 Rich called on Bill Schroeder, a Lockheed mathematician, and Denys Overholser, a computer scientist, to exploit Ufimtsev's work.The three designed a computer program called "Echo", which made it possible to design an airplane with flat panels, called facets, which were arranged so as to scatter over 99% of a radar's signal energy "painting" the aircraft.The first YF-117A, serial number "79-10780", made its maiden flight from Groom Lake ("Area 51"), Nevada, on 18 June 1981, only 31 months after the full-scale development decision.