Throughout the late 1980s and early 1990s, McDonnell-Douglas faced challenges in securing contracts for tactical military jets production. Despite submitting numerous proposals for the USAF’s Advanced Tactical Fighter (ATF) program in 1986, the company was ultimately excluded from consideration. Later, it formed a partnership with Northrop Grumman to develop the YF-23, but lost out to the F-22 in 1991.
Faced with these setbacks, company leaders recognized the need to regain lost ground. Acknowledging the importance of stealth technology and affordability for future success, they initiated a program in 1992 aimed at enhancing their capabilities. This program involved the development, manufacturing, and testing of an advanced research aircraft, eventually dubbed the Bird of Prey.
Taking inspiration from a Klingon spacecraft in Star Trek and designated as the ‘YF-118G,’ the jet boasted striking design both internally and externally. The fuselage, wings, and exterior were meticulously crafted to explore various aspects of stealth technology, resulting in a minimized radar cross section (RCS) estimated to be as small as that of a mosquito. Engineers also positioned the engine deep within the fuselage to reduce the infrared signature and carefully designed the paint shading to obscure the fuselage shapes in daylight, a feature not found in other stealth aircraft like the F-117 and B-2.
While less conspicuous, significant efforts were directed towards the company’s objectives of refining the design and assembly processes to enhance affordability. Employing rapid prototyping techniques facilitated by computer programs and 3D rendering, engineers simulated the performance of individual components and systems aboard the aircraft, reducing the necessity for producing and testing numerous physical iterations. These endeavors also encompassed simplifying and economizing the manufacturing of tools.
Concurrently, steps were taken to lower the aircraft’s costs by integrating off-the-shelf components wherever feasible. Utilizing components such as a business jet engine, landing gear from Beechcraft turboprops, an ejection seat from a Harrier, and cockpit controls from various existing tactical jets, the team scoured scrap yards while keeping expenses in check. Ultimately, the entire program purportedly incurred a cost of $67 million, less than that of two new 737s at the time.
Upon its inaugural flight in September 1996, the Bird of Prey’s flying performance was evidently lacking, owing to its highly-swept, 23-foot-span wing. However, this deficiency was deemed inconsequential as the aircraft prioritized low observability over aerodynamic performance. Consequently, its speeds, altitudes, and handling characteristics were not particularly remarkable.
The Pratt & Whitney JT15D engine, which shares similarities with the engines used in the Cessna Citation V and Beechcraft Beechjet, produced 3,190 pounds of thrust. Despite its thrust-to-weight ratio being comparable to those jets due to its maximum takeoff weight of 7,400 pounds, its focus on stealth performance resulted in an “operational speed” of 260 knots and a maximum operating altitude of 20,000 feet, as noted in an official Boeing press release. Nevertheless, a Pilatus PC-12 can achieve higher altitudes and faster speeds.
Despite this, the Bird of Prey underwent 38 test flights between 1996 and 1999, demonstrating sufficient success to survive the Boeing acquisition of McDonnell-Douglas in 1998. After being publicly unveiled in late 2002, the aircraft was relocated to the National Museum of the United States Air Force in Dayton, Ohio, where it remains on display today.
Even though it’s been exhibited, one aspect still intrigues observers—a notable absence of publicly accessible images featuring the cockpit or instrument panel. Although it’s improbable that these are still under official classification, the aircraft is currently positioned at a height that conceals these areas from view. Moreover, the cockpit windows of the Tacit Blue stealth testbed, which shares a similar mysterious aura, were deliberately painted black when displayed in the museum, thereby obstructing views into the cockpit.
Whether these measures are coincidental or deliberate, they undeniably contribute to the enigmatic nature of these aircraft, which have been veiled in secrecy since their inception.
