China’s WS-15 .. Does it challenge US dominance over fighter jet engine tech?

China’s fighter jet engine technology took a major leap forward on 29th June 2023‭, ‬when the first flight test was conducted on a‭ ‬new variant of the J-20‭ ‬stealth fighter‭, ‬with a serial number 2052‭, ‬powered by two WS-15‭ ‬turbofan engines‭.  ‬This long-awaited engine project has sparked intense interest within and outside China since the early 2000s‭, ‬thus this milestone prompts questions‭ ‬about the future of US dominance in fighter jet engine tech‭.‬

WS-15‭ ‬Development Background‭ ‬

In late June‭, ‬Chengdu Aircraft Corporation‭ (‬CAC‭) ‬conducted the maiden flight of the new variant J-20‭ ‬fighter‭, ‬fitted with two WS-15‭ ‬turbofan engines‭, ‬also known as‭ “‬Emei‭”. ‬China embarked on developing this engine in the mid-2000s‭, ‬originally under the J-XX‭ ‬program‭. ‬

A preliminary image of the WS-15‭ ‬engine emerged in 2006‭, ‬five years before the J-20‭ ‬prototype was unveiled‭. ‬However‭, ‬supplied components were only used for individual testing initially‭. ‬

The full-scale demonstration project was not completed until 2012‭ ‬and extensive trials followed over subsequent years‭. ‬In July 2018‭, ‬the Chinese academic overseeing aviation engine R&D in Beijing‭, ‬Liu Daxiang‭, ‬announced that WS-15‭ ‬development was progressing rapidly and would be fully completed within three years‭.‬

The J-20‭ ‬was intended to operate on WS-15‭ ‬engines but China’s fighter jet engine industry was still nascent‭. ‬This compelled China to use an interim engine to power its new stealth fighter until the primary engine was ready‭. ‬

Initially‭, ‬the Russian AL-31‭ ‬powered the J-20‭. ‬This was replaced by the domestic WS-10C engine in 2019‭, ‬which China started developing in the early 2000s for the J-11‭ ‬fighter‭. ‬While reducing imports‭, ‬the WS-10C lacked stealth‭, ‬supercruise and thrust vectoring capabilities‭, ‬making it an unsuitable long-term solution‭.‬

Estimates vary on when WS-15‭ ‬development actually began‭. ‬Some point to the 1990s‭, ‬while others believe the real start was in 2006‭, ‬arguing that the 1990s saw only preliminary steps before full-scale development‭. ‬In any case‭, ‬the long timeframe allowed repeated design enhancements before reaching the current version‭. ‬

While the full capabilities of the WS-15‭ ‬engine remain shrouded in some secrecy‭, ‬Western reports have revealed glimpses of its initial features‭. ‬

The Chinese engine promises higher thrust than the interim powerplants previously used for the J-20‭ ‬fighter‭. ‬It should also provide greater kinematic performance and supersonic speed for the aircraft‭, ‬increasing the platform’s air superiority potential‭. ‬

Moreover‭, ‬the WS-15‭ ‬features‭ “‬supercruise‭” ‬technology‭. ‬This makes it only the second fighter after the American F-22‭ ‬with this capability‭. ‬Supercruise enables supersonic flight without the need for fuel-guzzling afterburners‭.‬

The WS-15‭ ‬thrust reportedly reaches around 180‭ ‬kN‭, ‬surpassing even the F-22‭’‬s engine‭. ‬Although lower than the F-35‭’‬s F135‭ ‬engine‭, ‬the J-20‭’‬s twin WS-15s can jointly generate 360‭ ‬kN thrust‭, ‬furthermore‭, ‬the WS-15‭ ‬thrust-to-weight ratio is approximately 9.7-11‭.‬

Many Western analyses predict the WS-15‭ ‬will substantially boost the J-20‭’‬s performance and combat effectiveness‭. ‬It will likely‭ ‬achieve 2.8‭ ‬Mach speed‭, ‬fire Thunderbolt missiles‭, ‬and increase low-altitude manoeuvrability and supercruise potential‭. ‬This enhances the J-20‭’‬s air superiority and combat capabilities‭.‬

The WS-15‭ ‬relies on an after-burning turbofan configuration with advanced design features‭. ‬These help provide high thrust and improved fuel efficiency‭, ‬causing many analysts to compare the engine to the F135‭ ‬powering America’s F-35‭ ‬fighter‭. ‬

Furthermore‭, ‬the WS-15‭ ‬can boost kinematic performance and thermal management traits‭, ‬enabling consistent supercruise abilities‭ ‬and supporting electrical power generation‭, ‬thus the engine offers increased growth and sustainment potential over the long term‭. ‬

The initial J-20‭ ‬prototype powered by the WS-15‭, ‬is an upgraded J-20‭ ‬variant‭. ‬It contains extensive subsystem upgrades and external modifications‭. ‬The WS-15‭ ‬will likely see further enhancements‭.‬

