The J-7FS is the technology demonstration aircraft developed by Chengdu Aircraft industry Corporation (CAC) on the basis of the J-7II (Chinese copy of the MiG-21 Fishbed) fighter. The most important modification on the J-7FS is the replacement of the original round air inlet with a redesigned under-chin inlet similar to that of the U.S. A-7 Corsair and F-8 Crusader. The modification provides a ‘solid’ nose which could be used to accommodate a much larger fire-control radar antenna than the radar housed in the centre-body of the original J-7’s nose air inlet. Other improvements include a more powerful WP-13IIS turbojet engine, cooling system for the radar and other avionics equipment, and a GPS navigation.
The J-7FS demonstrates a low-cost and yet effective upgrade package for the existing J-7 and MiG-21 fighters still in both domestic and foreign services. CAC is teamed with a number of other organisations to develop the aircraft with their own funding. The first and only J-7FS prototype was converted from a second-hand J-7II fighter. The maiden flight took place on 8 June 1998. A total of two prototypes were built with one for flight test and the other for static tests.