The USA is revising its assessment of the Chinese advanced fighter, which is known by its US Office of Naval Intelligence (ONI) designation of "XXJ". At the same time, Shenyang is developing a multirole version of the J-8II air defence fighter.
Washington sources say the original information provided by the ONI in 1997, showing a design resembling the Boeing F-15 Eagle, has been superseded. The agency predicted the XXJ would be multirole, have stealth features and was expected to enter Chinese air force and navy service by around 2015.
This estimate has been revised to 2010. Both Chinese fighter companies - Chengdu and Shenyang - are thought to be working on advanced combat aircraft concepts.
Indications are that the XXJ will have a canard configuration and be equipped with twin thrust-vectoring engines. The design seems influenced by Sukhoi's advanced concepts such as the Su-37 and forward-swept wing S-37 Berkut, suggesting that Shenyang, which has a link with the Russian manufacturer dating from the early 1990s, is the developer. Combining a foreplane, a tailplane and thrust vectoring enhances manoeuvrability.
Engines are likely to be a version of the Wopen WP15 in the 26,000lb-thrust (115kN) class. Pictures of a large engine equipped with thrust-vectoring nozzles was displayed at last year's Zuhai aerospace show.
The fighter is expected to have a 20,000kg (44,000lb) empty weight and incorporate a fly-by-wire control system similar to that developed by Shenyang and tested in the J-8IIACT programme.
Meanwhile, Shenyang is building a new multirole version of the twin-engined J-8II fighter, reflecting China's doctrinal shift towards offensive capabilities. Creating a new version of a dated design underlines the country's urgency in building up its strike forces.
Taiwanese and US sources say the J-8IIC is a J-8IID development, incorporating the latter's in-flight refuelling system and true, instead of secondary, air-to-ground role.
The aircraft is equipped either with a new Chinese-developed dual mode radar or the Russian Phazotron Zhuk-8II (acquired for the F-811M export fighter). Both have a 70km (38nm) range.
Other likely enhancements include a new electronic warfare system and an upgraded cockpit with multifunction displays, head-up display and the new data-link.
The fighter will be powered by a Wopen WP14 engine developing up to 16,215lb thrust, an improvement on the J-8IID's 14,550lb-thrust WP13A.