China's long-anticipated J-20 stealth fighter aircraft have arrived … kind of.
In a post on the state outlet Xinhua News Agency, the Chinese government announced that the fighter jet — created to counter the capabilities of the American F-22 Raptor — has entered service in the People's Liberation Army with "comprehensive combat capabilities."
The J-20, like the F-22 Raptor, uses a specially-shaped airframe and advanced materials to minimize its radar signature — making it hard for enemies to detect by conventional means.
While the J-20 is operational, it doesn't yet have the capabilities to match its American counterparts, the South China Morning Post, a major Hong Kong newspaper, reported. Two military sources told the Post that the J-20s in service aren't equipped with the WS-15 engines they were built to fly with.
According to the Post's reporting, a WS-15 engine exploded in 2015 during a ground test, indicating quality-control issues with the single-crystal turbine blades necessary for the powerful turbofan engine.
The operational J-20s, the Post reported, are instead equipped with less powerful, modified WS-10B engines designed for the previous-generation Chinese fighters, the J-10s and J-11s. And even with enhancements for use in the J-20, they aren't powerful enough to enable the J-20s to "supercruise" like U.S. stealth fighters.
As Popular Science reported in September 2017, "supercruise" is the ability of a plane to accelerate to supersonic speeds without unstealthily dumping extra fuel to burn in the engine's jet pipe — that is, without engaging afterburners, which have a more easily-detectible radar signature.
According to the Post, the J-20's weapons array makes it the most effective fighter jet in the Chinese arsenal for countering the planes of a stealth-enabled superpower like the U.S., but the J-20 likely won't enter mass production until the WS-15 is ready. And that could take another eight years.
Only two other countries, the U.S. and Russia, build "fifth-generation fighters" like the J-20. The U.S. has the F-22 Raptor as well as the uber-expensive, slow-to-arrive F-35. Russia flies the Sukhoi T-50 PAK-FA stealth fighter. India and Japan also have fifth-generation fighters in development.
The exact definition of "fifth generation" is a bit vague. But public documents from China Power, an American project geared toward researching Chinese power, and Lockheed Martin, which builds the American fighters, suggest that fifth-gen aircraft are stealthy even when armed, can cruise at supersonic speeds and involve advanced computing, sensors and electronics.
Originally published on Live Science.