With the U.S. Air Force’s new crewed sixth-generation stealth combat jet, designated the F-47, speculation has surged about the aircraft’s final design. The limited imagery available raises, but comparisons to earlier demonstrators and concepts offer intriguing insights. The Phantom Works X-36 has drawn particular attention since the F-47’s unveiling.
Boeing’s X-45 UCAV demonstrators and the once-secretive Bird of Prey stealth jet have also been cited as potential influences. Furthermore, the F-47 bears some resemblance to Boeing concepts from the mid-1990s developed under NASA’s “Investigation Into The Impact Of Agility In Conceptual Fighter Design” study. These earlier designs explored unconventional configurations, seeking the optimal balance of maneuverability, stealth, and aerodynamics that could define the next era of air combat.
The strongest visual similarity, however, is between the F-47 and the X-36 Tailless Fighter Agility Research Aircraft, which was designed to represent a low-observable high-performance fighter. Developed in the mid-1990s by McDonnell Douglas Phantom Works (now Boeing), in collaboration with NASA, the uncrewed X-36 was a 28-percent scale model of a conceptual advanced fighter configuration. The X-36 was revolutionary, challenging conventional wisdom regarding fighter aircraft stability and maneuverability.
The X-36 eliminated traditional tail surfaces, incorporating canard foreplanes, split ailerons on a lambda-like wing, and an advanced thrust-vectoring engine nozzle for directional control. These design elements allowed the aircraft to achieve extraordinary agility while maintaining a low radar cross-section, a critical factor in modern air combat. Due to its instability in pitch and yaw, an advanced digital fly-by-wire system ensured stability and precise control. This system laid the groundwork for modern flight control technologies, potentially influencing the software-driven maneuverability of the F-47.
The aircraft, weighing around 1,250 pounds fully fueled, measured 19 feet in length, three feet in height, and had a wingspan just over 10 feet. It was powered by a Williams International F112 turbofan generating approximately 700 pounds of thrust. These specifications, while modest compared to operational fighters, provided valuable data on aerodynamic efficiencies and control mechanisms for tailless aircraft.
Controlled remotely by a pilot using a ground station with a standard fighter-type HUD and a moving-map display, the X-36 completed 31 test flights at NASA’s Dryden (now Armstrong) Flight Research Center in California from May to November 1997. Over 15 hours and 38 minutes of flight time, NASA determined the X-36 was “very stable and maneuverable,” exceeding project expectations and confirming the viability of tailless designs.
Additional test flights in late 1998, under an Air Force Research Lab (AFRL) contract, saw Boeing testing its Reconfigurable Control for Tailless Fighter Aircraft (RESTORE) software. This machine-learning-driven software was designed to compensate for in-flight damage or control surface malfunctions. This research foreshadowed modern adaptive control systems, which are expected to be integral to next-generation fighters like the F-47, allowing for real-time performance adjustments based on combat conditions.
With the F-47 likely adopting a tailless fighter design, the X-36’s influence seems substantial. The most visible similarity is the canard foreplane arrangement, though it is unclear if canards will feature in the final F-47 configuration. Canards generally pose challenges for low observability, but they have been included in stealthy fighter concepts, including Boeing’s NGAD-related designs and past Advanced Tactical Fighter (ATF) studies that led to the F-22 Raptor. If retained, canards could suggest innovative stealth treatments or the prioritization of agility and control over absolute radar signature reduction.
The F-47’s bubble canopy, designed for maximum pilot visibility, is another similarity to the X-36’s cockpit representation, though the latter was uncrewed. It remains uncertain whether the F-47 will be a single-seat or tandem-seat aircraft, with a two-seat configuration being plausible given its likely role as a drone controller within the broader NGAD system. This configuration could mark a shift in air combat doctrine, emphasizing networked warfare and human-AI teaming.
Additionally, the F-47’s broad, shovel-like nose bears resemblance to the X-36, likely housing a large radar array. Given the increasing emphasis on electronic warfare and sensor fusion in modern aerial combat, this could indicate an advanced suite of detection and targeting systems, possibly integrating elements of artificial intelligence to enhance situational awareness and target prioritization.
Beyond the X-36, other tailless demonstrators may have influenced the NGAD program. Lockheed Martin’s X-44 Manta concept, developed in the late 1990s, aimed to explore tailless aircraft using thrust vectoring for primary flight control. Although no hardware was known to have been built, the X-44’s objectives — enhancing speed, fuel efficiency, and maneuverability — align with potential NGAD requirements. If Boeing has incorporated similar thrust-vectoring technologies, the F-47 may achieve unprecedented levels of control and agility.
Another notable influence could be the A-12 Avenger II, a tailless stealth attack aircraft from McDonnell Douglas and General Dynamics. Though the A-12 was not a high-performance fighter, its flying-wing configuration demonstrated early stealth advantages in tailless designs. Its abrupt cancellation may have left valuable technological developments that resurfaced in later programs, including NGAD.
The Bird of Prey, an experimental Boeing aircraft flown in the 1990s, also contributes to the discussion. Featuring an unconventional, highly stealthy design with a significant wing dihedral, it tested new manufacturing techniques and visual stealth concepts. The F-47’s apparent wing dihedral could be a nod to this earlier project, possibly indicating an emphasis on reduced optical and infrared visibility alongside traditional radar stealth.
Rumors surrounding the so-called YF-24 further complicate the discussion. While never officially confirmed, some reports suggest the YF-24 was a Boeing demonstrator testing tailless fighter concepts. A related Boeing design study, labeled MRF-24X, depicts a single-engine, tailless fighter with an X-32-style wing, suggesting a potential link to NGAD research. If the YF-24 program indeed existed, it could have served as a crucial stepping stone toward the F-47, refining key design elements and performance parameters.
Tailless fighter configurations have been a significant research area since the 1990s, likely spawning multiple classified demonstrators at facilities like Area 51. Some of these predecessors may have influenced the NGAD program, including the two or more demonstrators known to have flown before the F-47’s selection. The extensive secrecy surrounding these projects suggests a high level of technological innovation, possibly incorporating next-generation propulsion systems, adaptive materials, or quantum computing-based avionics.
Ultimately, while much about the F-47 remains speculative, it is highly probable that lessons from past X-plane programs, particularly the X-36, have informed its development. The F-47 may represent the Pentagon’s first operational tailless fighter, but confirmation awaits further disclosures or official imagery of the aircraft’s complete design. If Boeing and the U.S. Air Force have indeed cracked the stability and control challenges associated with tailless designs, the F-47 could mark a revolutionary leap in fighter aircraft evolution, blending extreme stealth, agility, and artificial intelligence into a single lethal package.