Moreover‭, ‬It is expected to spawn new variants that will power China’s sixth-generation fighter program‭.‬

The latest variant of the J-20‭ ‬stealth fighter with the WS-15‭ ‬has some external design features‭. ‬It sports a distinctively long‭ ‬dorsal spine behind the cockpit for aerodynamic benefits‭.‬

The nose dome shape is slightly altered along with small inlet adjustments‭. ‬However‭, ‬major enhancements on this J-20‭ ‬variant appear invisible externally‭. ‬They include extensive avionics‭, ‬flight systems‭, ‬and growth capability upgrades‭. ‬Some assessments suggest the extent of improvements added could make this variant rival a 5.5-generation fighter‭. ‬Others consider it an interim 5th-6th generation platform‭. ‬

Moreover‭, ‬the Chinese military hasn’t settled on a name for the different variants of the J-20‭ ‬fighter yet‭. ‬Some call the new WS-15-equipped generation the J-20B‭, ‬while the previous single-seat variant‭, ‬powered by an AL-31‭/‬WS-10C engine is called the J-20A‭.‬

However‭, ‬sometimes J-20A refers to the newer WS-15-powered jet instead‭. ‬Here‭, ‬the current single-seat‭, ‬AL-31‭/‬WS-10C jet is simply called J-20‭. ‬As upgrades continue‭, ‬the J-20‭ ‬variant terminology remains fluid‭.‬

China’s Future Fighter Fleet

The maiden flight images of China’s J-20‭ ‬stealth fighter with the new engine generated enormous Western interest‭. ‬Despite representing a major accomplishment for China’s thriving aviation industry‭, ‬neither the US nor its allies expressed any alarm over the‭ ‬J-20‭ ‬itself as a 5th-gen stealth fighter‭. ‬However‭, ‬Washington appears extremely concerned by the pace of China’s fighter jet engine progress‭.‬

In March 2023‭, ‬WS-15‭ ‬project chief Chang Young at the AECC Beijing Institute of Aeronautical Materials announced at the 7th Chinese Aviation Innovation and Entrepreneurship Competition‭ (‬CAIEC‭) ‬that engine production bottlenecks were resolved thanks to domestic advances in metallurgy and manufacturing‭. ‬

This enabled supplying high-temperature components like single-crystal turbine blades‭, ‬superalloy disks and rings‭, ‬and mounting‭ ‬systems for advanced propulsion‭, ‬thus the WS-15‭ ‬is now ready for mass production‭.‬

This will boost Chinese fighter capabilities‭, ‬especially the 5th-gen J-20‭. ‬Simplified supply chains allow AECC to manufacture many engine components domestically‭. ‬

Estimates of the J-20‭ ‬fleet size have attracted intense Western interest‭. ‬Per the‭  ‬Zhuhai Airshow 2022‭ , ‬some estimates indicate‭ ‬the fleet exceeded 208‭ ‬airframes by November 2022‭. ‬Others show between 170-180‭ ‬airframes by the end of 2022‭. ‬

By June 2023‭, ‬more estimates revealed China’s J-20‭ ‬production surpassed the US F-22‭’‬s total production of around 187‭ ‬jets‭ ‬–‭ ‬years ahead of earlier forecasts‭. ‬

This highlights China’s accelerating production pace‭. ‬Reports suggest China’s annual J-20‭ ‬production nears 100‭ ‬jets‭. ‬Over 70‭ ‬were already delivered to the military by July‭. ‬China’s total J-20‭ ‬fleet likely reached 200-250‭ ‬fighters so far and is expanding steadily‭.‬

Challenging US Engine Dominance

Historically‭, ‬China relied on the Soviet Union‭, ‬and later Russia‭, ‬for fighter jet engines but also pursued indigenous production‭ ‬since the 1970s‭, ‬partnering with Russian and Western companies for spare parts‭, ‬assembly lines and know-how‭. ‬

This allowed for the gradual acquisition of technical knowledge and tools to incrementally develop domestic engines‭, ‬however eventually‭, ‬reverse-engineering Russian Su-27‭ ‬technologies enabled China’s first locally built engine‭. ‬

China’s first fully domestically designed‭, ‬manufactured and tested turbofan engine emerged at the Zhuhai Airshow 2022‭ ‬–‭ ‬the WP-14‭, ‬which took 20‭ ‬years to develop‭. ‬It powered later variants of China’s older Russian-derived fighters‭. ‬

Despite not being cutting-edge‭, ‬the WP-14‭ ‬marked a major milestone for China’s jet engine industry‭, ‬providing the foundation for‭ ‬the WS-10‭ ‬engine‭, ‬a key step in boosting China’s fighter jet engine capabilities and reducing foreign reliance‭.‬

Nonetheless‭, ‬China concluded it urgently needed to address shortcomings in designing reliable‭, ‬effective fighter jet engines and‭ ‬excessive foreign dependence‭. ‬

