As the Chinese military’s first fifth-generation stealth fighter, the J-20 has attracted substantial enthusiast and media interest. One of the suggestions to make its way into online publication over the last year is the prospect of a twin-seat variant of the J-20 emerging at some stage soon.
Fighter aircraft with twin seats have been a staple of air forces going back decades, either as a fighter’s primary configuration or as a twin-seat variant of a single-seat primary variant. However, there is currently no twin-seat fifth-generation fighter in existence; the United States, as the nation that first pioneered fifth-generation fighters in the form of the F-22 and F-35, has not chosen to pursue twin-seat variants either.
Therefore, a notional J-20 twin-seat variant appropriately prompts speculation about what rationale and role such an aircraft could fulfill, and how it might be configured. This piece will explore some of the commentary surrounding the idea of a twin-seat J-20, and consider how a twin-seat J-20 could fit in the context of contemporary and future air combat trends.
For the purposes of brevity, the interim designation “J-20S” will be used to refer to the prospect of a twin-seat J-20 in this article, consistent with usual People’s Liberation Army (PLA) designations (S, standing for “shuang” or “twin”). Note that “J-20S” is not an official designation.
Current Commentary So Far
One of the earliest well known English domain mentions of a J-20S featured in the Global Times in 2019. The article cited a CCTV television program where the idea of a twin-seat variant was floated, in the context of the J-20’s chief designer’s past comments about the fighter being customizable. The roles suggested for a J-20S included allowing the aircraft to prosecute additional roles simultaneously with its primary air superiority mission. It was also suggested that such an aircraft could be developed into a tactical bomber of an electronic warfare (EW) aircraft. It is important to note, however, that Chinese television, news and tabloids virtually never receive exclusive information on important PLA weapons developments even if they are technically “state media,” and often know only as much (if not less) as the general public. Therefore such discussions need to be treated with appropriate levels of caution.
More recently, in August this year, an article in the South China Morning Post by one if its most prolific writers on the PLA suggested that “China” had “unveiled” a twin-seat J-20 variant. The roles of this putative aircraft are described as including an airborne early warning and control (AEW&C) mission, and controlling drones, other aircraft, and support surface ships and ground-based missiles as well, suggesting a significant battle management (BM) role. Somewhat curiously, this article suggested the J-20S would feature side-by-side seating like Su-34 or F-111. Unfortunately, it is unclear what prompted speculation of a side-by-side seating configuration – there is a screenshot of an aerodynamic study of a stealth aircraft ejection seat process, described as a “similar cockpit configuration to the Russian Su-34.” However, the aircraft in question does not even resemble the J-20 (lacking canards, it is more consistent with the FC-31), and there is no indication to suggest it features side-by-side seating either.
Needless to say, “China” certainly did not reveal anything either – the Chinese government and military rarely if ever “unveil” big ticket weapons developments in an official capacity. The article unfortunately also still uses the incorrect designation of the 003 catapult carrier under construction at Shanghai (describing it as 002), and continues to speculate that a carrier-borne J-20 fighter is in active development for the Chinese navy’s fifth-generation carrier-borne fighter requirement.
The SCMP’s reporting was subsequently picked up by a few other outlets. A contributor to Forbes correctly pointed out that the SCMP article’s claims were based on a social media account of questionable credibility, as well as casting doubt on the prospect of a side-by-side seating configuration. The evidence for a J-20S is certainly far less concrete than what the SCMP article insinuated.
Either way, the idea of a J-20S twin-seater had entered the sphere of public discussion.
Tandem Versus Side-By-Side
It is instructive to first clarify the difference in twin-seat cockpit configurations. The majority of contemporary twin-seat fighter aircraft adopt tandem (or stepped cockpits), where two crew sit one forward, one behind. Conversely, a side-by-side cockpit places both crew next to each other. In short, a tandem twin-seat configuration extends the overall length of the cockpit compared to a single-seater, while a side-by-side configuration widens the overall width of the cockpit compared to a single-seater.
