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Thursday, November 20, 2014

Threat Analysis of Foreign Stealth Fighters: Shenyang J-31 Part I

Image 1: J-31 at Zhuhai airshow, 2014. Image Credit: Chen. 

The Shenyang J-31 made its official debut at the Zhuhai 2014 airshow earlier this month after images were first leaked of the aircraft in 2012. The combination of limited transparency of China's defense industry combined with frequent disinformation efforts by the Chinese Government makes obtaining verifiable information on the J-31 extremely difficult. This article's objective is to provide reliable information from reputable aerospace and defense publications on the potential domestic use, stealth characteristics, avionics, export prospects, and strategic ramifications of the Shenyang J-31. Any conjecture or educated guesses made by the author are noted. 

Domestic Prospects - PLAAF

The Chinese aerospace conglomerate, Aviation Industry Corporation of China (AVIC), maintains the J-31 is officially an export only aircraft and marketing materials at Zhuhai subsequently referred to the aircraft as the FC-31; fighter aircraft developed for the domestic market use the "J" designation in contrast to export aircraft which are assigned the "FC" designation such as the FC-1 fighter (Wong, 2014). However, given the limited transparency of the Chinese aerospace defense industry and the People's Liberation Army (PLA), its plausible that the aircraft could eventually enter service within the Chinese military. As Aviation Week observes, the People's Liberation Army Air Force (PLAAF) has consistently instituted a high-low mix fighter procurement strategy and either the 4.5 generation J-10B or the J-31 could hypothetically fulfill the low end spectrum with the J-20 serving as the high-end aircraft. The author is inclined to believe AVIC's remarks are legitimate given the separate public treatment between the J-31 and J-20. Under the assumption that the J-31 is an export only aircraft, the PLAAF must have a reason for choosing not to procure the J-31:
"What looks like a thoroughly modern stealth fighter is apparently not good enough to serve as China's next medium-weight combat aircraft...The J-20 was revealed in late 2010 and appears to have made its first flight in January 2011. It was not promoted at Zhuhai. And therein lies a key piece of evidence of the status of the J-31. The J-20 was not at Zhuhai because it is not for sale and because China does not want to reveal too much about it. It is intended for the Chinese air force. Conversely, because the J-31 was exhibited at Zhuhai and is promoted as an export product, the Chinese air force obviously does not want it."- Perrett, Hewson, Johnson, & Sweetman, 2014 
One possibility is that the PLAAF's existing 4th generation fighter force of hundreds of Su-27SK, J-10A, J-11B, and J-10B aircraft will be operational well into the late 2020s and likely 2030s; China is still replacing its hundreds of third generation fighters such as the J-7. Therefore, the PLAAF does not have an immediate need for a low end replacement fighter aircraft in the near future and might be more concerned with the development of the high end J-20. Feng from the China Air and Naval Power blog discusses the possibility that the current J-31 design may not meet PLA requirements and it is possible the design could undergo major changes before eventually entering PLAAF service several years from now. 

Domestic Prospects - PLANAF

The only operational J-31 demonstrator's nose landing gear features two side by side wheels, a common feature of carrier operated aircraft (Axe, 2014). Furthermore, a model J-31 was photographed on a Liaoning mock up in 2014. The combination of the nose wheels and the carrier mock up photographs has lead to speculation that the J-31 is being developed for the People's Liberation Army Navy Air Force (PLANAF).  

Image 2: J-31 model on Liaoning mock up flight deck, 2014. 

Given the current design of the J-31 demonstrator, the nose landing gear along with photographs of a model J-31 on a Liaoning mock up are insufficient to prove future PLANAF service. Carrier aircraft often feature a host of other design changes necessary for operating on a carrier deck such as foldable wings, arresting gear (tail hook), additional structural support to address the increased stress of carrier landings and take offs, protective salt water corrosion coatings, etc. Furthermore, given China's ongoing difficulty in the development of its first carrier operated fighter, the J-15 "flying shark", the concurrent development of a much more technologically demanding carrier based stealth fighter would be a poor management of risk. 

