What a 19-Year-Old Study Tells Us About China’s J-20
The Chinese fifth-generation J-20 remains one of the world’s more enigmatic and poorly understood modern combat aircraft, even 11 years after its maiden flight and some six years after it entered initial service with the People’s Liberation Army (PLA) Air Force. Deliberate PLA opacity and operational security is arguably the greatest cause of this.
However, in 2016, photographs of a Chinese language paper were posted on a Chinese language military forum. This study was dated to 2003, and titled “Strategic Study of China’s Fighter Aircraft Development” (to be referred to as “Strategic Study” in this article). The article briefly found its way onto a couple of English-language PLA-watching communities before fading into obscurity, a flash in the pan.
The Strategic Study is a product of military and aviation industry input. It describes the rationale, requirements, roles, and projections for a stealthy, heavyweight fifth-generation fighter. This study was published in 2003, and based on its references to achievements from the Eighth Five-Year-Plan, which lasted from 1991 to 1995, it was likely originally written and distributed sometime between 1996 and 2003. It was authored by academician Gu Songfen, who had served in various high levels roles in the Chinese aerospace industry, including as vice president and as chief designer at the Shenyang Aircraft Design Institute (601 Institute). Gu played leading roles in a number of Shenyang aircraft during the 20th century including the JJ-1, J-8, and J-8II, before serving as a leading aerospace academician in the Chinese Academy of Sciences and Chinese Academy of Engineering.
Therefore, the Strategic Study is arguably the most definitive publicly available early documentation for the Chinese fifth-generation fighter project that would become the J-20. It provides a glimpse into late 1990s-era Chinese assessments of future geopolitical, military technology, and air warfare trends out to the early 21st century, as well as assessments of China’s own aerospace industry, and performance and mission requirements for their fifth-generation aircraft as considered at the time.
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Over past months, this author, with support from colleagues, has translated the original Chinese language study into English, including diagrams, keeping the formatting and spirit as close to the original document as possible. This translated document, with the original Chinese language document, are provided to readers and the community free of charge. Click here for the full translated document in English (with Chinese language original included).
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(Note: The study is almost certainly non-classified in nature, and sensitive technical information is thus either omitted or included for representational purposes only. Additionally, for ease of reading, the Chinese fighter generational classifications have been converted to international generation classifications – e.g.: F-16, F-15, Mig-29, Su-27, J-10 are translated “fourth-generation” rather than the Chinese equivalent of “third-generation,” and F-22, F-35 and the Chinese future fighter/J-20 are translated as “fifth-generation” rather than the Chinese equivalent of “fourth-generation,” etc.)
This article will summarize the most interesting and consequential points from the Strategic Study, both in relation to what is known about J-20 itself, but also in relation to the way in which other big ticket PLA projects may be approached (specifically, the PLA’s sixth-generation fighter project).
Role and Pacing Threats
The Strategic Study clearly articulates the advantages that fifth-generation fighters enjoy over older fourth-generation fighters, in terms of stealth, firepower, maneuverability, information, and communication. The leading and decisive role of air power in modern warfare in terms of seizing air superiority, enabling sea control, and conducting electronic warfare are all clearly stated in a manner consistent with international understandings of the role of air power.
The development of a domestic fifth-generation fighter is described as a way of enabling the PLA Air Force to perform both offensive and defensive missions, as well as advancing the domestic aviation industry. Development of a fifth-generation fighter is also expected to result in technologies that can be helped to further improve and iterate on fourth-generation fighters. There is also a goal of achieving leapfrog development, by reducing the 20-25 year period between the emergence of foreign fourth-generation fighters and Chinese fourth-generation fighters down to a 10-15 year gap between foreign fifth-generation and Chinese fifth-generation fighters.
The fifth-generation fighter’s primary mission is clearly stated to be air superiority, to conduct aerial engagements at long range. Other secondary missions include being capable of air-to-surface strikes, maritime strikes, and suppression of enemy early warning and guidance and fire control systems; operating in informatized combat missions; acting as an auxiliary airborne early warning aircraft, to carry out electronic warfare missions; providing targeting information to friendly forces; and providing overall leadership and protection for other aircraft during missions.
The Chinese fifth-generation fighter is clearly stated in multiple sections of the study to be capable of competing with the U.S. F-22, and to hold key advantages over the F-35. Both of these U.S. aircraft are similarly described in great detail, and viewed as pacing threats, with the F-35 viewed as a possible part of the Republic of China (Taiwan) Air Force inventory after 2015. Threshold requirements for China’s fifth-generation fighter include stealth capability comparable to the F-22; supercruise; exceptional subsonic and supersonic maneuverability; a large operational radius; a highly integrated avionics and weapons suite; and good reliability, maintainability, and affordability. These are fully expanded on in their respective sections in the translated document and will not be reproduced here in the interests of article length. A specific section of the paper also weighs up the desirability of a heavyweight twin engine fighter versus a lightweight single engine fighter, and the heavyweight twin engine configuration is selected based on payload, range, and kinematic properties, as well as existing pre-research conducted for such a configuration.
