China's unveiling of a second low-observable (LO) or stealthy fighter, a Shenyang product possibly designated J-31, followed the same pattern as the revelation of the Chengdu J-20 at the end of 2010: Photos were leaked via the Internet on the eve of a U.S. defense secretary's visit to Beijing. The not-too-subtle message, as the U.S. follows through with its plans to shift air and naval forces to the Pacific region, is that China's own military modernization is not slowing down.

The first images of the J-31 show that the aircraft is very different from the large, canard-delta J-20. The Shenyang fighter appears to be much smaller than the J-20, with about two-thirds as much installed power. It is a quad-tail design with a moderately swept clipped-delta wing and large canted vertical tails, with a similar overall layout to the Lockheed Martin F-22—but more like the F-35A Joint Strike Fighter in terms of overall size. Weapon bays occupy the entire lower body aft of the inlets and ahead of the engine bays (unlike on the J-20, there are no side bays). Flight controls are conventional, with separate rudders and single-piece flaperons.

As in the case of the J-20, most of the stealth-shaping techniques are very similar to those on Lockheed Martin fighters, but the engine nozzles are conventional. The nozzle shape on the prototype is close to that of the Klimov RD-93 engine installation on the Chengdu JF-17 fighter, minus the tapered “collar” that fairs the latter's nozzle into the aft fuselage. Thrust vectoring has been studied in China but has not yet been demonstrated in flight.

One common feature of the J-20 and J-31 is that both, from images seen to date, appear to be beyond an “X-plane” stage. Both are equipped with weapon bays; both are full-scale demonstrators, and neither appears to use any components of existing aircraft. However, the timing of the development of operational variants and full-scale production remains uncertain. China is continuing the development of conventional non-stealthy fighters, and it remains to be seen when industry there can start producing competitive domestic engines and break the nation's dependency on imported Russian power. (So far, all production JF-17s have been RD-93-powered although a Chinese replacement, the Guizhou WS-13, is under development.)

Although there is no official information campaign for either of China's new stealth fighters, the “unofficial” information campaigns allowed to flourish on the Internet by government authorities have been markedly different, revealing much more about the Shenyang fighter.

In September 2011, China's Aviation Industries Corp. (Avic) sponsored a competition for unmanned aerial vehicle (UAV) models at the China Aviation Museum outside Beijing, and as part of the attendant displays, the Shenyang University of Aeronautics and Astronautics (SUAA) presented a model of a twin-engine stealthy fighter with the F-60 designator on the canted vertical stabilizer. SUAA has been involved in UAV, UCAV and now fighter design work for Shenyang.

Late in June, a crudely covered full-scale fighter, without its vertical stabilizers, was openly transported on a flatbed truck from Shenyang to Yanliang Air Base near the major aerospace city of Xian, home of the China Flight Test Establishment of the People's Liberation Army Air Force. At the time, there was speculation that this aircraft was intended for Yanliang's static stress-testing facilities. The aircraft shape was broadly similar to the SUAA model.

One reason for this difference, according to some Chinese sources, is that Shenyang's fighter may not be a fully air force-funded program, but an initiative derived from its losing competitor to the Chengdu J-20. The various plants of the Avic group, such as Chengdu Aircraft and Shenyang Aircraft, have a long tradition of rivalry. To overcome that, the group began bundling them together from 2008 into specialist subsidiaries in which they were supposed to work together. But the defense ministry opposed tight integration of the defense subsidiary—including Chengdu and Shenyang—in order to maintain closer control and probably to retain and foster competition among them.

But it is also possible that Shenyang's fighter does have an official sponsor: the Chinese navy. Shenyang is the builder of the navy's first carrier-based fighter–the Sukhoi Su-33-derived J-15. The J-31 would be more adaptable to carrier operations than the bigger J-20—although it might still need enhancements such as a bigger wing, an improved high-lift and control system, and thrust vectoring. Finally, the J-31 could be a smaller, less costly complement to the J-20.

J-31 Specifications (estimated)
Wingspan 37.5 ft.
Length overall 53 ft.
Height 15 ft.
Propulsion 2 X Klimov RD-93 engines
Intermediate thrust: 11,000 lb.
Maximum thrust: 18,300 lb.
Operating empty weight 27,500 lb.
Internal fuel 16,000 lb.
Internal weapon load 5,000 lb.
Normal takeoff weight 49,000 lb.
Sources: AW&ST Research