As part of China's broader effort to reduce US influence in the Western Pacific and implement an anti-access area denial strategy, its future carrier air wings do not have to be as large or powerful as their American counterparts. Bryan McGrath and Seth Cropsey both observe that the purpose of China's carriers would be to weaken the US network of alliances in the Asia-Pacific rather than take on the US Pacific Fleet:   
"China is building the capability to project power from the sea in order to build its strength relative to its neighbors, primarily those with whom it has ongoing territorial seas claims (including Vietnam, the Philippines, and Japan). China does not need to build a navy as large or as powerful as the U.S. Navy in order to create fear and uncertainty among its neighbors. It only needs to build a navy with the credible means to project power over those neighbors’ shores.'...the strategic target of the PLAN in building a carrier force is not the U.S. Navy, but the network of alliances that longstanding U.S. economic and security interests in the region aim to preserve. Creating uncertainty and doubt in the minds of regional governments that the United States can continue to assure their security is at the heart of China’s desire to see the U.S. diminished in the region." - Bryan McGrath & Seth Cropsey, 2014 

Image 3: Chinese carrier group in January of 2014 consisting of 12 ships including: Type 051C destroyers, Type 052C destroyers, one Type 071 LPD, Type 054A frigates, Type 093 SSN and a Type 094 SSBN. Note the lack of fleet replenishment oilers or logistics ships. 

In the near term, Chinese carrier groups with the J-15 would be sufficient to pressure US allied or sympathetic countries in the Western Pacific. In the event of hostilities, Chinese naval forces would require substantial land based missile and air support to mitigate which would be available within the first and second island chains.  Furthermore, the addition of carrier based stealth fighters would not address the most significant threat to Chinese naval assets the Western Pacific, US attack submarines.  Thus, China's broader strategic goals do not require stealth carrier based aircraft in the near term and the developmental risks of the concurrent development of the J-15 with a much more technologically demanding J-31 naval variant would be exceedingly high. As with the PLAAF, there is a remote possibility that the J-31 design could be adapted or be used as the basis for a new design for a future aircraft that would serve on China's yet to be constructed super carriers several years from now, but the probability that an aircraft similar to the current design will enter PLANAF service a few years from now is slim. 

Stealth & Airframe Characteristics

Image 3: Frontal aspect of J-31 demonstrator, note the intense smoke generated from the Russian RD-93 engines. The RD-93 is a variant of the RD-33 which was originally developed for the Mig-29 in the 1970s. The smoke from the rear of Mig-29 made it easier to track in visual range combat exercises between between Polish, German, and US forces after the end of the Cold War. 

The J-31 design makes use of planform alignment, the orientation of flight surfaces at a common angle to reflect incoming radar waves away from the source, to lower its radar cross section (rcs). The angle of the diverterless supersonic inlets (DSI) matches the angle of its vertical canted tails. Similarly, the 35° wing angles  match those of the horizontal stabilizers. The use of planform alignment and DSI within the J-31 airframe strongly resembles rcs reduction techniques used on the Lockheed Martin F-35. The current J-31 demonstrator does not incorporate sawtooth engine nozzles or other forms of rcs reduction measures on the exposed RD-93 engines. Given that none of the four more technologically mature J-20 prototypes incorporate sawtooth engine nozzles or specially shaped thrust vectoring nozzles, as used by the F-22A, it is possible China does not value rear aspect stealth. Bill Sweetman explains the exposed engine nozzles for both the J-20 and Russian T-50: 

"The rear-aspect view of the aircraft is not as stealthy, a feature also seen on the Sukhoi T-50. This is clearly an intentional trade, eliminating the heavy 2D nozzles of the F-22. In this respect, both the T-50 and J-20 reflect the philosophy behind the pre-1986 Advanced Tactical Fighter studies that preceded the F-22, based on the theory that a fast, high-flying, agile aircraft is relatively immune from rear-quarter attacks." - Bill Sweetman, 2012

