One doesn’t have to dig deep to find the most memorable American stealth aircraft when thinking of the names of the handful of the most famous ones, but only a few can be actually recognized – that is, the F-117 Nighthawk, the B-2 Spirit, and the F-22 Raptor. However, one of the most secretive and weirdest experimental aircraft ever made lies behind the fame of these – the Boeing YF-118G or the “Bird of Prey” as the “Bird of Prey”.
The program was never intended for warfare as the “Bird of Prey” was conceived in the dark during the 1990s at the extremely secretive Groom Lake test site, Nevada. Its mission was not combat but progression. The program’s objective was to advance stealth design, validate unconventional manufacturing methods, and uncover ways of producing next-generation aircraft faster and cheaper without giving up quality or performance.
Back then, McDonnell Douglas, before combining with Boeing, was feeling the heat to demonstrate that the company could still pull off groundbreaking technology. After losing out on major Pentagon contracts such as the Advanced Tactical Fighter program, the company’s Phantom Works division responded with an ambitious internal project in 1992. The task: come up with a demonstrator aircraft that would be the proof of the company’s capability to think out of the box and take stealth technology to untapped territory.
The project was under the leadership of Alan Wiechman, a veteran engineer who had previously worked on the F-117 Nighthawk. His skills and leadership aided the crew in stretching the limits of stealth shaping and materials science. The Bird of Prey, under his supervision, became a platform that kept the U.S. stealth development far ahead of competitors.
While it had a high-tech goal, the initiative was operating on a tight budget of $67 million. The designers depended on rapid prototyping and the smart reuse of the existing components. The aircraft was powered by an engine from a bizjet, the ejection seat borrowed from a Harrier aircraft, and the cockpit controls were taken from older fighter jets. Test pilot Col. Doug Benjamin was once comical about the plane’s clock, saying it was bought at a local store and the air system inside was similar to that of a hairdryer in terms of strength. Nevertheless, everything was working perfectly.
In terms of design, the Bird of Prey looked as if it were from a sci-fi film. Its smooth, tailless body and special gull-shaped wings were impressive designs and made it stand out right away. The aircraft was named after the Klingon “Bird of Prey” from the Star Trek series. Every part of its exterior was carved to lower radar detection and minimize heat emission. Also, the paint pattern on it was picked so that it could blend well with the bright sky during the day.
Although basic manual hydraulics were used in the construction of the aircraft instead of the modern fly-by-wire, it was still very easy and predictable to fly it. The engineers had achieved such a good tuning of the aerodynamics of the aircraft that it was flying with very high stability. By fighter standards, the plane was not fast or high-flying; it was powered by a single Pratt & Whitney JT15D-5C engine that was capable of taking it to about 300 mph and a ceiling of roughly 20,000 feet, but this was more than enough for the demonstration of its stealth and design principles.
The first launch of the Bird of Prey was performed on September 11, 1996. Over the next 3 years, it made 39 test flights, each time allowing refining of the design and validation of new construction methods. The outcomes of the project, which were wrapped up in 1999, had shown that stealth aircraft can be designed, built, and tested quickly and affordably without giving up innovation or safety.
Although it never went to war or loaded any weapons, the heritage of the Bird of Prey is massive. Most of the technologies and design ideas of it were later adopted by the Boeing X-45 Unmanned Combat Air Vehicle and even gave a hint to the development of the F-22 Raptor, F-35 Lightning II, and B-21 Raider. As Boeing executive Jim Albaugh put it, “We changed the rules on how to design and build an aircraft”.
Today, the only Bird of Prey ever constructed is exhibited at the National Museum of the U.S. Air Force in Dayton, Ohio, hanging just above an F-22 Raptor. People visiting cannot go inside – the cockpit is still classified – but being there, it is a reminder of all the work done invisibly behind the closed hangar doors.
YF-118G has never bombed any targets or shot any missiles, but it still has a huge impact on the future course of aviation. Its story is a quiet demonstration of the potency of experiments and the notion that not all aircraft are the ones that are made to fight; some are to change wars forever.