Hence‭, ‬in August 2016‭, ‬China consolidated various engine production units under the state-owned Aviation Industry Corporation of‭ ‬China‭ (‬AVIC‭) ‬into a new independent entity‭ ‬–‭ ‬the Aero Engine Corporation of China‭ (‬AECC‭), ‬valued then at‭ $‬7.5‭ ‬billion‭.‬

AECC is a prominent Chinese turbofan developer established alongside major investments to advance China’s fighter jet engine program‭. ‬By 2018‭, ‬AECC unveiled five different engines at the Zhuhai Airshow‭, ‬most notably the WS-10‭ ‬Taihang‭, ‬heralding a new generation of turbofan engines spearheaded by the WS-15‭.‬

A report by the US Center for Strategic and International Studies noted China’s investments are poised to threaten US dominance‭ ‬in fighter jet engine technology in coming years‭. ‬

China is taking a whole-of-government approach to rapidly narrow the traditional gap with the US‭.‬

‭ ‬Although the American model has proven responsive to innovation‭, ‬enabling successive generations of US fighters to maintain qualitative superiority through engine advancements‭, ‬China’s concerted efforts have led many US assessments to urge policymakers to‭ ‬take more decisive action to sustain the capabilities gap and reconsider the past decade’s low-risk‭, ‬low-R&D investment approach‭.‬

Unlike the Cold War‭, ‬the US now faces a rival with an equivalent‭ ‬–‭ ‬even superior in some domains‭ ‬–‭ ‬industrial base‭. ‬Hence‭, ‬even strategic surprises cannot be ruled out despite current US engine supremacy‭.‬

In summary‭, ‬developing the WS-15‭ ‬engine underscores the extent of China’s overall and turbofan-specific aviation industry progress‭. ‬It aligns with some Western estimates that China is moving swiftly towards the cutting edge of fighter jet engine technology‭.‬

Game Changer

Mastering fighter jet engines is a major technical achievement within reach of only a few nations‭. ‬China has emerged as a formidable new contender‭, ‬spending billions in recent years to rapidly build capabilities‭, ‬leveraging the global spread of technology‭.‬‭ ‬

Many anticipate the WS-15‭ ‬will propel Chinese aerospace to new heights‭. ‬The J-20‭ ‬is expected to generally outperform the American F-35‭. ‬The new engine will enable China to catch up with the US and Russia‭ – ‬the traditional leaders in combat engine technology‭.‬

As J-20‭ ‬production scales up‭, ‬China will likely accelerate the development of next-gen fighters‭.‬

Moreover‭, ‬given that the Chinese aerospace industry embraces a‭ “‬national teamwork‭, ‬comprehensive advancement‭” ‬philosophy of gradually substituting imported components with localized versions to increase self-reliance‭. ‬With continuous technological improvements‭, ‬China’s aerospace industry is poised to assume a leading position in the coming years‭, ‬especially regarding 6th-gen fighter development‭.‬

For instance‭, ‬AECC is developing new propulsion systems like the WS-19‭ ‬and WS-20‭ ‬engines‭. ‬The WS-19‭ ‬turbofan is meant for the next-gen carrier-based J-35‭ ‬fighter‭. ‬The WS-20‭ ‬is a high-bypass turbofan expected to power the Chinese Air Force’s Y-20‭ ‬transports‭.‬

Additionally‭, ‬greater range was previously the Su-35‭’‬s sole major advantage over the J-20‭, ‬with the latter superior in radar‭, ‬electronics‭, ‬avionics and other capabilities‭. ‬The J-20‭ ‬stealth fighter equipped with the WS-15‭ ‬turbofan could thus prove transformative‭, ‬not just vis-à-vis Russian jets but also American and advanced Singaporean fighters‭. ‬

Deploying the WS-15-powered J-20‭ ‬over the contested South China Sea can potentially establish Chinese air superiority in any conflict with the US‭.‬

Despite lingering challenges‭, ‬especially US restrictions on certain advanced technologies required by China‭, ‬American reports caution that further advances in fighter jet engine tech will not only increase China’s military power but also make it a powerful‭ ‬competitor in the global engine market‭, ‬especially given its willingness to sell products cheaply‭. ‬

These reports also allude to growing prospects of Russia supplying key technologies to China‭, ‬which could pave the way for ending the qualitative edge long enjoyed by the US and its allies‭.‬

In conclusion‭, ‬a decade after the J-20‭’‬s first flight‭, ‬it has matured with full operational capability and continues acquiring more capabilities and technological progress through incremental upgrades‭. ‬

Chief among them is the integration of the WS-15‭ ‬engine‭, ‬boosting the stealth fighter’s capabilities and production sustainability while narrowing the gap with the US on fighter jet engine technology‭.‬

‮»‬‭ ‬By‭: ‬Adnan Moussa‭ ‬‭(‬Assistant Lecturer at the Faculty of Economics and Political Science‭, ‬Cairo University‭)‬

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