All aspect stealth is critical when disabling an enemy's surface to air missile (SAMs) systems within an integrated air defense system (IADS). If an aircraft with only a forward stealth capability turns after missile release, it exposes its less stealthy rear aspect to enemy radars and it subsequently becomes vulnerable to SAMs. Russia and China field the largest respective SAM forces in the world including the S-300, HQ-9 and S-400 systems as part of their anti-access area denial strategies. Conversely, with the exception of the Patriot PAC-2, the United States mostly relies upon its fighter force to defend air space. Therefore, rear aspect stealth could be of less value to China and Russia relative to the United States given the comparatively few number of US SAM systems. The FC-31 model displayed at Zhuhai does incorporate sawtooth engine nozzles among other slight airframe and design changes from the J-31 demonstrator: 

"The airframe and control surfaces of the two aircraft are similar, comprising the low aspect ratio design and chined fuselage, with forward-swept engine intakes, 35° sweptback trapezoidal planform wings, and similarly-shaped tailplanes. However, the outward-canted twin vertical fins and rudders have now been updated, terminating in tips that are diametrically angled compared with the current design's flushed tips." - Kelvin Wong, 2014

Image 4: Sawtooth engine nozzles on FC-31 display mock up at Zhuhai. Image Credit: Defense Update, 2014. 

As for estimates regarding the rcs of the J-31, no credible figures exist. Without the use of an identical J-31 mock up with rcs reduction treatments and a radar testing facility, its unlikely figures posted online can be verified. In the case of the PAK FA, patent documents filed by Sukhoi indicated the aircraft had a much larger rcs than previously estimated by numerous online sources at between 0.1m^2 and 1m^2; The 1m^2 figure likely refers to the rear of the aircraft and the 0.1m^2 the comparatively more stealthy frontal aspect. In comparison the F-22A has a frontal rcs of 0.0001m^2 or - 40 dBSM and the F-35 has a frontal rcs between 0.005m^2 and 0.001m^2 or - 30 dBSM (Global Security & Kopp, 2011). Given the relative secrecy of Shenyang, its unlikely that similar patent documents will be available within the public domain. However, there is good reason to be skeptical of assessments which assert the J-31 is as stealthy or stealthier than the F-35; Shenyang still has difficulty with basic quality control on its fourth generation production fighters. Low observability is notoriously hard to maintain as small manufacturing discrepancies that undermine planform alignment or the radar-absorbent material coatings can negate rcs reductions. 

"Quality control, in general, could undermine the J-31’s biggest apparent selling point: its ability to evade radar. 'The potential problem with Chinese- and Russian-construction stealth fighters is that if there’s a bolt out of place, it shows up on a radar signature...Russian and Chinese construction is typically much looser.'”- Robert Farley, 2014 

A US intelligence official reporting to Defense News indicated China's domestic built copy of Russia's Su-27SK fighter, the J-11B, has experienced numerous crashes due to manufacturing issues (Axe, 2013). Furthermore, China's efforts to illegally obtain US aviation grade carbon fiber also suggests the Chinese aerospace industry is experiencing ongoing difficulties in the production of high quality aircraft materials. 

This is not to say the J-31 or FC-31 is not a low observable aircraft, but one should be skeptical of extraordinarily low J-31 rcs estimates. As a caveat, its also worth noting that the J-31 does not need to match US 5th generation low observability qualities to be a significant threat to US or allied forces. US fourth generation aircraft, specifically the legacy hornet and F-16C (after the cancellation of the CAPES upgrade program) would likely have significant difficulties in detecting the J-31 from the frontal aspect. Furthermore, as Part II will discuss, many of the countries interested in potentially acquiring the FC-31 would be satisfied with a moderately reduced rcs aircraft. Part II will also discuss the avionics and strategic ramifications of the Shenyang J-31