As far as development work is concerned, a tandem twin-seat variant of a single-seat fighter typically requires substantially less structural modifications than a side-by-side twin-seat configuration, as the latter necessitates a widening of the aircraft’s nose to accommodate the larger cockpit width. A widened aircraft nose may also require substantial rework of an aircraft’s overall fuselage, air intakes, and weapons bays, depending on the aircraft’s configuration.
In the case of J-20, as a fifth-generation aircraft with an integrated lift-body design with canard and leading edge root extensions and side air intakes, it is impossible to see how a side-by-side twin-seater variant would not demand a substantial redesign of the overall aircraft to such an extent that it would essentially be a new aircraft.
Therefore, if a J-20S does emerge, it is much more likely to adopt a tandem cockpit.
The Shape of Future Air Battles
Speculating the the rationale and roles of a notional J-20S demands consideration of the current and future shape of air combat. Certain trends are already in practice today: The importance of stealth aircraft, increased air-to-air engagement ranges, stand-off strike weapons, highly capable sensors and sensor fusion, increased workflow automation, highly networked system-of-system forces, and the role of force multipliers such as AEW&C and EW aircraft are all well accepted.
Emerging trends of air combat on the horizon yet to be operationalized include but are not limited to: more autonomous and larger formations of high-end unmanned aerial vehicles (UAVs and UCAVs) including loyal wingman and strike UCAVs, more distributed AEW&C and EW capabilities that are less vulnerable and more attritable, significantly more complex and dense sensor-shooter networking and EW environments, and a much higher prevalence of both friendly and hostile stealth platforms including not only manned fighter aircraft but also bombers, UAVs and missiles. Multi-domain networking and sensor-shooter networks will also continue to strengthen and evolve. In other words, the demands on the human pilot to process information and maintain situational awareness will only increase as the battlespace grows in complexity.
Future air battlespaces could easily be envisioned to involve dozens or even hundreds of friendly and hostile stealth aircraft, with extensive use of stealthy strike missiles, under heavy and distributed EW pressure, in a dense sensor and networking environment, integrated with multi-domain assets including friendly naval formations as well as land-based long range strike systems and potentially space systems, alongside large numbers of friendly and hostile UAVs and UCAVs fulfilling a range of different missions. Certainly, further progression of sensor fusion and artificial intelligence (AI) technologies could help pilots keep pace with future demands. However, even with those advancements, the simultaneous missions and decision making of a single aircraft will be rate limited by the number human pilots in the aircraft.
Battle Management and UAV Controller
In the context of the aforementioned vision of future air combat, this author humbly speculates that a notional J-20S would be capable of two enhanced roles in combat compared to a single-seat J-20 – that of battle management (BM) and UAV controller (abbreviated to UC for the purposes of this article). Such a J-20S would be identical to its single-seat sibling, the only difference being the extra tandem cockpit with the requisite life support and display, processing, and power requirements for the copilot. Sensors, datalinks and EW would be consistent, and weapons bay dimensions would remain unchanged, as would the overall dimensions of the aircraft. Fuel capacity might seek to be maintained by extending a dorsal hump on the aircraft, or a slight reduction in fuel capacity may even be accepted so as to minimize the additional developmental costs and time that structural changes may entail.
This vision of J-20S would be slightly heavier, slightly less maneuverable and slightly less stealthy than its single-seat sibling, but this is an accepted trade-off that twin-seat variants suffer, and must be weighed against the benefits of having an extra human to focus on the BM and UC roles. Both roles are fairly self-explanatory.
BM would involve monitoring and assessing the battlespace through the full spectrum of securely networked friendly sensors and shooters to maintain situational awareness beyond what a single pilot has the time and mental resources to process. This would provide enhanced command and control capabilities and prioritization among friendly assets across multiple domains, including EW. This role would take on some of the missions that a traditional AEW&C does, but does not replace AEW&C nor future distributed AEW&C solutions. Furthermore, the J-20S in question also wouldn’t be actively emitting its own sensors like an AEW&C, but rely on networked sensor feeds from the cloud of friendly, equally well-networked fighters, UAVs and other offboard force multipliers and sensors.
