The engines are distinguished by their serrated afterburner nozzles and interior flaps for manipulating the exhaust flow.
Once these new J-20s enter service, China will have comprehensively mastered the major parts of fighter technology, including radars, stealthy fuselage, missiles, computers, and engines.
The WS-10X (possibly officially designated WS-10G or WS-10IPE) has sawtoothed serrations on the edges of its afterburning nozzles, like the F-35’s F119 engine. The sawtooth edges provide a gain in stealthiness, as they redirect radar waves away from the nozzles. The straight edges on non-stealthy engines like the current Russian supplied AL-31 engines are major contributors to the radar cross section of a fighter.
China’s new engine compared to Europe and American fighter jet engine
The WS-10X is believed to provide about 14-15 tons of thrust. This may be enough power to allow the J-20 to engage in low supersonic supercruise at Mach 1-1.2 speeds. The Eurofighter Typhoon has a similar low supercruise capability, which means it can hit supersonic speeds without using fuel-thirsty afterburners.
The current F135 engines generates 28,000 lbs of thrust normally, but produces over 43,000 lbs of thrust with the afterburner engaged. Although no service has issued a requirement for an upgraded engine, Pratt and Whitney is cooperating with the US Navy on a two-block improvement plan for the F135 engine. The goals of Block 1 are a 7-10% increase in thrust and a 5-7% lower fuel burn. Technology to better cool turbine blades is included in the plans, which would increase the longevity of the engine and substantially reduce maintenance costs. The goal of Block 2 is to work with the US Air Force’s Adaptive Engine Transition Program, with the intention of introducing technology for an engine rated at 45,000 lb of thrust, to be used in a sixth-generation fighter.
China’s gains in engine connect to broader news in materials. The Chengdu Aerospace Superalloy Technology Company, a privately held corporation, made a major breakthrough in superalloy research. CASTC, according to the Global Times and People’s Daily, is producing world class single crystal turbine blades from rhenium-nickel superalloys; adding rhenium to nickel increases the superalloy’s melting point, allowing for a hotter and more efficient engine. High rhenium content superalloys are used in light weight, high thrust engines like the F-22 Raptor’s F109 turbofan. Previously, the development of Chinese engines like the WS-10 were delayed as they suffered from quality control issues regarding single crystal turbine blades.