The first few series of the J-7 modification failed to have significant improvements as a result the inherent design limitations of the MiG-21. Chengdu Aircraft Corporation launched the J-7MF fighter, which replaced the nose intake with a chin intake, in a bold attempt to break this fate. However, this attempt ultimately ended in failure. Chengdu developed the F-7MF as insurance against the FC-1, which was a joint program with Pakistan. Revealed for the first time at the Zhuhai air show in November 2000, the F-7MF was the latest Chinese development of the Mikoyan MiG-21C Fishbed airframe. At that time the manufacturer said the first prototype would fly in 2001, which, would constitute remarkable speed by Chinese standards.
Chengdu conceived the F-7MF in 1998 in order to develop a high technology fighter for export. It would also provide some insurance should the FC-1's problems end the program. The FC-1 - also known as the Super-7 - had been plagued by disagreement between Pakistan and China, and by the Western government embargo on mission systems. F-7MF development was supported by the J-7FS testbed, which emerged in 1998 and was used to test the chin air intake and engine. The F-7MF, however, had a shorter inlet.
The J-7MF's powerplant was a variant of the 14,600lb (65kN) thrust Liyang WP13F. The double delta wing developed for the J-7E/F-7MG is also used on the F-7MF, with two small canards added to the forward fuselage. The cockpit included a head-up display and two head down displays, while the aircraft would be equipped with an 80km (45nm) range multimode pulse-doppler radar, and seven pylons with a 3t load. Chengdu predicte a 2,600km range, Mach 1.8 maximum speed, 52,500ft (16,000m) ceiling and a 650m take-off run.
The J-7MF design had a superficial resemblance to the design of the MiG-21M, MiG-23, Ye-8, in that both feature a a chin inlet rather than a nose inlet, but otherwise the designs are entirely unrelated.
The J-7FS emerged in 1998 and was used to test the chin air intake and engine for the production J-7MG. The heavily modified F-7FS testbed was based on the earlier F-7II, but has a chin air intake with splitter in place of the original conical nose inlet. The larger-volume intake has permitted the installation of an uprated 73-78kN (16,500-17,600lb)-thrust turbojet developed from the Wopen WP13F. Reconfiguration of the nose inlet allowed a redesign the F-7's extremely confined radar bay and radome. The F-7FS nose is large enough to accommodate a new, locally developed 600mm-diameter multi-mode pulse-Doppler radar. This replaces earlier ranging radars, such as the GEC-Marconi Type 226 Skyranger in the F-7M and Chinese JL-7 fitted to the F-7III.
The F-7FS wase used primarily as a flying testbed for new radar and avionics systems, such as weapon management, global positioning systems and flight data recording systems. The aircraft was to be used to flight-test a yet-to-be-selected avionics and radar package for the planned Sino-Pakistani CACFC-1. The reconfigured F-7 flew for the first time in June 1998, starting a 22-month test program. Further modifications were planned to be tested on the F-7FS airframe, including a redesign of the aircraft's delta wing. The change was intended to build on the improved double-delta wing design of the improved production variant unveiled in 1996, the F-7MG.
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