The embryonic advanced combat aircraft to which the US Office of Naval Intelligence (ONI) originally allocated the provisional designation XXJ was last described in the late 1990s, at which time it was thought likely to be a Chengdu (CAC) design. Little was then heard of it for some years, but in the early months of 2001 further US sourced information indicated that the design had been considerably modified, then revealing a configuration suggesting some Sukhoi influence. This appeared to make Shenyang the more likely developer, although both Chinese companies are thought to have (possibly competing) advanced combat aircraft projects in hand. According to the 2001 information, the aircraft had a canard delta configuration, combined with clipped-delta horizontal tail surfaces and twin outward-canted fins and rudders. Conformal underfuselage intakes fed a pair of thrust-vectoring turbojets or tufbofans, possibly the new 116 kN (26,000 lb) class WP15. Empty weight was estimated at 20,000 kg (44,100 lb); stealth characteristics and FBW flight controls were assumed.
However, according to a senior AVIC I official in late 2002, this was one of a number of design concepts created by Shenyang in collaboration with No. 601 Research Institute, wind tunnel testing of which was then under way. Two such configurations were illustrated in an AVIC I video shown at Airshow China in November 2002, both showing twin-engined, tailed-delta designs broadly similar in outline to the fuselage of the US F/A-22 and the wings and vertical tail of the F-16. Possible power plant is the domestically developed Liming WS10A turbofan, with thrust-vectoring nozzles. Multifunction fire-control radars under consideration are said to include the Chinese Type 1473, reported to have a search range of 81 n miles (150 km; 93 miles) and be able to track up to 15 targets of which up to eight could be attacked simultaneously. Russia's Phazotron Zhemchug radar is also thought to be under consideration. The designs appear to cater for internal weapons stowage.