When most think of American stealth planes, the discussion tends to go toward splashy airplanes such as the F-117 Nighthawk, B-2 Spirit, or the F-22 Raptor. But lost in the underbelly of military aviation history is a much lesser-known experimental airplane that never saw battle but left its mark all the same—the Boeing YF-118G “Bird of Prey.”
Constructed in the 1990s under unprecedented secrecy at the legendary Groom Lake test facility—more popularly referred to as Area 51—the Bird of Prey was not intended for combat. Rather, it was a technological proving ground for stealth characteristics of the next generation and low-cost production techniques, several of which have since gone on to become standard fare in contemporary military aircraft design.
A Company in Transition
The Bird of Prey flew during a critical period for McDonnell Douglas. Having been excluded from flagship Pentagon programs such as the Advanced Tactical Fighter competition, the company had to demonstrate that it could compete again in an ever-changing aerospace industry.
To do that, its cutting-edge research unit, Phantom Works, initiated an internal project in 1992 to create something innovative, inexpensive, and stealthy. At the helm of the project was Alan Wiechman, a stealth expert who had worked on Lockheed’s F-117. His unobtrusive leadership guided the advance of U.S. stealth technology a decade and a half ahead of the country’s international competitors.
Whereas enormous, expensive government stealth programs were typical, Bird of Prey was an exercise in thrift. On a budget of $67 million—lower than the price of a couple of commercial aircraft—despite expectations to the contrary, the group relied on rapid prototyping, computer modeling, and innovative parts acquisition.
A lot of the plane was constructed from commercial or repurposed parts: its engine was borrowed from a business plane, its ejection seat stolen from a Harrier, and its cockpit cobbled together from old fighter controls. According to test pilot Col. Doug Benjamin, who once joked about it, the instrument clock was found at Wal-Mart, and the cabin air conditioning system was essentially a hairdryer.
Designed for Invisibility
The plane itself resembled a science fiction model—and indeed it was. Its design had been influenced by the Klingon Bird of Prey from Star Trek, and that’s how it became known. With its tailless gull-wing design, a 47-foot length, and a 23-foot wingspan, it was designed to be low observable.
Smooth lines, lack of vertical stabilizers, and a buried engine all served to decrease radar and infrared signatures. Even the paint was selected to camouflage the plane’s profile during the day.
Skip fly-by-wire controls in favor of less complex manual hydraulics—a stark exception for stealth planes—the Bird of Prey still flew remarkably steadily. Aerodynamics had to be perfect, and they were.
Flying Under the Radar, Literally
Performance-wise, the Bird of Prey wasn’t setting any speed records. Its single Pratt & Whitney JT15D-5C engine drove it to about 300 mph at a service ceiling of 20,000 feet. But speed and altitude weren’t what it was designed for. The whole project was about testing stealth design, manufacturing techniques, and control technology. On all of those scores, it was a resounding success.
The jet flew for the first time on September 11, 1996, and during the following three years, it completed 39 missions. Although early flights uncovered some idiosyncrasies—such as drag caused by the landing gear—each problem was addressed through painstaking iteration. By the time the last flight occurred in 1999, the Bird of Prey had done what it set out to do: demonstrate that cheap, highly stealthy planes can be produced rapidly and safely flown.
Lasting Impact
Although the Bird of Prey never went into active service, its DNA remains. Important lessons of the program directly impacted Boeing’s X-45 Unmanned Combat Air Vehicle (UCAV), which borrowed many of the Bird’s tailless, stealth-oriented design considerations.
And its stealth shaping and manufacturing technologies influenced the F-22 Raptor, the F-35 Lightning II, and even the new B-21 Raider. As Boeing executive Jim Albaugh succinctly explained, “We changed the rules on how to design and build an aircraft.” And he wasn’t exaggerating.
Legacy in the Shadows
Nowadays, the sole Bird of Prey ever constructed remains at the National Museum of the U.S. Air Force in Dayton, Ohio, hanging aloft dramatically above an F-22 Raptor in the Modern Flight Gallery. Interestingly, no close-up photos of the cockpit have ever been published, and the exhibit is mounted just high enough to prevent onlookers from peeking in. Whether that’s an accident or a last gesture toward its clandestine beginnings is anyone’s guess.
Though it never had guns, saw combat overseas, or hit the headlines like its more glamorous cousins, the Bird of Prey had a critical behind-the-scenes function of pushing the edges of stealth airpower. It’s a testament to the fact that some of the most impactful planes are never created for war—they’re created to try to define it.