J-20 and J-31 Pairing: Will China’s Air Force Field a Fifth Generation Fighter High-Low Combination?

<p >New images have provided previously unknown details on China’s FC-31 fifth generation fighter program, an aircraft which has shown growing signs of having begun serial production and which has been developed to provide a lighter counterpart to the J-20 heavyweight fighter of the same generation. The FC-31 design is confirmed to have been developed into a carrier based fighter, likely to be designated the J-31, as well as an export fighter designated J-35. It has remained in question, however, whether a third variant of the design has also been planned for service in the Chinese People’s Liberation Army [PLA] Air Force. The fighter’s much shorter range, smaller radar, and expected lower operational costs relative to the J-20 have raised the possibility of the service will procuring two fighter classes of the same generation to form a high-low combination.</p><p ><img src="https://militarywatchmagazine.com/m/articles/2025/06/22/article_685838377f7ba5_06349229.jpeg" title="Image of FC-31 Prototypes Released in June 2025"></p><p >A primary factor which makes procurement of the FC-31 by the PLA Air Force appear unlikely is premium the the service has placed on fielding heavier aircraft with very long ranges. A further factor is the <a href="https://militarywatchmagazine.com/article/worlds-largest-fighter-plane-china-ultra-long-range-sixth-gen" >considerable progress </a> that has been made developing two separate sixth generation fighters for the Air Force. Two separate sixth generation fighter classes were <a href="https://militarywatchmagazine.com/article/china-unveiled-stealthiest-fighter-sixth-generation" >unveiled</a> in December 2024, both of them in flight testing stages, with the two expected to enter service as a high-low combination in the early-mid 2030s. The lighter of the two aircraft, informally called ‘J-50’ by netizens, is expected to have a similar range to the J-20, while the larger one is expected to have a range heretofore unseen for a tactical combat jet. Investment in procuring shorter ranged fighters like the J-31 likely to be limited. </p><p ><img src="https://militarywatchmagazine.com/m/articles/2025/06/22/article_68583589400684_02349189.webp" title="Chinese Heavyweight (left) and `Ultra Heavy` Sixth Generation Fighter Demonstrator Airframes" ></p><p >The extent to which the scale of production of the J-20 has <a href="https://militarywatchmagazine.com/article/how-many-j20-stealth-fighter-will-china-build-top-expert-predicts-over-1000" target="_blank" >continued to be expanded</a> has provided a further indicator that interest in splitting investments between two separate fifth generation fighter classes is likely to be very limited. Annual J-20 procurements are expected to reach 120 fighters in 2025, up from around 100 in 2024. To place this in perspective, the Western world’s only fifth generation fighter in production today, the F-35, is being procured by the Air Force at rates of just 24-48 per year, with planned orders for Fiscal Year 2026 having <a href="https://militarywatchmagazine.com/article/us-air-force-f35-orders-cut-50pct-sixth-generation" target="_blank" >recently been cut to 24</a>. Investment in acquiring the J-20 on such a large scale would leave only limited room for another fifth generation fighter in the fleet. A focus on procuring the J-20, and resulting expansion in the proportion of heavyweight fighters the Air Force’s fighter fleet, was projected by leading expert on the program Abraham Abrams in his recent book <a href="https://www.pen-and-sword.co.uk/Chinas-Stealth-Fighter-Hardback/p/50764" >China's Stealth Fighter: The J-20 'Mighty Dragon' and the Growing Challenge to Western Air Dominance</a>, in which he observed: </p><p >“The fighter program [J-20] could fuel further expansion of the heavyweight fleet as a proportion of all PLA fighter units…. The distances separating Chinese air units from their leading potential adversaries, the expected importance of being able to loiter for extended periods over the Pacific in a potential future war, and the benefits of being able to contribute to operations from a much wider range of dispersed air bases, are all important factors in the favour of an increasing focus on high endurance heavyweight fighters.”</p><p ><img src="https://militarywatchmagazine.com/m/articles/2025/06/22/article_685839cbc01c68_77077720.png" title="PLA Air Force Second Air Brigade J-20 Fifth Generation Fighter"></p><p >Despite a likely lack of procurements of the J-31 to serve in the Air Force, the FC-31 design still plays a critical role in further China’s security interests. The fighter’s development costs are estimated to have been low, as its used technologies that were already developed for the J-20 which minimised the need for major new R&D expenses. The fighter is also simpler, and lacks the complexities of the J-20’s unique canard design. The FC-31 nevertheless provides a robust stealth fighter capability for the People’s Liberation Army Navy’s growing carrier fleet, in particular for the service’s <a href="https://militarywatchmagazine.com/article/china-rival-ford-supercarriers-nears-service-entry-fujian" target="_blank">first supercarrier the Fujian</a>, which is scheduled to enter service before the end of 2025. As the J-35, the fighter also provides a means of bolstering strategic partners, such as Pakistan, while competing at the top end on global markets. The ban on exports of the J-20, J-16, and before them the J-11B, makes the J-35 the first Chinese fighter class to compete on an equal or higher level to its most capable American and Russian counterparts. Development of high-low combination of fighters in which the ‘low’ fighter is allocated primarily to export markets, is far from unprecedented, and would mirror the parallel development of the F-4 and F-5 third generation fighters in the United States, and the F-5’s production primarily for foreign use. The development of the aircraft makes China the only country in the world to have serially produced two fifth generation fighter classes in parallel – a unique position which the country is also set to retain in the sixth generation. </p>