Reviewing China’s New Stealth Fighters

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Reviewing China’s New Stealth Fighters

What we know about the twin seat J-20 and carrier-borne FC-31 fighter – and a mystery tailless airframe captured in satellite imagery.

Reviewing China’s New Stealth Fighters

An unofficial image of the J-XY, China’s first carrier-borne stealth fighter.

Credit: Weibo/ 燃烧的哈尔科夫

In the last week of October 2021, a number of Chinese combat air developments were uncovered in a short span of time. The first of these was the emergence of the expected twin-seat variant of the J-20 air superiority fighter at Chengdu Aircraft Corporation (CAC), documented by progressively clearer photos and videos. The second was the emergence of the long awaited carrier-borne variant of the twin-engine medium-weight FC-31 stealth fighter intended for People’s Liberation Army Navy (PLAN) use at Shenyang Aircraft Corporation (SAC).

Additionally, commercial satellite imagery taken of CAC was also published and released online, capturing a tantalizing new tailless airframe with potentially significant implications and applications for sixth-generation fighter aircraft development efforts as well as unmanned aerial vehicle (UAV) purposes.

This article will review some of these recent developments in the context of the PLA’s overall tactical air power efforts and tentatively predict the likely progression of other forthcoming aircraft projects that are currently under development.

J-20S: The First Twin-Seat Stealth Fighter

Rumors of a twin-seat J-20 had been in circulation since the mid-2010s; however, it was only over the last two years that such an aircraft was considered by the PLA watching community to be a definitive project expected to emerge. I published an article documenting these indicators in October 2020 – by coincidence, almost exactly a year prior to photographic evidence of the real aircraft being leaked online.

Progressively clearer imagery and videos provided details and general characteristics of the aircraft. It bore the serial number “2031,” and preliminary imagery assessment suggested it retained the overall dimensions and configuration of the standard single-seat J-20. Subsequent clearer frontal and side profile imagery of its cockpit and canopy demonstrated the poor visibility of the rear cockpit position, as well as indicating the overall canopy was now made of two pieces with a major reinforcing external frame between the two, while the forward canopy piece retained the small internal forward brace. Overall, initial assessments of the aircraft’s configuration seem to very closely resemble the computer rendered image of the twin-seat J-20 briefly glimpsed in an industry video released by AVIC in early 2021. Subsequent imagery confirmed the aircraft’s maiden flight in early November 2021, marking the first flight of a twin seat fifth-generation fighter aircraft.

In characteristic PLA fashion, many simple facts have yet to be established. The name of the twin seat J-20 is unknown, with the most widely used designations being J-20S (or J-20AS) and J-20B. Given this aircraft appears to retain the same overall dimensions, planform, and airframe as the standard single seat J-20, as well as likely possessing the same weapons bay dimensions and powerplants, I will refer to it as J-20S for the purposes of the article.

Similarly, the intended role of the J-20S is unclear as well. There has been some consideration of the J-20S as a combat capable conversion trainer; however, given modern training regimes, increasingly capable simulation systems, and the proliferation of advanced trainers such as the JL-10, it is doubtful whether conversion training would be a worthwhile use of resources both in terms of developing a twin seat fifth-generation aircraft, as well as the use of airframe hours of fifth-generation aircraft in service. The aforementioned poor visibility of the rear seat cockpit would seem to further cast doubt on the viability of J-20S as a regular conversion trainer, though ad-hoc training roles for advanced tactics cannot be ruled out.

Instead, one of the increasingly speculated roles for the J-20S is to leverage the standard single seat J-20’s avionics and networking capability, to provide an enhanced general battle management and command and control aircraft relative to a single seat J-20. The fighter would provide a more survivable and distributed supplement to traditional manned airborne early warning and control aircraft and airborne command posts. Part of this enhanced command and control capability is likely to involve UAVs and UCAVs in some capacity, with some recent disclosures suggesting the PLA intends for manned fighters such as the J-20 to be capable of controlling drones, which is consistent with broader international trends of integrating UAVs and UCAVs into manned-unmanned-teaming complexes.

Increasing automation at present, and into the future, is likely to increase the ability of human crew to perform more complex battle management and command tasks; however, even in the context of advanced automation and burgeoning artificial intelligence, the rate limiting step of an aircraft crew to perform a large number of complex tasks will depend on the number of human beings to absorb information, delegate tasks, and make tactical decisions. Therefore, by extension, it is also impossible to gauge how capable the single seat J-20 is at performing battle management and command roles, except that the J-20S is likely to be significantly more capable than the single seat fighter.