Seasoned PLA watchers will recognize the air superiority role the Strategic Study describes for the fifth-generation fighter, which is entirely consistent with the long-term rumors associated with the J-20 during the late 2000s, as well as subsequent official statements about the aircraft’s mission in recent years. In particular, rumors around requirements for the J-20 to compete with the F-22 and to hold some advantages over the F-35 are also well known and were widely circulated in the late 2000s, but may be confronting to foreign observers less acquainted with the aircraft’s history or who remain skeptical about the extent of the aircraft’s maturity or industry base.
It is worth noting that the requirement for China’s fifth-generation fighter to “compete with the F-22” and “hold some advantages over the F-35” is not accompanied by specific operational scenarios or force balances in which these aircraft may see confrontation. Given the period in which this was written, the F-22 was likely perceived as the more serious and mature threat, expected to field superior kinematic properties and equal or superior stealth, avionics/sensors, and weapons to the then-gestating F-35, and the F-22 was also likely expected to be procured on a much larger scale than the 187 airframes that were ultimately built. Indeed, it is likely that through the 2000s, the relative requirements of the Chinese fifth-generation fighter would have similarly evolved as greater understanding of the respective strengths and fleet sizes of both the F-22 and F-35 emerged.
Keeping those caveats in mind, however, the fifth-generation aircraft described by the Strategic Study remains categorically one intended to symmetrically compete with and engage the leading fifth-generation types of the time on the basis of its own merits. It is not described as an aircraft limited to only intercepting slow-moving force multiplier aircraft and egressing when confronted by opposing fifth-generation fighters, nor is it a dedicated striker that places primacy on the air-to-surface mission at the expense of the air-to-air role.
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Schedule, Risks, and Risk Mitigation
The above requirements and capabilities for China’s fifth-generation fighter seem audacious, bordering on insurmountable, when considering those formulations would have been made in the late 1990s and early 2000s, at a time when China’s aerospace industry had only recently completed the maiden flight of the domestic J-10 (which remained half a decade away from entering service), and only started to produce kit-built J-11A (Su-27SK) fighters imported from Russia.
However, great emphasis is placed on pre-research conducted for the fifth-generation fighter project during the Eighth Five-Year-Plan in the early 1990s. The Strategic Study also emphasizes industry domains where risk is lower (such as airframe design technology, flight control systems, electromechanical systems, and air-to-air missiles), and identifying areas where risk is greater (such as engine technology and avionics systems), and accounting for the need to use interim systems where appropriate. Most notably, the Strategic Study correctly identifies that domestic development of a thrust-to-weight ratio 10 (TWR 10) engine – needed for the J-20 to comfortably achieve supercruise – would likely suffer delays; therefore a WS-10/Taihang engine would likely be required at least for the tests of initial airframes. Indeed, subsequent development and production has shown that initial testing and first batch production used Russian Al-31 engines, and subsequent batch production is currently using WS-10 engines, while the TWR 10 engine (WS-15) is in advanced testing as of this writing.
The Strategic Study offers a projected developmental timeline, suggesting the aircraft would begin full-fledged development in 2006-2007, start flight testing around 2013, and be commissioned into service in 2019-2020, with delivery of an initial batch of six aircraft carried out in 2020. Meanwhile, the TWR 10 engine would begin preproduction delivery around 2017 and start small batch delivery in 2021. In retrospect, the development and delivery of WS-15 has lagged from this projection, while the overall J-20 aircraft (using interim Al-31 and WS-10 engines) began development and production earlier than this projection, having begun flight tests in early 2011, started delivery of the first batch of six aircraft in 2016, and entered small batch delivery around 2018, three to four years ahead of this projection. Still, the projected timeline seemed fairly accurate and reasonable in hindsight.
A preliminary unit cost of the fifth-generation fighter was also included, described at 450-500 million renminbi, presumably at early 2000s exchange rates, though the scale of production is not listed and may represent unit cost in early batch production. A life cycle of 40-50 years is listed for this aircraft, and engine, avionics and weapons systems are listed as areas of potential future upgrades, but the airframe itself would be more limited given the innate nature of a fuselage for a fifth-generation aircraft.
Technical Characteristics and Subsystems
Various initial technical characteristics were also presented in the study, describing an advanced aerodynamic layout featuring high lift, low drag, and high stealth attaining a lift coefficient of 2, and attaining a radar cross section of less than 0.3 square meters, at least in the forward aspect. It would be powered by two TWR 10 engines with full afterburner thrust of 15 tons of force, and use lightweight structural materials including but not limited to titanium alloys and composites.
