the angular aircraft looked like nothing that had been seen before-or since. Later stealth designs such as the B-2 Spirit and the F-35 feature curved surfaces. However, the F-117 was designed before there were advanced computers with the calculating power to produce such curved surfaces. Thus, the F-117 alone among stealth aircraft is distinguished by its faceted 2-dimensional design.

The constraints this imposed meant the design was aerodynamically unstable, and required sophisticated fight computers combined with quadruple-redundant fly-by-wire controls to compensate and keep the aircraft in a flyable state. The Have Blue prototypes earned the nickname "Wobbly Goblins," and both crashed during the testing process.