Going forward, important milestones to watch for include: confirming the dimensions of the J-20S’s weapons bay (expected to be the same as the single seat J-20); confirming the J-20S’s powerplant (likely to be the same WS-10s that power all production J-20s since mid-2019); and awaiting its development and testing duration prior to entry into service. On the basis that the J-20S is indeed merely a twin seat variant of the standard J-20 without significant structural changes beyond the addition of a second crewmember, it is plausible that it could enjoy a relatively brisk testing and development period of three to four years prior to entry into service sometime before 2025.

J-XY: China’s Long Awaited Carrier-borne Stealth Fighter

The PLAN’s carrier-borne fifth-generation aircraft has been known to be based on SAC’s FC-31 technology demonstrator aircraft, since at least three years ago. This aircraft has been expected to be imminent since early 2020, as I have written in the past. Shortly after the Zhuhai Airshow, rumors in October 2021 suggested it had made its first flight, but it was only in late October that the first images of the aircraft in flight were leaked online, although the images could not be accurately dated. Amusingly, the name of the aircraft has yet to be confirmed, and the PLA watching community continue to call the aircraft “J-35” or “J-XY” as temporary designations. For the purposes of this article, the aircraft will be referred to as J-XY, to keep consistency with prior articles.

The few images of J-XY that are accessible confirm a number of important characteristics. The presence of a catapult launch bar on the nose landing gear, and the visible wing fold lines, both categorically confirm that J-XY is intended for carrier-borne use. Current photo angles and resolution do not reveal details of the rear landing gear nor the rear ventral fuselage where a tailhook would be located; however, this is likely a matter of waiting for additional images. Other airframe modifications are also confirmed, including impressions of a wider overall wingspan (as was indicated by the J-XY mockup aboard the PLAN’s carrier mockup facility at Wuhan), as well as an enlarged dorsal fuselage immediately posterior to the canopy. A redesigned canopy is also distinctly present, with rumors indicating that the canopy now opens from the back, rather than the front. A chin mounted faceted housing is also present, likely intended for an EO IRST (electro optic, infrared search and track) type sensor similar the EO IRST on the J-20, or to the EOTS on the United States’ F-35.

A number of remaining questions still persist for the J-XY. The size of the J-XY’s ventral weapons bay is still unknown, with one long-standing rumor previously suggesting the aircraft’s weapons bay would have the same dimensions as the J-20’s ventral bay, which could provide useful commonality for their weapons suites. The details and identity of the J-XY’s powerplant are also unknown – upgraded WS-13 engines have long been rumored to be the J-XY’s initial powerplant, and technically this has yet to be photographically confirmed. The exact folded dimensions of the J-XY, the presence of a folding ladder, the potential for commonality of avionics between the J-XY and the  J-20, are also details we’ll need to wait to flesh out.

The J-XY is obviously intended to be for catapult launch, and will find a home on the 003 carrier currently under construction as well as future catapult equipped carriers that the PLAN procures. However, one additional key determinant of its flexibility will be whether the J-XY is also capable of operating from PLAN’s ski jump carriers, CV-16 Liaoning and CV-17 Shandong. The ability to operate J-XYs from these two carriers as well would greatly enhance their overall capability as well as their longevity in service.

The J-XY prototype as sighted appears to be in a relatively complete state – that is to say, it seems to have more in common with the J-20 201X series of prototypes, rather than the J-20 200X technology demonstrator prototypes or the two flying FC-31 technology demonstrators. Given the preexisting testing conducted on the two FC-31 demonstrators, it is not a surprise that J-XY appears relatively mature in configuration, but will of course now proceed into an extensive testing and integration program. As a carrier-borne fighter, carrier-related milestones in the future will include the first land based arrested landings and catapult launches (and possibly ski jump launches), as well as the first arrested landings and catapult launches (and possibly ski jump launches) aboard a carrier at sea.

If the J-XY is capable of leveraging relevant experience in the flight testing of the FC-31 demonstrator airframes, as well as applying subsystems from the J-20, a development and test period of five years may lie within reach, which could see initial airframes commissioned by the PLAN around 2026. Needless to say, such projections remain very preliminary and will be revised in coming months and years as the program proceeds.

A Tailless Mystery

Finally, the third tactical air development in late October was a series of satellite images taken of a mysterious airframe discovered at CAC’s factory in Chengdu. These images, taken by commercial satellite companies, were first published by The Warzone, and in totality included images taken over multiple months in both color and greyscale, from multiple angles in 2021.

The airframe is estimated at about 14 meters long, with a 12-meter wingspan, characterized by a large delta wing, and lacking any visible tails or horizontal stabilizers, and a continuous slight dorsal hump along its centerline that strongly implies it to be a single engine aircraft. The identity of this mystery airframe is far less concrete than the J-20S and the J-XY, yet may prove to be more consequential in the long term.

