American people often mind their stealth aircraft with names such as the F-117 Nighthawk, B-2 Spirit, or F-22 Raptor, but buried further in the history of flying machines is an experimental airplane that never saw combat but went about affecting the future of stealth technology—the Boeing YF-118G, more popularly referred to as the “Bird of Prey.”
Born in secret in the 1990s at the mythical Groom Lake test facility, or Area 51, the Bird of Prey wasn’t constructed for combat. Its mission was strictly experimental: to evaluate next-generation stealth designs and develop cost-effective, efficient production methods, many of which would come to define contemporary military aircraft.
The project occurred during a turning point for McDonnell Douglas. Having been omitted from large Pentagon projects such as the Advanced Tactical Fighter competition, the company had to demonstrate it was capable of innovating in a fast-paced aerospace world. Phantom Works, its cutting-edge research arm, began the project in 1992 with an objective to design a small, fast, and extremely stealthy aircraft. Alan Wiechman, who had experience on the F-117 program, led the effort unobtrusively, remaining ahead of the curve without fanfare.
Differing from the large, costly government stealth programs of the time, the Bird of Prey was constructed on a shoestring budget of only $67 million. The group utilized rapid prototyping, computer modeling, and innovative reuse of existing components. The engine was sourced from a corporate jet, the ejection seat from a Harrier, and the cockpits were cobbled together from outdated fighter control systems. Col. Doug Benjamin has even joked that even the clock on the instrument panel was purchased from a store, and that the cabin air system more closely resembled a hairdryer than standard air conditioning.
Its form was as if from science fiction, and it earned its nickname from the Klingon “Bird of Prey” starship in Star Trek. Tailless gull-wing form, 47 feet long with a 23-foot wingspan, was designed to cut radar and infrared signatures. Smooth surfaces, no vertical stabilizers, and a buried engine allowed it to remain all but undetectable, and the paint was selected to make it least visible in daylight.
Instead of employing sophisticated fly-by-wire systems, the Bird of Prey used manual hydraulic controls, but the aircraft flew with stunning stability. All parts of the aerodynamics had to be perfectly executed, and the aircraft responded magnificently for an aircraft so radically different in design.
Performance was never a matter of speed or height. It had a single Pratt & Whitney JT15D-5C engine that could get it up to about 300 mph with a 20,000-foot ceiling, sufficient for evaluating stealth handling and flight performance.
It first flew on September 11, 1996, and went on to fly 39 missions over the next three years. Early idiosyncrasies, such as drag from the landing gear, were eliminated through iterative flight testing. By its final flight in 1999, the Bird of Prey had shown that a low-cost, highly stealthy plane could be designed, built, and safely flown.
Even though it never entered service, the Bird of Prey made a lasting impression. Its construction and design lessons contributed to Boeing’s X-45 Unmanned Combat Air Vehicle and shaped the stealth shaping of the F-22 Raptor, F-35 Lightning II, and B-21 Raider. Boeing executive Jim Albaugh put it in perspective by stating, “We changed the rules on how to design and build an aircraft.”
Today, the sole Bird of Prey ever constructed hangs at the National Museum of the U.S. Air Force in Dayton, Ohio, suspended over an F-22 Raptor. The cockpit is tactfully obscured from sight, a quiet reminder of its classified origins.
The Bird of Prey never bore weapons, participated in a war, or hit the headlines like more well-known siblings. But its real achievement lay off-camera, surreptitiously developing the envelope of stealth technology and demonstrating that some of the most powerful airplanes are not designed for warfare, but to chart the course of flight.