Avionics would include an active phased array radar with a tracking range of 200 kilometers able to track 20 targets simultaneously and carry out multi-target engagement, combined with an open architecture avionics suite with extensive sensor fusion, and stealthy communication capabilities, and an integrated electronic warfare suite. A lightweight and low footprint electromechanical system and comprehensive power and environmental management system would be used. Primary weapons would include beyond visual range air-to-air missiles and high off boresight within visual range air-to-air missiles that would be primarily mounted internally, as well as being capable of carrying weapons externally including air-to-surface weapons.
The aircraft’s aerodynamic design and powerplants would comfortably allow for supercruise. Though no supercruise benchmark requirement is listed, a Mach 1.7 speed is described for the purposes of illustration. The aircraft’s combat radius is depicted in a diagram of the region as over 1,000 kilometers and below 2,000 kilometers. The exact number cannot be discerned due to the quality of the original photographs, but based on geography, it can be estimated to be anywhere between 1,300 and 1,800 kilometers. The study states that the fifth-generation fighter operating from airfields in Chinese territory should be capable of operating over the capitals of other nations in the region without air refueling, and should be capable of operating over the entirety of the Japanese islands with one air refueling.
Caveats of Note
The Strategic Study sheds light on multiple details of the project that would become the J-20; however, certain caveats need consideration for the study’s implications for the J-20 proper. Given this paper does not have a classification rating, and given it was produced from the late 1990s to early 2000s, it is likely that various requirements, technical domains, and risk assessments would have evolved between that time and when the J-20 began full scale development in the mid to late 2000s. Thus, the Strategic Study certainly is far from an exhaustive documentation of the present-day J-20’s characteristics.
The aforementioned projected timeline for the development and production of the aircraft and its engine are examples of where the real-world outcome differed from the study’s statements. Other deviations also likely exist.
For example, the requirement of the aircraft’s AESA radar yielding a tracking range of 200 kilometers and the ability to track 20 targets likely would have been revised over the years. Indeed, similar or superior parameters have been observed on contemporary Chinese fighter AESAs offered for the export market, such as LKF601E, slated as an affordable upgrade solution for legacy fighter aircraft.
Similarly, the TWR 10 engine is described as yielding thrust force of 15 tons, though a thrust range of 16 to 17 tons has been described for WS-15, and there is no reference to a thrust vectoring nozzle in the study despite multiple rumors alluding to one on WS-15. The RCS requirement for the aircraft also requires some nuance for interpretation, given only a minimum requirement is provided for the front sector, and no RCS requirements is provided for other sectors of the aircraft. Given the sensitivity of RCS for a fifth-generation aircraft, it is very likely the true details of such information were deliberately omitted for a non-classified document.
The emergence of the F-35 in the United States and the culling of F-22 production numbers during the mid to late 2000s likely would have also substantially affected the pacing threat requirements for avionics, datalinking, and sensor fusion, as well as affecting the required procurement scale of J-20s and fifth-generation fighters in general.
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The Strategic Study describes potential mixed formations of unmanned aerial vehicles (UAVs) with fifth-generation fighters emerging after the 2010s, but only in passing. Given recent global and Chinese pursuits of manned-unmanned-teaming, remarks surrounding J-20 operating with UAVs, and the emergence of the J-20AS twin-seater aircraft, which is likely to yield enhanced command capacity, it is likely that greater emphasis and operationalization on collaborative operations with UAVs would have been carried out as development of the project proceeded.
Implications for Other Projects
Judging by its content, the Strategic Study is not intended to be a highly technical document. Based on the opening paragraph, this appears to be a paper intended for readership by civilian government, military, and industry elements, to guide more detailed research and development.
However, the timeline of pre-research, applied development, systemic de-risking, and projected schedules depicted by the paper is a very useful demonstration of the gestational periods such projects require, and thus may provide useful general insights into other similar projects that the PLA may be carrying out currently. The most directly applicable project would be the PLA’s sixth-generation fighter project, which has had multiple industry allusions and studies made to it, with some speculative generic depictions having been displayed as well. As I have previously written, little is known about the PLA’s sixth-generation fighter project; however, it has been previously stated as seeking to enter service before 2035.
Rapid prototyping and digital design technologies may yield shorter development cycles for new aircraft in development, including sixth-generation fighters. However, it is very likely that an equivalent paper similar to the Strategic Study would have been written and distributed in the last few years for the sixth-generation fighter project. Pre-research and development are likely to have already been underway for some time, and this has been stated by industry figures as well. There is evidence of research for planforms with possible applications for sixth-generation fighters in recent years, and studies into multiple high-speed tailless flying wing configurations have been identified, as well as a mysterious full sized tailless flying wing airframe visualized at Chengdu Aircraft Corporation. These are likely only part of the small, publicly identified crumbs that bear relevance to the PLA’s sixth-generation effort, but the lessons from the Strategic Study should demonstrate that when the sixth-generation fighter emerges, it will have resulted from a similarly long cycle of academic assessment, pre-research, and developmental work.
