By Kris Osborn, President, Center for Military Modernization
Very little is known about China’s highly-touted J-31 carrier-launched 5th-generation stealth fighter, as the program seems largely shroud in secrecy. This is not surprising given China’s current deficit in the area of ocean-launched 5th-generation aircraft, yet the People’s Liberation Army Air Force and Navy have made some comments about the jet’s progress and even released photos showing its upgraded configuration.
In recent years, Chinese newspapers have published some photos show design configuration enhancements reportedly capable of further reducing the aircraft’s radar signature.
An interesting write up in Aerocorner says the J-31 is still only in the prototype phase and only two have been built thus far.
“The FC-31 is still something of a secret, but it’s thought to measure 56 feet 9 inches, be able to reach Mach 1.8 via 2×RD-93 afterburning turbofans, and be capable of being armed with yet unknown air-to-air and air-to-ground missiles and bombs,” Aerocorner states.
A quick look at available photos reveal a very noticeable similarity between the external configuration of the J-31 and US F-35 and F-22. Prototype J-31s have an F-22-like dual engine configuration and a distinctly F-35-like looking fuselage. China is well known for being suspected of “ripping-off” advanced US military technologies and in many cases simply “copying” US weapons platforms. Pr
Several years ago, a Global Times report said the J-31 showed design improvements at the 2019 Paris Air Show. Photos from the story reveal profound visual similarities between the F-35 and J-31. This is not without precedent, as the Chinese media itself has noted similarities between the two aircraft.
Portions of a story from the Chinese government’s “People’s Daily Online” as far back as 2013 specifically cites design similarity between the emerging Chinese J-31 and the F-35, writing that the “J-31 and F-35 use the same DSI inlet (non-boundary layer-separated lane supersonic inlet).” The only major difference, the paper notes, is that the U.S. has an F-35B Short Take Off and Landing variant and that the J-31 uses two engines compared to the F-35’s single engine propulsion configuration.
J-31 & F-35C
The article’s reference to a “non-boundary layer separated lane supersonic inlet” appears both interesting and significant, as it pertains to designs engineered to manage heat and air movement signatures demonstrated by the aerodynamic phenomenon of air flow surrounding supersonic flight. “Boundary layer” aerodynamics, referring to the air flow surrounding a weapon or platform as it transits, can greatly impact the flight stability and stealth characteristics of an aircraft.
A pertinent comparison can be found in the Air Force Research Laboratories’ current work on “boundary layer phenomenology” related to next-generation hypersonic weapons.
Senior Air Force science and technology leaders and weapons developers told me at the Air Force Association symposium in 2019 that “boundary layer phenomenology” was figuring prominently in ongoing research and development regarding future weapons and platforms.
Managing heat flow and temperature is, of course, vital to maintaining flight stability for hypersonic weapons traveling at speeds up to five-times the speed of sound. Developers seek to engineer configurations which will generate a “laminar” or smooth airflow as opposed to “turbulent” boundary layer to enable a weapon to sustain an accurate trajectory and manage excessive heat.
Therefore, by extension, it seems apparent the same aerodynamic principles apply to stealth aircraft configurations which seek to manage the heat signatures and turbulence potentially generated in the air flow boundary layers of stealth jets flying at supersonic speeds.
Accordingly, a “non-boundary layer separated lane” for airflow, (as cited by the article) which does not break up or radically change airflow trajectory, could not only ensure smoother flight at high speeds but also help manage temperature.
Of course, there would be significant differences between the thermal management technical engineering needed for hypersonics and stealth aircraft, yet smoother wing-body melded external designs, absent hard or protruding edges, clearly bring the added advantage of a smoother and cooler air flow boundary layer.
The exact number and production status of the J-31 seems difficult to discern, yet the existence of a carrier-launched stealth fighter might help China close its massive deficit with the US Navy’s carrier-launched F-35C and Corps’ F-35B. At the moment, China is massively outmatched when it comes to maritime 5th-generation aircraft when compared to the US Navy ,however China’s is well known for its ability to produce and build new platforms quickly.
Kris Osborn is the President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University
