The Chinese J-31 5th-Gen Stealth Fighter May Be a Total F-35 "Rip-Off"

Kris Osborn

Video: Networked Army Radar Destroys 2 Maneuvering Cruise Missiles

by Kris Osborn - Warrior Maven

Specific F-35 Rip-Off

(Washington D.C.) Chinese media reports have been referencing new photos of the emerging J-31 5th-Gen stealth fighter appearing on social media, ostensibly showing various design improvements to the new radar-evading multi-role aircraft. 

A May 5th report in the Global Times, an English Language Chinese newspaper, says the new photos show an …. “upgraded version with modifications made to its aerodynamic design just like the prototype that made its maiden flight in 2016, instead of the original version that made its public debut at Airshow China in 2014.” 

Improvements or changes to the J-31 likely continue a long-standing pattern of China’s apparent and somewhat visible effort to copy, steal or mirror designs used for the U.S. F-35. Virtually all photos and renderings of the J-31, since first unveiled, revealed a striking resemblance to the U.S. F-35. This does not come to the surprise of many in the U.S., given China’s well-known and documented cyber espionage efforts. A 2014 “U.S.-China Economic and Security Review Commission” Congressional report specifically cites a Defense Science Board finding that Chinese cyber attacks resulted in the theft of significant specs and technical details of a range of U.S. weapons systems—including the F-35. 

At the same time, a 2018 Pentagon news story about DoD’s annual China report mentions that apparent similarities between the F-35 and Chinese J-20 could very well be a result of espionage. A cursory look at the J-20 does appear to show some resemblance to the F-35, particularly the blended wing-body front end and internally built, conformal exhaust pipes. These similarities do appear, despite the apparent differences, as the J-20 has a wider and longer lower-body. However, available photos show an even larger measure of similarity between the F-35 and Chinese J-31 multi-role fighter. 

As recently as last year, another 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.

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 smother wing-body melded external designs, absent hard or protruding edges, clearly bring the added advantage of a smoother and cooler air flow boundary layer. Along these lines, the 2019 Global Times report details a few design changes to the 2019 J-31 which, according to the photographs, show a smoother, less-jagged exterior behind the cockpit as opposed to earlier models.

The Chinese newspaper stops short of exploring a fully-detailed discussion of aerodynamic designs related to the aircraft, but does cite a Chinese Air Force test pilot expert as saying “the J-31’s stealth aerodynamic design, stealth engine design and stealth coating design have all reached internationally advanced standards in stealth technology.” (China’s Air Force test pilot expert Xu Yongling.)

However, external configuration and some elements of visible heat-signature management represent merely a few of many characteristics when it comes to stealth technology; stealth designs also often incorporate internally-built engines, radar absorbent coating materials and internal weapons bays, among other things. Along these lines, the People’s Daily Online report makes the claim that the J-31 has a superior weapons payload capability compared with the F-35. However, available specs report that the J-31 travels with six external weapons hardpoints… the same number as the F-35. 

As for how the J-31 may be employed, Chinese and U.S. newspapers are filled with various kinds of speculation; some reports say the fighter is intended for export as a way to counter the reach and scope of the F-35, however other reports cite Chinese officials saying the J-31 is intended for domestic use and possibly could even fly off of Chinese aircraft carriers. 

Chinese’ progress with the J-31 calls to mind several timely strategic calculations. A more recent Congressional report, the 2018 U.S. China Economic and Security Review Commission, makes specific reference to concern regarding China’s expansionist aims when it comes to projecting air, land and sea power. The text of the review points to dramatic upticks in “long-distance over-water training” exercises over new areas in recent years which, the study goes on to suggest, improves the PLA Air Force’s capability to gather intelligence and “execute maritime missions against the U.S.”

“In November and December 2017, China’s People’s Liberation Army (PLA) Air Force conducted at least nine long-distance training flights over maritime areas along China’s periphery, continuing a trend that began in 2015,” stated the 2018 U.S. China Economic and Security Review Commission.

All of this pertains to the often and widely discussed recognition that China has long-since past its ambitions to operate as a dominant regional power and migrated aggressively toward positioning itself as a massive, leading global power.

New Photo?

A new, yet unverified social-media picture of China’s J-31 5th-Gen stealth fighter, sometimes referred to as the FC-31, may indicate that the airplane has been upgraded with new avionics, according to a report published in the South China Morning Post, cited by Newsweek. 

The photo, see above, reportedly appearing on a Chinese social media site called Weibo, may show a recent test flight of the FC-31 Gyrfalcon fighter. The Newsweek report includes some observations of the aircraft which could indicate that the Chinese have made some technical adjustments

“Earlier prototypes showed an airspeed measurement device on the nose of the stealth fighter, but this appears to be missing from the latest version. This might indicate the jet now has fitted avionics, the Post noted. The newspaper also said the canopy over the FC-31's cockpit now appears more similar to the J-20, plus changes to improve the jet's wind resistance,” the Newsweek report states

This observation raises several interesting questions about the emerging Chinese fighter, a maritime variant of which is believed to be intended to fly from carriers. It is well known that the J-31 is without question intended to function as a counterbalance or rival to the F-35. Its exterior appears to be a transparent F-35 “rip-off” in terms of its stealth configuration, yet a full margin of comparison, it would seem, hinges more fully on avionics, sensors, weapons, engine propulsion and maneuverability, all things less detectable to an observer’s eye. 

Interestingly, its visible similarity to the F-35 does not, by many estimations, appear to be accidental. A Congressional report from many years ago, the 2014 U.S.-China Economic and Security Review, specifically cites a 2010 Defense Science Board report finding which stated that Chinese cyber espionage led to the theft of numerous U.S. weapons specs, to include the F-35. 

As recently as last year, 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.

Therefore, despite its apparent external similarity, there does not appear to be any kind of decisive indication or evidence that the aircraft does truly rival the F-35 in any measurable way. 

Upgrades Coming?

However, should there be a sensor upgrade of some kind, or improvements to the J-31s avionics as suggested in the story, that could be considered substantial. The advantages of the F-35, many maintain, reside in its description as a “flying computer” engineered with advanced, high-resolution, long-range sensors able to detect and target enemy targets before the aircraft itself is seen. 

The Chinese are known to be quite advanced in the area of AI, yet that might not mean that the J-31 is comparable in terms of the “sensor fusion,” weapons range or even maneuverability of the F-35. Nonetheless, the aircraft is expected to bring new threats to the equation, particularly when it comes to maritime attack. Should the J-31’s functional capability, weapons, speed and attack envelope mirror the F-35, the new Chinese aircraft might erode the clear Naval airpower advantage provided by the U.S. F-35B and carrier-launched F-35C. 

-- Kris Osborn is the Managing Editor of Warrior Maven and The Defense Editor of The National Interest --

Kris Osborn is the new Defense Editor for the National Interest. 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.

Comments (3)
No. 1-3

No shit. The Chinese don't have an imagination so they are forced to steal from the smart people.


Why does the USA let this continue? Our Secrets appear wide open and accessible to anyone. Perhaps the US Military could hire some guy who is not doing much at present and give him the job of Security for our Military.


The only way Chicom can make matching avionics and sensors is by using our semiconductors. Well known they are over a decade behind. Examples include the transmit/receive chips (500-2500 for each radar). Supposed to be strategic export controlled. How can we let them buy?!🥵🥵