China’s New WS-15 Jet Engine Finally Enters Serial Production: How Will it Supercharge J-20 Stealth Fighters?

The WS-15 afterburning turbofan engine under development for the Chinese People’s Liberation Army (PLA) Air Force’s top air superiority fighter the Chengdu J-20 has reportedly entered serial production, according to a statement by an Aero Engine Corporation of China (AECC) official. The long awaited engine is thought to currently be in low rate initial production, and is expected to fully phase out the WS-10C turbofan which the large majority of J-20 units currently rely on. Where the WS-10C represented a heavily enhanced variant of a fourth generation engine design, the baseline WS-10B, the WS-15 is a clean sheet new design which is expected to remain in production in enhanced forms past past the year 2050. Development makes China the first country to serially produce an engine with such high specifications after the United States, which developed the F119 engine for its equivalent fighter to the J-20 the F-22 Raptor, and subsequently an enhanced derivative the F135 for its lighter single engine F-35 fighter. The WS-15 is expected to not only have a much longer life and lower maintenance requirements than the WS-10, but also a massively greater power output which will give the J-20 more thrust than any other tactical combat aircraft in the world. The engine is also expected to introduce two or three dimensional thrust vectoring capabilities for improved manoeuvrability.

Introduction of the WS-15 is expected not only to make the J-20 far more manoeuvrable, but also provide much more energy for onboard sensors and other avionics and potentially provide a more viable option for powering future directed energy weapons such as laser weapons. While the J-20 already has a much longer range than any Western fighter, the WS-15 is expected to extend this significantly further still due to its greater fuel efficiency. It will allow the fighter to fly at much higher supersonic speeds without using afterburners. A new variant of the J-20, which is speculated to be the new airframe type first seen in December 2022 with improved stealth features, is thought to have been modified to make better use of the new powerplant and may be designated the J-20B – where the baseline J-20 used stopgap Russian engines and the improved J-20A was produced from 2019 with the WS-10C.

Although the J-20 entered full scale production in late 2021, and has been entering service very quickly since at far greater rates than the F-22 ever did, the WS-15’s potential lowering of the fighter’s lifetime costs and expanding of its advantages over other fighter classes could well lead to production on a larger scale still – potentially accelerating the phasing of the Air Force’s other heavyweight fighter class the older fourth generation J-16 out of production. The J-16, as well as the J-20’s direct fourth generation predecessor the J-11, are both powered by the WS-10B. The J-20 is third in the world among fighters today in terms of its scale of production, surpassed only by the American F-35 and China’s own lightweight single engine fighter the J-10C, with some estimates placing J-20 production rates at close over 40 per year. To place this in perspective, the F-22 was produced at rates of around 20 per year, although its production run was ordered cut less than four years after it entered service due to multiple issues with the design. The competing Russian fifth generation fighter the Su-57, although by some estimates much cheaper than the J-20, saw just six produced in 2022 and is not expected to see production rise above around 20 aircraft per year. 

The J-20 is one of just two fighters of its generation both in production and fielded at squadron level strength alongside the F-35, with the two having had their first encounter confirmed in March 2022 over the East China Sea. Beginning development in the mid 1990s, work on the engine was long expected to be the most protracted part of the program. The PLA only got its first  indigenous fourth generation afterburning turbofan the WS-10B meaningfully into service in the early 2010s, and only reached reliability levels seen as sufficient to power single engine fighters near the end of the decade, which made moving on to a fifth generation engine as ambitious as the WS-15 particularly groundbreaking. The engine was first seen being flight tested on a J-20 airframe in January 2022, with multiple further sightings having been made since. It has been widely reported but remains unconfirmed that fighters integrating two WS-15s have been seen, although whether any of these are serial production models or only prototypes is unknown. The United States, while moving to retire the troubled F-22, is strongly considering developing a new engine for the F-35, since the F135 was developed at a time when the fighter was expected to be significantly lighter meaning it leaves it underpowered today. The F135’s very significant reliability issues have also been a key driver of the F-35’s low availability rates, which has only further fuelled calls for a new engine. As China moves to begin fielding J-20s with WS-15 engines, this is likely to only strengthen arguments in the U.S. for what is increasingly seen as an urgently needed engine replacement for the F-35.