Enhanced Variant of China’s J-20 Stealth Fighter Makes First Flight With Twin Next Gen. WS-15 Engines: What Does It Mean Going Forwards?

The Chengdu J-20 fifth generation heavyweight air superiority fighter was revealed on June 29 to have made its first flight using the new WS-15 afterburning turbofan engine in twin configuration. The flight occurred at the Chengdu Aircraft Industry Corporation’s test airfield which is co-located near its primary aircraft plant, which is the only one outside the United States to have produced multiple squadrons’ worth of fifth generation fighters. Although the engines could not be visually confirmed as the WS-15, a banner adjacent to the runway announced the event while the powerplants produced a distinctly different sound, available for the public to hear for the first time, compared to the WS-10C that previously powered the aircraft. The WS-15 was first seen integrated onto the J-20 in single configuration for a test flight in January 2022, with the move to flights in twin configuration within just 18 months indicating a very rapid rate of progress for the program. Use of the engine in twin configuration indicates a higher degree of confidence in its performance, since flying it with a second engine from an older more tested design, namely the WS-10C which currently powers most J-20 units, would allow a fighter to land on the WS-10 if the WS-15 suffered from performance issues. 

Due to its size the J-20 was designed to be powered by two engines much like the American F-22 Raptor, but unlike the U.S. Air Force’s much lighter F-35 single engine fighter which was developed with a single engine to reduce lifetime costs at the expense of a far inferior flight performance in all parameters. An enhanced variant designed J-20B has integrated the new engines, and was first seen in December 2022 with a much flatter low profile canopy. This is expected to significantly improve the airframe’s stealth capabilities and aerodynamics, and allows for a better blend into the fighter’s raised spine – mirroring similar changes made on China’s other fifth generation fighter program the FC-31. The J-20B was reported to be entering production in July 2020, while the WS-15 itself was reported to have begun full serial production in March 2023. The first clear images showing the engine in flight testing was published on April 5 2023. The J-20 is already thought to have a significantly greater endurance than any Western fighter class, with the WS-15 expected to extend this far further due to its greater fuel efficiency. This could allow J-20 units to operate on longer ranged patrols, loiter during air defence duties, more easily engage targets on Taiwan from its less well defended eastern coast, and potentially even carry out strike missions against Western facilities in Japan without a heavy reliance on aerial refuelling. 

The WS-15 is almost unanimously expected to be the most powerful engine ever integrated onto a twin engine fighter, particularly as the Soviet AL-41F for the MiG 1.42 fighter and the D-30F-6 for the MiG-31M interceptor were cancelled after the state’s disintegration. Where the F119 powering the F-22 currently leads with 17.5 tons of thrust, estimates for the WS-15 have consistently been as high as 19-20 tons with an estimated thrust/weight ratio comparable to the F135 that powers the F-35. The engine is expected to significantly improve all aspects of the J-20’s flight performance, while also lowering its operational costs and possibly its overall lifetime costs due to its lower maintenance needs than the WS-10C. While the WS-10C allowed the fighter to supercruise – to reach supersonic speeds without using afterburners – which made it the world’s only fifth generation fighter in production with this capability, the WS-15 is expected to allow it to cruise at significantly higher speeds.

The J-20 and F-35 are the only fighters of their generation both in production and fielded at squadron level strength, with the troubled F-22 having seen orders to terminate production given less than four years after it entered service and set to begin very early retirements from service this year. The two saw their first encounter confirmed in March 2022, after which the head of Pacific Air Forces General Kenneth Wilsbach praised the aircraft’s operations and particularly its associated command and control. The fighter combines the benefits of a high flight performance and large weapons carriage that the F-22 has, with advanced avionics features seen on the F-35 such as distributed aperture systems and helmet mounted sights, allowing it to surpass both American platforms in their areas of greatest shortcomings.