The Shenyang WS-6 was an unsuccessful Chinese turbofan

Turbofan

The turbofan is a type of airbreathing jet engine that is widely used for aircraft propulsion. A turbofan combines two types of engines, the turbo portion which is a conventional gas turbine engine, and the fan, a propeller-like ducted fan...

 production programme.

J-13 light fighter programme

At the end of the 1970s, the PLAAF started looking into new light fighter designs to replace the J-6

Shenyang J-6

The Shenyang J-6 was the Chinese-built version of the Soviet MiG-19 'Farmer' fighter aircraft.-Design and development:...

, which was based on the 1950's vintage MiG-19. Shenyang nr. 601 institute proposed an 11,5 ton light fighter design with cantilever wings and fuselage side mounted air intakes, which in some ways resembled a smaller sibling of the Dassault Mirage F1

Dassault Mirage F1

The Dassault Mirage F1 is a French air-superiority fighter and attack aircraft designed and built by Dassault Aviation as a successor of the Mirage III family. The Mirage F1 entered service in the French Air Force in the early seventies...

. Although airframe design advanced fairly rapidly with a preliminary prototype finished in the early 80s, engine integration proved a difficult task. Both the recently acquired Spey Mk. 202 turbofan, built under license as the WS-9, and an indigenous engine, known as the WS-6, where considered to power the light fighter. As the fighter was to have a single engine, the PLAAF considered the 9,300 kg thrust WS-9 to be somewhat inadequate, since the design required the J-13 to have a thrust to weight ratio of at least 1:1.
The WS-9 was supposed to become a 12,200 kg thrust turbofan, but development proved to be a very challenging task. As the
J-8II programme started to florish in the middle 1980s, the J-13 programme was accord lower priority, but in the wake of the new and very successful F-16 and Mig-29 programmes abroad, the programme continued non the less. In 1992 the PLAAF finally put a stop to the project because of the progress of the Lavi/J-10 programme and the access to Russian Su-27 Flankers and engine technology.

WS-15

In 1982, China received a handful of Mig-23MS fighters from Egypt, in exchange for a 'friendship price' (at the time quoted to be only 1 million dollars each) for the recent F-6 and F-7 fighters sold to the Egyptian air force. Apart from serving the J-8II project with a successful engine inlet architecture, which resulted in the final success of the 'Finback', the deal also provided China with a new engine design. The Tumanski R-29, with a dry thrust of 10,000 kg, was also considers to be a viable candidate for the J-13 programme, and was to be produced internally with the WS-15 name. Again, the programme didn't flourish, mostly because of the availability of modern Russian turbofan engine technology from 1990 onwards. Confusingly, the WS-15 name tag seems to have been recycled for powerplant of the 2011 J-20 twin-engined fighter.