Lockheed Have Blue

Lockheed Have Blue was the code name for Lockheed's proof-of-concept demonstrator for a stealth fighter. Have Blue was designed by Lockheed's Skunk Works division and tested at Groom Lake, Nevada. The Have Blue was the first fixed-wing aircraft whose external shape was defined by radar engineering rather than by aerospace engineering. The aircraft's faceted shape was designed to deflect electromagnetic waves in directions other than that of the originating radar emitter, greatly reducing its radar cross-section.

To design the aircraft, Skunk Works engineers used the mathematical theory and tools published by Soviet physicist and mathematician Petr Ufimtsev about the reflection of electromagnetic waves. A stealth engineer at Lockheed, Denys Overholser, had read the publication and realized that Ufimtsev’s work enabled finite element analysis of radar reflection.

The eventual design had faceted surfaces to deflect radar waves away from a radar receiver. It had highly swept wings and inward-canted vertical stabilizers, which led to its nickname "the Hopeless Diamond"—a pun on the Hope Diamond. The first operational aircraft made its maiden flight on 1 December 1977.

Two flyable vehicles were constructed. Both were lost due to mechanical problems. Nevertheless, Have Blue was deemed a success, paving the way for the first operational stealth aircraft, Senior Trend, or Lockheed F-117 Nighthawk.