China is planning to replace the Russian AL-31F engines, which power its fifth-generation J-20 stealth fighter jets, with the upgraded version of its home-grown WS-10 engines.
According to a military insider, Chinese aircraft engineers found the indigenously built WS-10C engines to be as capable as the Russian-made AL-31F ones.
The Chengdu J-20 stealth fighter is a single-seat, twinjet, all-weather multirole fighter, which currently stands as the most advanced indigenously built aircraft in the ranks of the Chinese military.
The fighter, which has been developed and manufactured by Chengdu Aircraft Industry Group (CAIG), was flown for the first time in January of 2011. It is capable of carrying out air-to-air, air-to-ground combat roles with supersonic cruise speed and features modern avionics.
Most importantly, the combat aircraft has long been depicted as the competitor to the American fifth-generation stealth duo of Lockheed Martin F-35 Lightning II and F-22 Raptors. However, that did not happen due to engine issues.
China has been using two Russian AL-31 engines to power the J-20 fighters, however, the engines are considered to be less capable than China’s very own WS-10B.
Experts say using less-powerful engines on such powerful modern fighters could limit the capabilities of the aircraft, besides affecting its maneuverability, fuel efficiency, and stealth capabilities at supersonic speeds.
According to Justin Bronk, an analyst at the Royal United Services Institute, in terms of stealth, F-35 and F-22 are classified as very- low-observable (VLO) aircraft, but the Chinese J-20 still remains only a low-observable (LO) aircraft.
“The J-20A features forward canards which are not ideal from a VLO perspective, and initial batches have been powered by Russian AL-31 series engines without LO serrated nozzles,” he said.
These engines not only leave the “design somewhat underpowered and likely unable to supercruise but also increase the radar cross-section when viewed from the rear, overhead or underneath,” added Bronk.
China has in the past tried pushing Russia into making a deal to sell its more advanced engines for the J-20 fighters. However, Moscow has refused to budge due to fears that Beijing will reverse-engineer them as it has done with other military hardware.
This has now prompted Beijing to make use of the modified versions of their homegrown engines.
“It’s impossible for China to rely on the Russian engine because Russia asked China to purchase more Su-35 fighter jets in exchange for the AL-31F engine deals,” a military source said.
“The key problem is – except for its longer combat range advantage – the radar, navigation system, and other electronic components on the Su-35s are inferior to Chinese aircraft like the J-16 strike fighter,” the source added.
A photo clicked by a military enthusiast last year showed a prototype of a J-20 fighter with a new serial number “2021” but it did not have a Russian engine.
According to the military source cited above, the new fighter prototype was powered by two WS-10C engines, however, the modified engines are only a stopgap choice for the J-20 fighters.
“The use of WS-10C to replace Russian engines was caused by the failure of WS-15 to pass its final evaluation in 2019. The air force is not happy with the final results, demanding that engine technicians modify it until it meets all standards, for example, matching the F119 engine used by the Americans’ F-22 Raptor,” the source said.