Few aircraft have etched their mark so indelibly upon the annals of stealth technology as did Boeing’s Bird of Prey. This single-seat stealth technology demonstrator first saw action in the fall of 1996, representing a groundbreaking project for testing advanced “low-observable” techniques and new methods for aircraft design and construction. The Bird of Prey, so named for its resemblance to the cheating Klingon spacecraft of the series Star Trek, was a statement of innovation and looking into the future.
The Bird of Prey project ran from 1992 to 1999, cloaked in secrecy. During 38 test flights, the aircraft explored means to make aircraft less detectable to both the naked eye and radar. It also validated new design and construction methods, like very large single-piece composite structures, computerized “virtual reality” design and build, and disposable tooling. By the time the Bird of Prey became public knowledge in 2002, the design techniques for it had become commonplace and were found in the Boeing X-32 Joint Strike Fighter demonstrators and the X-45A Unmanned Combat Air Vehicle.
The advanced stealth concepts were something that the Bird of Prey was perhaps best known for. With control surfaces that had both the leading and trailing edges smoothed into the wings, the radar profile of the aircraft was far smaller than anything else in the air. Its engine intake was completely shielded from the front, further enhancing its stealth characteristics. The Bird of Prey employed some “off the shelf” technology to keep costs low and production levels high, offsetting some of the cost of the technology development itself. Its control system was completely manual, without computer assistance, and had the landing gear of the Beech King Air and Queen Air.
The Bird of Prey was powered by a Pratt& Whitney JT15D-5C turbofan engine that produces 3,190 pounds of thrust. The maximum speed of the aircraft was 300 mph, with a maximum ceiling set at 20,000 feet. Although the stunts it could pull in the air were not so catchy, it was evident at production that what valued the aircraft most were its stealth capabilities manifested in other innovative approaches in design and technique.
The Bird of Prey program itself dates back to the late 1980s and early 1990s, an era in which McDonnell-Douglas was desperate for tactical military jet contracts. After first having lost the Advanced Tactical Fighter Program with the USAF and the ensuing YF-23 project, the firm realized the future of contract awards depended on bringing prices down and incorporating stealth technology. So, the Bird of Prey program was born in 1992.
Both internal and external of the Bird of Prey, dramatic design elements abounded. Fuselage, wing, and exterior designs all minimized RCS, with it being estimated that the RCS was no larger than that of a mosquito at times. The engine was deeply buried inside the fuselage to minimize the infrared signature, with carefully designed paint shading that visually masked the actual fuselage shapes in daylight.
Equally important were the efforts to work out easier design and assembly processes. Rapid prototyping techniques that included simulations of the performance of individual parts and systems through the use of computer programs and 3D rendering therefore meant that multiple physical iterations of parts would not be necessary. This carried through to an easier and less expensive pathway to create tooling.
Cost savings embodied the heart of the Bird of Prey program. By using existing off-the-shelf components wherever possible—a business-jet engine, landing gear from Beechcraft turboprops, an ejection seat from a Harrier, and cockpit control from various previous tactical jets—the team remained within the program’s total cost of just $67 million, less than that of two new 737s at that time.
Despite the unconventional configuration of the airframe and its not using fly-by-wire technology, the Bird of Prey managed to fulfill its test flights from 1996 to 1999. The latter fact is proved by the program’s survival through Boeing’s acquisition of McDonnell-Douglas in 1998. Following its public unveiling in 2002, the Bird of Prey was donated to and is on display at the National Museum of the United States Air Force in Dayton, Ohio.
No doubt the Bird of Prey was meant for operational service; the legacy it leaves behind is quite enormous in the context of the present-day aviation world, specifically in stealth technology and the design of aircraft. The very making of this aircraft is a tribute to the innovative spirit and efforts of its initiator and designers. They stretched the envelope beyond the imaginations of the time in the field of stealth technology.