Related Articles 


  1. Avic Promotes J-31 As An Export Fighter, Perrett, Hewson, Johnson, & Sweetman, 2014
  2. With a Stealth Fighter, China Tries to Gain Attention, Christina Larsonnov, 2014.
  3. Taking Off: Implications of China’s Second Stealth Fighter Test Flight, Andrew Erickson, 2012.
  4. China vs. America in the Sky: A Stealth-Fighter Showdown Is Brewing, Dave Majumdar, 2014
  5. Airshow China 2014: AVIC unveils FC-31 export fighter concept, Kelvin Wong, 2014.
  6. China shows off new stealth fighter, AFP, 0214.
  7. With J-31 Flight, China Makes a Statement, Wendell Minnick, 2014.
  8. What does J-31 tell us about China, Feng, 2012.
  9. Zhuhai airshow and other PLAAF news, Feng, 2014.                                                  
  10. New Chinese Stealth Fighter Relies on Russian Jet Engine, Dave Majumdar, 2014
  11. U.S. Pilots Say New Chinese Stealth Fighter Could Become Equal of F-22, F-35, Dave Majumdar, 2014                                                                                                                     
  12. What We Know So Far About The J-20, Jen DiMascio and Bill Sweetman, 2014.
  13. China Plans To Export J-31 Stealth Fighter, Wendell Minnick, 2014.
  14. Airshow China 2014: Pakistan in talks to buy '30-40 FC-31s', Farhan Bokhari, 2014.
  15. China Airshow Will Unveil J-31, Wendell Minnick, 2014.
  16. China's Selling the J-31, But Who's Buying?, Robert Farley, 2014.
  17. Pakistan & China’s JF-17 Fighter Program, Defense Industry Daily, 2014.
  18. Pakistan Rolls Out 50th JF-17, Block II Production To Commence, Usman Ansari, 2014.
  19. Thunder Resonates as Modernization Inches Forward in Pakistan, Usman Ansari, 2014.
  20. Chinese Airborne Radars, 2014.                                                                                            
  21. JF-17 Thunder Avionics, 2014.                                                                                             
  22. China's J-31 Stealth Fighter: Then And Now, Jeffrey Lin and P.W. Singer, 2014.
  23. The Chinese Air Force Evolving Concepts, Roles, and Capabilities, Edited by Richard P. Hallion, Roger Cliff, And Phillip C. Saunders, 2012.
  24. Air Combat Tactics among the Fourth Generation Fighters Rong Yang, 2014.
  25. AVIC unveils J-31 Stealth Fighter Jet, Defense Update, 2014.                                             
  26. Which Fighter Plane is the No:1 in the Indian Subcontinent in the BVR(Beyond Visual Range) arena?, fighter planes tk, 2012.
  27. Air Force Systems, Global Security, 2014.
  28. The Naval Institute Guide to World Naval Weapons Systems, 1997-1998, Norman Friedman, 1997.
  29. Dose Chinese J-10 Fighter use Russia Zhuk Radar?, 2012.                                                 
  30. First Block 2 JF-17s under construction in Pakistan, Alan Warnes, 2014.
  31. Israeli Technology Transfers to China and India: A Short Assessment, Frost & Sullivan, 2003.,-india.html
  32. EL/M-2032, 2014.                                                                                                                 
  33. Flanker Radars in Beyond Visual Range Air Combat, Carlo Kopp, 2012.
  34. Is China Buying Russia’s Su-35 Fighter?, Wendell Minnick, 2012.|head
  35. F-22 Raptor News New F-22 Raptor performance statistics released, Lieven Dewitte, 2009.
  36. The Real Reason China Wants Aircraft Carriers, Bryan McGrath & Seth Cropsey, 2014.
  37. Just how good is China's new 'stealth' fighter?, Reuben F. Johnson, 2014. 


  1. Excellent article, thanks!

  2. Hi Matt

    Very Nice Article.

    Been a long time, I have been working alot.

    Have had a few discussion's regarding the J31, but 2 points that could be worth noting, and this are just my thought's.

    1)PLA don't want the J31 due to it's range,(lack off) the J21 is a big bird and has engines and range to match.

    2) "Spartan horse" Beware of Greeks bearing Gifts.
    The J31 could be a cheap 5th/4th Gen fighter, but it has a lot of Technology that china can offer.

    The mind set behind it is, sell it as a Trojan horse.

    Sell it to a country like Brazil, get them to co-invest/partnership in radar, engines and so on. Then use the technology at home. Smart by the chines, but also very effective. Let's them build trust and partner ships.

    If they where to sell it to Turkey all hell would break lose in the UN, which could be another angle china is looking at, F35 project causing ever country problems due to price and performance. Turkey has ambitions to build there own 5th gen even though they are buying the F35.

