As part of a secret project that ran from 1992 to 1999, the single-seat aircraft was actually a demonstrator used to test “low observable” stealth techniques as well as new methods of aircraft design and construction.

Sci-fi fans should also appreciate that the experimental craft was tested at the top-secret “Area 51,” where it made its debut flight in 1996.

The YF-118G Legacy

While it didn’t boldly go where no one had gone before, the YF-118G took to the skies a total of 38 times, and it was used to determine ways to make aircraft less observable not only to radar but also to the eye. More importantly, the program helped validate new ways to design and build aircraft using large single-piece composite structures, as well as “virtual reality” computerized design and assembly and disposable tooling.

Boeing also utilized standard “off the shelf” technology to reduce costs to develop the test aircraft, and that further sped its production. Among the not-so-secret components was its control system which is all-manual with no computer assists, while its landing gear was adapted from Beech King Air and Queen Air aircraft.

The Bird of Prey couldn’t reach warp speed either – as it was powered by a single, readily available Pratt & Whitney JT15D-5C turbofan that still provided 3,190 pounds of thrust, and allowed the craft to reach a maximum speed of 300 miles per hour, and a ceiling of 20,000 feet.

The aircraft made its final flight in 1999 and it was declassified three years later when its design techniques had become standard practice. Thanks to the Bird of Prey, Boeing was able to use those techniques in the development of X-32 Joint Strike Fighter demonstrators and later in its X-45A Unmanned Combat Air Vehicle prototype.

Part of the lasting legacy of the Bird of Prey remains its ability to demonstrate advances in stealth concepts, notably the “gapless” control surfaces that were developed to blend smoothly into the wings to reduce radar visibility, while the engine intake was completely shielded from the front.

Boeing donated the sole YF-118G Bird of Prey to the National Museum of the United States Air Force at Wright-Patterson Air Force Base (AFB), outside of Dayton, Ohio in 2002.