Lockheed F-117 Nighthawk

Development
• Background and Have Blue
In 1964, Pyotr Ufimtsev, a Soviet mathematician, published a seminal paper titled Method of Edge Waves in the Physical Theory of Diffraction in the journal of the Moscow Institute for Radio Engineering, in which he showed that the strength of a radar return is related to the edge configuration of an object, not its size. Ufimtsev was extending theoretical work published by the German physicist Arnold Sommerfeld. Ufimtsev demonstrated that he could calculate the radar cross-section across a wing's surface and along its edge. The obvious and logical conclusion was that even a large aircraft could be made stealthy by exploiting this principle. However, the airplane's design would make it aerodynamically unstable, and the state of computer technology in the early 1960s could not provide the kinds of flight computers which allow aircraft such as the F-117 and B-2 Spirit to stay airborne. However, by the 1970s, when Lockheed analyst Denys Overholser found Ufimtsev's paper, computers and software had advanced significantly, and the stage was set for the development of a stealthy airplane.