Last year, one of Russia’s advanced, fifth-generation stealth fighters, the Su-57, crashed in the nation’s far east region. Soon after, evidence began to emerge that the crash may have involved the nation’s first-ever serially produced Su-57.

This isn’t the first embarrassment for the long-troubled Su-57 program, but it could potentially be among the last. After years of development struggles, there may not be enough spit and polish left in the Kremlin to make this flying turd shine.

The Su-57 began its life as a joint venture between Russia and India, with India backing out of the program when it became apparent that the expensive platform couldn’t deliver on its promises of stealth performance. Since then, the 12 prototype stealth fighters Russia built have served as the nation’s “fifth-generation” fleet, though only one came equipped with the engine Russia intended all Su-57s to run.

These jets have garnered headlines over the years thanks to carefully chosen public displays and even a photo-op deployment to Syria, where the jets landed, took off, and did little of anything else.

Russian production practices seem to lack the tight tolerances required to make a platform like the Su-57 as stealthy as the competition coming out of Lockheed Martin. But it’s really Russia’s economic woes that have kept the fighter from seeing large-scale production. Thanks to a stagnating economy and international economic sanctions levied on Russia, it’s nearly impossible for Russia to build a real fleet of these stealth fighters without compromising funding to other essential programs: The return on investment for the Su-57 simply isn’t there. Additionally, the Su-57 doesn’t offer Russia the same threat projection that its submarines with their doomsday torpedoes do, since it wasn’t built for carrier operations. This will probably further decrease the desirability of building an Su-57 fleet.

China went a different route with their entry into the fifth-generation fighter competition, opting to steal plans of America’s venerable F-22 Raptor, then repurposing them into the Chengdu J-20. This platform is also the subject of debate when it comes to stealthiness, with many contending that its radar cross-section will be much larger than the F-22’s from any angle other than head-on, thanks to the Chinese fighter’s side canards.

But the real issue with the J-20 fighters isn’t their stealth capability: it’s the engines that run the jet. China has continued to struggle to develop engines worthy of their advanced fighters — and thus far they have come up short. China’s small fleet of J-20s (likely around 20 or so) currently runs Russian-sourced engines that lack the super-cruise capabilities found in the F-22 and that China hopes to eventually field on the J-20.

“Supercruising,” put simply, is the ability to maintain supersonic flight without the use of afterburners. A jet’s afterburners are a huge fuel draw, so flying at a high rate of speed without using them gives the F-22 the ability to arrive on target with more fuel to fight with, allowing for longer loiter times and greater combat radius.

According to the aviation website “Alert 5,” China’s production estimates in the coming years only account for building five WS-15 and WS-19 engines a year through 2026. These engine platforms were designed especially for China’s J-20 and forthcoming FC-31 — meaning that China only intends to properly field about five of these platforms per year. Other jets may be built as well, but they’d be running older, less capable engines.

Of course, neither nation boasts any of these jets in sufficient numbers to stand up to America’s fleets of F-22 Raptors and F-35 Joint Strike Fighters and neither nation allows for nearly as much seat time in their aircraft as American pilots get. Also notable is the fact that the J-20, in its current trim, isn’t well suited for carrier ops, and Russia may soon not have a carrier at all. While the U.S., on the other hand, is already fielding F-35s on both aircraft carriers and smaller amphibious assault ships.

So what’s wrong with Russian and Chinese fifth-generation stealth fighters? At first pass, quite a bit, but the situation is changing rapidly, and things could look quite different in 10 years.

This article was first published in December 2019. It has been edited for republication.