The Boeing Bird of Prey single-seat stealth technology demonstrator has been one of the leaders in advanced stealth techniques and aircraft design methodology. The ‘black’ program began in 1992 and continued through 1999 with its first flight made in the fall of 1996. It was called a ‘Bird of Prey’ due to its resemblance to the Klingon spacecraft in the science fiction series Star Trek, and it was a classic example of new-age aero-space engineering ingenuity.
During 38 test flights, the Bird of Prey explored methods to make an aircraft less visible to the human eye and radar. It also validated several innovative design and construction techniques, including large single-piece composite structures, virtual reality for design and assembly, and disposable tooling. By 2002, these techniques were in common use, carrying over to Boeing’s X-32 Joint Strike Fighter demonstrators and the X-45A Unmanned Combat Air Vehicle prototype.
It represented several advanced stealth concepts, including “gapless” control surfaces blending into the wings without visible separation to reduce radar visibility and an engine intake with a cover that was completely hidden from the front. Some “off the shelf” components were included to help save money and time in the prototyping. There were no computer assists for its control system; thus, the controls were entirely manual. Its landing gear came from Beech King Air and Queen Air aircraft.
The Bird of Prey was powered by a single Pratt & Whitney JT15D-5C turbofan engine that generated 3,190 lbs. of thrust. Its top speed was 300 mph, and it flew as high as 20,000 feet.
The Bird of Prey program emerged from the adversity that McDonnell-Douglas faced during the late 1980s and early 1990s concerning securing contracts for tactical military jets. Following up on the loss of the USAF’s Advanced Tactical Fighter program and the subsequent YF-23 project, the company strove to get back on its feet by further enhancing emphasis on stealth and affordability. In this regard, the Bird of Prey was born with radical design attributes to bring down RCS and IR signatures.
The fuselage, wing, and exterior of the aircraft were carefully designed to investigate several aspects of stealth technology. Paint shading techniques that allowed the fuselage shapes to be hidden from the human eye during the day were also used by engineers, something that was not even done with the F-117 and B-2. The Bird of Prey was also being developed through another technique: rapid prototyping. This process allows engineers to model or simulate the performance of various individual parts or systems, enabling them to reduce the number of physical tries they need to make.
It had a large focus on cost reduction, mainly due to the use of off-the-shelf components. It used a business jet engine, Beechcraft turboprop landing gear, an ejection seat from a Harrier, and cockpit controls from a variety of existing tactical jets. In this way, the program remained within a $67 million cost envelope, less than the cost of two new 737s at the time.
Although less than impressive in its flying performance, the Bird of Prey did lay the foundations for future stealth technology. The wing was straked at quite a steep 23 feet in span, optimized for low observability, which resulted in only an operational speed of 260 knots with a maximum altitude of 20,000 feet.
The Bird of Prey program was very successful even after Boeing merged with McDonnell-Douglas in 1998. After its public debut in 2002, the aircraft was donated to the National Museum of the United States Air Force in Dayton, Ohio, where it is displayed today. The ejection seat is visible to visitors to the museum, but the cockpit and instrument panel are not, a factor that has contributed to the aircraft’s mystique.
This Bird of Prey did offer a quantum jump in the evolution of stealth technology and gave way to further designs, setting new standards for aircraft developers.