YF-118G Bird of Prey
Stealth Technology Demonstrator
Boeing unveiled, on October 18, 2002 the "Bird of Prey," a technology demonstrator that pioneered breakthrough low-observable technologies and revolutionized aircraft design, development and production. The once highly classified project ran from 1992 through 1999, and was revealed because the technologies and capabilities developed have become industry standards, and it is no longer necessary to conceal the aircraft's existence with the aircraft eventually scheduled to end up at the Air Force Museum located in Dayton, Ohio.
In addition to proving many new stealth concepts, the Bird of Prey program demonstrated innovative rapid prototyping techniques. Developed by the Boeing Phantom Works advanced research-and-development organization, the Bird of Prey was among the first to initiate the use of large, single-piece composite structures; low-cost, disposable tooling; and 3-D virtual reality design and assembly processes to ensure the aircraft was affordable to build as well as high-performing.
The program reportedly went through dozens of variations within a span of four years before being flight capable. It is reported that the aircraft made a total of 38 flights over a three-year testing period above Area 51, in the state of Nevada.
Fully funded by Boeing, the Bird of Prey project costs $67 million. A subsonic, single-seat technology demonstrator, the aircraft completed 38 test flights as part of its flight-demonstration program. Its first flight took place in fall 1996. Bird of Prey has a wingspan of approximately 23 feet and a length of 47 feet, and weighs nearly 7,400 pounds. Powered by a Pratt & Whitney JT15D-5C turbofan engine, the Bird of Prey has an operational speed of 260 knots and a maximum operating altitude of 20,000 feet.
The edges of the Bird of Prey's fuselage and wings are parallel to each other, resulting in radar waves reflections being limited to directions where detection is unlikely. The Bird of Prey's upper and lower skins are made out of large single carbon composite pieces, fashioned on plywood frames beneath glass-fiber molds. Other characteristics used to augment its stealth capability include the use of special materials and the treatment of the aircraft's seams with special sealing treatments. The Bird of Prey also features only one removable service panel, located within the landing-gear wells, for easy access by mechanics.
Other peculiarities of the aircraft include its top-mounted engine-air inlet which is located behing the cockpit and its diamond-shape exhaust outlet, located at the tail.
The X-45A Unmanned Combat Air Vehicle, or UCAV, technology demonstrator draws directly on its Bird of Prey experience. Some aspects of the UCAV's innovative radar-evading design, such as its shape and inlet, were developed from this project.
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