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WS6

In the 1960s, new China had just recovered from bloody civil war and Korea war. Chinese people established primary aviation industry by the captured Japan planes in Manchuria and help from CCCP. To China, Aircraft engine was like a high mountain to impossible overcome because of the so complicated machining technologies and advanced materials production. However, China never says gives up. In 1961, 606 Engine Design Institute was founded and it had begun to focus on the era's most senior aircraft engine--Turbofan engine. Under the direct order from General Chief Staff Gen. Luo Ruiqing, Chinese researchers began the preliminary technical preparation.

In May 1964, Chinese PLA Airforce announced a requirement for a new fighter which was better than J-7 (Mig-21). As well as seeking an engine (the LMC WP-7B) for the J-7 and JJ-7, a further meeting was held to select an engine for a larger and more advanced fighter of indigenous design. For the first time it was decided to attempt to design an advanced supersonic-fighter and its engine entirely in China.

Hereafter, Shenyang 601 Aircraft Design Institute and 606 Engine Design Institute cooperated to provide the plan, and drawings were produced in 1964-66. After the consultant between Airforce and industries, the new fighter would come out in two steps. One, to design a new frame with two improved turbines (it is the origin of J-8 fighter and WP-7A turbine engine); two, a whole new high altitude and high-speed interceptor equipped with a new afterburning turbofan. The serial code of the interceptor was J-9 and the new engine was WS-6.

In 1964, in a CAE meeting on the assessment of the design proposal for a new fighter, the design of a complete new engine for its powerplant was proposed. SARI made a comparison of 3 types of engines (two spool turbojet, one spool turbojet and turbofan) and 22 design proposals. It was agreed that the turbofan was of a higher standard than the other two types and thus the WS6 was selected. It would be a high thrust, two spool, bypass turbofan with reheat - the design initiated by China. Its maximum dry thrust was 71 kN (7,270 kgf), the thrust with reheat was 122 kN (12,460 kgf), the thrust to weight ratio was 5.93. The design was led by Wu Daguan, Yuan Meifang and Li Zhiguang successively. The total developments were divided into 3 phases of the drawing design, production of a prototype and engine test.

The argumentation of WS-6 was finished in September 1965. From October 1964 to April 1966, the design drawings were finished. At the beginning of 1966, SEF started to produce the prototypes. May 1966, the project was turned into trial production. In June 1968, the first experimental WS-6 engine was test on platform. However, Cultural Revolution seriously interrupted the research of WS-6. It was the time of the "great cultural revolution" and the places for making the engines were changed several times so the development work was seriously affected. Not a single engine was produced for nearly 10 years.

The engine test started in 1968. It covered the 5 milestones of running test, performance adjustment, endurance test, simulated altitude test, flight test, and the State type certification test. The engineers and technicians of SARI, persistently and dauntlessly did repeated tests, amended the design, carried out around 30,000 hours component rig tests and more than 300 hours engine tests and overcame more than 100 key technical problems. Finally the performance of the engine met the design targets. Up to 1969, two prototype engines had been made.

Before testing and development could start, the Cultural Revolution delayed the program by almost 10 years. In 1970, some PLA leaders required large jet transporters. For this difficult project, China began to get WS-6A engine from WS-6, which was using a single stage fan and middle compressor. The airflow and bypass ratio increased and get off the afterburner. China produced 3 WS-6A engines. But the project was cancelled just because the jet airlift was too unpractical for Mao's China. This improper behavior also diverted the research team of WS-6.

Through 5 years' effort since commencement of the running test, the problem of poor efficiency of the compressor parts and the small surge margin of the HP compressor were solved. In 1974 the engine speed reached 100% design speed and entered high speed running test. The three critical technical problems of the unallowable vibration of HP rotor, surge at high r.p.m. and higher TET came out successively. After analysis and test, measures were taken to take out the inner of the HP compressor stator and improve the turbine sealing. Then the improper matching of the flow field between the fan and HP compressor and the dismatching of the power between HP turbine and HP compressor were eliminated. Thus the 3 key technical problems were cleared one by one.