    Sell it to countries that want to build there own productions lines and not relay on USA aircraft. If china sell's the body and Technology, why not use that as a base. Just like the HQ missile deal with Turkey.

    Most countries these days want to build there own 5th Gen Fighter at home. Weather china is worth buying from is another question.

    Lockheed Martin and Boeing, have been charging an arm and a leg for to many years, countries are getting smarter and technology is easier to transfer.

    Still China nowhere near the USA, but very unlikely to see that changing any time soon.

    All the best MATT :-)

    1. Hi Stone! Good to hear from you! 
      I've been pretty busy myself with course work and applications, hence the lack of articles. I’ve been reading a lot about the J-20 lately and you are right it’s certainty optimized for range. Of the various theories on its potential use, I would argue it’s tailored for China’s very specific strategic context of enforcing an anti-access strategy out towards the second island chain rather than being a conventional stealth air superiority fighter. Bill Sweetman argues it’s specialized to hunt US ISR and Tanker assets in the Western Pacific which would greatly constrain the US’ ability to operate in theatre. I would certainly prefer the PLAAF doesn't field a low end stealth fighter to complement the J-20 so I wouldn't be too disappointed if the J-31 never entered PLA service :D

      The Trojan horse idea is pretty interesting. In that respect, I’ve read that China has benefited from its collaboration with Pakistan on the JF-17/FC-1. In general, the JF-17 gives some insight as to the potential prospects of the FC-31 and the fact that as an export product, more information will likely be available than other Chinese aircraft. The lack of technically detailed non subscription based English source material is pretty frustrating when researching China. Also, Erdogan has been guiding Turkey’s foreign policy away from the US for years so I wouldn't be too surprised for more Chinese imports but the HQ-9 deal has likely gone sour given the intense US and European criticism (and the fact that we can prevent them from integrating the HQ-9 from all NATO radar facilities in the country which severely limits its potential effectiveness)

    2. HI Matt,

      If the Hq-9 deal is dead, then China will keep pushing on. If not this decade, then the next.

      They can't rely on the J20 alone, they are still missing a low cost production 5th gen.

      If not J31 then what? not any of the Su27/J10 or any other aircraft that I can see. Unless the are going to build mass J20's in different varieties.

      China still need's a long rang boomer and long rang refueling aircraft. They will need a long range J20 able of protecting the aircraft. A Su-35 (or copy) :-) would be ideal, but still will require at least one J20 for add protection.

      J31 would be ideal, low cost, mass production.

      But no matter what they decide, it will come down to Radar, avionics and missile technology. Hence the Trojan Horse. China need's partners outside of Russia. Country are looking to build there own 5th Gen Fighter jet, without the Billions to build one from scratch.

      People can criticize the J31, but it has a few things going for it,
      Stolen technology from the USA,
      It's flying
      China airframe is built from scratch
      They are knocking up the Air hr's in the air.
      Radar, Engines (even thought they might be Russian, need to check that fact's a lot of reports saying yes and no on it)
      China can mass Produce the J31
      China is willing to transfer Technology for it as well.

      Let me put it this way, if Japan was given the F35 blue prints and 50 f35 and all technology was transferred over, how long would it take them to build it 10/15/20 years.

      China have Built the J20, and J31 in 10 years ( say12-15yrs), without any flying version of there own. Virtually from blueprints

      You can't take that fact from them.

      To a country wanting to build there own 5th gen, they would be looking as a option.

      But unlikely to buy it, not in this decade. (next 10 years)

      China is playing the long game, and they are very good at that. Putting the West to Shame, who can only look at the next election cycle every 2 to 4 years.

      This is a long chess game that is being played.

      Be good to read your next article on who will buy it. I have been out of touch with most of the Forums and discussion threads. ( I didn't know the Hq-9 deal is dead, until reading your comments) good to know you are on top of it.

      All the best
      Stone 30 :-D

  3. Hi Matt

    Merry Xmas and Happy New Year :-)

    1. Merry Christmas and a Happy New Year to you too! :D