UC overlaps with the BM role, as it requires the same level of complex networking and situational awareness, but instead acts as the decision maker and overseer of friendly UAV and UCAV formations, whether they are conducting air-to-air missions, or sensor, strike, surveillance or electronic warfare missions. Future UAV and UCAV aircraft will certainly enjoy far more autonomy than today’s drones; however, in a high EW pressure environment, a line-of-sight manned controller in the same battlespace will likely still be needed to ensure tactical decisions and mission oversight of multiple large formations of drones are executed correctly and can respond quickly to sudden changes in the battlespace.
It is worth noting that in the above vision of J-20S, a single-seat J-20 would still be able to fulfill both the BM and UC mission to an extent. But having an second human copilot focusing entirely on those roles allows the pilot to also conduct their primary mission – whether it’s combat air patrol, strike, or otherwise. The benefit, then, is allowing the aircraft overall to perform the BM and UC mission much more effectively than a single-seat aircraft would in the same situation.
What About Strike and EW?
Finally, there has been some speculation that a potential J-20S could either be developed into a dedicated strike or EW variant, or perhaps that J-20S itself might emerge as a dedicated strike variant to begin with.
While the possibility of a dedicated strike or EW variant of J-20 cannot be ruled out, this author believes the extent of structural changes needed to make the aircraft a worthy strike aircraft or EW aircraft may be too significant to make it worthwhile. For example, a dedicated strike J-20S variant should at least seek to carry longer and larger diameter strike weapons, such as the KD-20 or YJ-12; however, these weapons are so large that they would require much larger internal weapons bays, in turn demanding a much larger overall aircraft to the extent that it would likely be more worthwhile developing an entirely new dedicated medium bomber design. On the other hand, a less extensive strike J-20S variant with only a modestly increased weapons bay size would still require structural changes and development costs and time, while offering only marginally improved strike capacity, making alternative procurement choices seem more attractive – whether that involves producing additional J-20s and J-20Ss, procuring more future anticipated H-20 stealth bombers, developing and procuring stealthy UCAV platforms, or a combination of all three.
An EW J-20S variant is slightly more plausible than a dedicated strike variant; however, it would also require significant structural modifications for installation of EW equipment. Furthermore, trends of EW aircraft tend to favor podded EW systems, which offer more flexibility and greater long-term potential than integrated conformal systems. Thus an EW J-20S would likely be required to carry EW pods, which even if stealthily shaped and treated, would likely compromise its radar cross section far more than the introduction of a tandem cockpit. In the longer term, when sixth-generation fighters emerge, it is plausible that the J-20 and other contemporary fifth-generation fighters like the F-35 may take up the EW role that inherently requires actively emitting, but until then it is likely that dedicated fifth-generation EW aircraft will remain elusive.
A Tentative Prospect
All this said, the emergence of a potential J-20S is not guaranteed. There is enough noise in the Chinese language PLA-watching sphere – including from individuals with established track records who have spoken of the BM and UC missions themselves – to consider it as a tentative prospect, but it is not at the stage of confidence or expectation, for example, that the fifth-generation carrier-borne fighter or H-20 currently enjoy.
It is also unknown when a potential J-20S could emerge, as current J-20A production utilizes stopgap WS-10 powerplants (with initial production aircraft using Russian Al-31s), and it is possible that a twin-seat J-20S might await the more powerful WS-15. Even the designation of a notional J-20S could change depending on aircraft powerplant – if a WS-15-powered J-20 is designated J-20B then the actual twin-seat designation would be J-20BS, while a twin-seat variant of the WS-10 powered J-20A would be J-20AS.
However, if a J-20S twin-seat variant does emerge, it would likely reflect a PLA desire for a fighter capable of carrying out enhanced BM and UC missions while fully combat capable with virtually the same degree of survivability and lethality as its primary mainline stealth fighter.