The quality of the imagery makes it impossible to assess if the airframe is a proper, functioning, and flyable aircraft, or a mockup. Furthermore, we cannot determine if the airframe is intended to be manned or unmanned, as the imagery cannot definitively rule out the presence of a cockpit. The presence of J-10 and J-20 aircraft at the factory site allows for comparisons with the mystery airframe, and it is fairly obvious that it is distinct from both of those two types, given the dimensions of the airframe, and the distinctive planform of a large delta wing and lack of tails or stabilizers.

Regardless of whether the airframe in question is a mockup or a flyable aircraft, and regardless of whether it is manned or unmanned, the applications of a relatively sizable, tailless delta wing airframe are fairly obvious. Both sixth-generation aircraft and emerging future UCAV designs are likely to apply tailless, flying wing-delta planforms to some degree, and development and testing of demonstrator aircraft are likely to occur as pre-developmental work. As a 14m x 12m airframe, this mystery airframe would be within the expected size of a medium weight fighter aircraft as well as a large size UCAV – however, it would also be within the size of a demonstrator aircraft, not dissimilar to X-planes such as the American X-29 and X-31, or the Japanese X-2/ATD-X.

Given the lack of any rumors of a new tailless delta fighter aircraft expected to emerge from CAC, it seems unlikely this airframe is intended as a prototype of a new fighter aircraft. However, its application as a demonstrator aircraft or as a prototype for a new UCAV is somewhat more viable.

The appearance of a new planform at CAC itself is not fully unexpected. An unassuming placard in 2019, produced by the collaborative innovation center for future aerospace vehicles of Northwestern Polytechnical University (NPU), detailed various aerospace milestones. One of these milestones described collaboration between NPU and CAC/601 Institute to conduct China’s first research and development on sixth-generation fighter aircraft, including the proposal of eight planforms for sixth-generation applications, and the subsequent flight demonstration of four of those planforms. The timing of this mystery airframe caught on satellite at CAC means it could be one of those four flight demonstrators investigated between NPU and CAC. Initiating pre-developmental work and flight demonstrator platforms at that stage in time would be consistent with the expected emergence of an in-service sixth-generation fighter aircraft before 2035, as described previously by authorities in the Chinese aerospace industry and documented by this author.

A relatively sizeable 14m x 12m demonstrator airframe, compared to a smaller subscale demonstrator, might also enable more representative demonstrations of digital design and rapid prototyping technologies that have been described by Chinese aerospace engineers as highly relevant for sixth-generation aircraft projects.

Regardless of the exact explicit role of this specific airframe, however, it is an appropriate reminder that recent, newly emerged PLA fifth-generation aircraft are appearing in context of hidden and likely substantial efforts in pursuit of the next generation of combat air power as well.

On the Horizon

Both the J-20S and the J-XY can be considered as “confirmed” projects, with definitive photographic evidence at hand and with both having made their maiden flights. The J-20S holds distinction as the first ever twin seat fifth-generation fighter, while J-XY is the second fifth-generation fighter designed for arrested landing carrier operations.

However, a few other combat aircraft projects are expected to emerge in the next few years, leading up to 2025.

The most immediate of these is the catapult compatible 4.5th generation J-15 variant, sometimes dubbed J-15B. In fact, there are some indicators that this aircraft might have already conducted its maiden flight, but with decisive evidence being deliberately withheld. A catapult compatible variant of the J-15D is also expected to enter production, in context of the appearance of the related land-based J-16D aircraft that is confirmed to have entered service.

Additionally, a production ready variant of the FC-31, intended for the PLA Air Force, is expected to emerge within the next year or so. It is likely to be a land-based variant of the J-XY and thus share significant subsystems, logistics, and enjoy overlaps in testing and development. This aircraft has sometimes been referred to as the J-21, and has been spoken of as a more affordable, medium weight fifth-generation fighter to complement the Air Force’s more expensive, heavy weight J-20.

Finally, the long-awaited H-20 stealthy strategic bomber is likely to make its appearance sometime within the next two years, with prototype airframes said to be in advanced stages of construction.

A number of stealthy UCAV and UAV platforms are also expected to emerge by 2025, and persistent but unconfirmed rumors insist that a theater range, stealthy fighter bomber (sometimes dubbed as JH-XX) might be in development as well.

Thus, after a relatively quiet past five or six years, without any new Chinese combat aircraft types emerging in that time period, 2021 may prove to be the opening set of a new cycle of various combat aircraft projects reaching fruition.