China’s long-touted Chengdu J-20, claimed to be the nation’s first fully functional fifth generation fighter platform, is neither fully functional nor is it technically a fifth-generation fighter — despite already being entered into service in China’s People’s Liberation Army.

Fighter generations are not determined by a formal committee; generational labels are more like industry shorthand to help quickly assess the type of capabilities a platform possesses. The line between fourth and fifth generation fighters, as a result, tends to move depending on who you ask. For the most part, however, what separates a fifth generation platform from its predecessors can be boiled down to three things: an airframe designed from the ground up to maximize stealth capabilities, the ability to serve as a data hub the melds information from multiple sources, and “super-cruise” capabilities — which means maintaining supersonic speeds without having to engage the jet’s afterburner.

It’s in that third category that the J-20 continues to fall short. While China did develop the aircraft using stolen Lockheed Martin plans for the F-22, their method of developing new technologies through theft often comes back to haunt them. In the case of the J-20, it is widely believed that, despite having the plans for the aircraft, China lacks the ability to manufacture jet engines that are comparable to America’s or to produce the stealth absorbent coating seen as integral to the F-22’s small radar signature.

F-22 Raptor courtesy of WikiMedia Commons

Questions remain regarding China’s capacity to produce and utilize that classified stealth coating material — but last week’s massive Chinese air show made it clear that they continue to struggle with the engine issue. The existing J-20s in service all utilize older Russian sourced powerplants that require the continued use of afterburners to maintain supersonic speed. This significantly limits the operational range of the fighter if it intends to close with a threat quickly because of the afterburner’s massive fuel requirements. As a result, China’s current J-20s can either operate for a normal amount of time or go supersonic. They can’t do both.