Not a single engine was produced for nearly 10 years. After 1978 eight more WS6 engines were built. The development was sped up and Wu Xia and other leaders of SEF took effective actions and strengthened the management. They timely expelled obstacles in production and greatly improved the situation. By the end of 1979, the engine could run at high r.p.m steadily for a long time.

By 1980, 7 prototype engines had been made progressively, thus speeding up the development of the WS6 engine. Until October 1980, the performance of WS-6 had reached the design target. Then 24 months later, WS-6 passed the 24 hours preliminary flight rating test, PFRT. The whole testing time was totally 334 hours. In 1980, during the performance test the measured thrust and s.f.c. reached and exceeded the design targets. In January 1981, engine tests with afterburner were carried out and the measured wet thrust was 122 kN (12,490 kgf), which reached the design performance. Then came the endurance test. In July 1981, the prototype engine was run continuously for 12 hours for the first time. In October, the 24 hours exploratory long run test was accomplished and in October 1982, the engine formally passed the 24 hours' "Preliminary Flight Rating Test".

In 1980, a modification program was launched to increase the reheated thrust to 138 kN (14,100 kgf) and thrust-to-weight ratio to 7.0, with the external dimensions of the engine remaining unchanged. In February 1982, the modified prototype test was carried out and the measured full reheated thrust reached what was expected. It showed the modified WS6 engine could have a thrust-to-weight ratio of 7.0. In 1980, 606 Institute also designed WS-6G, an improved type of WS-6. This modified type has higher low pressure rotor speed, three-stage fan and higher turbine inlet temperature. And former cannular combustor of WS-6 was turned to annular combustor in WS-6G. Under the same size and lightening 100 kg from WS-6, WS-6G's afterburning thrust raised 13.2% and thrust to weight ratio up 18.9%. In February 1982, WS-6G entered quasi demonstration engine test. The accomplishment of expected thrust proved the technical feasibility of WS-6G.

China made major progress in designing the 12 ton (120 kN) thrust class turbofan engine with reheat. The development work trained and practiced personnel, sped up the construction for the test facilities and promoted the application and development of new technology, new material, new production techniques and accessories. Because of the insufficient technology base, the development of such a high performance engine was very complicated and extremely difficult. In addition, the task changed several times and the place for trial production changed frequently. It took as long as 18 years, to make the engine reach its ground performance target.

In the meantime, the aircraft for which the engine was designed was stopped and the engine had to be given up. The associated fighter program had been replaced by the XAC JH-7, powered by the WS9, so the WS6 was never used. Instead, the Shenyang LM company was assigned manufacture of the WS10, a later and significantly more advanced design created by the 606 and 624 Design Institutes.

From 1965 to 1984, what the Chinese people got was a semi-finished turbofan engine, which is still 1960s technology. No flight-test and lots of works were waiting to be finished. Under the most optimistic estimation, WS-6 will be realized in later 1980s. As being a thrust to weight ration of 6, WS-6 is just a second-generation engine and has 30 years gap with USA and Russia. WS-6G's thrust to weight ratio is 7 and its initial work just began in early 1980s. WS-6G's technologies and high reliable materials were hardly resolved at that time. By China's estimate, WS-6G was going to be finished in mid 1990s, but it still not a third generation aircraft engine which can not be applied with China's next generation fighter (J-10). Besides, the WS-9 turbofan engine (Code Name: Qingling), a strypped-down of Britain's 1970s product Spey MK 202, was being carried on and this project was finished in 2002. The copy of Spey MK 202 also tells a truth that the project of WS-6 and WS-6G are impossible missions.

The termination of the WS6 project was a rational measure. Then China halted the rough and tumble investment in aviation engine industry. China started to import and learned engine technologies from foreign countries.




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