Last week, as the Chengdu J-20 entered into service, China became the second nation on the planet to field a fifth generation fighter platform… or at least that’s what they’ve claimed. New reports in Chinese media, however, indicate that issues with the advanced fighter’s intended power plant, combined with the Chinese government’s hurry to get the J-20 into service, may have actually cost the stealthy fighter its distinction as a true fifth generation platform.

According to sources in the South China Morning Post, the People’s Liberation Army rushed the J-20 through the final stages of development last year, prompted by heightening tensions throughout the region as a result of China’s expanding claims over the South China Sea. The advanced fighter platform’s design phase was already dramatically expedited, many believe, by using stolen plans for America’s advanced fighter, the F-22, accounting for the striking resemblance between the two aircraft.

Experts have long attested that, despite their similarities, the J-20 likely lacks the same stealthy profile employed by the F-22, in part due to the stabilizing canards added to the plane, but also thanks to still-classified methods utilized in the F-22’s construction. That potential gap in stealth capability, however, is not enough to cost the J-20 its position as the third ever fifth generation fighter to take to the skies… instead, it would appear, the issue lies with its engines.

The J-20’s intended engines, dubbed WS-15s, were purpose built for the new platform, but have suffered repeated setbacks that seem to be tied to their ability to mitigate the immense levels of heat they produce while in operation.

The WS-15 engine designed for the J-20 exploded during a ground running test in 2015,” a source that requested anonymity said to the South China Morning Post. “The explosion indicated the WS-15 is not reliable, and so far there is no fundamental solution to overcome such a problem … that’s why the J-20 is using WS-10B engines now.”

By using the WS-10B engines previously seen in Chinese fighter platforms like the J-10 and J-11, China was able to get their latest fighter into the skies right away, however, their limitations not only question the J-20’s position as a truly “next generation” fighter, they may also compromise the very function the fighter was designed for. The WS-15 engines were designed to permit the J-20 to do something called “supercruising,” which means maintaining supersonic speeds without engaging the aircraft’s afterburners. Both of America’s fifth generation fighters, the F-22 and F-35, are capable of this feat, but with the the wrong engines, China’s J-20 is not.

The major drawback from not having the ability to supercruise in this case would be having to choose between using a great deal of fuel to go supersonic or stay subsonic and accept shorter effective range from the fighter’s missiles and an inferior energy position compared to a supercruising opponent,” Justin Bronk, a combat aviation expert at the Royal United Services Institute said of the revelation.

This significant gap between the operational capabilities of America’s and China’s top-of-the-line fighters may not only be enough to classify the J-20 as an extremely capable 4th generation jet, it also represents a compromise in the intended use of the platform itself. According to analysis from Western experts, the J-20 appears to have been purpose built for launching long range attacks at supersonic speeds, something it is less capable of doing if it must rely on afterburners to maintain that velocity.

The J-20, in particular, is different than the F-22 in the context that, if you take a look and analyze the design, it may have some significant low-observable capabilities on the front end, but not all aspects — nor is it built as a dogfighter,” Retired US Air Force Lt. Gen. David Deptula said of the J-20 last year. “But quite frankly, the biggest concern is its design to carry long-range weapons.”

The long range missiles the J-20 is equipped with, in particular, were actually designed specifically to function best when launched at supersonic speeds, making them less effective at the subsonic speeds that the jet will likely need to utilize in order to maintain its stealth profile, as using afterburners to maintain speed isn’t only an issue in terms of fuel consumption; it also compromises the aircraft’s stealth capabilities.

Afterburners do make any fighter much easier to detect, track and target using Infra-Red and Electro-Optical systems at closer ranges when in use.” Brock added.

Nonetheless, the J-20 is reportedly now in use as a combat operational platform in China’s People’s Liberation Army’s 9th Brigade, who reportedly traded up to the J-20 from their previous Russian Su-30 platforms. Even that announcement has been met with some skepticism, however, as pilots and air crews have hardly had enough time to master the new platform. By American standards, the J-20 likely wouldn’t be considered combat operational for some time, based on that issue alone.

So, while China rushed to be the second nation on the planet to field a fifth generation fighter, it would seem that the J-20, at least as it currently sits, is far from a match for America’s own fifth generation aircraft… and may not even be fifth generation at all.

Feature image courtesy of Flickr