This phantom aircraft, the YF-118G, vanished from public view yet laid the groundwork for today's advanced stealth fighters, shaping their evolution.
By Kris Osborn, Warrior
Known as the “Bird of Prey,” the experimental YF-118G demonstrator can be summarized in terms of a duplicity, meaning it both disappeared and never came to fully exist, yet the aircraft also exacted a positive influence upon stealth aircraft for future stealth aircraft. The design was innovative, bold and enterprising, as the aircraft was smoothly shaped with few vertical structures and a horizontal blended wing-body-type configuration. The plane certainly looked stealthy, and when it was unveiled in 2002 as a testbed, it was designed to optimize cost, benefit and production variables in tandem with innovations in the realm of stealth flight.
The McDonnell Douglas (later Boeing) aircraft was intended as a developmental effort to identify low cost and efficient methods of stealth aircraft manufacturing, yet the platform also represents an evolutionary bridge from the Cold War jet into a modern stealth era. This meant the aircraft was not exceptional in terms of many of its performance parameters, meaning it was not exceptionally fast, maneuverable or high-altitude. The YF-118G rather was a stealth technology developmental testbed which served as a thread connecting the earliest stealth concepts with radar signature reducing technologies fundamental to the F-22 and F-35.
Stealth development
The “Bird of Prey” was not intended for major, large-scale great power air combat but rather built to expand and expedite the technological “acceleration” and “maturation” of what has become modern stealth. Specifically, the platform was built with a smooth, rounded stealthy exterior and also engineered with a heat-signature reducing internally buried engine and managed or suppressed exhaust emissions. These technologies became fundamental pillars in the rapid progression of stealth technology in recent decades. Overall, the aircraft achieved over forty flights between 1996 and 1999, validating many aspects of its design. Therefore, while the Bird of Prey never achieved the highest raw performance metrics, its flight operations provided invaluable real-world data on how stealth geometry behaves in the air.
YF-118G Manufacturing
In addition to its contribution to the development of stealth technology, the Bird of Prey was also instrumental in helping advance manufacturing and production techniques. Construction of the aircraft included rapid prototyping and high-volume use of composite materials. The aircraft was built relatively quickly and at comparatively low cost—an achievement for a program that required both precision and secrecy. Public reports identify that many of the production methods, declassified years after the existence of the aircraft became public, have been subsequently embraced by weapons developers. This includes the use of single piece composite structures and methods of fastening and “tooling” to maximize and blend engineering and affordability.
Influence 6th-Gen
Perhaps the most striking influential element of the less-recognized and often forgotten Bird of Prey pertains to its fully horizontal configuration. Clearly the front end of the design appears to have influenced the rounded, yet aerodynamic “blending” now evident in the F-22 and F-35, yet the absence of “vertical” structures resembles elements of the F-47. Could engineers have begun to make progress with an ability to vector and maneuver without needing “tails” or “fins” or protruding structures? If so, this could be some of the early signs of what is now 6th-generation stealth technology, a breakthrough development which appears to merge bomber-like stealth with fighter-jet like agility and speed. While the speed and maneuverability of the Bird of Prey were far inferior to the F-22 and also far inferior to the F-47, it does seem apparent that the stealth configuration itself may have been a 1990s-era precursor to 6th-gen stealth technology.
Kris Osborn is the President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a highly qualified expert in the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University