China will start upgrading the engines of its most advanced stealth fighter jet to catch up to the US’s F-22

• A Chinese military source says the J-20 will be fitted with thrust vector nozzles to improve performance.
• China has spent decades trying to master the technology and the upgrade comes after work on a purpose-built engine fell behind schedule.

China will start upgrading the engines of its most advanced stealth fighter jet, the J-20, this year to bring its performance closer to the American F-22 Raptor, according to a military source.

The performance of the fighter, also known as the Mighty Dragon, had been limited because it has been using a stopgap engine, the WS-10C, the latest model of an engine used in earlier Chinese warplanes.

These are now being fitted with new thrust-vectoring nozzles, a technology Chinese engineers have spent two decades trying to master and which the country first unveiled at the 2018 Zhuhai air show.

The US Raptor uses the technology, which controls the direction of the engine thrust, allowing the jet to perform sudden manoeuvres that earlier generations of aircraft cannot.

Chinese engineers have been developing a high-thrust engine, known as the WS-15, to allow its most advanced fighter to close the gap with US warplanes.

But this project has fallen behind schedule, prompting its developer, the Chengdu Aircraft Industry Group, to use the WS-10C on the planes instead.

A source familiar with the engine development programme said all WS-10C engines fitted to J-20s will be given thrust vectoring capabilities this year.

“Because verification of the two-dimensional thrust-vectoring nozzles, the technology used by the F-22, has been completed, the manoeuvrability and stealth capability of the J-20s will be upgraded,” the source, who requested anonymity due to the sensitivity of the topic, said.

“The upgrading project aims at meeting the PLA’s intensive training demands, as the country plans to deploy about 200 J-20s.”

State media has previously reported that the PLA has deployed the J-20 to air force units responsible for the Taiwan Strait and East China Sea — which would involve at least four brigades or 150 fighters.

This week, state broadcaster China Central Television aired footage showing J-20 brigades conducting nighttime combat drills and other clips that showed the planes had been fitted with WS-10C engines.

Macau-based military observer Antony Wong Tong said: “It’s the first time the PLA showed simulated dogfight drills between different J-20 brigades, which is supposed to be regular training for PLA fighter jet pilots.

“But the thrust of the J-20 will still lag behind the US F-22, until China delivers the WS-15 engines for the aircraft.”

The J-20 entered service in 2017 after the US deployed more than 100 F-35s to Japan and South Korea.

At the time it was equipped with a Russian-made engine and China only began producing J-20s equipped with the domestically produced WS-10C engine in 2020.

The source said checks on the WS-15 engine are taking place and are expected to finish next year.

“The J-20 engines will be replaced by the WS-15 once the checks are completed,” the source said, adding there would be no technological problems because the existing Russian and Chinese engines were a similar size and shape.