The J-7 III is a high-medium altitude, high speed all-weather fighter and it can operate by day or night. Many modifications were introduced into the J-7 M. Compared with the J-7 II , 80 per cent of components and 43 per cent of vendor-furnished-equipment were different. 37 new materials and 190 new vendor-furnished-items were used. The main improvements were: incorporation of an all-weather radar and an advanced fire control system, increased capabilities in carrying missiles and rockets, a new WP13 engine, improved ejection system, additional fuel tanks and changes in structure and geometry.
Development was jointly undertaken by the Chengdu Aircraft Design Institute, the Chengdu Aircraft Company and the Guizhou Aircraft Company. The Chengdu Aircraft Design Institute [Design Institute No.611] was responsible for design. Production responsibilities were shared by the Chengdu Aircraft Company and the Guizhou Aircraft Company. the Chengdu Aircraft Company for the manufacture of, the fuselage, final assembly and flight test, and the Guizhou Aircraft Company for the manufacture of the wing and main landing gear. The development program was managed by system engineering. Development was led by Gao Zhenning, vice Minister of MAI, and Song Wencong was appointed chief designer. An Management Office for the program was set up in April, 1983 and Xie Ming was appointed its director. During the prototype production the staff of the office worked on the spot, directing and providing services and, so a matrix managerial system was formed to facilitate development.
The J-7III was developed via a computer aided design system at Design Institute No.611 in 1981, and component manufacture in 1982. Final assembly began after the mating of the fuselage and the wing for the first J-7III in December 1983.
During final assembly the Chengdu Aircraft company was the mainstay and the vendors cooperated closely. The Chengdu Aircraft Design Institute sent more than 100 designers to the factory to follow production and to solve various problems. The leading cadres also worked on site. With the hard work of hundreds of final assembly workers and engineers excellent quality and high efficiency were achieved. The final assembly of the first J-7 III took only 30 days and nights and was completed on 06 February 1984.
An unexpected accident happened during a period of intense work. An urgent report came froni the ejection system test range in Henan province on March 23, saying that the rocket sled had turned over when a rocket ejection seat was undergoing a ground test, the fuselage and the rocket sled were destroyed and the test had to be terminated. In view of the fact that the rocket ejection test was a major test which had to be completed prior to the first flight of the newly developed aircraft, the Management Office immediately decided to build another fuselage test section and rocket sled and to carry out the test from the beginning. The Chengdu Aircraft Company built a new fuselage test section in 9 days and the Hubei Escape System Research Institute built a new sled in 7 days. The test was resumed at the test range on April 9 and was successfully completed in 6 days, the shortest period of time that this kind of test had ever been carried out. It saved time and ensured the smooth development of the J-7 III.
Static testing of the airframe was completed in April 1984. On April 6 the full-scale static test was successfully performed and on April 26 test pilot Yu Mingwen flew the J-7 III for its first time. There were no occurrences of sideslip, and the systems -all operated normally. The flight program was completed by the end of December, 1984.
Guizhou Engine Company and the Chengdu Engine Company co-developed the WP13 engine. The WP13 engine had good structural integrity. The engine also had a surge margin that was substantially increased after an improved compressor was used. The compressor case's weight was decreased after replacing its material with titanium. The engine's operational stability and reliability of was increased. The WP13's service life was lengthened after the addition of a metal chip detector to the engine's oil system. Development of the WP13 was begun in 1978. Ten prototypes were constructed by 1984. The engine passed its certification tests the ext year in 1985.
The success of the J-7 III development program was a crystallization of the hard work and wisdom of the workers, engineers and cadres who worked for the program. The practices of the system engineering management and the matrix management system, and the wide applications of new technology, new manufacturing techniques, ' new vendor¬furnished-equipment and new materials marked a new phase in the design and production of Chinese fighters. It was the first time since the founding of the aircraft industry to construct the prototype aircraft by two factories in different places, Chengdu and Guizhou. The experience was obtained in sharing and cooperating on the prototype production.
The J-7III ran into the same problems with weight increase that plagued later Soviet MiG-21 development, and in general did not meet PLAAF specifications. Only a few dozen were built. The engineering team tried to save the program with a "J-7IIIA" or "J-7D" that featured an improved radar and WP-13FI engine, but the results were still unsatisfactory. After production of another small batch, the program was terminated.
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